^S?9&l&AlH&*3&SJi fopvrigltfN 1*12,0 ©OPXMGHT DEPOSIT. Electrical Tables and Engineering Data A Book of Useful Tables and Practical Hints for Electricians, Foremen, Salesmen, Solici- tors, Estimators, Contractors, Archi- tects and Engineers By HENRY C. HORSTMANN and VICTOR H. TOUSLEY Authors of " Modern Wiring Diagrams," " Modern Electrical Con- struction," "Practical Armature and Magnet Wind- ing," "Electrician's Operating and Testing Manual," "Modern Illumination, Theory and Practice," "Alternating Cur- rent," "Motion Picture Oper- ation, Stage Electrics and Illusions." ILLUSTRATED CHICAGO FREDERICK J. DRAKE & CO. Publishers T!T isi Copyright 1920 and 1916 by Henry C. Horstmann and Victor H. Tousley ^o 5> JUL -I 1920 ©CI.A570540 PREFACE This book is an attempt to furnish electricians generally and I others interested in electrical work with a reference and table book which can be con- veniently carried in the pocket. It contains no theo- retical discussions. Its scope is limited to practical information which is daily called for but , seldom available at the time most needed. The matter is arranged in alphabetical order which enables one to find any item with a minimum of delay. The tables provided assist in the calculation of al- most every conceivable problem with which con- struction men have to deal, and by their use many hours of tedious calculations may be avoided. THE AUTHORS. ELECTRICAL TABLES AND ENGINEERING DATA Acid Fumes. — In places where acid fumes or cor- rosive vapors may exist, the nature of the vapors will determine the insulation to be used. Consult chemists and Inspection Department having juris- diction. Conduit work is not favored much in such places, but if it can be shown that the vapors in question are not harmful to the metal it is permissi- ble. Adapters. — There is no objection to the use of adapters, provided they are of approved type. Adjusters. — The use of cord adjusters should be discouraged, but there is no very serious objection to the use of any that do not severely damage the cord. Air Compressors. — Air compressors are usually driven by series wound motors and made to stop and start automatically. For a. e. work induction motors are used. Tanks should be of a capacity equal to about 50 per cent of the rated capacity of the compressor per minute. The air should be dry and cool, as most of the moisture will be precipi- tated. One H.P. will compress about 5% cu. ft. of free air per minute to 90 lbs. Alternating Current Wiring. — For alternating cur- rent systems the two or more wires must be run in the same metal conduit, armored cable or metal moulding. In open wiring the greater the separa- tion of wires, the greater will be the inductive drop. 7 8 ELECTRICAL TABLES AND DATA See also special tables for sizes of motor wires anu wiring systems. Alternators. — Alternating current generators and their exciters are not usually provided with fuse protection. Aluminum. — Aluminum is used as a rule only for outside work and for bus-bars. It can be soldered, but soldering is more difficult than with copper wire and clamps are therefore much used. When used for bus-bars the current density ranges from 1,000 to 1,200 amperes per sq. in. for the smaller sizes, and about 500 for the heavy bars. See Bus-Bars for table. For insulated aluminum wire the safe carry- ing capacity is 84 per cent of that given for copper wire of same insulation. Aluminum is electroposi- tive and must be tied with aluminum wire and nc other metal must be allowed to touch it. Comparison of Copper and Aluminum : Aluminum Copper Specific gravity 2.68 8.93 Eelative specific gravity 1.00 . 3.33 Conductivity 61 to 63 96 to 99 Weight for equal area 47 100 Area for equal conductivity 160 100 Diameter for equal conductivity. 126 100 It will be noted that an aluminum wire of equal conductivity is about two sizes larger by B. & S. gauge than a copper wire. The tensile strength of aluminum is from 20,000 to 35,000 pounds per square inch; that of copper from 20,000 to 65,000. For carrying capacity, etc., see Wire Calculations. Ammeters. — It is customary to provide an ammeter for each generator connected to a switchboard, and only the very smallest and cheapest boards are ever put up without one. The cord sent out with shunt ammeters must always be used full length and need not be protected by fuses. Never place an ammeter ELECTRICAL TABLES AND DATA 9 in any lead that can be affected by equalizer current. An ammeter used for battery charging should indi- cate direction of current. Ampere's Rule. — Imagine yourself swimming with the current and facing the center of the coil; the left hand will then point toward the north pole of the magnet. Anode. — The anode is the positive pole. Annunciators. — Unless the annunciator is known to be especially constructed for high voltage, no at- tempt should be made to operate it from light or' power circuits. Use bell ringing transformers, mo- tor generators or battery. Annunciators cannot be operated in parallel successfully. Apartment Buildings. — If practicable, meters should be placed in basement. In some cities spe- cial rules for the wiring of apartment buildings ex- ist. No cut-outs should ever be placed in closets; place them in kitchen if possible. To determine ap- proximate size of mains necessary to supply lighting in apartment buildings, estimate one watt per square foot and consult table of carrying capacities. Arcades. — The illumination of arcades should be kept low so as not to interfere with show windows. Arc Lamps. — In laying out wiring for arc lamps the question of drop need not be considered unless incandescent lamps are also on the circuit. A wire smaller than No. 6 should not be used for theatre, or moving picture arc lamps. Two dissolving stereop- ticon lamps are usually rated as about equal to one stage or moving picture arc lamp. Plugs used for arc and incandescent lamps should not be interchangeable. The light from direct cur- rent arc lamps is much better than that from alter- nating current. Series arc lamps are now operated almost entirely from constant current transformers; each transformer being limited to one circuit. 10 ELECTRICAL TABLES AND DATA © ooo c ioio §'2| Tj< Tf CQ WCM 7 1 T 1 1 1 1 1 1 J J CO 00 OOO O CO CM 0} MM CO OO S5 > © 3 H 3 • *§2 •A "AAA •a ©>> B !z Kfta w w : go • • : ft-g : :5 j ;; r| o 'c oocc o o • : o OOCOi- LO to o a 1 |3 ■ ■ 1 o coo og TH Tt »Jt C\ 1 1 totoC I 30 " I to to • to t- 1>XX >3 t>i>T* r> t- . : co d ^ be LO If ® : t>rHr- CD!> !> CD to w — t> :coco s ® 1 1 1 1 i 1 H H 1 . 1 1 £g< IOCOCC o c coco CD toto | to ;^^ si ccoi CO CO CD to o d • — | © a p cc "^ aJBi K cfl ©2jE A a ■ s • • a, cs 5 © : © : : ©■£ ^ a 1 1 © ' : S3 'Ess s 3 I ft O fl c .- c"£ c 'u s b£ : bj)i ^ © © © b£ : bC^^ gg^ isfisl all > ^®sa Pi H g g g - s, ? 2 -r = 5 = 2 -- o ~ : w % a © © =. S S"5 © © 2 © CD £ '-■ z - - ■_ •_ - wS5S a a a O A ft < < ^ ^ M ES K c^ s ELECTRICAL TABLES AND DATA 1£ Armored Cable and Cord. — Armored conductors are very suitable for "fish work." The radius of the curve of the inner edge of anj^ bend must not be less than iy 2 inches. "Where moisture exists the con- ductors should be lead-covered under the armor. Ar- mored cable is not nail proof under- all circumstances.. TABLE I Outside Diameters of Armored Cables and Weight Per 100 Ft. Greenfield Flexible, Steel Armored Conductors Solid Stranded Dia. Wt. Dia. Wt. B& in. lbs.: B&S in. lbs. Single conductors, type D. .14 .37S 20 10 .450 23 12 .384 21* 8 .469 28 10 .434 26 6 .631 54 8 .464 28 4 .717 63 6 .609 54 2 1 .783 .900 71 98 Twin conductors, BX .14 .630 45 8 .830 77£ 12 .670 48 6 1.1-16 121 10 .720 54 4 1.203 143 Three conductors, BX3... .14 .675 53 8 .890 93 12 .715 561 6 1.144 153 10 .785 66 Single conductors, DL .... 10 8 .506 .564 53 72 Lead covered, and steel 6 4 .713 .780 95 110 armored 2 1 .825 .897 125 165 Twin conductors, BXL... .14 .730 68 8 .978 136 Steel armored and lead 12 .758 78 6 1.152 205 covered .10 .14 .863 .782 110 78 8 1.056 Three conductors, BXL3 , . 164 Lead covered and steel 12 .815 97 armored .10 .933 129 18 .414 Steel armored, flexible- 20 cord, Type E 16 .447 22 14 .625 38 Steel armored, flexible re- 18 .530 25 inforced cord, Type EM. 16 14 .540 .652 26 48' 12 ELECTRICAL TABLES AND DATA Armory. — Armories are often classed with thea- tres and assembly halls, and must be wired accord- ingly. The most important part of an armory is the drill hall. This requires an illumination equal to about two or two and one-half foot candles. This is best obtained by placing large units high up out of the range of vision. Artists. — Require an adjustable light and pendant drops are most serviceable. Art Gallery. — Art galleries are also often classed with assembly halls. In illuminating statuary, the aim must be to produce some shadow effect because of the uniformity of color. Lights should be hung high. For white statuary an illumination of two- foot candles will be sufficient; for bronze statuary about four times as much should be provided. Paint- ings are often illuminated by strips and reflectors, and also by indirect lighting or Holophane globes. As many paintings must be viewed from a distance, a bright illumination of about five foot candles is recommended. Asbestos. — This becomes a conductor when wet, and must not be used in damp places. Asbestosless than -J inch thick is not considered serviceable. ' As- bestos covered wires are much used for connecting arc lamps and rheostats where the wire is subject to much heat. Assembly Halls. — The National Electrical Code prescribes that if any part of a building is "regu-" larly or frequently used for dramatic, operatic, moving picture, or other performances or shows, or has a stage used for such performances used with scenery or other stage appliances, ' ' it must be classed as a theatre, and wired according to theatre rules. It is usual to specify that all wires must be in con- duit and that there must be a separate system of lighting, independent of the main system, for use of ELECTRICAL TABLES AND DATA 13- the audience in leaving the building in case of fire,, or other emergency. Attachment Plugs. — Must be of approved type. They should be of the pull-out type, and the socket so placed that the plug can pull out in case strain is; put upon it. Automatic Cut-outs are required to protect every device, or wire, which is connected to any power circuit, except alternators and constant current generators. For details see Cut-outs. Automobiles. — In wiring automobiles it is custom- ary to disregard all ordinary construction rules. Electric motors are connected without any fuse pro- tection. A fuse blowing on a heavy up-grade might cause disaster. Auto-Starters. — As a general rule, auto-starters are not used with motors smaller than 5 H.P. Auto starters provided with overload release devices, and so arranged that the handle cannot be left in the starting position, are obtainable and should be used. Small auto-starters have usually three taps, and these are arranged to give about 50, 65 or 80 per cent of the line voltage. Larger starters usually have four taps arranged respectively for 40, 58, 70 and 80 per cent of the line voltage. Always make connections. to the lowest voltage tap that will give the necessary starting torque. Wherever possible, place starter in sight of motor. For motors smaller than 5 H.P., throw-over switches are often used. Bakeries. — In bakeries, hot places will be found in which rubber-covered wire is not suitable. Balance Sets. — Balance sets are made up of motor generators or transformers, and exist for the pur- pose of obtaining a neutral wire and low voltage for a small lighting load operated in connection with a higher voltage two-wire generator. They are also used where motors operate at two voltages. The 14 ELECTRICAL TABLES AND DATA capacity of a balancing set is usually only a small percentage of the total load. Balancing". — Three-wire systems are usually ar- ranged so that a minimum of current may pass through the neutral wire. A good balance cannot always be obtained, and in some cases considerable judgment is required to determine which is the best arrangement of apparatus. Three wires should be carried to every center supplying more than one circuit. Safety rules require the neutral wire to be of same size as the outside wire, but in large systems this wire will seldom be called upon to carry more than 10 per cent of the current used at any time. Ball Rooms. — Ball rooms are often classed with theatres. The illumination should be general, and lamps hung high. A general illumination of from two to four foot candles is recommended. Recep- tacles for musicians' use should be provided. Banana Cellars. — These places are always hot and moist and the vapors are very corrosive. Conduits corrode very fast, and especially the small screws in outlet boxes ; brass screws are often used. Open wiring, if it can be protected, is preferable. Banks. — In that part of a bank occupied by the clerical force, a general illumination of from three to four foot candles is recommended. These lights are in use most of the time, and high efficiency lamps should be arranged for. In that portion used by the public the illumination is not so much used, and may be of a lower order. Numerous outlets for adding machines and fan motors should be provided. In some banks the private depositors' rooms are fitted with two lights, one above and one below desks, and provided with three-way switches so that only one light can be used at a time; this for con- venience of customers who may have dropped things on the floor. ELECTRICAL TABLES AND DATA 15 Barber Shops. — Good illumination of barber shops can be arranged for by placing clusters of fairly large candlepower close to the ceiling and a little to the rear of chairs. Placed in this manner, the light will not be forced directly into the line of vision of the customer, and yet give the desired illumination. The mirrors in front of chairs will reflect much of the light back to the chair. Often lights are placed along the mirrors, but this practice is not to be recommended. Outlets for cigar-lighters, curling-iron heaters, vibrators, etc., will be appre- ciated. Barns. — The use of brass shell sockets should be avoided in horse barns. Avoid placing lights in front of horses, and keep all lights well up above horses' heads. Use weatherproof construction in wash rooms. Place lights in all dark corners. Bases. — All electrical contacts must be mounted on non-combustible, non-absorbtive insulating material. Other materials than slate, marble, or porcelain are not favored much, and are allowed only when the first named are too brittle. Sub-bases are generally provided for all switches and other devices which would otherwise allow the wires to come against wood or plaster. Base Frames, — Base frames are required under all generators and motors, and where the voltage is not in excess of 550 volts it is customary to use insulated base frames. If the motor operates at a voltage in excess of 550, it is better to ground the frame thor- oughly. Where frames cannot be insulated they must be grounded. Basements. — Basements are often damp, and must then be wired in accordance with rules for such places. As ceilings are usually low, protection against mechanical injury is often necessary. 16 ELECTRICAL TABLES AND DATA Batteries, Primary. — Dry batteries are much used at the present time. They require no attention and when worn out are simply thrown away. The dry battery is at present made only for open circuit work. The wet battery used mostly for open circuit work consists of carbon and zinc elements immersed in a solution of sal-ammoniac. The carbon is the positive pole. This battery is charged by dissolving about four ounces of sal-ammoniac in sufficient water to fill the jar about three-fourths full. Never use more sal-ammoniac than will readily dissolve. It is preferable to make a saturated solution and, after filtering it through cloth, to add about 10 per cent of water. Keep jars in a cool place to prevent evapo- ration. Never allow water to freeze. Keep exposed parts covered with paraffine. Do not allow battery to be short circuited or run down. If this has oc- curred, it will often pick up if left on open circuit for a few hours. If the solution appears milky, more sal-ammoniac is required. Impure zincs which do not eat away evenly facilitate the formation of crystals which greatly increase the resistance. The best known of the closed circuit batteries is the gravity type. The elements in this cell are zinc and copper, immersed in a solution of sulphate of copper (blue vitriol). The copper element rests on the bot- tom of the jar, and the blue vitriol is placed around it and the jar filled with clean water. The cell must be short circuited for a few hours to start the action. The blue solution should rise to about midway be- tween the two elements. This cell must be kept in action or it will rapidly deteriorate. Connect all batteries so that the resistance of the battery is nearest equal to the resistance of the de- vices it is to operate. Series connection should be used when the external resistance is higher than the internal battery resistance. If the external resist- ELECTRICAL TABLES AND DATA 17 ance is lower than that of the battery, group cells in multiple. When arranging small storage batteries to be charged from lighting or power circuits, pro- vide double throw switches to entirely disconnect battery from power circuit while it is on the bell circuit. Install all wiring subject to power voltage in accordance with rules for that voltage. Batteries, Secondary. — Small storage batteries- may be carried about and used. The larger ones must remain stationary and are used as compensa- tors for feeder drop, equalizers on three-wire sys- tems, preventives against shut down and as a com- bination of all of these. Medium size storage batteries are also much used with automobiles. All storage batteries with exception of the Edison, use lead plates. The active material is sponge lead im- mersed in a weak solution of sulphuric acid. The positive plates when fully charged are of a chocolate color and the active material is quite solid. The negative plate is more of a slate color and softer. The unit of capacity is the ampere hour. A 60- ampere-hour battery, for instance, can deliver a cur- rent of three amperes for twenty hours, or seven and one-half amperes for eight hours. High voltages are obtained by connecting a number of cells in series. High amperage is obtained by connecting . plates in parallel. The voltage is independent of the size of the cell, but the amperage capacity varies with the surface of the opposed plates. The effi- ciency is roughly about 75 per cent. The safe rate of charge and discharge varies from five to ten am- peres per square foot of positive plate surface, both sides of plate being measured. The voltage should never be allowed to fall below 1.8, and when fully charged is about 2.6. The condition of full charge is indicated by both the positive and negative plates, gassing freely. 18 ELECTRICAL TABLES AND DATA Before manipulating or attempting to connect any storage battery, the instructions of the maker should be obtained. The following instructions form only a general guide : Keep electrolyte well above plates. See that the cells are kept clean and allow nothing that could short-circuit the plates to accumulate at the bottom. Keep whatever separators there may be in place. Allow no metal except lead in the battery room. Insulate cells from ground and from each other. See that battery is recharged as soon as pos- sible after being used. Do not overcharge. When the negative plates begin to give off gas, it is time to quit. Never allow the voltage to fall below 1.75 per cell. The temperature of the battery should not rise above 110 degrees. The capacity of battery needed is governed by number of units in the gen- erating plant. It is not likely that more than one unit will give out at a time. Bells. — Bell-ringing transformers are much used in connection with alternating current in place of bat- teries. To operate bells in series, jump circuit breaker on all but one. If bells are to be operated from lighting circuits, the wiring must be installed in accordance with rules for the voltage used, and the bell must be specially approved for that service. The chief hazard that exists with low voltage bell wires is the possibility of coming in contact with other wires. If storage batteries of high amperage capacity are used, the wires should have fuse protection. Belting. — Figure 1 is an illustration of a service- able method of belt lacing. Thread lacing from left to right according to heavy lines, double up at ends and return to starting point; cross lacing on out- side of belt only, and keep laces on inside parallel with length of belt. ELECTRICAL TABLES AND DATA 19 Holes should be punched as nearly as possible according to the following table : TABLE II Width of Belt 2 to 6 to 12 to 18 to Distance from edge of belt — 6 in. 12 in. 18 in. 24 in. First row i f ,| 1 First row i f | 1 Second row. £ 1 1£ 1§ Second row 1 1^ 1J 2 Distance apart of each row of holes 1 1J 1| 2 Size of lace leather T 3 s i f J If pulleys are of same size, or far apart if of different sizes, the length of belt can be quite approx- imately found by the following rule : Add diameters Figure 1. — Method of Belt Lacing. of pulleys and multiply by 1.57 ; to this add 2 times the center-to-center distance. The length of belting contained in a roll can be found by reference to Table III. Multiply number of layers in roll by number found where outside diameter of roll and diameter of hole in center cross. Example. — A roll of belting of 48 inches outside diameter has a hole in the center six inches in diam- 20 ELECTRICAL TABLES AND DATA eter, and there are 88 layers of belting. Where the line pertaining to 48 inches outside diameter crosses the line pertaining to 6-inch hole, we find the num- ber 7.04, which multiplied by 88 gives 619.52 feet of belting. The width of a single belt necessary to perform a certain amount of work can be found by the formula W = 1200xH.P.-rF, where W stands for width, H.P. for horsepower, and V for velocity of belt in feet per minute. This formula will give a belt of ample size, and a smaller one can be made to do the work by giving it greater tension. Table IV is calculated from the above formula and shows the capacity of belts of various widths and operating at various velocities. Belts should run horizontally and the pull should be on the under side. Tightener should be on slack side and close to main pulley. Belts running ver- tically must be kept very tight, especially if the lower pulley is small. The proportion between two pulleys close together should not be greater than 6 to 1. Double belting should not be used on pulleys less than 3 feet in diameter. Rubber belting is pref- erable in damp places. Thin belting is best for high speeds. Belts operating at high speeds should be cemented, not laced. Pulleys should be perfectly smooth. Billboards. — A very bright illumination of from ten to twenty foot candles is often used. Lights must be encased in reflectors so as not to be visible to the observer. Install wiring according to rules for outside work. Billiard Halls. — A general illumination of about one foot candle is recommended. Above each table there should be an illumination of four or five-foot candles. The light over the table should be uniform. At least two lamps should be provided for each table, and should be so encased that the lights are ELECTRICAL TABLES AND DATA 21 TABLE III Table for Calculating Length of Belting, Eope or Wire in Coils Outside i Diameter of Hole in Inches > Diameter 2 3 4 5 6 7 8 9 10 11 12 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 22 24 26 28 30 32 34 36 38 40 42 44 46 ...1.05 1.17 1.30 1.44 ...1.17 1.31 1.44 1.57 1.70 ...1.31 1.44 1.57 1.70 1.83 1.96 ...1.44 1.57 1.70 1.83 1.96 2.09 2.23 ...1.57 1.70 1.83 1.96 2.09 2.23 2.46 2.49 ...1.70 1.83 1.96 2.09 2.23 2.36 2.49 2.62 2.75 ...1.83 1.96 2.09 2.23 2.36 2.49 2.62 2.75 2.8.8 3.01 ...1.96 2.09 2.23 2.36 2.49 2.62 2.75 2.88 3.01 3.14 3.27 ...2.09 2.23 2.36 2.49 2.62 2.75 2.88 3.01 3.14 3.27 3.40 ...2.23 2.36 2.49 2.62 2.75 2.88 3.01 3.14 3.27 3.40 3.53 ...2.36 2.49 2.62 2.75 2.88 3.01 3.14 3.27 3.40 3.53 3.66 ...2.49 2.62 2.75 2.88 3.01 3.14 3.27 3.40 3.53 3.66 3.79 ...2.62 2.75 2.88 3.01 3.14 3.27 3.40 3.53 3.66 3.79 3.92 ...2.75 2.SS 3.01 3.14 3.27 3.40 3.53 3.66 3.79 3.92 4.06 ...2.88 3.01 3.14 3.27 3.40 3.53 3.66 3.79 3.93 4.06 4.19 ...3.14 3.27 3.40 3.53 3.66 3.79 3.92 4.05 4.19 4.32 4.45 ...3.40 3.53 3.66 3.79 3.92 4.05 4.19 4.31 4.45 4.58 4.72 ...3.66 3.79 3.92 4.05 4.18 4.31 4.45 4.57 4.71 4.84 4.97 ...3.92 4.05 4.18 4.31 4.44 4.57 4.71 4.83 4.98 5.11 5.24 ...4.18 4.31 4.44 4.57 4.70 4.83 4.98 5.09 5.23 5.36 5.50 ...4.44 4.57 4.70 4.83 4.96 5.09 5.24 5.35 5.49 5.62 5.75 ...4.70 4.83 4.96 5.09 5.22 5.35 5.50 5.62 5.75 5.88 6.01 ...4.96 5.09 5.22 5.35 5.48 5.67 5.76 5.88 6.02 6.15 6.28 ...5.22 5.35 5.48 5.61 5.74 5.88 6.02 6.14 6.28 6.41 6.54 ...5.48 5.61 5.74 5.87 6.00 6.14 6.28 6.41 6.57 6.68 6.82 ...5.74 5.87 6.00 6.13 6.26 6.40 6.54 6.67 6.81 6.94 7.08 ...6.00 6.13 6.26 6.39 6.52 6.66 6.80 6.93 7.07 7.20 7.34 ...6.26 6.39 6.52 6.65 6.78 6.92 7.06 7.19 7.33 7.46 7.60 ...6.52 6.65 6.78 6.91 7.04 7.18 7.32 7.45 7.56 7.72 7.86 This table may also be used to estimate length of rope or wires in coils if number of turns can be determined. ELECTRICAL TABLES AND DATA TABLE IV The table below is calculated from the above formula and shows the number of H. P. belts will transmit Belt Speed in Ft n. r ~ i fVidtr of Belt in Inches — Per Mi 1 2 4 5 6 7 8 9 10 200 . . . .16 .33 .50 .66 .83 1.00 1.16 1.33 1.50 1.66 300 . . . .25 .50 .75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 400 . . . .33 .66 1.00 1.32 1.66 2.00 2.33 2.66 3.00 3.32 500 . . . .42 .84 1.25 1.67 2.10 2.50 2.95 3.34 3.75 4.20 600 . . . .50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 700 . . . .58 1.14 1.75 2.33 2.90 3.42 4.08 4.67 5.25 5.80 800 . . . .67 1.34 2.01 2.66 3.34 4.02 4.67 5.33 6.00 6.68 900 . . . .75 1.50 2.25 3.00 3.75 4.50 5.25 6.00 6.75 7.50 1000 . . . .83 1.66 2.49 3.33 4.15 4.98 5.83 6.66 7.50 8.30 1200 . ..1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0 1400 . ..1.16 2.32 3.50 4.67 5.80 7.00 8.13 9.3410.5 11.6 1600 . ..1.33 2.66 4.00 5.33 6.66 8.00 9.33 10.6 12.0 13.3 1800 . ..1.50 3.00 4.50 6.00 "7.50 9.00 10.5 12.0 13.5 15.0 2000 . ..1.67 3.34 5.00 6.67 8.36 10.0 11.7 13.4 15.0 16.7 2200 . ..1.83 3.66 5.50 7.32 9.15 11.0 12.8 14.6 16.5 18.3 2400 . ..2.00 4.00 6.00 8.00 10.0 12.0 14.0 16.0 18.0 20.0 2600 : ..2.16 4.32 6.50 8.66 10.8 13.0 15.1 17.3 19.5 21.6 2300 . ..2.33 4.66 7.00 9.33 11.6 14.0 16.3 18.6 21.0 23.2 3000 . ..2.50 5.00 7.50 10.0 12.5 15.0 17.5 20.0' 22.5 25.0 3200 . ..2.66 5.32 8.0010.6 13.3 16.0 18.6 21.2 24.0 26.7 3400 . ..2.83 5.66 8.50 11.3 14.1 17.0 19.8 22.6 25.5 28.2 3600 . ..3.00 6.00 9.00 12.0 15.0 18.0 21.0 24.0 27.0 30.0 3800 . ..3.16 6.32 9.50 12.6 15.8 19.0 22.1 25.2 28.5 31.6 4000 T ..3.33 6.66 10.0 13.3 16.6 20.0 23.3 26.6 30.0 33.2 4200 . ..3.50 7.00 10.5 14.0 17.5 21.0 24.5 28.0 31.5 35.0 4400 . ..3.67 7.34 11.0 14.6 18.3 22.0 25.6 29.2 33.0 36.6 4600 . ..3.83 7.6611.5 15.3 19.1 23.0 26.8 30.6 34.5 38.2 4800 . ..4.00 8.0012.0 16.0 20.0 24.0 28.0 32.0 36.0 40.0 5000- . ..4.17 8.34 12.5 16.7 20.9 25.0 29.2 33.4 37.5 41.8 ELECTRICAL TABLES AND DATA TABLE V Table showing approximate lengths of material which must be cut out of belts to double the tension; sag on upper and lower sides assumed equal. Eeducing sag by one-half- ap- proximately doubles the tension. Distance Between Pulley Centers in Feet t Dimensions Below in 64th of an Inch \ 4— Sag 31 46 62 77 92 108 123 138 154 Cutout 2 3 5 7 10 13 17 20 6— Sag 46 69 92 115 138 161 184 207 231 . Cutout ... 1 3 5 7 11 15 19 25 30 8— Sag 62 92 123 154 185 216 246 277 308 Cutout ... 1 4 6 10 15 20 26 33 41 10— Sag 77 115 154 192 230 269 307 346 384 Cutout ... 1 4 8 12 18 25 32 41 50 12— Sag 92 138 184 230 276 322 368 415 462 Cutout ... 2 5 9 14 21 29 38 49 59 15— Sag 115 173 231 288 345 402 459 518 577 Cutout ... 2 7 12 18 28 37 48 62 76 l S _Sag 138 207 277 346 415 485 554 623 693 Cutout ... 3 8 14 22 33 44 58 74 91 21— Sag 161 242 323 404 485 566 647 727 807 Cutout ... 3 9 16 26 39 51 70 87 106 25— Sag 192 288 384 480 576 672 768 864 960 Cutout ... 4 12 19 31 46 61 SI 104 127 30— Sag 231 346 461 576 691 806 9211036 1151 Cutout ... 4 14 23 37 55 74 97 124 152 The above table is based upon the ratio of deflec- tion and elongation of wires in spans, and it is assumed that the additional strain produces no immediate elongation of the belt. 24 ELECTRICAL TABLES AND DATA not visible to the players. A switch for each table will be a convenience. Outlets for cigar-lighters and fan motors should be provided. Bonds. — Rail bonds should not be smaller than No. 000. The area of contact should be about eight times the cross section of the bond. In some in- stances the size of bond is determined by the size of supply wires, the total cross section of all bonds at any point being made equal to the cross section of the supply wires for that point. For a ratio of 1 : 12 the copper in circular mils necessary to equal the conductivity of steel rails can be found by multiply- ing the weight per yard of rail by 10,000. Boosters. — Boosters may be in the form of trans- formers or motor generators, and are used to raise or lower voltage, also in some cases in return rail- way circuits to lessen electrolysis. The installation of boosters is not profitable except on long lines when the cost of copper to prevent the drop is greater than the cost of boosters. Boosters may be compounded so that the regulation becomes auto- matic. Bowling Alleys. — The illumination should be ar- ranged so that no light is visible to the players. An illumination equal to one and one-half or two foot candles is advisable for the alley, and about double that much for the pins. Branch Blocks must always provide double pole fuse protection for each circuit. Branch Circuits. — The term, " branch circuit," is here used to describe that part of the wiring between the last fuse and the lights, motors, heaters, or other translating devices. Branch circuits should be grouped as far as possible and arranged so that the cut-out cabinet may be in a safe and convenient place. It is advisable to place the switches outside of cut-out cabinets. In the best arranged theatres ELECTRICAL TABLES AND DATA 25 all -branch circuits, except those for emergency lights, are carried to stage switchboards. By run- ning mains as far as possible, and shortening the branch circuits, a much evener voltage at lamps will be secured than is possible from long branch cir- cuits. The drop in voltage should never be over 2 per cent. Most lamps are marked for three voltages, top, middle, and bottom, and there is a difference of four volts between them. "With a 4 per cent drop a 110-volt lamp will be at different times subject to all three voltages and the illumination will vary greatly. For best location of cut-outs, see table on calcu- lation of materials. The following table shows drop in voltage with different wires at different distances. A run of No. 14 wire 110 feet long feeding twelve lights evenly spaced ten feet apart will cause a drop of about one and one-quarter volts between first and last lamps. The table below shows the drop with wires from No. 14 to 6, carrying six amperes the distances gtiven at top of table. TABLE VI Distance in feet; one 1 e g B & S 20 40 60 80' 100 120 140 160 180 200 14 .. .63 1.3 1.9 2.5 3.2 3.8 4.4 5.0 5.7 6.3 12 .. .40 .80 1.2 l.G 2.0 2.4 2.8 3.2 3.6 4.0 10 .. .25 .50 .75 1.0 1.3 1.5 1.8 2.0 2.3 2.5 8 .. .15 .30 .45 .60 .75 .90 1.1 1.2 1.4 1.5 6 .. .10 .20 .30 .40 .50 .60 .70 .80 .90 1.0 Burglar Alarm. — A good burglar alarm is one so wired that it is under constant test, so as to give immediate notice when any part of it is out of order. The closed circuit system complies with this require- ment. With open circuit systems it is best to pro- vide " silent test" by which it can be tried out every night without causing an alarm. To guard against purposive incapacitating, some installations are 26 ELECTRICAL TABLES AND DATA mixed open and closed circuit system, so that it is impossible to know which wire to cut or short-circuit in order to prevent an alarm. In some systems "balanced" relays are used and the wires are inter- woven so that it is impossible to interfere with them in any way without giving an alarm. "Where either the simple open or closed circuit system is used, the wires and batteries should be protected against inter- ference. Bus-Bars. — The term, "bus-bar," refers, strictly speaking, only to those conductors on a switchboard which are connected directly to all of the machines. In common practice, however, it is understood that all of the current-carrying bars on a switchboard come under this classification. For high voltages it is usual to cover the bars with insulation, but for low voltages it is customary to leave them bare. The proper separation of bus-bars is 2-J inches for volt- ages less than 300, and 4 inches for the higher, in- cluding 550 volts. Copper and aluminum are used. Systematize bus-bars by placing all positive poles at top or right-hand- side of circuit. A current density of 1000 amperes per square inch is common practice for bus-bars, but is too high for the large ones. Table number VII shows the current-carrying capacity of bus-bars calculated on a basis of -1000 amperes per square inch cross section. For very small bars 1-J times as much current may be allowed, while for the very large ones not more than half the current given in the table should be used. The carry- ing capacity of aluminum is given as 84 per cent of that of copper. Bushings. — In connection with very high voltages, specially constructed bushings must be used through walls. Ordinary bushings cause trouble. If possible the wires should be run in without touching any- thing. . ELECTRICAL TABLES AND DATA TABLE VII Table of Bus-Bar Data Carrying Capacity 1000 Amperes Amp. Per Sq. In. -tick Area in Lbs. Per Foot Per Sq. In . Alumi- ness ' Width Sq. in. Copper Aluminum Copper num A i .0313 .1205 .0361 32 27 -h i .0469 .1807 .0542 47 39 & i .0625 .2410 .0723 63 53 & « .0938 .3615 .1084 95 80 i i .0625 .2410 .0723 63 53 ft i .0938 .3615 1084 95 80 § i .1250 .4820 .1446 125 105 * li .1875 .7230 .2169 188 158 § 2 .2500 .9640 .2892 250 210 i 1 .1875 .7230 .2169 188 158 I 1 .2500 .9640 .2892 250 210 1 U .3125 1.205 .3615 315 265 1 14 .3750 1.446 .4338 375 315 £ If .4375 1.687 • .5061 435 365 i 2 .5000 1.928 .5784 500 420 i 21 .5625 2.169 .6507 565 475 i 2i .6250 2.410 .7230 625 530 i I .3750 1.446 .4338 375 310 1 1 .5000 1.928 .5784 5C0 420 1 U .6250 2.410 .7230 625 525 I n .7500 2.892 .8676 750 630 1 if .8750 3.374 1.1122 875 735 i 2 1.000 3.856 1.1568 1000 840 | 2-i 1.125 4.338 1.3014 1125 995 2 21 1.250 4.820 1.4460 1250 1050 1 2f 1.375 5.304 1.5912 1375 1155 I 3 1.500 5.784 1.7352 1500 1260 1 3i 1.625 6.266 1.8798 1625 1365 1 31 1.750 6.748 2.0244 1750 1470 i 3f 1.875 7.230 2.1690 1875 1575 i 4 2.000 7.712 2.3136 2000 1680 1 1 .750 2.892 .8676 750 63Q 1 li 1.125 4.338 1.3014 1125 945 t 2 1.500 5.784 1.7352 1500 1260 1 21 1.875 7.230 2.1690 1875 1575 t 3 2.250 8.676 2.6118 2250 1890 1 31 2.625 10.122 3.0366 2625 2260 1 4 3.000 11.568 3.4704 3000 2520 28 ELECTRICAL TABLES AND DATA The Aluminum Company of America recommends 1200 amperes per square inch for the smaller bars and 500 for the largest. Cabinets. — Metal cabinets only are used in con- nection with conduit systems. Cabinets are obtain- able in four thicknesses of steel, viz., 16, 14, 12, and 10 U. S. Standard gauge, equal to 1/16, 5/64, 7/64, and 9/64 inches respectively. The thin metal is used only for the smaller boxes, and the heavy for the large ones. The depth of cabinets is usually great enough to allow door to close with small switches in any position, and the large ones thrown way back. For necessary dimensions, see Cut-outs, Panel Boards, or Switches. "Where conduits enter all from one end, a wiring gutter space equivalent to about i square inch for each circuit of number 14 twin conductor should be allowed. Cabinets should be provided to enclose all cut-outs. If practicable, locate them so as to reduce likelihood of rubbish being stored in them to a minimum. To locate switches outside of cut-out cabinets is good practice. In ordering cabinets note the following points; Wood or metal. Wall or flush mounting. With or without lining. With or without wiring gutter. Thickness of steel desired. Over-all dimensions of cut-outs, panel board, or switch. Inches of back wiring pocket. Inches of side wiring pocket. Spring hinges or not. Type of handle or lock. Side on which hinge must be. Finish and nature of door. Candle Power. — This term is rather loosely used and has no very definite meaning, unless qualified by one of the following terms: Apparent candle power ; equivalent candle power ; mean lower hemi- spherical candle power; mean horizontal candle power; maximum candle power. The candle power of no lamp is the same in all directions. ELECTRICAL TABLES AND DATA 29 Canopies. — The number of lamps to be used for the illumination of outlines in canopies is usually governed by the design of the canopy. The best effect, where outline lighting is to be installed, is obtained from many small lamps of low intrinsic brilliancy. Keep lamps and sockets out of the weather. Fixture canopies must be insulated wher- ever an insulating joint is called for on fixture. Carbons. — For life of carbons with various types of arc lamps, see Arc Lamps. The upper carbon is usually the positive, and for projecting arcs is larger than the lower. The positive carbon holds its heat longer than the negative. If carbons are too large, the arc will travel around them. With direct cur- rent, the upper or positive carbon is consumed twice as fast as the other. Flaming arc carbons contain special materials in the core, and the color of the arc is governed by this material. Car Houses. — A main switch is usually provided by which all wires in the car house can be cut off. Where a car house contains many sections it is better to provide a switch for each section. The illumina- tion of car houses is usually by series incandescent lighting. Carriage Calls. — These are usually made up in the form of electric signs, and located above canopies of theatres and hotels. They consist of a large num- ber of monograms and require a large number of wires to be run to them. Outdoor wires should be run in water-tight conduit system. If armored cable is used outdoors it must be lead-covered insulation. Cathode. — The cathode is the negative pole. This term is used in connection with batteries and electro- lytic devices, mostly. Ceiling Fans. — These must never be fastened rigidly, but in such a manner as to allow them to find their own "centers" when running. Not more 30 ELECTRICAL TABLES AND DATA than 660 watts may be connected to one circuit. One fan to 400 or 500 square feet floor space is com- mon practice. Celluloid is highly inflammable, and must never be used exposed to heat or flame. "Where a trans- parent medium of a similar appearance is needed, gelatine is used. Cement when wet is a good conductor and may easily cause grounds. Centers of Distribution. — In most cases the loca- tion of centers is governed by other conditions than economy of copper, and is dictated by the desire of the user. Where, however, free choice of location is given, the following tabulation showing the rela- tive number of circular mils for each branch cir- cuit of 660 watts at 110 volts will be of use. The table shows that with small mains, and especially three-wire systems, the amount of copper in the mains may be much less than in the branch circuits, and that it will be more profitable to run mains into the area to be served. This advantage grows less with larger mains. Branch circuits require 8214 circular mils per circuit of 660 watts. The theoretical requirements per 660 watts for mains supplying centers is given below: TABLE Vin Mains B. & S. 2 Wire 3 Wire 14 3286 2460 12 3957 2968 10 5000 3752 8 5693 4270 6 6325 4744 5 7227 5426 4 7200 5397 3 7914 5934 Chandeliers. — No part of any chandelier should less than six feet two inches above floor. The usual . ELECTRICAL TABLES AND DATA 31 height ranges between this and seven feet. In thea- tres and similar places where chandeliers hang very high, arrangement should be made for. either raising or lowering to admit of lamp renewals. For large chandeliers special permission to rise 1320-watt cir- cuits can usually be obtained. Chemical Works. — Before undertaking work in such places, investigate the nature of fumes, and chemicals used, with reference to effect upon copper and insulating materials, especially metal conduits,, if considered. Choke Coils. — These are used mostly in connec- tion with lightning arresters. They must be as well insulated- as the circuit wires to which they are- connected. Churches. — Some of the large churches require a lighting equipment similar to that of theatres. In choir lofts and at altars, pockets for special lights are often required. Indirect lighting is very useful in churches, as the light should be kept out of the line of vision of the speaker as well as the audience. From two to three foot candles are necessary. Emer- gency lighting should also be provided. Circuit Breakers are much more sensitive than fuses. Many of them are so constructed as to allow a considerable overload for a short time, and the length of this time is adjustable. Circuit breakers should ordinarily not be set more than 30 per cent above the rated carrying capacity of the wire they are to protect. Coils. — The coils of a magnet must be connected so as to form a continuous spiral. Coloring Lamps. — Coloring and frosting of lamps reduces the light from 30 to 50 per cent. Amber coloring reduces the light about 20 per cent, while green and red take up from 50 to 90 per cent, according to the density and shade. Prepared color- i 32 ELECTRICAL TABLES AND DATA ing materials can be had at all supply stores. A few amber-colored lamps are sometimes mixed in with white lights to give a warmer glow to the light. Color of Light Sources. — Moore tube (carbon dioxide gas) White Intensified arc White Magnetite arc White Open arc Nearly white Tungsten lamp Nearly white Tungsten lamp, gas-filled White Nernst lamp Nearly white Enclosed arc (short arc) Bluish white Tantalum lamp Pale yellowish white Gem lamp Pale yellowish white Carbon lamp Pale yellowish white Regenerative flame arc Yellow Flaming arc Variable with different carbons Mercury lamp (glass tube) Bluish green Enclosed arc (long arc) Bluish white to violet High sun White Low sun Orange red Skylight Bluish white Welsbach mantle Greenish white Common gas burner Pale orange yellow Kerosene lamp Pale orange yellow Candle Orange yellow TABLE IX Comparison of Fahrenheit and Centigrade Thermometers Pah. Cent. Fah. Cent. Fah. Cent. Fah. Cent. Fah. Cent. 212 100 165 73.8 118 47.7 71 21.6 24 — 4.4 211 99.4 164 73.3 117 47.2 70 21.1 23 — 5.0 210 98.8 163 72.7 116 46.6 69 20.5 22 — 5.5 209 98.3 162 72.2 115 46.1 68 20.0 21 — 6.1 208 97.7 161 71.6 114 45.5 67 19.4 20 — 6.6 207 97.2 160 71.1 113 45.0 66 18.8 19 — 7.2 ELECTRICAL TABLES AND DATA 33 Fall. Cent. Fah. Cent. Fah. Cent. Fah. Cent. Fah. Cent. 206 96.6 159 70.5 112 44.4 65 18.3 18 — 7.7 205 96.1 158 70.0 111 43.8 64 17.7 17 — 8.3 204 95.5 157 69.4 110 43.3 63 17.2 16 — 8.8 203 95.0 156 68.S 109 42.7 62 16.6 15 — 9.5 202 94.4 155 68.3 108 42.2 61 16.1 14 —10.0 201 93.8 154 67.7 107 41.6 60 15.5 13 —10.5 200 93.3 153 67.2 106 41.1 59 15,0 12 —11.1 199 92.7 152 66.6 105 40.5 58 14.4 11 —11.6 198 92.2 151 66.1 104 40.0 57 13.8 10 —12.2 197. 91.6 150 65.5 103 39.4 56 13.3 9 —12.7 196 91.1 149 65.0 102 38.8 55 12.7 8 —13.3 195 90.5 148 64.4 101 38.3 54 12.2 7 —13.8 194 90.0 147 63.8 100 37.7 53 11.6 6 —14.4 193 89.4 146 63.3 99 37.2 52 11.1 5 —15.0 192 88.8 145 62.7 98 36.6 51 10.5 4 —15.5 191 88.3 144 62.2 97 36.1 50 10.0 3 —16.1 190 87.7 143 61.6 96 35.5 49 9.4 2 —16.6 .189 87.2 142 61.1 95 35.0 48 8.8 1 —17.2 188 86.6 141 60.5 94 34.4 47 8.3 —17.7 187 86.1 140 60.0 93 33.8 46 7.7— 1 —18.3 186 85.5 139 59.4 92 33.3 45 7.2— 2 —18.8 185 85.0 138 58.8 91 32.7 44 6.6 — 3 —19.4 184 84.4 137 58.3 90 32.2 43 6.1—4 —20.0 183 83.8 136 57.7 89 31.6 42 5.5— 5 —20.5 182 83.3 135 57.2 88 31.1 41 5.0— 6 —21.1 181 82.7 134 56.6 87 30.5 40 4.4— 7 —21.6 180 82.2 133 56.1 86 30.0 39 3.8— 8 —22.2 179 81.6 132 55.5 85 29.4 38 3.3— 9 —22.7 178 81.1 131 55.0 84 28.8 37 2.7—10 —23.3 177 80.5 130 54.4 S3 28.3 36 2.2—11 —23.8 176 80.0- 129 53.8 82 27.7 35 1.6—12 —24.4 175 79.4 128 53.3 81 27.2 34 1.1—13 —25.0 174 78.8 127 52.7 80 26.6 33 0.5—14 —25.5 173 78.3 126 52.2 79 26.1 32 .0—15 —26.1 172 77.7 125 51.6 78 25.5 31 —0.5—16 —26.6 171 77.2 124 51.1 77 25.0 30 —1.1—17 —27.2 '70 76.6 123 50.5 76 24.4 29 —1.6—18 —27.7 169 76.1 122 50.0 75 23.8 28 —2.2—19 —28.3 168 75.5 121 49.4 74 23.3 27 —2.7—20 —28.8 167 75.0 120 48.8 73 22.7 26 —3.3 166 74.4 119 48.3 72 22.2 25 —3.8 To convert degrees Centigrade into Fahrenheit, if the temperature given is above zero, multiply by 1.8 34 ELECTRICAL TABLES AND DATA and add 32. If it is below zero multiply also by 1.8, but if this product is less than 32, subtract it from 32 ; if more, subtract 32 from it. To convert Fahren- heit into Centigrade, if the temperature given is above zero, subtract 32 and divide the remainder by 1.8 ; if below zero, add 32 and divide by 1.8. Concentric Wire. — Concentric wires are seldom used except in mines and similar places. Such a wire fully insulated would require more insulating material and be more bulky than the ordinary duplex wire. The concentric wire recently put upon the market has only one wire insulated. The other wire is a metal sheath which entirely surrounds the inner wire and its insulation. The sheath must always be thoroughly grounded. Condensers must be enclosed in noncombustible cases and installed with the same precautions as the wires of the system to which they attach. Con- densers are usually rated in microfarads, and a condenser of two or three microfarads is considered quite large. Conduits. — Conduit installations materially reduce the fire hazard, but to some extent increase the minor troubles. They produce many grounds and short circuits, but confine the trouble. Careful work- manship, especially at junction and outlet boxes, will reduce such troubles to a minimum. Install conduits so they will drain, and avoid their use in wet places unless lead-encased wires are used. . Skilled conduit workers avoid the use of elbows with small wires as much as possible. The following tables (X and XI) give the sizes of conduits recom- mended by the National Electrical Contractors' Association of the United States in connection with various sizes and numbers of wires. These recom- mendations are based on actual tests and can be relied upon. ELECTRICAL TABLES AND DATA 35 TABLE X Standard sizes of conduits for the installation of wires and cables as adopted and recommended by The National Elec- trical Contractors' Association of the United States and the N. E. Code. Conduit sizes are based on the use of not more than three 90° elbows in runs taking up to and including No. 10 wires; and two elbows for wires larger than No. 10. Wires No. 8, and larger, are stranded. One "Wire Two Wires Three Wires Four Wires Approx. in a Conduit in a Conduit in a Conduit in a Conduit B. & S. Diameter , — Diam. . , — Diam. — , , — Diam.— N , — Diam.' — ^ Gauge of Wii e Int Ext.' Int. Ext . Int. Ext Int. Ext. 14 18 / 6 4 % .84 y 2 .84 % .84 % 1.05 12 2 %4 y 2 .84 % 1.05 % 1.05 % 1.05 10 2 %4 % .84 % 1.05 % 1.05 1 1.31 8 2 %4 % .84 i 1.31 1 1.31 1 1.31 6 3 %4 % .84 i 1.31 iy 4 1.66 1% 1.66 5 31 /64 % 1.05 i% 1.66 1% 1.66 1% 1.66 4 3 %4 % 1.05 i% 1.66 1% 1.66 1% 1.90 3 3 %4 % 1.05 i% 1.66 1% 1.66 1% 1.90 2 3 %4 % 1.05 i% 1.66 iy 2 1.90 1% 1.90 1 4 %4 % 1.05 i% 1.90 1% 1.90 2 2.37 4 %4 i 1.31 i% 1.90 2 2.37 2 2.37 00 4 %4 i 1.31 2 2.37 2 2.37 2y 2 2.87 000 5 %i i 1.31 2 2.37 2 2.37 2y 2 2.87 0000 5 %4 U4 1.66 2 2.37 2y 2 2.87 2% 2.87 250,000 5 %4 1% 1.66 2% 2.87 2y 2 2.87 3 3.50 300,000 6 %4 1V4 -1.66 2% 2.87 2% 2.87 3 3.50 400,000 6 %4 1% 1.66 3 3.50 3 3.50 3% 4.00 500,000 7 %4 1% 1.90 3 3.50 3 3.50 3% 4.00 600,000 8 %4 l% 1.90 3 3.50 3% 4.00 700,000 8 %4 2 2.37 3% 4.00 3% 4.00 800,000 8 %4 2 2.37 3% 4.00 4 4.50 900,000 9 %4 2 2.37 3y 2 4.00 4 4.50 1,000,000 97 / 6 4 2 2.37 4 4.50 4 5.00 1,250,000 10 %4 2% 2.87 4y 2 5.00 4y 2 5.00 1,500,000 117 /64 2y 2 2.87 4% 5.00 5 5.56 1,750,000 12 %4 3 3.50 5 5.56 5 5.56 2,000,000 133/ 64 3 3.50 5 5.56 6 6.62 Duplex Wires 14 3 %4 y 2 .84 % 1.05 1 1.31 1 1.31 12 3 %4 y 2 .84 % 1.05 1 1.31 l 1 /! 1.66 10 3 %4 % 1.05 1 1.31 1% 1.66 1%. 1.66 36 ELECTRICAL TABLES AND DATA TABLE XI Standard sizes of conduits for the installation of wires and cables. 3 "Wire Convertible System 3 Wire Convertible System 2 Wires Size 2 Wires Size B.&S. 1 Wire Conduit B. & S. 1 Wire Conduit 14 10 % 00 350,000 2y 2 12 8 % 000 400,000 2y 2 10 6 1 0000 550,000 3 8 4 1 250,000 600,000 3 6 2 1% 300,000 800,000 3 5 1 1% 400,000 1,000,000 3y 2 4 1% 500,000 125,000 4 . 3 00 1% 600,000 1,500,000 4 2 000 iy 2 700,000 1,750,000 4y 2 1 0000 2 800,000 2,000,000 4y 2 250,000 2 Single Wire Combination. Number of single No. 14 wires in one conduit. Straight run; no elbows. Special permission is required. Conduit Size 3 No. 14 rubber covered double braid % 5 No. 14 rubber covered double braid % 10 No. 14 rubber covered double braid 1 18 No. 14 rubber covered double braid 1% 24 No. 14 rubber covered double braid 1% 40 No. 14 rubber covered double braid. 2 74 No.. 14 rubber covered double braid 2y 2 90 No. 14 rubber covered double braid 3 Signal Systems. Straight runs; no elbows. No. Wires B.& S. Conduit Sizes 10 16 Lt. ins. fixture wire V2 20 16 Lt. ins. fixture wire % 30 16 Lt. ins. fixture wire 1 70 16 Lt. ins. fixture wire 1% 90 16 Lt. ins. fixture wire 1% ELECTRICAL TABLES AND DATA No. Wires B.&S 150 16 Lt. ins. fixture wire 18 18 Lt. ins. fixture wire 30 18 Lt. ins. fixture wire 40 18 Lt. ins. fixture wire 100 18 Lt. ins. fixtrue wire 130 18 Lt. ins. fixture wire 200 18 Lt. ms. fixture wire Conduit Sizes 2 i i% i% 2 Telephone Circuits. Not more than two 90° Elbows. No. 19 braided and twisted No. 20 braided and twisted pair switchboard or desk pair switchboard or desk instrument wires. instrument wires. No. Pairs Conduit No. Pairs. Conduit 3 % 5 y 2 6 % 10 % 10 1 15 1 16 li/i 25 1% 25 1% 35 iy 2 35 2 50 2 Conduits and Wires. — Two sides of the smallest rectangular enclosures that will contain a given D number of wires are : (Dxa) + — and D x h x 86. D 2 being the diameter of the wire, a the number of wires in longest row, and b the number of rows. The nearer square this enclosure can be made, the greater the economy of material. The greatest number of wires that can be placed in a rectangular enclosure \D 'y X \Dx.86J L being the length of the enclosure, E the height, and D the diameter of the wire. This formula is only approximate and in using it all fractions obtained by -^ and ^ — ^r must be _ D Dx.86 dropped. 38 ELECTRICAL TABLES AND DATA Example. — Given an enclosure 6 inches long and 2 inches high, how many wires can it hold, the diam- eter of each wire being .7? 6 divided by .7 equals 8.6. Dropping the .6 and subtracting \, we have 7.5 for the first factor. Next, .7 times .86 equals .602; 2 divided by this equals 3.3 ; dropping the .3, we now have to multiply the 7.5 by 3, which equals 22.5, or 22 wires. For circular enclosures no general formula can be given because the percentage of waste space varies greatly with different wires. The first chart may be used to determine the smallest conduit that will enclose a certain number of wires. This chart shows graphically how nearly different numbers of wires fill out circular spaces. To use this chart, multiply diameter of wire by the number given in connection with circle containing the requisite num- ber of wires. This will give the smallest diameter of tube or conduit that will receive these wires. How much larger the conduit to be used must be depends upon circumstances. The number and na- ture of bends, nature of insulation, flexibility of wire, as well as temperature and inspection require- ments, must be taken into consideration. The charts illustrate the relative spaces occupied by the different conduits, viz. : 3", 2£", 2'', \\" , \\" , 1", etc., and the wires considered. The sizes of con- duits are marked in the various circles and each horizontal row pertains to one size of wire, with exception of the 4th and 5th in each row and a few at the top of one of the charts. The 4th shows a neutral wire of half the carrying capacity, and the 5th of double the carrying capacity of the outside wires. The different sizes of conduit given in each case will enable one to judge the most appropriate size to be used under different circumstances. The wires shown are all double braid stranded cables. ELECTRICAL TABLES AND DATA ELECTRICAL TABLES AND DATA 1000000 CM. 1250000 CM. 1500000 CM. 800000 CM. (D 900000 CM. (D 600000 C 700000 C 500000 CM- 400000 CM. 300000 CM. 250000 CM. ELECTRICAL TABLES AND DATA OOOB.&S. OOB.&S OB.&S 1B.&S. 2B.&S. 3B.&S. i 42 ELECTRICAL TABLES AND DATA In the preceding pages are given the conduit sizes recommended by the National Electrical Contractors' Association of the United States. These should be followed as far as they apply. Contacts. — The standard materials for mounting contacts are slate, marble, porcelain, and glass. Where these are liable to breakage, other materials are allowed, but they should always be submitted to inspection departments for approval. A surface contact of one square inch for each 75 amperes is good practice for knife-switches and similar devices. Controllers. — Methods of motor and light control are numerous. Lights are usually controlled by cutting resistance into the mains. A certain con- troller is suitable only for a certain number of lights requiring a certain amperage. The reduction of voltage is equal to the product of the amperes times the resistance, and the effect upon the lights is greater than indicated by the drop in voltage. The speed of motors may be altered by cutting resist- ance into the mains, altering the field connections, arranging taps of different voltages, and connecting armatures in multiple or series. Cooking. — Almost any kind of cooking can be accomplished electrically, but the expense is higher than with gas. It is best to be honest and advise customers correctly about these things than to cause disappointment. The advantages are con- venience and rapidity of results with many of the devices. Cooper-Hewitt Lamps (Mercury Vapor). — These lamps may be obtained for either alternating or direct-current use, and for 110 or 220 volts. The light given out is of a greenish hue, and gives a ghastly effect to faces and hands. Many persons object to working under it, while others seem to like it. The efficiency of the lamp compares favor- ELECTRICAL TABLES AND DATA 43 ably with others ; it is easy to operate, and the light is practically shadowless. With alternating currents the light flickers somewhat, and is said to give a deceptive appearance to some surfaces. Not more than one lamp should be installed on one circuit. Use double-pole switches and avoid plug cut-outs for 220 volts. Current sent through direct-current lamps in wrong direction will ruin tubes. Where inflam- mable gases exist, the sparking of some of the lamps is dangerous. The life of a tube is now claimed to be 5000 hours. The current ranges from 3.5 to 2.0 amperes for different types, and the efficiency is given as from 0.51 to 0.64 watts per mean lower hemispherical candle power. The light is mostly thrown downward. Copper weighs about 556 pounds per cubic foot; its specific gravity is about 8.9, and it melts at 1196 degrees Fahrenheit. The tensile strength of an- nealed copper may be taken as about 35,000 pounds per square inch, and that of hard drawn copper as about 55,000. Cross Currents pass between A.C. generators, and also between synchronous motors when they are operating in parallel and not perfectly in phase. These currents heat the wires and overload the machines unnecessarily. Cut-outs. — In connection with installations served by central stations, the type of cut-out and fuse preferred by that company should be installed. This will usually obtain free fuse renewals. The installa- tion of cartridge-type fuses is not advisable except in establishments where a competent electrician is always on duty. The dimensions of several types of cut-outs are given below. ELECTRICAL TABLES AND DATA TABLE XII Paiste Panel Cut-Outs (See Figure 2). 125 Volt Sizes. Capacity of Switches 30 Amperes Figure 2. — Paiste Panel Cutouts. Cat. No. Main Branches Width (inches) Length (inches) 4012 4015 4026 4013 4103 2-Wire 2-Wire 3-Wire 3-Wire 3-Wire Single, 2-Wire Double, 2-Wire Single, 2-Wire Double, 2-Wire Single, 3-Wire 3% 3 3% 3% 5 5% 10% 7% 10% 8% 250 Volt Sizes . Capacity of Switches 30 Amperes =4101 =4105 2-Wire 2-Wire Single, 2-Wire Double, 2-Wire 3% 3% 7 11% ELECTRICAL TABLES AND DATA TABLE XIII Dimensions for Plug Cut-Outs (See Figure 3). No.2,165 N0.8OU Figure 3. — Plug Cutouts. No. ^3 5 it. No. Length Width Height (inches) (inches) (inches) 2569 2% 2 1« 2965 2V 2 3^ 111 2165 2 T % 4y 2 111 8020 3% 3% 1% 1935 m 3^ HI 2587 6* 3 Hi 2150 4% 3 HI 2109 6* . 2i§ Hi t -, • -> m 4|| HI Z1Z5 6% 4A Hi ELECTRICAL TABLES AND DATA 7 &- -m 3H rig 10 OP 0.8 r. —a Fig II 3t»2wir» O.B -1 14 Fig 6 TP08 Rgia 2WiP* Figure 4.— D. & W. Cutouts. ELECTRICAL TABLES AND DATA 47 TABLE XIV Dimensions of D. & W. 250 Volt Cut-Out's (See Figure 4). Amperes Fig. A B . C D E 0-30 1 31 1 ift 31 li 0-30 2 3ft 2| ift 3ft 14 0-30 3 3ft 4 ift 3ft 14 0-30 4 41 2| ift 41 14 0-30 5 6 4 ift 6 14 0-30 10 7| 2| ift 7| 14 0-30 6 . 8if 4ft ift 841 14 0-30 11 8*1 21 ift 841 14 0-30 12 3* 3| ift 3s 14 31-60 1 41 If iii 5ft 2| 31-60 2 4-1 3ft IS 5ft 1ft 31-60 3 4| 5" 11 5ft 1ft 31-60 4 61 W 11 641 1ft 31-60 5 8 5 If 8ft 1ft 31-60 10 10tt 3| 24 us 141 31-60 6 12 5ft 24 121 Hi 31-60 11 12 314 24 121 Hi 61-100 7 64 24 2ft 6S 41 61-100 8 81 4ft 2ft 81 141 61-100 9 81 61 2ft 81 141 101-200 7 71 2| 31 84 51 201-400 7 9i 31 4ft 104 6f 401-600 7 11 3* 4f 12f 81 Delta Connection. — This method of connection is used only with three-phase a. c. currents. If the connection of a generator is changed from "star" to "delta," its current will be increased 1.73 times 48 ELECTRICAL, TABLES AND DATA for the same power delivery. If it is changed from " delta' 3 to "star," its e.m.f. will be increased 1.73 times. A synonymous term for delta is "mesh." Demand Factor. — At present it is customary among inspection bureaus to demand conductor capacity equivalent to the whole connected load operating at its maximum capacity. Experience, however, has shown that in many cases this leads to a great waste of copper. In very many installations it has been found that not over 20 per cent of the connected load is ever in s "H 5* «5 r 5 •^ ^ ** ^» -is* ■*! ss? -51 c*|«»c*M Demand Factor Chart. use at the same time. Tables of demand factors ap- plicable to many classes of service have been worked out and are in existence. But as far as the authors are aware, these are all arranged from the standpoint of the central station engineer and are hardly applicable to individual installations. As a matter of fact, the authors have failed to find any two installations, even in the same line of business, quite alike. ELECTRICAL TABLES AND DATA 49 INDIVIDUAL MOTORS Many motors are now designed and rated to carry a certain overload, usually 25 per cent, for a short time. This fact should be taken into account wher- ever it seems necessary. Whenever motors are de- signed for a short time rating, instead of for con- tinuous use, it seems but right that the conductors be chosen with the same length of time in view. Insofar as the heating of conductors is concerned, it is un- necessary to pay any attention to the ordinary start- ing current. The only justification for the ex- cessive carrying capacity usually demanded for in- dividual motors, lies in a possible necessity to take care of overloads. GROUPS OF REGULARLY REVERSING MOTORS A graphic representation of current values in a series of cycles of operation of a reversible motor operating a large washing machine is given in Figure 4b. In connection with such motors, it is quite usual to reverse without giving the armature time to come to rest. The reversed current through the armature must first bring the machinery to rest and then start it in the opposite direction. The majority of such motors reverse at intervals of 10 or 12 seconds and the average peak current lasts about one second. In this connection it will be well to note that, in order to give this study a practical value, we must take a course about midway between absolute accu- racy and haphazard guess work. The heating effect of various kinds of motor loads cannot be accurately determined without the use of graphic current charts SO ELECTRICAL TABLES AND DATA and these are seldom available at the time the installa- tion is made. The contractor and the inspector are thus, in the majority of cases, compelled to judge by the rated h. p. of the motors required. In order, therefore, to make these tables of general use to the public, the carrying capacity of conductors required Fig-ure 4'b must be based upon the h. p. intended to be installed. It is principally for this reason that the following table has been arranged in the form given. The table gives factors which express the ratio of the h. p. equivalent of intermittent or fluctuating currents to the heating equivalent of the same cur- rents. The h. p. value of a fluctuating current (volt- age assumed constant) is proportional to the average sum of all the ordinates of a curve representing it. The heating effect of the same current is proportional to the r. m. s. value of the same ordinates. Thus, if we divide the r. m. s. value of a certain fluctuating current by its h. p. value, we shall obtain a factor by which we may multiply the h. p. delivered by a motor in such service in order to find the amperage for which conductor capacity should be provided to guard against overheating. ELECTRICAL TABLES AND DATA 50a At the top of the table we have the various per- centages of time of minimum and peak currents. In the first vertical row we have various percentages of peak currents expressed in terms of the minimum current used. In this form we may use the factors in connection with the rated h. p. of the motors, pro- vided we know, in a general way, the approximate ratio of the minimum to the peak currents required by the fluctuating load. As an example: If we have a motor reversing regularly and requiring a peak current five times as .great as its running current, and this during half of the time of each cycle, we look where the lines per- taining to 50 per cent peak and minimum current time cross the line pertaining to the 500 per cent peak, and find there the factor 1.21, which indicates that the amperage to be provided for must be 1.21 times that called for by the h. p. rating of the motor. Table Percent time of peak current. 10 20 30 40 50 60 70 80 90 Percent time mm. current.. . . 90 80 70 60 50 40 30 20 10 Percent f 200% 1.04 1.05 1.06 1.06 1.05 1.04 1.04 1.04 1.01 peak load 300% 1.12 1.15 1.15 1.14 1.12 1.10 1.07 1.05 1.02 in terms 400% 1.22 1.25 1.23 1.21 1.17 1.13 1.10 1.07 1.03 of min. 500% 1.31 1.34 1.30 1.26 1.21 1.16 1.11 1.07 1.03 !oad..<| 600% 1.41 1.42 1.37 1.29 1.23 1.18 1.12 1.08 1.04 700% 1.50 1.50 1.40 1.32 1.25 1.19 1.13 1.09 1.04 800% 1.59 1.54 1.44 1.35 1.27 1.20 1.15 1.09 1.04 900% 1.67 1.59 1.47 1.37 1.28 1.21 1.15 1.09 1.04 1 1000% 1.74 1.63 1.50 1.39 1.29 1.22 1.15 1.09 1.04 The factors here given are correct for single motors and are based on the worst possible condition under which a group of motors can operate; viz., all peaks superimposed. This is a condition which may at times 50b ELECTRICAL. TABLES AND DATA be attained, but if a large group of motors is con- sidered, the chance of its recurrence is exceedingly small. With these considerations in view, we deduce the following formula to find the fraction of the total time during which the peaks of all the motors in use are likely to be superimposed : A b In this formula, A represents the fraction of the time of a cycle of operation during which the peak is in use, and b the number of motors in use. In the case of laundry motors of the characteristics shown in Figure 4b, the peaks, when once coincident, will remain so for some length of time or until one or more have been stopped and the combination broken. In the case of elevator motors the combination will al- most immediately be broken. GROUPS OF REVERSING MOTORS WITH VARIABLE TIME INTERVALS In many machine shops the planers are equipped with reversing motors. Some very clever systems of dontrol have been worked out and in some of these the carriage is made to return at a high rate of speed after making the cut. The length of time during which such a motor moves in either direction is variable and the power required by the forward and return strokes is also variable. The periodicity, as well as the relative amount of current, vary and are governed by the work in hand. Since there is no permanent regularity about any of the operations, no exact forecast as to what will happen at any particular time can be made. A study ELECTRICAL TABLE'S AND DATA of the conditions as illustrated in Figure 4c will, however, assist materially in judging what the cur- rent demands of a group of such motors may be at times. In the figure we have five motors, denoted by black circles, in operation and reversing regularly at in- tervals of 12, 6, 8, 4 and 9 seconds. An inspection of the figure will show at a glance that, with any num- Figure 4=c ber of motors, if they start in synchronism, the time of coincidence of the peak of all of them will be pro- portional to the least common multiple of all of their time intervals. In this case that number is 72 ; hence, at intervals of 72 seconds these motors will all come into synchronism as far as their peaks are concerned. Their minima of current will, of course, also come into synchronism regularly. If they do not start in synchronism, those starting at time intervals which form a multiple of their own time, remote from that of other motors, will work into synchronism and out of it in a perfectly regular manner, just as will those shown in the figure. Those that start at different time intervals, however, will not. As an example, if the motor having a period of 6 seconds starts either 1, 2, 3, 4, 5, 7, 8, 9, 10 or 11 seconds after the other, it will never superimpose its 50d ELECTRICAL TABLES AND DATA peak entirely upon that of the other, although a part of it may overlap. It must, however, be borne in mind that the motor having the shortest periods governs the chances of falling into step. A motor having a period of 4, for instance, will have only one chance in 4 of missing regular synchronism of peaks with other motors having periods of 8 or 12. With motors on this kind of work then, we may be certain that there will be coincidence of peaks at times. In con- nection with motors of this kind it will be safe to use about the average multipliers given in the table, the average being determined from the characteristics of the different motors. PASSENGER ELEVATOR AND SIMILAR MOTORS In the kind of service here considered, the current is either entirely on or off. If calculations are to be based upon current or power charts the equivalent current of a cycle of operations should be determined by the r. m. s. method. The formulae and the tables herewith furnished, however, are so arranged that, for general purposes, we need merely know the rated h. p. of the whole group and the relative time of the on and off periods. In the preliminary operation of finding the current required it is to be assumed that the motors are de- livering their rated capacity continuously, regardless of the nature of their rating. The formula given below is also independent of the number of motors and the demand factor obtained is a function of the relative on and off times of the motors, which is assumed to be the same for all. A conductor is used to the best advantage with ELECTRICAL TABLE'S AND DATA 50e reference to heating when subjected to a steady cur- rent flow. Hence, if another conductor be called upon to transmit an equivalent amount of energy with intermittent service, the carrying capacity of the ' second conductor must be correspondingly increased. If the load is of such a nature that the- conductor is idle half of the time, it must carry double current during the other half of the time. As the heating is proportional to the square of the current, it follows that a double current during half time is equivalent in heating effect to V2 times the normal current used continuously. The same relation holds for all other time divisions and this will allow us to find the value of a steady current, to be denoted by I, which will be the equivalent of any regularly intermittent cur- rent of the nature here considered by the formula as. , given below: \fJrXW where i is the theoretical current based on the total motor rating, t the fraction or percentage of time in a cycle of operation during which the motor is using this current, and V the time of a complete cycle of operation. This formula will give us a multiplier, virtually a demand factor, by which we can find the current having an equivalent heating effect to that required by the motors under the assumption that they are all working under the worst possible condi- tion, i. e., all motors taking their maximum current at the same instant. The factors calculated according to the formula as applying to the various percentages of time dur> 50f ELECTRICAL TABLES AND DATA ing which the current is in use, are given below. The upper line gives the percentage of time during which current is used, and the lower line gives the multiply- ing factors. Percentage of Time 10 20 30 40 50 60 70 80 90 Factors 32 .45 .55 .66 .71 .78 .84 .89 .95 ^GROUPS OF MOTORS OF INDISCRIMINATE CHARACTERISTICS This classification embraces all kinds of motors as usually found in shops .and factories. There are two ways of arriving at the probable demand factor of such groups. One way consists of consulting tables made up from experiences with similar installations. This method has the great disadvantage that it is almost impossible to find two installations near enough alike to warrant very accurate comparisons. Such tables are given further on, but should be used only as general guides and the final determination made only after making a careful analysis of the installa- tion. A simple method of analyzing a motor installation and determining its demand factor is as follows : Take any piece of ordinary ruled paper and number as many lines as there are hours of the day to be con- sidered. Let these lines be horizontal. Next draw as many lines vertically across them as there are motors to be considered. Also place each line so that in position and length it may cover the hours of the day during which the motors are thought to be in use. There are two ways in which such a representation can be made. If the motors have no fixed time at which they run, their running time may be laid out .-at the bottom of the figure ; the main point being that ELECTRICAL. TABLES AND DATA 51 the lines give a fair idea of the proportionate running time per day. If the stopping and starting intervals are not too short, a series of snch lines, representing the estimated number of starts, may be used. If any of the motors are used only during certain hours of the day, the line pertaining to these motors may be placed in the horizontal lines pertaining to the hours of the day, as for instance A and B in the figure. These two motors never interfere with each other, but do occasionally come in at the same time with some of the other motors plotted at the bottom of the line. Department Stores. — Such places usually require large quantities of power for illumination, electric signs, and motors. The demand factor for lighting is very close to 100 per cent. If economy is not too much insisted upon, a bountiful circuit capacity should be provided. This will allow brilliant illumi- nation wherever it is needed. As department stores contain nearly all of the goods handled in other stores, hints on illumination of special places should be looked up under the corresponding headings — dry goods stores, jewelry, etc. As there are usually large areas visible from any one place, good appear- ance demands some uniform arrangement of fixtures. If this does not provide sufficient light for certain goods in show cases, local illumination is provided in the cases. If branch circuit capacity for five watts per square foot is provided, it will enable very brilliant illumination of spots without over- loading circuits and not interfere with the frequent changes which are made. The capacity of general mains need not be greater than two watts per square foot on the most important flows. 52 ELECTRICAL TABLES AND DATA Depreciation. — Depreciation must be duly consid- ered in dealing with, any form of apparatus. The depreciation is governed entirely by the useful life of the device, but this in turn is governed by the amount of wear and tear which cannot be repaired for from time to time; obsolescence, possibly in- adequacy after a time, or probable cessation of busi- ness. Depreciation should not be confused with maintenance, to which should be charged all mis- haps which, do not permanently lessen the natural useful life of the apparatus. From 10 to 20 per cent is often charged to depreciation, but it is better to estimate it carefully in each case unless a parallel case is well understood. Desk Lighting. — The illumination of desks by indi- vidual lamps is never to be advised, except in the case of individuals with very poor eyesight or in locations where desks are far apart or used but a few hours per day. Where individual desk lighting is provided, the cost of energy may sometimes be lower, but the first cost of installation, and also maintenance, is always high. There is, further, al- ways a considerable fire hazard, and all of these offset the saving in energy to a large extent. A general and fairly shadowless illumination also adds much to the efficiency of clerks. The following table shows the comparative cost of proper general illumination as compared with local for desks of various spacing. It is assumed that a general illumi- nation of 1J watts per square foot is provided, and that at each desk a 25-watt lamp is also used, while the general illumination with which this desk light- ing is compared is obtained through the medium of the most efficient large wattage lamps at present on the market. One watt per square foot will give good general illumination, which will need to be helped out by local lighting only for persons with I ELECTRICAL TABLES AND DATA 53 weak eyes. Where local desk lighting is resorted to the- wattage requirements will be about as follows : A v. sq. ft. per desk. . . .20 25 30 35 40 45 50 Total watts per sq. ft. . 1.5 1.25 1.08 0.96 0.87 0.80 0.75 It will be noted that where desks are close to- gether the general illumination is not only the easiest installed but also the cheapest to operate. If the desks are used only a small part of the time the local illumination will be the cheaper. Lamps used for desk lighting should either be frosted or encased in diffusing globes. Diamagnetic. — Zinc, antimony, bismuth, and cer- tain other metals are repelled when placed between the poles of strong magnets, and are said to be dia- magnetic. Metals which are attracted by magnetism are said to be paramagnetic. Dielectric. — Any substance which is an insulator and allows electrostatic induction to take place through its mass. Usually taken as synonymous with insulation. Dry Kilns. — Such places are too hot for rubber- covered wire. Use asbestos-covered. Place cut-outs and switches outside. Eddy Currents. — Useless currents which are pro- duced in the iron of pole pieces, etc., subject to . motion in a magnetic field, or to the influence of coils in which a fluctuating current exists. They cause a waste of energy and heat the metal. Efficiency. — The efficiency of motors, transformers, and other similar translating devices is found by dividing the output by the input. In connection with sources of electric illumination the term efficiency has an entirely different meaning. The efficiency of such devices is spoken of as a certain 64 ELECTRICAL TABLES AND DATA number of watts per candle power. In this case, the higher the efficiency, the more uneconomical is the lamp. See Motors and Illumination for practical applications. Egg Candling. — One light must be provided for each workman, and it should be located about waist high. The wires should be run at this height so as to avoid use of long cords. The light is always made adjustable, and is encased in a small metallic hood with a small opening. Electric Braking.— This is also sometimes termed " dynamic braking.'' If an electric motor is dis- connected from its source of supply, and its arma- ture circuit closed while the armature is still in motion, it will generate current and consume power, and may be brought to rest very quickly in this manner. Where the necessary provisions for this purpose are installed this method of braking is very successful. Electrolysis. — Nearly all electrolysis is due to the fact that piping and other metallic structures near a ground return system of electrical distribution afford a return circuit of such low resistance as compared to the return circuit provided, that a large part of the current returns over the piping. It is impossible to prevent electrolysis entirely ex- cept by insulating the return wires. The troubles may, however, be materially reduced. The current does damage only where it leaves the pipes or other structures which it has entered, and the damage is in proportion to the amperes carried. The methods used for lessening electrolysis are the following : 1. Protection of structures by concrete or other forms of insulation, or keeping them as far as pos- sible from ground return circuits. Insulation of piping is not advisable; it is likely to concentrate the trouble at spots where it is poor. ELECTRICAL TABLES AND DATA 55 2. Bonding pipes, etc., so as to prevent current which has once entered them from leaving, except at predetermined places, and then never to earth. 3. Negative boosters have been suggested, but have not been extensively tried. A negative booster is a low-voltage dynamo connected into the return circuit in such a manner as to draw current from the rails and earth and deliver it back to the sta- tion. 4. Reinforcing the rails, etc., by large conductors, thus increasing the conductivity of the return, and lowering the p. d. between the rails and the sta- tion. In most cities ordinances mention the difference in- potential which may be allowed to exist between any two points on the return wires. In Chicago it is provided that all uninsulated electrical return circuits must be of such current-carrying capacity and so arranged that the difference of potential between any two points on the return circuit will not exceed the limit of twelve volts, and between any two points on the return 1000 feet apart within a one-mile radius of the City Hall will not exceed the maximum limit of 1 volt, and between any two points on the return 700 feet apart outside of this one-mile radius limit will not exceed the limit of 1 volt. In addition thereto, a proper return conductor system must be so installed and maintained as to protect all metallic work from electrolysis damage. The return current amperage on pipes and cable sheaths must not be greater than 0.5 amperes per pound-foot for caulked cast iron pipe, 8.0 amperes per pound-foot for screwed wrought iron pipe, and 16.0 amperes per pound-foot for standard lead or lead alloy sheaths of cables. All insulated return current systems must be equipped with insulated pilot wire circuits and volt< 56 ELECTRICAL TABLES AND DATA meters, so that accurate chart records will be obtain- able daily, showing the difference of potential be- tween the negative bus-bars in each station and at least four extreme limits on the return circuit in its corresponding feeding district. Also with recording ammeters, insulated cables, and automatic reverse load and overload circuit breakers which will record and limit the maximum amperes drained from all the metallic work (except the regular return feed- ers) to less than 10 per cent of the total output of the station. Figuring on the basis of the average resistance of cast iron, wrought iron, and lead, the above amperages will exist with the following differ- ence of potential per running foot, and will be inde- pendent of the thickness or size of pipe : Cast iron, 0.000711 volt per foot ; measurements must be taken on solid pipe and not across any joint. Wrought iron, 0.001568 volt per foot; measurement to be taken as above. Lead sheaths, 0.007497 volt per foot; as joints in lead sheaths are always soldered and wiped, no attention need be paid to them. The lower amperage for the iron piping is specified be- cause joints will usually be found of higher resist- ance than the piping, and at each joint current is likely to leave piping and enter it again just beyond. The proper treatment of electrolysis may require all four methods outlined above. The method most to be recommended in a general way is that of re- inforcing the return conductors sufficiently to limit the difference of potential as prescribed. The following table shows the size of copper con- ductors necessary with rails of various weights per yard to reduce electrolysis to 4, ^, and J, etc.; the specific resistance of the rails being taken as 10 times that of copper, and the resistance of bonds as negligible. ELECTRICAL TABLES AND DATA 57 TABLE XV Showing e. m. of copper necessary to reduce p. d. of electrolysis to the fraction of its original value given. height o f Circular Rails Pei Mils 1 -2 1-3 1-4 Yard of Rail 40 4,950,000 495,000 990,000 1,485.000 45 5,600,000 560,000 1,120,000 1,680,000 50 6,230,000 623,000 1 246,000 1,869,000 60 7,500,000 750,000 1,500,000 2,250,000 70 8,770,000 87 7,000 1,754,000 2,631,000 80 9,900,000 990,000 1,980,000 2,970,000 90 11,200,000 1,120,000 2,240,000 3,360,000 100 12,500,000 1,250,000 2 500,000 3,750,000' Weight Circular of Rails Mils 1-5 1-6 1-7 1-8 Per Yard of Rail 40 4,950,000 1,980,000 2,475,000 2,970,000 3,465,000' 45 5,600,000 2,240,000 2,800,000 3,360,000 3,920,000 50 6,230,000 2,492,000 3,115,000 3,738,000 4,361,000 60 7,500,000 3,000,000 3,750,000 4,500,000 5,250,000 70 8,770,000 3,508,000 4,385,000 5,262,000 6,039,000 80 9,900,004 3,960,000 4,950,000 5,940,000 6,930,000 90 11,200,000 4,480,000 5,600,000 6,720,000 7,840,000 100 12,500,000 5,000,000 6,250,000 7,500.000 8,750,000 For a comprehensive treatment of electrolysis a map of the return circuits and adjacent piping should bo made. Tests determining p. d. and direction of cur- rent should be made, and results marked upon the map. In many cases currents will be found in oppo- site direction at the same point at different times. In estimating the current strength from p. d. noted between track and piping the distance of the latter from the track must be taken into consideration. If this is small a low p. d. may deliver considerable current. Often the trouble can be reduced suffi- ciently by running comparatively short lengths of heavy copper. In testing p. d.'s it is best to use a- sensitive galvanometer. Such an instrument may be calibrated with reference to a milli-volt meter. 58 ELECTRICAL TABLES AND DATA TABLE XVI The table below shows the approximate amperage per milli-volt p.d. per foot which will be found in the various kinds and sizes of piping and sheaths given. Cast Iron, Average Wrought Iron, Average Lead Sh saths, V a " Inside wt., Am- Inside wt., Am- Outside Amperes Diam. Per Ft peres Diam. Per Ft. peres Diam. Approx. 3 16 12 i .87 4£ 1.26 5 4 22 15 t 1.15 5* 1.50 6 6 35 25 l 1.70 8 1.58 6 8 50 37 11 2.25 11 1.65 6.6 10 67 50 li 2.75 14 1.68- 6.9 12 87 65 2 3.60 18 1.72 7.0 14 110 82 2i 5.80 30 1.78 7.1 16 135 102 3 7.65 40 1.84 7.2 18 165 123 3* 9.00 48 1.90 7.5 .20 190 141 4 11.0 57 1.95 7.7 24 255 190 4i 12.5 66 1.98 7.9 30 370 275 5 15.0 80 2.00 8.0 36 500 375 6 19.0 100 2.05 8.2 42 665 500 7 24.0 125 2.10 8.4 48 850 635 8 29.0 155 2.15 8.6 54 1,050 775 9 34.0 180 2.19 8.8 60 1,300 970 10 41.0 220 2.21 8.9 72 1,575 1,200 11 46.0 250 2.24 9.0 84 1,850 1,400 12 51.0 275 2.32 9.3 Electrolyte is the name given to the solution used in storage batteries and other batteries. Electromagnets, — The magnetic flux is equal to the magnetomotive force divided by the reluctance. The magnetomotive force is the product of current times number of turns of wire and is known as ampere turns. The reluctance of the iron of all well designed magnets is very low but that of the air gap is high, so that roughly speaking we can judge the total reluctance by the air gap. In any given case the magnetic flux is approximately proportional to the current strength up to a point at which the iron ELECTRICAL TABLES AND DATA 5S becomes nearly saturated. After this the increase is slow until the point of full saturation is reached and after this it is very slow. To increase the magnetization (e.m. f. being fixed) we must increase the size of wire ; winding more turns of the same wire upon a spool simply decreases the current required for a given magnetization but does not alter the magnetization itself. The self-induction and the sparking are proportional to the square of the number of turns of wire. The heating is pro- portional to the square of the current used. The heating of the coils sets the limit of the current which may be used. A radiating surface of from 1 to 3 square inches per watt consumed in the coil is usually provided. One watt per square inch will heat the coil very much if it is in use continuously. The possible traction of electromagnets is about 200 lbs. per square inch for good annealed wrought iron, and 75 for cast iron. This, however, varies widely with the quality of iron used. In laboratory experiments as high as 1,000 lbs. per square inch has been obtained. Single phase a-c. magnets do not give a constant pull but two and three phase magnets are very serviceable. The "chattering" of single phase magnets can be lessened by a "shading coil." Lifting magnets are extensively used. They are built with the two poles concentric and the material to be lifted constitutes the armature. Per- manent magnets are used only in small sizes. USEFUL FORMULAS AND TABLES In the following formulas it is assumed that the wires lie squarely over one another in the coil, each wire fully occupying a space equal to the square of its diameter. As in most coils some insulating me- dium is placed between the different layers, this is about the condition which exists in practice. 60 ELECTRICAL TABLES AND DATA The symbols used in the formulas are as follows: d- diameter of wire, in inches, over insulation. I- length of wire, on spool, in inches. nt = number of turns. r = resistance of one foot of wire. rs= radiating surface. B = diameter of core and insulation, in inches. D = diameter over outside of completed winding, in inches. L = length of winding space on spool, in inches. N - depth of winding from core to outside, in inches. W = weight of wire. a, c,k-= constants for use in the formula, given in the tables below. Each constant has a different value for each size and kind of wire used. Number of turns in a given spool (see Figure 5) : m z _ i _y - -i Dm Figure 5. LxN nt Diameter of wire to give a certain number of turns : d =4 J LxN nt ELECTRICAL TABLES AND DATA 61 Cross-section of winding space, or LxN, necessary to accommodate a certain number of turns of a given wire : LxN -d 2 xnt. Length of wire on a given spool : 1= (D 2 -B 2 ) Lxk. See table below for value of k.. "Weight of wire on a given spool : W= (D 2 -B 2 ) Lxc. See table below for value of c Resistance of wire on a given spool : R= (D 2 -B 2 ) Lxa. See table below for value of a.. Radiating surface for a given spool : rs = DxS.UxL. TABLE XVn CONSTANTS. Constant for Length Constant for Weight Constant for Resistance- Pi Q IB CQ H 02 CQ fi OQ «2 20 40.9 50.4 56.7 .137 .162 .177 .415 .512 .57© 21 50.4 64.1 72.7 .638 .812 .920 22 60.2 78.0 89.7 .97 1.257 1.445 23 68.3 89.7 104.7 1.387 1.82 2.08 24 83.6 113.5 135. .1115 .149 .169 2.14 2.91 3.46 25 97.2 135. 163. 3.14 4.36 5.27 26 114. 163. 202. 4.65 6.65 8.24 27 135. 202. 255. . 6.94 11.75 13.1 28 148. 226. 291. .0845 .122 .148 9.60 14.62 18.82 29 182. 291. 387. - 14.85 23.7 31.6 30 201. 334. 454. 20.7 34.4 46.8 31 226. 387. 542. 29.36 50.25 70.4 32 255. 454. 655. .0687 .1045.132 41.8 74.4 107.2. 33 291. 542. 812. 60.33 114.5 168. 34 334. 655. 1023. 87.1 170.5 266.5 35 354. 712. 1140. 116.2 234. 374.8- 36 387. 811. 1340. .0492 .0825 .1115 160. 335.5 555. 37 422. 897. 1582. 220.5 468. 806. 38 457. 1023. 1825. 308. 674. 1192. 39 496. 1170. 2165. 412. 972. 1795. 40 532. 1300. 2525. .038 .0615 .0888 557. 1360. 2645^ 52 ELECTRICAL TABLES AND DATA Depreciation. — Depreciation must be duly consid- ered in dealing with any form of apparatus. The depreciation is governed entirely by the useful life of the device, but this in turn is governed by the amount of wear and tear which cannot be repaired for from time to time; obsolescence, possibly in- adequacy after a time, or probable cessation of busi- ness. Depreciation should not be confused with maintenance, to which should be charged all mis- haps which do not permanently lessen the natural useful life of the apparatus. From 10 to 20 per cent is often charged to depreciation, but it is better to estimate it carefully in each case unless a parallel case is well understood. Desk Lighting. — The illumination of desks by indi- vidual lamps is never to be advised, except in the case of individuals with very poor eyesight or in locations where desks are far apart or used but a few hours per day. Where individual desk lighting is provided, the cost of energy may sometimes be lower, but the first cost of installation, and also maintenance, is always high. There is, further, al- ways a considerable fire hazard, and all of these offset the saving in energy to a large extent. A general and fairly shadowless illumination also adds much to the efficiency of clerks. The following table shows the comparative cost of proper general illumination as compared with local for desks of various spacing. It is assumed that a general illumi- nation of 1J watts per square foot is provided, and that at each desk a 25-watt lamp is also used, while the general illumination with which this desk light- ing is compared is obtained through the medium of the most efficient large wattage lamps at present on the market. One watt per square foot will give good general illumination, which will need to be helped out by local lighting only for persons with ELECTRICAL TABLES AND DATA 53 weak eyes. Where local desk lighting is resorted to the- wattage requirements will be about as follows : Av. sq. ft. per desk 20 25 30 35 40 45 50 Total watts per sq. ft. 1.5 1.25 1.08 0.96 0.87 0.80 0.75 It will be noted that where desks are close to- gether the general illumination is not only the easiest installed but also the cheapest to operate. If the desks are used only a small part of the time the local illumination will be the cheaper. Lamps used for desk lighting should either be frosted or encased in diffusing globes. Diamagnetic. — Zinc, antimony, bismuth, and cer- tain other metals are repelled when placed between the poles of strong magnets, and are said to be dia- magnetic. Metals which are attracted by magnetism are said to be paramagnetic. Dielectric. — Any substance which is an insulator and allows electrostatic induction to take place through its mass. Usually taken as synonymous with insulation. Dry Kilns. — Such places are too hot for rubber- covered wire. Use asbestos-covered. Place cut-outs and switches outside. Eddy Currents. — Useless currents which are pro- duced in the iron of pole pieces, etc., subject to . motion in a magnetic field, or to the influence of coils in which a fluctuating current exists. They cause a waste of energy and heat the metal. Efficiency. — The efficiency of motors, transformers, and other similar translating devices is found by dividing the output by the input. In connection with sources of electric illumination the term efficiency has an entirely different meaning. The efficiency of such devices is spoken of as a certain 64 ELECTRICAL TABLES AND DATA number of watts per candle power. In this case, the higher the efficiency, the more uneconomical is the lamp. See Motors and Illumination for practical applications. Egg Candling. — One light must be provided for each workman, and it should be located about waist high. The wires should be run at this height so as to avoid use of long cords. The light is always made adjustable, and is encased in a small metallic hood with a small opening. Electric Braking.— This is also sometimes termed "dynamic braking.' ' If an electric motor is dis- connected from its source of supply, and its arma- ture circuit closed while the armature is still in motion, it will generate current and consume power, and may be brought to rest very quickly in this manner. Where the necessary provisions for this purpose are installed this method of braking is very successful. Electrolysis. — Nearly all electrolysis is due to the fact that piping and other metallic structures near a ground return system of electrical distribution afford a return circuit of such low resistance as compared to the return circuit provided, that a large part of the current returns over the piping. It is impossible to prevent electrolysis entirely ex- cept by insulating the return wires. The troubles may, however, be materially reduced. The current does damage only where it leaves the pipes or other structures which it has entered, and the damage is in proportion to the amperes carried. The methods used for lessening electrolysis are the following : 1. Protection of structures by concrete or other forms of insulation, or keeping them as far as pos- sible from ground return circuits. Insulation of piping is not advisable; it is likely to concentrate the trouble at spots where it is poor. ELECTRICAL TABLES AND DATA 55 2. Bonding pipes, etc., so as to prevent current which has once entered them from leaving, except at predetermined places, and then never to earth. 3. Negative boosters have been suggested, but have not been extensively tried. A negative booster is a low-voltage dynamo connected into the return circuit in such a manner as to draw current from the rails and earth and deliver it back to the sta- tion. 4. Reinforcing the rails, etc., by large conductors, thus increasing the conductivity of the return, and lowering the p. d. between the rails and the sta- tion. In most cities ordinances mention the difference in- potential which may be allowed to exist between any two points on the return wires. In Chicago it is provided that all uninsulated electrical return circuits must be of such current-carrying capacity and so arranged that the difference of potential between any two points on the return circuit will not exceed the limit of twelve volts, and between any two points on the return 1000 feet apart within a one-mile radius of the City Hall will not exceed the maximum limit of 1 volt, and between any two points on the return 700 feet apart outside of this one-mile radius limit will not exceed the limit of 1 volt. In addition thereto, a proper return conductor system must be so installed and maintained as to protect all metallic work from electrolysis damage. The return current amperage on pipes and cable sheaths must not be greater than 0.5 amperes per pound-foot for caulked cast iron pipe, 8.0 amperes per pound-foot for screwed wrought iron pipe, and 16.0 amperes per pound-foot for standard lead or lead alloy sheaths of cables. All insulated return current systems must be equipped with insulated pilot wire circuits and volt< 56 ELECTRICAL TABLES AND DATA meters, so that accurate chart records will be obtain- able daily, showing the difference of potential be- tween the negative bus-bars in each station and at least four extreme limits on the return circuit in its corresponding feeding district. Also with recording ammeters, insulated cables, and automatic reverse load and overload circuit breakers which will record and limit the maximum amperes drained from all the metallic work (except the regular return feed- ers) to less than 10 per cent of the total output of the station. Figuring on the basis of the average resistance of cast iron, wrought iron, and lead, the above amperages will exist with the following differ- ence of potential per running foot, and will be inde- pendent of the thickness or size of pipe : Cast iron, 0.000711 volt per foot ; measurements must be taken on solid pipe and not across any joint. "Wrought iron, 0.001568 volt per foot; measurement to be taken as above. Lead sheaths, 0.007497 volt per foot; as joints in lead sheaths are always soldered and wiped, no attention need be paid to them. The lower amperage for the iron piping is specified be- cause joints will usually be found of higher resist- ance than the piping, and at each joint current is likely to leave piping and enter it again just beyond. The proper treatment of electrolysis may require all four methods outlined above. The method most to be recommended in a general way is that of re- inforcing the return conductors sufficiently to limit the difference of potential as prescribed. The following table shows the size of copper con- ductors necessary with rails of various weights per yard to reduce electrolysis to -J, f, and ^, etc.; the specific resistance of the rails being taken as 10 times that of copper, and the resistance of bonds as negligible. ELECTRICAL TABLES AND DATA 57 TABLE XV Showing e. m. of copper necessary to reduce p. d. of electrolysis to the fraction of its original value given. height of Circular Rails Per Mils 1 -2 1-3 1-4 Yard of Rail 40 4,950,000 49 5,000 990,000 1,485.000 45 5,600,000 560,000 1,120,000 1,680,000 50 6,230,000 623,000 1 246,000 1,869,000 60 7,500,000 75 1,000 1,500,000 2,250,000 70 8,770,000 877,000 1 754,000 2,631,000 80 9,900,000 990,000 1,980,000 2,970,000 90 11,200,000 1,120,000 2,240,000 3,360,000 100 12,500,000 1,250,000 2 500,000 3,750,000' Weight Circular of Rails Mils 1-5 1-6 1-7 1-8 Per Yard of Rail 40 4,950,000 1,980,000 2,475,000 2,970,000 3,465,000' 45 5,600,000 2,240,000 2,800,000 3,360,000 3,920,000 50 6,230,000 2,492,000 3,115,000 3,738,000 4,361,000 60 7,500,000 3,000,000 3,750,000 4,500,000 5,250,000 70 8,770,000 3 508,000 4,385,000 5,262,000 6,039,000 80 9,900,00D 3,960,000 4,950,000 5,940,000 6,930,000 90 11,200,000 4,480,000 5,600,000 6,720,000 7,840,000 100 12,500,000 5,000,000 6,250,000 7,500,000 8,750,000 For a comprehensive treatment of electrolysis a map of the return circuits and adjacent piping should be made. Tests determining p. d. and direction of cur- rent should be made, and results marked upon the- map. In many cases currents will be found in oppo- site direction at the same point at different times. In estimating the current strength from p. d. noted between track and piping the distance of the latter from the track must be taken into consideration. If this is small a low p. d. may deliver considerable current. Often the trouble can be reduced suffi- ciently by running comparatively short lengths of heavy copper. In testing p. d.'s it is best to use a- sensitive galvanometer. Such an instrument may be calibrated with reference to a milli-volt meter. 58 ELECTRICAL TABLES AND DATA TABLE XVI The table below shows the approximate amperage per milli-volt p.d. per foot which will be found in the various kinds and sizes of piping and sheaths given. Cast Iron, Average Wrought Iron, Average Lead Sheaths, %" Inside wt., Am- Inside wt., Am- Outside Amperes Diam. Per Ft peres Diam. Per Ft. peres Diam. Approx. 3 16 12 1 .87 4£ 1.26 5 4 22 15 1 1.15 5* 1.50 6 6 35 25 1 1.70 8 1.58 6 8 50 37 n 2.25 11 1.65 6.6 10 67 50 li 2.75 14 1.68- 6.9 12 87 65 2 3.60 18 1.72 7.0 14 110 82 2J 5.80 30 1.78 7.1 16 135 102 3 7.65 40 1.84 7.2 18 165 123 3* 9.00 48 1.90 7.5 .20 190 141 4 11.0 57 1.95 7.7 24 255 190 4i 12.5 66 1.98 7.9 30 370 275 5 15.0 80 2.00 8.0 .36 500 375 6 19.0 100 2.05 8.2 42 665 500 7 24.0 125 2.10 8.4 48 850 635 8 29.0 155 2.15 8.6 54 1,050 775 9 34.0 180 2.19 8.8 60 1,300 970 10 41.0 220 2.21 8.9 72 1,575 1,200 11 46.0 250 2.24 9.0 84 1,850 1,400 12 51.0 275 2.32 9.3 Electrolyte is the name given to the solution used in storage batteries and other batteries. Electromagnets. — The magnetic flux is equal to the magnetomotive force divided by the reluctance. The magnetomotive force is the product of current times number of turns of wire and is known as ampere turns. The reluctance of the iron of all well designed magnets is very low but that of the air gap is high, so that roughly speaking we can judge the total reluctance by the air gap. In any given case the magnetic flux is approximately proportional to the current strength up to a point at which the iron ELECTRICAL TABLES AND DATA 5S becomes nearly saturated. After this the increase is slow until the point of full saturation is reached and after this it is very slow. To increase the magnetization (e.m. f. being fixed) we must increase the size of wire ; winding more turns of the same wire upon a spool simply decreases the current required for a given magnetization but does not alter the magnetization itself. The self-induction and the sparking are proportional to the square of the number of turns of wire. The heating is pro- portional to the square of the current used. The heating of the coils sets the limit of the current which may be used. A radiating surface of from 1 to 3 square inches per watt consumed in the coil is usually provided. One watt per square inch will heat the coil very much if it is in use continuously. The possible traction of electromagnets is about 200 lbs. per square inch for good annealed wrought iron, and 75 for cast iron. This, however, varies widely with the quality of iron used. In laboratory experiments as high as 1,000 lbs. per square inch has been obtained. Single phase a-c. magnets do not give a constant pull but two and three phase magnets are very serviceable. The "chattering" of single phase magnets can be lessened by a "shading coil." Lifting magnets are extensively used. They are built with the two poles concentric and the material to be lifted constitutes the armature. Per- manent magnets are used only in small sizes. USEFUL FORMULAS AND TABLES In the following formulas it is assumed that the wires lie squarely over one another in the coil, each wire fully occupying a space equal to the square of its diameter. As in most coils some insulating me- dium is placed between the different layers, this is about the condition which exists in practice. 60 ELECTRICAL TABLES AND DATA The symbols used in the formulas are as follows: d= diameter of wire, in inches, over insulation. I- length of wire, on spool, in inches. nt = number of turns. r = resistance of one foot of wire. rs= radiating surface. B = diameter of core and insulation, in inches. D = diameter over outside of completed winding, in inches. L =s length of winding space on spool, in inches. N - depth of winding from core to outside, in I inches. W = weight of wire. a, c,k- constants for use in the formula, given in the tables below. Each constant has a different value for each size and kind of wire used. Number of turns in a given spool (see Figure 5) : Figure 5. nt-. LxN Diameter of wire to give a certain number of turns : ELECTRICAL TABLES AND DATA 61 Cross-section of winding space, or LxN, necessary to accommodate a certain number of turns of a given wire : LxN = d 2 x nt. Length of wire on a given spool : I- (D 2 -B 2 ) Lxk. See table below for value of k.. Weight of wire on a given spool : W= (D 2 -B 2 ) Lxc. See table below for value of cS Resistance of wire on a given spool : B - (D 2 - B 2 ) L x a. See table below for value of a„ Radiating surface for a given spool : rs = DxZ.14:xL. TABLE XVII CONSTANTS. Constant for Length Constant for Weight Constant for Resistance- 20 40.9 50.4 56.7 .137 .162 .177 .415 .512 .57© 21 50.4 64.1 72.7 .638 .812 .920 22 60.2 78.0 89.7 .97 1.257 1.445 23 68.3 89.7 104.7 1.387 1.82 2.08 24 83.6 113.5 135. .1115 .149 .169 2.14 2.91 3.46 25 97.2 135. 163. 3.14 4.36 5.27 26 114. 163. 202. 4.65 6.65 8.24 27 135. 202. 255. . 6.94 11.75 13.1 28 148. 226. 291. .0845 .122 .148 9.60 14.62 18.82-' 29 182. 291. 387. 14.85 23.7 31.6 30 201. 334. 454. 20.7 34.4 46.8 31 226. 387. 542. 29.36 50.25 70.4 32 255. 454. 655. .0687 .1045 .132 41.8 74.4 107.2, 33 291. 542. 812. 60.33 114.5 168. 34 S34. 655. 1023. 87.1 170.5 266.5 35 354. 712. 1140. 116.2 234. 374.8- 36 387. 811. 1340. .0492 .0825 .1115 160. 335.5 555. 37 422. 897. 1582. 220.5 468. 806. 38 457. 1023. 1825. 308. 674. 1192. 39 496. 1170. 2165. 412. 972. 1795. 40 532. 1300. 2525. .038 .0615 .0888 557. ELECTRICAL TABLES AND DATA TABLE XVLTI Round Cotton-covered Magnet Wire American Steel & Wire Co. Coarse Sizes 55 Allowable Variation Either "Way in Per Cent. Rated Area in Cir. Mils. Cov'ered Approxi- mate Values Outside Feet Diameter per Inches Pound Covered Approx imate Values Outside Feet Diameter per Inches Poun 0.3249 £ofl 105,625 .333 3.1 .339 3.1 l .2893 iof 1 83,694 .297 3.9 .303 3.9^ 2 .2576 lofl 66,358 .266 5. .272 4.9 3 .2294 fofl 52,624 .237 6.2 .243 6.2 4 .2043 fofl 41,738 .212 7.8 .218 7.8 5 / .1819 f ofl 33,088 .190 9.9 .196 9.9 6 .1620 fofl 26,244 .170 12.5 .176 12.4 7 .1443 fofl 20,822 .152 15.7 .158 15.6 8 .1285 1 16,512 .136 19.8 .142 19.6 9 .1144 1 13,087 .121 24.9 .125 24.7 10 .1019 1 10,384 .108 31.4 .113 31.1 11 .0907 1 8,226 .097 39.5 .102 39.1 12 .0808 n 6,528 .087 49.6 .092 49.2 13 .0720 H 5,184 .078 62.5 .083 61.7 14 .0641 H 4,108 .070 78.6 .075 77.5 15 .0571 1* 3,260 .063 98.9 .068 97 16 .0508 1* 2,580 .056 125 .060 122 17 .0453 11 2,052 .050 157 .054 153 18 .0403 1* 1,624 .045 198 .050 192 19 .0359 If 1,288 .041 248 .045 240 ELECTRICAL TABLES ANp DATA ENAMELED MAGNET WIRE Enamel insulation has a dielectric strength far in excess of silk or cotton covered wire. It will also withstand a much greater heat, as silk and cotton insulation will char at 270° Fahr., whereas enamel insulation will withstand 450° Fahr. without the slightest deterioration. Another decided feature about enamel insulation is the economy of space where this material is used for coil windings, and it takes up much less space than the single silk insulation. This feature is a very important one, especially to manufacturers of electrical instruments and apparatus where space economy is essential. TABLE XIX m acM Diam. Approx. Approx. Dlam. Approx. Approx. n . Enam. Feet Turns per Size Enam. Feet Turns per- izjffl Wire per Lb. Sq. In. B. & S. Wire per Lb. Sq. In. 16 126 359 29 .0122 2570 7900 17 159 447 30 .0109 3240 10000 18 .... 201 567 31 .0097 4082 12620 19 .... 253 715 32 .0087 5132 16020 20 .0337 320 885 33 .0077 6445 20400 21 .0302 404 1126 34 .0069 8093 25200 22 .0269 509 1400 35 .0062 10197 31900 23 .0241 642 1736 36 .0055 12813 40000 24 .0215 810 2160 37 .0049 16110 51600 25 .0192 1019 2770 38 .0044 20274 65700 26 .0171 1286 3460 39 .0039 25519 81600 27 .0153 1620 4270 40 .0035 32107 104000 28 .0136 2042 5400 * <64 ELECTRICAL TABLES AND DATA TABLE XX Table for Insulated Copper Wire. (Belden Manufacturing Co.) Single Cotton, Double Cotton, Single Silk, Double Silk, Total Insulation Total Insulation Total Insulation Total Insulation Thickness 4 Mils. Thickness 8 Mils. Thickness 1% Mils. Thickness 4 Mils. 21 Ohms per pound Feet Ohms per per pound pound Feet per pound Ohms per pound Feet per pound Ohms per pound Feet per pound 20 3.15 311 3.02 298 3.24 319 3.18 312 21 4.99 389 4.72 370 5.12 403 5.03 389 22 7.88 488 7.44 461 8.15 503 7.96 493 23 12.44 612 11.7 584 12.92 636 12.65 631 24 19.55 762 18.25 745 20.50 800 19.95 779 25 30.8 957 28.45 903 32.50 1005 31.5 966 26 48.6 1192 44.3 1118 51.29 1265 49.7 1202 27 76.45 1488 68.8 1422 82.00 1590 78.3 1542 :28 120. 1852 106.5 1759 129.00 1972 123.5 1917 29 188.5 2375 164. 2207 205.00 2570 194. 2485 30 294.6 2860 252. 2534 328.5 3145 306.5 2909 31 460.5 3800 384.5 2768 512.3 3943 477. 3683 32 716. 4375 585. 3737 810.0 4950 747. 4654 33 1117. 5390 880. 4697 1277.5 6180 1165. 5689 34 1720. 6580 1315. 6168 2018. 7740 1810. 7111 35 2642. 8050 1960. 6737 3175. 9680 2820. 8534 36 4060. 9820 2890. 7877 4970. 12000 4340. 10039 37 6190. 11860 4230. 9309 7940. 15000 6660. 10666 38 9440. 14300 6150. 10666 12320. 18660 10250. 14222 39 14420. 17130 8850. 11907 19200. 23150 15600. 16516 40 22600. 21590 12500. 14222 30200. 28700 23650. 21333 ELECTRICAL TABLES AND DATA TABLE XXI Table of Diameters (d) and Square of Diameters (d2) fop Insulated Copper Wire. \.&s. Double ) Cotton Singh Cotton Single Silk d d2 d d2 d d2 20 .040 .0016 .036 .001296 .034 .001156 21 .036 .0013 .032 .00102 .030 .0009 22 .033 .00109 .029 .00084 .027 .00073 23 .031 .00096 .027 .00073 .025 .000625 24 .028 .000784 .024 .000576 .022 .000484 25 .026 .000675 .022 .000484 .020 .0004 26 .024 .000575 .020 .0004 .018 .000324 27 .022 .000484 .018 .000324 .016 .000256 28 .021 .000441 .017 .000289 .015 .000225 29 .019 .00036 .015 .000225 .013 .000169 30 .018 .000324 .014 .000196 .012 .000144 31 .017 .000289 .013 .000169 .011 .000121 32 .016 .000256 .012 .000144 .010 .000100 33 .015 .000225 .011 .000121 .009 .000081 34 .014 .000196 .010 .000100 .008 .000064 35 .0136 .000185 .0096 .000092 .0076 .0000576 36 .013 .000169 .009 .000081 .007 .000049 37 .0124 .000155 .00845 .000073 .00645 .0000415 38 .012 .000143 .008 .000064 .006 .0000362 39 .0115 .000132 .0075 .000056 .0055 .0000303 40 .0111 .000123 .0071 .0000504 .0051 .000025 66 ELECTRICAL TABLES AND DATA Elevators. — Electric motors are used direct con- nected or belted; in some cases they are used to pump water for hydraulic elevators. Motors should be capable of exerting a strong starting torque, and are generally compounded. Means are usually pro- vided for cutting out the compound winding, or otherwise weakening the field to obtain high speeds. To prevent sparking at the brushes, commutating poles are frequently used. The ordinary commer- cial motor is seldom used for elevator service. The methods of speed control with d. c. motors consist in weakening the field and cutting resistance out or in; dynamic braking is also used in some cases for slowing down. With a. c. motors wound rotors are often used. Single phase as well as two and three phase motors are practicable, and variable speed motors are often employed. Hydraulic elevators require about 1.7 as much power as direct connected. A.-c. elevator motors under the same conditions require about 20 to 30 per cent more power than d. c. motors. The H. P. required can be found by the formula 33,000xe where 1 = unbalanced load in pounds, 5 = speed in feet per mmute, e = combined efficiency of motor and ele- vator machinery. This is usually about 0.50. The speed of freight elevators often runs as low as 65 to 85 feet per minute, while some passenger elevators run as fast as 700 feet per minute. As the load is always intermittent motors may be rated high, and the starting torque is from two to two and one-half times running torque. The following table gives the H. P. required to lift various loads at speeds given ; a combined efficiency of 50 per cent being assumed. ELECTRICAL TABLES AND DATA TABLE XXII Table showing H. P. required to lift unbalanced loads at ~.s given. Efficiency of 50 per cent assumed. in Feet Per Minute Lbs. 75 100 125 150 200 250 300 400 500 1000... 4.5 6.1 7.6 9.1 12.1 15.1 18.2 24.2 30.2 1250... 5.7 7.6 9.5 11.4 15.2 19.0 22.8 30.4 38.0 1500... 6.8 9.1 11.4 13.6 18.2 22.8 27.2 36.4 45.6 1750... 7.9 10.5 13.3 15.8 21.0 26.6 31.6 42.0 53.2 2000. . . 9.1 12.1 15.2 18.2 24.2 30.4 36.4 48.4 60.8 2500... 11.3 15.1 19.0 22.6 30.2 38.0 45.2 60.4 76.0 3000... 13.6 18.2 23.7 27.2 36.4 47.4 54.4 72.8 94.8 3500... 15.9 21.2 27.5 31.8 42.4 55.0 63.6 84.8 110.0 4000... 18.2 24.2 30.4 36.4 48.4 60.8 72.8 96.8 121.6 4500... 20.4 27.3 34.2 40.8 54.6 68.4 81.6 109.2 136.8 5000... 22.7 30.3 38.0 45.4 60.6 76.0 90.8 121.2 152.0 6000... 27.2 36.4 45.4 54.4- 72.8 90.8 108.8 145.6 181.6 Emergency Lighting. — This is usually required in churches, theatres and other places where large num- bers of people congregate. The purpose is to pro- vide a system of illumination which shall be in service if the main system should fail. In large cities the emergency lighting is supposed to be used during the entire time the audience is in the build- ing. An entirely independent and separate service should be provided for it, and there should be no switches or fuses except those absolutely necessary. Equalisers. — Equalizer wires are used in connec- tion with two or more compound generators operated in parallel. All connections must be to the same terminal with series field. Wires should be led to switchboard, and connected to middle blade of switch. Arrange switch blades so that equalizer will be connected slightly ahead of other wire. The lower the resistance of the equalizer, the closer will be the regulation of the machines. Never con- nect ammeter on same side with equalizer. 68 ELECTRICAL TABLES AND DATA Factors. — Assurance Factor.— This is the ratio of the voltage at which a wire or cable is tested to that at which it is to be used. Demand Factor. (See Demand Factor). — This is the ratio or the maximum demand of any system, or part of a system, to the total connected load of the system, or of the part of the system under consider- ation. Diversity Factor. — The diversity factor of any part of a system of distribution is the ratio of the sum of the maxima of the subdivisions to the maxi- mum demand on the source of supply during some given time. To find the diversity factor we divide the sum of the maxima of the consumers during a given period of time by the maximum registered at the source of supply during the same time. If all consumers use their maximum energy at the same instant the diver- sity factor is 1. A large diversity factor is a dis- tinct advantage. In a central station system a cer- tain diversity factor will be found to exist between the consumers maxima, and the transformer serving them; between the various transformers and the main serving them there will be another diversity factor; between the mains and their feeder still another will exist, and so on between mains, sub- stations, transmission lines, and central station. The diversity factor of the last station is found by multi- plying together all the other diversity factors. Average diversity factors for a large central sta- tions as given by Gear & Williams are : Residence lighting. Diversity factor from 3.32 to 3.40. Commercial lighting. Diversity factor from 1.40 to 1.51. General power. Diversity factor from 1.39 to 1.60. Load Factor. — The load factor is the ratio of the average load to the maximum load demanded by a ELECTRICAL TABLES AND DATA 6& consumer, a group of consumers connected to a sin- gle transformer, a group of transformers, feeders, mains, transmission lines, substations, generators, or central stations. For each of these on the same sys- tem it has a different value which is found by divid- ing the average load by the maximum load. A low load factor is a disadvantage. The following data are condensed from fables pub- lished by Gear & Williams in ' ' Electric Central Sta- tion Distributing Systems." Eesidence lighting. Individual consumer's average load factor =7%. Transformer load factor = 23% to 24%. Commercial lighting. Average consumer's load factor = 10% to 13%. Transformer load factor = 15% to 19%. General power. Average consumer's load factor = 15% to 21%. Transformer load factor =21% to 30%. Plant Factor. — This is the ratio of the average load to /the rated capacity of the power plant. Power Factor. — The power factor is the ratio of the true power to the volt-amperes. In the case of sinusoidal voltage and current, the power factor is equal to the cosine of their difference in phase. The power factor is always less than unity and may be either lagging or leading. Reactance Factor. — This is the ratio existing be- tween the reactance of a circuit, and its ohmic resist- ance. Reactive Factor. — The reactive factor expresses the ratio of the wattless volt-amperes to the total volt-amperes. It is equal to the reactance divided by the impedance, which is equal to the sine of the angle between the impressed voltage and the current. Safety Factor.-^-The ratio of the strength of ma- terial to the load to which it is to be subjected. It is 70 ELECTRICAL TABLES AND DATA common practice to use a safety factor of 4 or 5. Saturation Factor. — The saturation factor of a ma- chine is the ratio of a small percentage increase in the field excitation, to the corresponding increase in voltage thereby produced. Factories. — It is an old custom to illuminate fac- tories by means of small c. p. lamps distributed among machinery so as to give each workman in need of it one lamp. Since the advent of the large wattage tungsten, or Mazda lamps, this has been somewhat changed. The change has been further helped along by individual drive machinery which has eliminated the belting and shafting. Where the work is not particular, one 100 watt tungsten lamp, if kept clean, to every 200 or 300 square feet of floor surface will give good results. Where particular work is done this illumination must be helped out by a 15 watt local lamp. A general illumination has the advan- tage that it will not have to be changed every time a machine is moved, which frequently happens. Where individual lighting for machinery is to be provided it will be well to avoid placing lamps before the machinery is located ; plans are seldom reliable. The mercury vapor lamp gives a very serviceable illumin- ation for some purposes, but it is said that fine ma- chine work is not well done under it ; also because of the ghastly appearance is gives faces, many men do not like to work under it. Oil dissolves rubber very fast, and when flexible cord is used around machinery it is well to encase it in loom. To avoid interference with open wires run them as far as possible between joists or along beams. Drop all lights from ceiling and never use floor pockets or side wall outlets. Make ample provision for glue pots and small portable motors. (For hints on motors, see Motors.) Fans. — (See Ventilation.) ELECTRICAL TABLES AND DATA 71 Farad. — The practical unit of capacity. A con- denser or conductor in which a charge of one coulomb (1 ampere for 1 second) produces a p. d. of one volt has a capacity of one farad. The farad is much too large for practical work, and micro-farads' are used. A condensor of two or three micro-farads is quite large. Faradic Current. — This term is used in therapeu- tics, and designates the current taken from an induc- tion coil as distinguished from a galvanic or direct t-.urrent. Faure Plate. — In this type of storage battery plate, the active material is pasted onto the supporting material, instead of being formed there. This type of plate is used mostly for vehicles. It gives a maxi- mum of capacity with a minimum of weight. Feeders. — These are the wires which start from a central station, substation, or other center and feed a group or center from which mains supply translating devices. The term is always rather loosely used. There may be feeders and sub-feeders. A voltage of about 1,000 per mile of feeder length is customary. Festoons. — Festoons to be strung across streets are usually wired with number 8 or 10 wire, and weather- proof sockets. As a rule they are supported in the center of the street, and swung from pulleys which allow of lowering for lamp renewals, etc. In order to allow for graceful hanging the wires should be from 1.3 to 1.6 times the width of street. Lights are usually spaced from 18 inches to two feet apart. At street intersections two festoons are often swung diagonally across, and in such a case the length of wire should be two times the width of street. The supporting cables from which the festoons are swung are attached to buildings and poles on opposite side of street and in many cases they must be run diag- onally to find attachments which will allow the fes- 72 ELECTRICAL TABLES AND DATA toon to come in its proper place. This often necessi- tates very long spans and requires strong cables. Three-eighths and half-inch steel cables are often used. Where festoons are swung over trolley lines strain insulators are used. Festoons for theatre work are made up of stage cable and weatherproof sockets; joints are staggered, and taped to prevent strain on joints. Fiber. — This, in general, is a serviceable insulating material, but on account of the fact that it does not resist moisture, and swells and warps when wet, it is not approved for light and power voltages. Field.— This term describes either a magnetic, or an electrostatic field. Field magnets are the electro- magnets which produce the electric field in which the armature revolves. Field coils are the coils in which the magnetizing current circulates. A field rheostat is one which regulates the current in the field coils. A field of force is the space traversed by an electro- static, or magnetic flux. The field windings of induc- tion motors are those in which the rotating field is produced. Fire Alarms. — May be either automatically, or manually operated. In the manual system a glass disk is usually broken to send in an alarm. In the automatic system a fuse opens, or closes a circuit and sends in the alarm. A system in which the cur- rent is constantly flowing is always preferable be- cause it is always under test, and failure of any kind will send in an alarm. Means of testing without sending in alarms should be provided. The common fire alarm telegraph system consists of boxes con- taining notched wheels which are released when the box is pulled, and send in the code signal. Fish Work. — For light and power voltages ar- mored cable, or single rubber covered wires in cir- cular loom are used; never use twin wire. When ELECTRICAL TABLES AND DATA 73 one is alone on a fish job, a bell and battery con- nected to the fish wire with one pole, and to a coil of wire inserted in the hole at the other end with the other, is very useful. When the fish wire touches the other wire the bell will ring. Use a small chain for dropping and a spring wire for other work. Fixtures. — The height of hanging varies from 6 feet 2 inches to 7 feet. The so-called art-domes are hung much lower, but they are a passing fad. Memorandum of Fixture Work Name Eoom or Circuit Number Address No. of gas lights ^ Style of finish . £h Catalogue number T3 Sketch number Size of holders Height lowest point above floor Size of gas stub No. of elec. lights Kind of sockets No. gas lights * Style of finish a Sketch number (£} Kind of glassware Catalogue number Height above floor Size gas stub No. switches Kind of switch Style of finish 74 ELECTRICAL TABLES AND DATA The standard height of brackets is from 5£ to 6 feet above floor. No fixture should ever be selected except with reference to the room in which it is to be hung, and it should be neither conspicuous for its expensiveness or cheapness. Elaborate fixtures made up of cheap material should never be used; pretense is always abomina- ble. Before installing, test each fixture for con- tinuity, short circuits and grounds ; move wires while Figure 6. — Method of Tying Knots in Flexible Cord. testing. The following memoranda will be of use in ordering fixtures: Flashers on branch circuits usually operate single pole. In such a case one-half of the cut-outs may be located at flasher, the other half, if more convenient, in the sign. Although the flasher allows the use of only a part of the lights at a time, it is customary to run mains for the full requirements of all the lights. Flat Irons constitute a considerable fire hazard and every precaution should be taken to install them safely. A pilot lamp is very useful. Provide extra flexible cord to help out the cord furnished with iron so the two will be long enough to allow iron to fall to the floor without straining fixture or other attach- ment. The common domestic flat irons weighing ELECTRICAL TABLES AND DATA 75 from 3 to 8 lbs. require from 250 to 635 watts. A substantial metal stand should always be provided and should separate the iron about 2-J inches from cloth on board. Flexible Cord improperly used causes the majority of electrical fires. The common cord should always hang free in air ; should never be spliced, and should be soldered only where it connects to line wires. In sockets, rosettes, and outlet boxes it must be knotted to prevent strain from coming on the joints. The best method of tying knots is shown in Figure 6. Foundries. — The general illumination of foundries is commonly effected by means of arc lamps or clus- ters of incandescent lamps. The flaming arc is very effective. Strong shadows are useful, as all objects soon assume the same color. Cleaning of lamps is an important item and for this reason clusters of incandescent lamps are often encased in outer globes, which are more easily cleaned. In addition to the general illumination, each molder requires an indi- vidual lamp for his 'own use. Frequencies. — A frequency of 25 cycles per second is generally used for rotary converter work, and power transmission. Arc and incandescent lamps do not operate well with such low frequencies, hence a frequency of 60 cycles is generally used for illumina- tion. In any given circuit, the higher the frequency, the greater will be the reactance. If the frequency is too high for a given device the current will be insufficient, if too low it will be excessive. A fre- quency changer is a machine usually installed in substations. A frequency indicator is usually in- stalled upon switchboards, or used in connection with a large motor installation. Fuses. — Fuses are divided into three general classes: open, enclosed, and expulsion. The fuse metal itself is never hard enough to stand up well 76 ELECTRICAL TABLES AND DATA under binding screws, hence copper tips are neces- sary. If these are not used there will be much un- necessary blowing 1 . All fuses should be placed in cabinets not only to prevent molten metal from caus- ing fires, but to insure greater reliability of the fuse by protecting it against drafts. The fusing of branch, and main circuits inside of buildings is thoroughly covered by the National Electrical Code. The rule in general is to provide fuse protection wherever the size of wire changes. The fuse to be of such size as to prevent current rise above the safe carrying ca- pacity of wires as given in the Code. Each motor or other translating device also requires separate fuse protection except that small devices aggregating not more than 660 watts capacity may be grouped under one fuse. All plans of fusing are a compromise between the desire to obtain adequate protection on the one hand, and escape the trouble caused by the many accidental breaks and uncalled for operations of fuses. Overhead systems as a rule are not fused where they leave the switchboard, but are equipped with switches or disconnectives. Feeders leaving the transmission lines are also usually left without fuse protection, but equipped with disconnectives. Fuse protection is fully demanded only where the chances of short circuits or grounds are quite great, and this point is not reached until the transformers are reached. It must be borne in mind that all con- sumers devices are protected by service fuses and switches, and these protect the outer lines fully against everything except what occurs on the poles. The primary side of transformers of small and me- dium capacity is usually protected by fuses, but the fuses are made large enough so that ordinary over- loads will not cause them to blow. ELECTRICAL TABLES AND DATA 77 TABLE XXIII The following table gives fuse sizes often used with transformers of the capacities given. K.W. Capacity Size Fuse K.W. Capacity Size Fuse Amperes Amperes 13 15 15 2 3 20 15 3 ' 3 25 20 4 3 30 20 5 5 40 30 7Y 2 10 50 40 10 10 On the secondary side of transformers, fuses are not ordinarily used and it is not advisable to have them. In case a number of transformers feed a net- work the blowing of one fuse may cause the blowing of another, etc., until all are out. Under such cir- cumstances fuses cannot well be replaced until the load on the main is sufficiently reduced to allow one transformer to carry it, or until the feeder supplying the network has been opened ; in this case the feeder must be left open until all fuses have been replaced. In connection with underground circuits the case is different. Here short circuits and grounds are much more likely to occur. Such systems also always sup- ply a much larger number of customers within a given space, and more care is necessary. Under- ground networks are usually fused at each junction point so that, if an overload causes one fuse to blow, the other will follow and clear the balance of the circuits from trouble. Wherever parallel lines are run they should be equipped with reverse current circuit breakers. Three phase four wire systems are usually provided with a single pole switch in each leg, thus any phase can be disconnected without in- terfering seriously with the others. For three phase three wire systems three pole switches are used. All telephone circuits should be protected by fuse and 78 ELECTRICAL TABLES AND DATA in addition with " sneak coils" and air gap arresters. Heat coils are arranged to open the circuit when a small or "sneak current " has passed through them for a considerable time, or a large current in an instant. Air gap arresters are supposed to open the circuit whenever unduly high potentials come to exist at their terminals. TABLE XXIV Tested Fuse Wire from y 2 to 100 Amperes Safe Best Len g-ths for Use Carrying and Fusing- Cur- Length Mils. Capacity- rents for such Per Lb Diam Amperes Lengths Inches Amperes Ft. In % 1 11/2 2550 10 % 1 2i/i 1516 13 1 IV 3 993 16 2 1% 5 407 25 3 1% 7 265 31 4 1% 9 207 35 5 1% 10 167 39 6 2 12 144 42 7 2 13 120 46 8 2 15 .106 49 9 2 16 94 52 10 2% 17 84 55 12 2% 20 68 61 14 2% 23 58 66 15 2% 24 55 68 16 2i/ 2 25 49 72 18 2y 2 28 43 77 20 2y 2 30 37 10 82 25 2% 37 28 9 94 30 ■2% 43 24 103 35 3 49 20 113 40 3 56 17 2 122 45 3 62 15 4 129 50 3 69 13 6 137 60 3% 81 10 3 158 70 3V4 ( 93 8 10 170 75 31/2 99 7 9 182 80 - 3% 106 7 2 189 90 31/2 118 5 8 212 100 4 129 5 ELECTRICAL TABLES AND DATA 79 Tested Fuse Strip from 50 to 600 Amperes Safe Best Lengths ! for Use Weight Carrying and Fusing Cur- Per Foot Capacity rents for ; such Ounces Amperes Lengths Inches Amperes 50 3 69 1% 60 3% 81 1% 70 3% 93 1% 75 3V 2 99 1% 80 3y 2 , 106 2.% 90 . 3% 118 2y 2 100 4 129 3 125 4y 4 158 3% 150 1 4i/2 — 187 4% 175 4% 215 6 200 4% 243 6% 225 4% 270 7% 250 4% 298 8% 275 4% 325 9% 300 5 351 10% 350 5% 402 12% 400 5%l 450 14% 450 5V 2 500 17 500 6 550 2oy 2 600 ey 2 675 35 The current required to fuse metals can be found by the well known Preece formula: where I— current in amperes, d = diameter of wire, and a = a constant for different kinds of metal as given below : Copper 10244 Iron 3148 Aluminum 7585 Lead 1379 German Silver 5230 80 ELECTRICAL TABLES AND DATA The table below is calculated from the above for- mula and constants, and gives the current required to fuse wires of various sizes. TABLE XXV B. &S. Copper Aluminum German Silver Iron Lead 4 942 698 481 290 127 6 666 493 339 204 90 8 471 349 240 145 63 10 334 247 171 103 50 12 235 174 120 72 32 14 165 122 84 51 22 16 117 86 60 35 16 18 82 60 42 25 11 20 58 43 29 18 8 21 49 36 25 15 6 22 40 29 21 12 5 23 36 26 19 11 5 24 29 21 15 9 4 25 25 18 13 8 3 26 20 15 11 3 27 17 12 9 5 2 28 14 10 7 4 2 29 12 9 6 4 1.5 30 10 8 5 3 1.2 31 8.5 6 4 2.6 1.0 32 7.0 5 4 2.2 0.9 The strands of which flexible cord is made up range from No. 26 to 36. Galvanic. — A term much used in therapeutics to denote continuous, or direct current. ELECTRICAL TABLES AND DATA 81 Garages. — The gasoline vapors so prevalent in garages do not ordinarily rise more than 4 feet above the floor. Avoid all possibility of electric sparks at this level, especially in pits. Electric lights should be well guarded with elastic lamp-guards which will protect the lamp against breakage even when it falls. Gas Lighting' may be effected by pilot flame, a small quantity of sponge platinum on mantle, or by high-tension electric sparks jumping a number of spark gaps in the gas jets, or low-tension sparks applied to jets in multiple. A spark coil is required and it should be connected with a tell-tale relay and bell which will ring in case the system becomes grounded. Electric gas lighting wires must not be used on same fixtures with electric light. Gauges. — The American, or Brown & Sharp wire gauge, abbreviated respectively A. W. G. or B. & S., is the one commonly used for measuring copper,, aluminum, and resistance wires in general. The U. S. steel wire gauge is commonly used for steel and iron wire. This is also known as the Washburn and Moen ; Koebling, and American Steel and Wire,, and is generally abbreviated Stl. W. G. The Birmingham or Stubs' Wire Gauge is some- times used for brass wire. It is commonly abbre- viated B. W. G. This, although spoken of as Stubs, is not identical with the Stubs' Steel Wire Gauge. The British Standard Wire Gauge, the Edison Wire Gauge and the Stubs ' Steel Wire Gauge are not much used in this country in electrical work. A compari- son of the different wire gauges is given below, diameters being given in mils (thousandths of an inch). ELECTRICAL TABLES AND DATA CIRCULAR OF THE BUREAU OF STANDARDS TABLE XXVI Tabular Comparison of Wire Gauges. Diameters in Mils. d © fcJO o3 c3 O 4£s o £ © o3 bD bo os O h 05 cc bX) II? •"£ .M i— i 05 !.§ oa£ 05 - bJD ,£3 ?-. eS £ 2 05 d Q5 bO 7-0 490.0 500. 7-0 6-0 461.5 464. 6-0 5-0 430.5 432. 5-0 4-0 460. 393.8 454. 454. 400. 4-0 3-0 410. 362.5 425. 425. 372. 3-0 2-0 365. 331.0 380. 380. 348. 2-0 325. 300.5 340. 340. 324. 1 289. 283.0 300. 300. 227. 300. 1 2 258. 262.5 284. 284. 219. 276. 2 3 229. 243.7 259. 259. 212. 252. 3 4 204. 225.3 233. 238. 207. 232. 4 .5 182. 207.0 220. 220. 204. 212. 5 6 162. 192.0 203. 203. 201. 192. 6 7 144. 177.0 180. 180. 199. 176. 7 8 128. 162.0 165. 165. 197. 160. '8 9 114. 148.3 148. 148. 194. 144. 9 10 102. 135.0 134. 134. 191. 128. 10 11 91. 120.5 120. 120. 1S8. 116. 11 12 81. 105.5 109. 109. 185. 104. 12 13 72. 91.5 95. 95. 182. 92. 13 14 64. 80.0 83. 83. ISO. 80. 14 15 57. 72.0 72 72. 178. 72. 15 16 51. 62.5 65. 65. 175. 64. 16 17 45. 54.0 58. 58. 172. 56. 17 18 40. 47.5 49. 49. 168. 48. 18 19 36. 41.0 42. 40. 164. 40. 19 20 32. 34.8 35. 35. 161. 36. 20 .21 28.5 31.7 32. 31.5 157. 32. 21 22 25.3 28.6 28. 29.5 155. 28. 22 ELECTRICAL TABLES AND DATA © © bjo Pi o American Wire Gauge (B. & S.) 22 CD r-< Birmingham Wire Gauge (Stubs') Old English Wire Gauge (London) U 1 © OJ fejo I.S (British) Standard Wire Gauge d CD bn O 23 22.6 25.8 25. 27.0 153. 24. 23 24 2CL1 23.0 22. 25.0 151. 22. 24 25 17.9 20.4 20. 23.0 148. 20. 25 26 15.9 18.1 18. 20.5 146. 18. 26 27 14.2 17.3 16. 18.75 143. 16.4 27 28 12.6 16.2 14. 16.50 139. 14.8 28 29 11.3 15.0 13. 15.50 134. - 13.6 29 30 10,0 14.0 12. 13.75 127. 12.4 30 31 8.9 13.2 10. 12.25 120. 11.6 31 32 8.0 12.8 9. 11.25 115. 10.8 32. 33 7.1 11.8 8. 10.25 112. 10.0 33 34 6.3 10.4 7. 9.50 110. 9.2 34 35 56 9.5 5. 9.00 108. 8.4 35 36 5.0 9.0 4. 7.50 106. 7.6 36 37 4.5 8.5 6.50 103. 6.8 37 38 4.0 8.0 5.75 101. 6.0 38 39 3.5 7.5 5.00 99. 5.2 39 40 3.1 7.0 4.50 97. 4.8 40 41 6.6 95. 4.4 41 42 6.2 92. 4.0 42. 43 6.0 88. 3.6 43 44 5.8 85. 3.2 44 45 5.5 81. 2.8 45 46 5.2 79. 2.4 46 47 5.0 77. 2.0 47 48 4.8 75. 1.6 48 49 4.6 72. 1.2 49 50 4.4 69. 1.0 50 The American Wire Gauge sizes have here been rounded off to about the usual limits of commercial accuracy. The Steel Wfrre Gauge is the same gauge which has been known by the various names: li Washburn and Moen, " "Boebling," " American Steel and Ware Co. 's." Its abbre- viation should be written ' ' Stl. W. G ., ' ' to distinguish it front "S. W. G., " the usual abbreviation for the (British) Stand- ard Wire Gauge. 84 ELECTRICAL TABLES AND DATA Generators. — Alternating Current generators may be of the revolving field or revolving armature type. The revolving field type is easier to insulate and less troublesome to maintain, hence is most widely used. There is another, known as an inductor type, in which usually all electrical parts are stationery and an iron spider is caused to revolve, it being so arranged as alternately and regularly to alter the magnetic flux and thus cause induction of e. m. f . This type is not much used. The so-called Induction generator is another type, and is similar to an induction motor; in fact, an induction motor, when driven above the speed of synchronism becomes an induction generator, and delivers current to the line. This type of generator cannot operate unless other alternators provide it with the necessary exciting current. The capacity in generators for field excitation must be nearly equal to one-third of the capacity of the induction gener- ators. This type of generator is well suited for fluc- tuating speeds such as are given by gas engines, but it can never constitute an entire plant. Alternating current generators are made to operate single-phase, two-phase and three-phase. The single-phase machine is not well suited for power work, and is more expen- sive per unit of output than polyphase machines. The two-phase generators are, as a rule, used only on old direct current installations which have been adapted to a.-c. operation. The three-phase system is the most economical and is almost universally used. It is well suited for either light or power transmission. Alternators may be built to be self -exciting, bui this is not often done. Most of them require a direct current exciter. Efficiency. — Approximate efficiencies of generators of various sizes are given about as follows: 100 K.V.A., 91 per cent; 500, 94; 1,000, 95; 2,000, 96; ELECTRICAL TABLES AND DATA 85 3,000, 96 to 97 ; 5,000, 97 or better. These efficiencies vary of course with the power factor, load, voltage, etc. Frequency. — The common frequencies are 25 and 60 cycles per second, the lower being used for trans- mission to substations and for power alone. The higher frequency is used for mixed lighting and power, and also for lighting alone. In a single-phase machine the current and voltage per phase have but one meaning. The power is equal to Zx^xpower factor, and the product of volts and amperes gives the volt-ampere rating of the machine. In a two- phase alternator each half supplies half of the cur- rent and power. The usual four transmission wires are sometimes combined into three wires, and in such a case the voltage between the two outside wires is 1.41 times the phase voltage, and the current in the middle wire is 1.41 times the current in the outside wires. The power in such a combination may be found in two ways. Measuring current in the middle wire and the voltage across both phases, the power is equal to IxE x power factor. Measuring current in one of the outside wires, and using phase voltage, the power is equal to / x 2? x 2 x power factor. Three- phase generators are always connected by means of 3 main wires, and sometimes a neutral, but may be either delta or star. If the delta connection is used, the phase voltage is the same as the voltage between any two wires, but the current in any phase is 1.73 times the current in any one of the wires. If the star connection is used, the voltage between any two wires is 1.73 times the voltage of any phase winding, and the current to deliver the same power will be only 0.58 of the former current in the line wires. The power with either connection is equal to 7x2£xl.73x power factor* Frequencies. — The common frequencies are 60 and 86 ELECTRICAL TABLES AND DATA 25 cycles. The higher frequency is used for light, and mixed light and power loads. The lower is used for power alone and also for transmission lines to substations or converters. The frequency of any gen- erator depends upon the speed and number of poles and may be found by the formula: ._ r. p.m. number of poles '" 60 X 2 The table below shows the speeds at which gener- ators provided with a certain number of poles must operate to deliver current at the frequencies given. TABLE XXVII 60 Cycles. No. Poles. . . . .... 4 8 12 16 20 24 R. P. M ....1,800 900 600 25 Cycles. 450 360 300 No. Poles.... .... 4 8 12 16 20 24 E. P. M .... 750 375 250 187i/ 2 150 125 Operation of Alternators in Parallel. — In order that alternators may be operated in parallel they must be identical in four respects. The frequency must be the same. The voltage must be the same. The current and voltages must be in phase, i.e., their maxima and minima must occur at the same instant. The wave form of the machines should be as near as possible alike. The frequency is governed by the speed, and. if it is not correct, the speed must be adjusted either by ELECTRICAL TABLES AND DATA 87 adjusting the engine, or diameters of pulleys. The voltage can be determined by a voltmeter test. Whether the machines are in or out of phase can be determined only by properly connected synchroniz- ing lamps, or synchronizing instruments. The synchronizing and keeping in step of alter- nators will be made easier by synchronizing the piston strokes of engines as far as possible if they are sepa- rately driven, or, if driven from a common shaft, by running one of the machines with a slack belt, which will allow it to fall in step more readily. "Where synchroscopes are used the pointer will indicate which machine is running too fast or too slow: Where the synchronizing is done with lamps they may be con- nected so as to indicate synchronism either by dark- ness or light. If the machines are not in phase there will be alternations of darkness and light in the lamps which will alternate with great rapidity if the ma- chines are much out of synchronism, but will be at longer and longer intervals as they are brought more nearly into step. The proper time to close the switch is just a moment before the period of full darkness. If the machines are nearly in synchronism when thrown together, there will be cross current which will help to bring them together, but it is best to have them synchronized perfectly before connecting. The load cannot be divided among alternators by increasing the field excitation as with direct-current machines; it is necessary to give more steam to the engine of the light running generator. This tends to advance the generator and causes it to take more cur- rent. The power factor can be improved or altered by adjusting the field excitation. Adjust fields so that power factor of each machine is the same. Single Machine, Operation of. — See that machine is entirely disconnected from the load. Inspect all bearings and see that they are well oiled and that oil 88 ELECTRICAL TABLES AND DATA rings work properly. Adjust field rheostat so that all resistence is in circuit and close exciter circuit. Start machine, bringing it gradually up to speed and cutting out resistance in field rheostat until generator voltage comes to its proper value. Next throw in switches, bringing load on gradually if possible, and adjust rheostat to maintain voltage properly. Test speed to see that it is at its proper value ; the speed is of greater importance with alternators than with direct current generators. Rating. — For full details as to rating, the reader is referred to the Standardization Eules of the A. I. E. E., which are too lengthy to be given here. The maximum, or continuous, rating of an alter- nator is commonly taken as the load in kilowatts it can carry at 100 per cent power factor with a maxi- mum rise in temperature of any part of 50° C. (122° F.) above the surrounding air when that is 25° C. (77° F). Corrections for other surrounding temperatures to be made according to A. I. E. E. Standardization Rules. Another rating, used mostly in connection with street railway work, allows a tem- perature rise of 45° C. (113° F.) under the same conditions as above, and requires that 50 per cent more than the rated load used for two hours shall not cause a temperature rise of more than 55° C. (131° F.). Voltage. — A voltage in excess of 12,000 or 13,000 is rarely generated direct; higher line voltages are ob- tained mostly by step-up transformers. Direct Current Generators, Compound Machines. — This is a combination of shunt and series dynamo, and a distinct improvement over the shunt machine. The compound winding can be adjusted to regulate the voltage as desired. It requires the same instru- ments as the shunt, and in addition heavy equalizing ELECTRICAL TABLES AND DATA 89 wires run between each pair of machines. These should be carried to the board and the main switch should be triple pole. The machine may be connected either long shunt (shunt winding bridging compound fields as well as armature), or short shunt (shunt field bridging only armature) ; it is merely a ques- tion of convenience. All these machines may be bi-polar or multi-polar, direct or belt connected and provided with com mutating or interpoles. Bating. — Machines are commonly rated on the basis of their continuous output in kilowatts with a maximum rise in temperature of 50° C. (122° F.) above the surrounding air at 25° C. (77° F.). For full information see A. I. E. E. Standardization Rules. The common voltages are 110 volts for light- ing and small power (used mostly in isolated plants) ; 220 to 250 also for lighting and power, but used mostly in larger plants, and for short distance dis- tribution; 500 to 600 volts, used almost exclusively for street railway work ; 2,000 to 6,000, or more, used for series arc lighting by direct current. The Series Machine is used only for constant cur- rent work. It requires the following instruments and fittings : Short circuiting switch for fields. Ammeter, a switchboard equipped with plugs and jacks. A polarity indicator is often advisable. The Shunt Machine is used for all variable current work. Its voltage regulation is poor, and requires constant attention. It requires a field rheostat, fuses, main switch or circuit breaker, volt meter, ammeter, ground detector, switchboard and pilot lamps. The voltage of this machine is variable and automatically decreases with an increase in the devices it supplies. Greek Alphabet. — Greek letters have become the standard symbols for many quantities dealt with in $0 ELECTRICAL TABLES AND DATA electrical and mechanical calculations. The letters and their pronunciations are given below: A a — Alpha. I i — Iota. P p — Rho. B (3 — Beta. K k — Kappa. 5 o- — Sigma. r y — Gamma. A X — Lambda. T r — Tau. A 8 — Delta. M /x — Mu. Y v — Upsilon. E e — Epsilon. N v — Nu. 3> — Phi. Z £ — Zeta. S £ — Xi. X x — Chi. H rj — Eta. O o- — Omicron. * \j/ — Psi. © — Theta. n tt — Pi. O w — Omega. Gram or Gramme. — The gramme is the mass of a cubic centimeter of water at the temperature of its greatest density. It is the unit of mass and is equal to 15.43235 grains; 7,000 grains equal 1 lb. av. Gravity Cell. — This is a cell in which copper and zinc immersed in a solution of blue vitriol are the active elements. It is used for continuous work and where small constant currents only are required. Ground Detectors. — It is customary to provide ground detectors on all switchboards from which entirely insulated circuits are run. Tests should be made quite frequently, so as to catch a ground as soon as it comes on. When grounds exist on both sides of a system, detectors are not reliable and the part to be tested must be disconnected from the board. Con- tinuously indicating detectors are preferable; static instruments are made which can be so used even on high voltage lines with perfect safety. Grounding. — Any connection of any part of a cur- rent carrying conductor, or live metal part of any device which has become connected to a foreign con- ducting medium so as to deliver current or potential to it, is spoken of as being grounded. Some devices and circuits are purposely grounded, the frame or the earth being relied upon as return conductors. ELECTRICAL TABLES AND DATA 91 The purposive grounding 1 of wires used in connection with, electrical work may be divided into two classes: The grounding of frames, conduits, etc., which are not supposed to become alive except through a break- down of the insulation, and the grounding of wires, or devices which usually do carry current. The life and fire hazard from electrical sources may be greatly reduced by improving the insulation, so that the chance of any person or material being affected by the current is small, or by arranging a bypath which shall carry the current safely away in case live parts of the conductors come in contact with it. To provide such a shunt is the object of all grounding. Wherever a ground connection is provided, it in- creases the liability of a breakdown in the insulation of the device, but at the same time reduces the possi- bility of serious damage from that source. Connect- ing the frame of any device to ground weakens the natural insulation of that device, but protects persons and property otherwise liable to injury to a consider- able extent. Good cause for the grounding of live parts of electrical circuits for the purpose of protec- tion exists only in cases where two or more voltages exist in such close proximity that there is liability of the higher voltage becoming impressed upon parts normally intended only for the lower voltage. And even under these conditions the N. E. C. authorizes the grounding only when, normally, no current is supposed to be flowing over the ground connections. The grounding of any part of a live circuit under the above conditions increases the chances of trouble but confines the trouble to that which may be possible with the lower voltage. If, for instance, the ground on the secondary of a transformer is in perfect con- dition, it will give positive assurance that the primary voltage cannot be impressed upon any part of the secondary system, but it will also give assurance that 92 ELECTRICAL TABLES AND DATA any workman who may come in contact with live parts on the ungrounded side, while making a ground himself, will receive the full benefit of the secondary voltage. In general, since the grounding takes away the natural insulation, which is often relied upon to some extent but quite often does not exist at all, it will force upon manufacturers a higher standard of construction, and the net result will be increased safety in all respects except life. In order to keep the life hazard within bounds it is not customary to ground live wires operating with a potential above 250. As a general rule, all metallic structures or pipes not normally connected to electrical sources, but liable to be accidentally so connected, should be grounded. Connection to an extensive water pipe system makes the best possible ground. Steam and hot water piping is not so reliable even if connected to water pipe systems. The steel frames of buildings are useful only with supposedly smell currents con- fined to the same building. Gas piping is likely to cause fires if contacts work loose, or if there is any electrolytic action. "Where the above means of making ground connections are not available the most eco- nomical connection is made with a galvanized iron pipe driven into the ground. The practice of one large company is to use a 1-J-inch pipe 8 feet long, and drive its full length into the ground, burying the connection with it. Another company uses a -J- or f-inch pipe. The resistance of the ground itself is so much higher than that of the pipe that the con- ductivity of the larger pipe is not much better than that of the smaller, but it is more reliable for driving purposes. "Where the ground is of very great impor- tance, it is advisable to use several pipes. The pipe should enter the earth at least 6 feet, and it is prob- able that an additional foot or two will more than ELECTRICAL. TABLES AND DATA 93 double the usefulness in dry seasons. The resistance of the earth varies with its composition, its degree of moisture, and distance from piping, etc. Gravel and sa^id, because so easily drained, make very poor grounds, and rock cannot be used at all. Overhead cables and messenger wires are provided with about one ground per mile. Ground connections may be tested with an ammeter and a voltmeter. Connect one pole of current source to nearest hy- drant or other available piping and the other to the ground. The voltage divided by the current will equal the resistance of the ground, since the piping itself may be considered as comparatively without resistance. Hanger Boards are required for incandescent lamps indoors on series circuits, but are not neces- sary with arc lamps, although advisable. Heat Coils are usually installed in connection with signaling circuits. They are arranged to open the circuit when a large current flows through them for a short time or a small current for a longer time. Their office is to guard against sneak currents too small to blow fuses. Heating by Electricity. — The heating of buildings by electricity is not commercially practicable, except on a small scale, or under particularly favorable cir- sumstances. It is used on a large scale only in con- nection with street cars. In residences, offices, fac- tories, etc., it is used only for small spaces, or where a limited quantity of heat is required for a short time only. Since there is practically no heat wasted, no air vitiated, little space occupied, no dirt caused, the fire hazard greatly reduced and the heaters are easily portable, it compares under suitable conditions, very favorably with other means of heating. One watt hour will raise the temperature of 1 cubic foot of air about 200 degrees Fahrenheit. 94 ELECTRICAL TABLES AND DATA The heat represented by one B. T. U. is sufficient to raise the temperature of 1 lb. of water or 55 cubic feet of air 1 degree Fahrenheit. One watt equals 3.412 B. T. U.S. In order to heat a room properly we must first supply sufficient heat to raise the temperature the required amount; next, furnish a steady supply of heat to make up for the absorption of walls, floor and ceiling; third, heat the fresh air which must be ad- mitted for ventilating purposes. For a rough esti- mate it is customary to require from one to two watts per cu. ft. in room. The wattage necessary to raise the temperature of a room may, however, be more accurately found by the formula: Cxi 60 200 m where W = watts = cubic feet of air in room t = number of degrees F. that temperature must be raised m = the number of minutes in which this rise must take place. The above formula makes no allowance for radiation or ventilation. Under average conditions it may be assumed that every square foot of wall, ceiling, and floor space will absorb heat as given in Table XXX for various tem- peratures. If we multiply the surfaces by the num- bers given we shall obtain the rate at which watts must be supplied to maintain the temperature in a hermetically sealed room after the desired tempera- ture has been secured. Every human being should be provided with 3,000 cubic feet of fresh air per hour, although it is possible ELECTRICAL TABLES AND DATA 95 to do comfortably with 2,000 feet. If the allowance per hour, however, is as low as 1,000 feet, conditions will be decidedly injurious to health and also imme- diately uncomfortable. Since all rooms electrically heated are small, fresh air requirements demand that the air must be changed several times per hour. In order to facilitate the calculations three tables are provided. Table XXVIII shows the number of cubic feet of air contained in rooms of various dimensions likely to be warmed with electrical heat, the height of rooms being assumed as 9 feet. This table also shows the number of square feet of radiating surface, includ- ing ceiling and floor. There is further given, in connection with each size of room, the number of times the air should be changed per hour for each occupant to afford fair ventilation. The figures given are such as it is believed the occupants will naturally provide by opening windows or doors. In Table XXIX we have constants by which the. cubic contents of rooms must be multiplied to find the number of watts necessary to raise the tempera- ture of rooms the number of degrees given at top, in the number of minutes given at the left. To find the watts necessary to provide for air changes per hour we must multiply the cubic contents by the constants given for 60 minutes and by the number of times per hour the air is to be changed. To find the watts lost in radiation we multiply the wall surface by the figures given in Table~ XXX. Example. — A bathroom 6 by 8 feet is to be heated 20 degrees F. above the temperature of the surround- ing rooms and the rise in temperature must be brought about in five minutes and then maintained for an hour afterward. "What size of heater will be required ? There are 432 cu. ft. in such a room and by Table XXIX for 20 degrees and five minutes we find 1.20 and multiplying this by 432 we have 518 watts re- 96 ELECTRICAL TABLES AND DATA quired to heat the air without allowing for conduction or ventilation. From Table XXVIII we also see tliat there are 348 feet of surface which, multiplied by 2.5, taken from Table XXX, for twenty degrees, give us 870 watts to make up for conduction through walls. Table XXVIII further shows that the air ought to be changed five times per hour; hence, tak- ing the constant 0.10 from Table XXIX for 60 min- utes and 20 degrees and multiplying this by 5, we have 0.50, and this, multiplied by the number of cu. ft., gives us 216 watts for air changes, and this, added to 870 watts for conduction, gives us a total of 1,088 watts to keep up the temperature of four bathroom 20 degrees above that of the surrounding rooms. A 1,500-watt heater would serve such a room very nicely. Every occupant of such a room will contribute about 125 watts of this. With all doors and windows closed the average house is supposed to allow a change of air at least once per hour. If a room is to be used only for a short time, a change of once per hour may thus be calculated upon. In laying out heating plants in residences where com- ' fort of the user is the main desideratum, it is advis- able to err on the side of plentiful capacity; in com- mercial installations where the installation is more for the benefit of workmen it may be more judicious to err in the interest of a somewhat small capacity. In small rooms a heater should always be placed as near as possible where the cold air enters, but in large rooms, if only a portion of the room is to be heated, it should be located out of the way of drafts. The coils should be divided into proportional sections equal to 1 and 2. This will enable l/3d, 2/3ds or the full capacity of the heater to be used as desired. Electric heating has one advantage over other forms. ELECTRICAL TABLES AND DATA 97 and this consists in its ability to give instantaneous results, and these are best attained with heaters of comparatively large capacity, so that there will be no temptation to keep up the temperature except when it is actually needed. TABLE XXVILT Showing number of cu. ft.; wall surfaces (includ- ing ceiling and floor) and necessary changes of air per occupant per hour in room of dimensions given ; height of ceiling 9 ft. Width Length in Feet. 5 6 7 8 9 10 11 12 fCu. feet 225 270 315 360 405 450 495 540 5 J Wall surf ace.. 230 258 286 314 342 370 398 426 [Air changes.. 9 8 .7 6 5 54 4 ("Cu. feet 270 324 378 432 486 540 594 648 6 \ Wall surf ace.. 258 288 318 348 378 408 438 468 [Air changes.. 866 5 4443 fCu. feet 315 378 441 504 567 630 693 756 7 \ Wall surf ace.. 286 318 350 382 414 446 478 510 [Air changes.. 76544333 fCu. feet 360 432 504 576 648 720 792 864 8 \ Wall surf ace.. 314 348 382 416 450 484 518 552 [Air "changes.. 65443333 fCu. feet 405 486 567 648 729 810 891 972 9 \ Wall surf ace.. 342 378 414 450 486 522 558 594 [Air changes.. 5 4 4 3 3 2.5 2.2 2 fCu. feet 450 540 630 720 810 900 9901,080 10 J Wall surf ace.. 370 408 446 484 522 560 598 636 [Air changes.. 4.4 4 3.2 3 -2.5 2.3 2 2 [Cu. feet 495 594 693 792 891 9901,0891,188 11 \ Wall surf ace.. 398 438 478 518 558 598 638 678 [Air changes.. 4 3.2 3 2.6 2.2 2.0 1.9 1.7 fCu. feet 540 648 756 864 9721,080 1,188 1,296 12 { Wall surf ace.. 426 468 510 552 594 636 678 720 [Air changes.. 4 3 2.6 2.3 2 2 1.8 1.7 98 ELECTRICAL TABLES AND DATA TABLE XXIX To find watts required to heat air in room (no allowance for radiation or changes) multiply cubic feet of air by factor in table below. Minutes in which Bise in Temperature, I\ rise is to take place 10 15 20 25 30 35 40 5 0.60 0.90 1.20 1.50 1.80 2.10 2.40 10 0.30 0.45 0.60 0.75 0.90 1.05 1.20 15 0.20 0.30 0.40 0.50 0.60 0.70 0.80 SO 0.10 0.15 0.20 0.25 0.30 0.35 0.40 45 0.07 0.10 0.14 0.17 0.20 0.23 0.27 60 0.05 0.07 0.10 0.12 0.15 0.18 0.20 TABLE XXX To find watts needed to make up for conduction multiply wall surface by factors below. Temperature Bise 10 1.5 15 2.0 20 25 30 2.5 3.1 3.6 35 4.3 40 5.0 To find watts necessary for ventilation, multiply watts required to heat air in 60 minutes by number of changes of air required per hour. DOMESTIC HEATING DEVICES (77estinghouse Electric & Mfg. Co.) Apparatus Watts Broilers, 3 ht 300 to 1,200 Chafing dishes, 3 ht. 200 to 500 Cigar lighters 75 Coffee percolators 380 Coil heaters 110 to 440 Corn poppers 300 Curling irons 15 Curling iron heaters 60 ELECTRICAL TABLES AND DATA 99 Apparatus Watts Double boilers for 6 in. 3 ht. stove 100 to 440 Flat irons, 3 to 8 lbs., domestic sizes 250 to 635 Foot warmers 50 to 400 Frying kettle, 8 in 825 Frying ^pan 250 to 500 Griddle cake cookers, 9x12, 3 ht 330 to 880 Griddle cake cookers, 12x18, 3 kt 500 to 1,500 Grill 600 Heating pads 50 Instantaneous flow water heaters 2,000 Kitchenettes (complete), average 1,500 Nursery milk warmers 500 Ornamental stoves 250 to 500 Ovens 1,200 to 1,500 Plate warmers 300 Radiators . 500 to 6,000 Eanges, three heats, 4 to 6 people 1,000 to 4,515 Ranges, three heats, 6 to 12 people 1,100 to 5,250 Ranges, three heats, 12 to 20 people 2,000 to 7,200 Samovar . . 500 Saute pans 165 to 660 Shaving mugs 150 Stoves (plain) 4 in 50 to 220 Stoves (plain) 6 in., 3 ht 125 to 500 Stoves (plain) 7 in., 3 ht 120 to 600 Stoves (plain) 8 in., 3 ht 165 to 825 Stoves (plain) 10 in., 3 ht 275 to 1,100 Stoves (plain) 12 in., 3 ht 325 to 1,300 Stoves, traveler's . . . . 200 Toaster stoves, 5 in. by 9 in .- 500 Toasters, 9 in. by 12 in., 3 ht... 330 to 880 Toasters, 12 in. by 18 in., 3 ht 500 to 1,500 Urns, 1 gal., 3 ht 110 to 440 Urns, 3 gal., 3 ht 220 to 440 Urns, 3 gal., 3 ht 330 to 1,320 Urns, 5 gal., 3 ht 400 to 1,700 Waffle irons, two waffles 770 Waffle irons, three waffles 1,150 Water cup 500 Water heater, bayonet type 700 to 1,500 ELECTRICAL TABLES AND DATA ELECTRIC HEATING DEVICES FOR INDUSTRIAL PURPOSES Apparatus Watts Annealing furnaces 200 Bar or barbers' urns, 1 to 5 gal., 3 ht 200 to 1,700 Bakers ' ovens, 30 to 80 loaves 6,000 to 10,000 Branding tool 10 to 500 Button dye heater 100 Chocolate warmers 55 to 250 Coffee urns, 1 to 20 gal 200 to 4,000 Corset irons 350 Dental furnaces 450 Embossing head 100 to 1,000 Glue pot, % pt. to 25 gal 150 to 5,000 Glue pots 110 to S80 Hat irons (small) 200 Hatters' iron, 9 to 15 pounds 450 Instrument sterilizers 350 to 500 Japanning oven 1,000 to 10,000 Laboratory apparatus flask heaters 500 Linotype pots 485 Machine irons, 2 to 18 lbs 770 Matrix dryer 28,000 Melting pot 13,000 to 30,000 Oil tempering bath . . 6,000 to 20,000 Pitch kettles, 12 and 15 in. 3 ht 300 to 1,500 Polishing irons, 3.5 to 5.5 lbs 330 to 550 Eadiators, various sizes 700 to 6,000 Sealing wax pots, .5 to 1.5 pt 175 to 300 Shoe irons .200 Soldering irons (various sizes) 100 to 450 Soldering pots, 4 to 15 lbs. capacity 200 to 440 Tailors ' iron, 12 to 25 lbs 660 to 880 Vulcanizers for automobile tires 100 to 450 ELECTRICAL TABLES AND DATA 101 High Tension. — The N.E. C. classifies as "high potential" all voltages above 550 and below 3500, allowing a 10 per- cent additional in the case of 550 volt motors. Voltages above 3500 are classed as ' "extra high potential." Special points to be noted with very high potentials are the Corona effect and the fact that ordinary bushings must not be used where wires enter buildings. It is best to enter wires through large open spaces. Horsepower. — 746 watts equal 1 horsepower, abbreviated H. P. One H. P. is sufficient to raise 33,000 lbs. 1 foot per minute or 1 lb. 33,000 feet per minute. Hospitals. — In the corridors, only an indifferent illumination of about 0.5 watts per square foot is needed. Good exit and emergency lighting is usually insisted upon and as most of the inmates are helpless every possible precaution against the fire hazard should be taken. Good ventilation is also essential. In the public wards inverted lighting or lights encased in strongly diffusing globes would give the best results. By no means should direct lighting from the ceiling be favored. A plentiful supply of outlets for heating pads, etc., will be found convenient. In the private wards the illumination should be by means of lights placed at the head of bed and never by ceiling lights. Each lamp should be controllable by pendant switch, so as to enable patient to operate it. Separate receptacle for heating pads and other devices should be provided. In the operating rooms a very bright shadowless illumination should be pro- vided, and this should be fitted with ample switching facilities so as to adjust it to the special needs of any operating physician. Arrange the operating lights so that no one fuse can put all of them out, or at least provide throw over switch to another set of fuses. Signaling circuits are usually also provided for all patients. 102 ELECTRICAL TABLES AND DATA Hotels. — Exit and emergency lights should be pro- vided in all large hotels. It is a good plan to arrange the lighting so that two circuits enter each room or apartment which contains more than one outlet. Where floors are alike this can sometimes be done by running branch circuits straight up and down, and locating all cut-outs in basement. Hall circuits should always be independent of room circuits, so as to reas- sure guests in case of a blowout of large fuse, or other accident which darkens a large part of the house. Door switches will be found useful for closets as well as for rooms. Vacuum cleaner circuits should be pro- vided in all halls, close enough together to avoid the use of very long cords. In the case of hotels planned for families, a large number of outlets with which to supply lights for illumination of pictures, lamps in cozy corners, etc., will be useful. If these are not pro- vided, the rooms will likely soon be found strung full of flexible cord, which will introduce a considerable fire risk. Special systems of wiring enabling one to turn on lights in rooms even though* they be switched off there, will be very serviceable in case of fire or panic, but will add considerable to the expense. In large hotels equipped with banquet halls, carriage calls are often provided. In such halls a special outlet for moving picture arc, or stereopticon should be provided. Hunting. — Whenever anything causes fluctuations in the speed of an alternator operating in parallel with others, it will either deliver current to the others or draw current from them. Under certain circumstances this condition may become fixed and the machines are then said to be hunting or phase swinging. This condition is liable to be most severe with machines having a large number of poles. To prevent hunting the prime mover should have a governor which is not too sensitive. The connections between the machines ELECTRICAL TABLES AND DATA 103 should not have too much resistance, and the ma- chines should be equipped -with damping coils. To prevent excessive short circuits, reactances are some- times cut into the external circuit. To prevent over- heating, thermometers or pyrometers electrically con- nected are sometimes embedded in the hottest parts of machines and arranged to indicate temperatures at the outside. Hysterisis. — This is the term which describes the lagging of the magnetism behind the magnetizing force. It causes heating of the iron and loss of energy, and is much greater with steel than with soft iron. Illumination. — Illuminating engineering is more an art than a science, and to master it properly re- quires considerable experience and knowledge of many factors which can only be hinted at in a work of this kind. By means of the hints given out and the tables following, anyone, however, should be able to design a pretty satisfactory installation where ordinary com- mercial effects are desired. Where special effects in illumination of statuary, altars, etc., is desired, experi- ments with temporary lights should be made. The main requisite, where economy is not too much insisted upon, is plenty of capacity. It is never advisable to figure illumination for light colors, since colors are apt to be changed. If there is plenty of circuit ca- pacity, a wide choice as to candle power of lamps *s possible and many experiments may be made until the most satisfactory effects are obtained. In addition to'* the matter contained in this chapter, practical hints on the illumination of special places are given in the alphabetical order of locations referred to, and it is advisable to consult these before deciding upon any work. The circuit capacity necessary to be installed to arrange for any degree of illumination can be deter- 104 ELECTRICAL TABLES AND DATA mined readily by reference to Table XXXI. Multiply the floor area to be illuminated by the number of watts per square foot recommended with the various illumi- nants and by the foot candles desired. The result will give the number of watts for which provision should be made. Except in special cases (see National Elec- trical Code Rules) one circuit at least should be pro- vided for each 660 watts. If large units are used, the first cost will be less, but evenness of illumination will be sacrificed unless lamps can be hung high. The intensity of illumination obtainable from a given source varies with the height and distribution of lamps; condition, type and kind of reflectors or enclosing globes; nature and color of ceilings and walls; also with the voltage maintained, and is never quite the same at all parts of the working plane. The figures given below are intended as approxima- tions and for quick determination of the number of lamps required. The watts per square foot given in connection with the various illuminants are thought to be sufficient to provide an illumination of one foot candle ; for greater intensities they must be multiplied by the number of foot candles desired. Table XXXII is prepared to illustrate the difference in the quantity of wiring material required for illumi- nation brought about by the use of large and small units or clusters of lamps. The line "Wire used per sq. ft." refers only to the wire (one leg) used between lamps. The wire needed to feed the circuits must be separately calculated. In case of arc lamps, or large incandescent lamps using one per circuit, no wire between lamps will be used. No allowance is made for switches or drops to brackets and it is assumed that circuits are run according to N. E. C. rules, never more than 660 watts per circuit. The table is not quite accurate unless the space illuminated is of such size as to allow of the use of full circuits. ELECTRICAL TABLES AND DATA CD ^ CD & j , o E . 1 2 g. Kg w O O O O O O O O £ ^ O M CO OT rf^ W k) M 9Q CD popoooop © M ^ 00 OS h^ *CO M ososco©coos©oo p p p p p Ifk 1— ' u^ CQ W !z! O M O O O O OS CO \o bs '^ to CO ox so en -^ Whit Near Pale Pale Yello Near * CD £> 0$ !■§ B «ss b)0 o3 o3 bC ^ rj rj W to w ELECTRICAL TABLES AND DATA to OX o to o o 1-1 I— 1 en o o o as o ox ^ to o o o\ to CO rf^ as H-i co as as Diam Wire Diam Wire 5 § 5 3 32 P* £> 3 3 p- p Pj- p p- p 05 g 05 g 05 g 5 ° CD Hs Pj 02 ►d p O) cs H 05 ol ^ Pj ob >d d p 05 C5 H 05 as ° ot ° O) Hs fo Hj d 53 *d p 2 n 2 ° H 05 ^ 05 m ° O) l-fe p-l 03 d 53 O) a, H 05 03 ° 02 ° 03 ° 05 Hs 05 Ms 05 Hs pJ 02 P-l 03 Pj 03 tj y ^ *d p *d p *d p 05 cs 05 o 05 o h a> ^ 05 h a> -Q 05 P o> Hs _ Hb |_i n r i . ^ • >d ■& 05 Hi _j ct- 53 : B • ►d 5? ^d S "d gw ^ CD ^ CD J2 CD i-S >-S >-i c+- 53 c+- p c+- p : 3 : 3 : 3 . »rJ • - >d • >d CO O M tO tO CO (-» 1— ' 1— ' 1— ' oooorf^ooocno^otooo O -3 O CO CO ^ oarooooxoi— 'oaso £»• ox. as ~4 oo co L0 to o to CO |-» M M M ooo^qorf^oooooooo^ O^OOOCOOt-iOCO rf^ ai as -a co MOPCHH O 1— i rf^ |_i M M H-» ooooooosoai OOJOWOMOUll-'tO OS OS -q CO h- ' CO rf^ oo en l-j h-i (_» M OUlO^OtOOOO~qO- MWHG5 l-i 00 H ^ M 00 CO S CO l—i -^ en O M J-» to o O O O 00 O v| O Ol p w p rfi. p w to m o "m ^ I- 1 h-» m "en "to o to "en to en o t— 'tocncoococoo OOOOOOSOClO^Ol^O^OWM h-» O h-» CO CO H S M OJ tO tO co as i- 1 CO OX CO o co to to en to d OCOMOSOOipi^p^pwOMW J-i 5_i J_ i i>o f_i J_i u_i ^q to en to f— i to as co co o LO . W CH 00 eo ■ ' If* OQ CT <=* ^^ 3 fej ^ O B p^ ^ a* — rt> tf) ►1 5 ^ CD ^ ~ C/i CD o o 3 .^h,^ Pi o t=l* OQ P.. (-+• 4 P^ O a> Pi CO pi pa o p H' h-b r+ J> pT'vj § o fet U ^ P C£> CfP & d CD 50 h-" & ^.tg •U CD ^ P 4 03 -• CD' £2 B-S P o p p ^p 108 ELECTRICAL TABLES AND DATA Average illumination, if made up of spots of very bright light alternating with low illumination, is no criterion of the value of illumination. The very bright spots only make the others appear less brilliant. The eye has great powers of adjustment and can get along with low illumination if it is even, but with elderly persons it cannot rapidly and often change its adjust- ment without causing pain and injury. The quantity of illumination should be adjustable, for not all per- sons can be comfortable with the same intensity. The source of light should never be visible, especially if it is of high intrinsic brilliancy. The best light is one sufficiently diffused to cast but a slight shadow. In offices, however, where one source of light must serve many persons, an absolutely shadowless inverted light is desirable. It is good practice to space outlets so that the space between lamps is from one to two times the height of lamps above the working plane. This rule requires large units for high ceilings and small ones for low places. Special reflectors, however, have a certain ratio of spacing to height which should be obtained from the maker. Buildings containing many windows require more artificial light for night work than the ordinary building. The following tables are based on Holophane Intensive, or medium reflectors, and will give fair approximations of results to be expected from other reflectors. Holophane reflectors are of high efficiency and in some cases allowance must be made for this. Incandescent Lamps. — These lamps are operated mostly in multiple, and when so used never at a higher voltage than 250. On series circuits the voltage used runs into the thousands, but special lamps are re- quired. Most lamps are built marked with three voltages: top, middle, and bottom. The top voltage is ■preferably used ; with this voltage the efficiency is the highest but the life shortened; with botton voltage ELECTRICAL TABLES AND Di Height of lamps in feet above plane to be illuminated. »lo'looi|oi|if*>l LTA Orf^tO OOOI o*-w OOOI CDrf^tO OOOI ©*-tO OOOI o*-to OOOI ©*-tO OOOI ©**to OOOI 3 g crc? COMH cobto *-tOM CTCOtO 1 ©coto C0HO Mb'co tOM **tOM 01 co to ©COtO 00 01 CO OlOKO £0 CON m*-oi -3-3 00 COtOM ©CO 01 tooto HCOO0 tOMM COMM bbb COtOM bb*- *>tOM J pCOtO *»<1t0 b^w Cl 3 MMO MKOO bibi'o COtOM bob COMM *.tOH *-bbb b\k>l^ 1 fc O CD 12' MHO bb oo (OHM bebb COMM MbtO COtOM J^tOM b MOO bbob t^pp MOO bop bob*- tetg MJ f 1 Q I ^ ^ O ^J O 109 •=3 a en Q 5-1 K Q CO Ml Ml o mIPh m3 O m3 *3 > ^ M CO s b § ^ ^ 3 CO t) w as i— i en m: O H m-i co Mj (_t o Q b to M O CO co ^ N M o 110 6 O t> ELECTRICAL TABLES AND DATA 5 ^ ^ Eh Eh « Eh < < Ph < Eh o a 3 rH H Eh J O I? go r LO *S£ o o ^ o < Eh o << o o few fc o " £ M Eh CD GOCQ-H i.-Oi> lOCOTji OOC5 Pisa OCOiO r-itHIQ Or-ICQ OrHrH OOH lOCDO coooco !>OiO i>r-IJ> G0CQ02 l>rH00 cooco OOH OCrt OHft OrHrH OrHrH o J. Sj ft P-§9 HOX IOC? 00 iHl-Q O^tH COO?r-l t-rHt- 10 0IO (NCOIO rHOlCO ^^CQ OHN On« G-r-lr-l OOH ©Is* OlOCO CQt-t- CQCSO 03O-H r-IOOO OCDCO O-H<03 £ HHCQ Hri« rHrHCO rHrHCO r-tr-ICO rHrHCNl OHN 00 i u ft CO COO t>ooc>: CON^H CQOO r-JCSOO OCDCO OO^CO" P-Cr 1 N^CO lHCAiTj< rHNCO rHCQCO rHHOl tHi-KM OHN cocao LOCO'* LOTH00 rJ00 rHCOlO ffiOO COXCO ^00 00 NJ,H( pq§2 NCOLO CiCOlO CNiCOlO rHCOO rH«^ rHOJCO HHCO £ © a t-ooo CXJC01O QOI> J>t>r*< CDlOr-l COrHCD OTOH (M^t- WC01O HM^ iHCa!^ r-)CM-* rHCMCO HHCO P-2 . £ ft © © a HOO ONCD CDOGO CO COO T-IC0K5 cot>ia ^COOO C0t«J> CAC*J> CMtJHCO OJC0CO CMCOlO rHCQ^< HCMCO LO P-5 CO CD CO i>CQO lOOOCO CQ^CO OC500 ' 00 CDt-lO ^COOO co»ooo CQt}ooo CQtHtH O"#C0 COrHOO rHC0"# 1>OOCO £ ^ M Cxirtl> !>CvJO CQCO00 00 00 00 c 3 P^ •tft-O COlOO coiooo WTf,2> CQ^tiO OJCOO H«Tf ill ooco C0r-lr4 OONCn rHt-CNJ CD001O 00 COO 03 00-H^ £ tOr-lOO lOOLO ■*I>C0 tHCDt-I H COiOO «Tjii> NCOCD 00 © ft eg P~i TH0000 IO00CO t-Tj4-tf tHLOOO C0!>1> OOIOCD CQCDH coco rHiH iOX'* ^hi>CNJ ^cdo COiOCl N^i> 03 CO CD tt d £ lOOO Ca!-*C0 lOOO KrJiCD lOOO lOOO N"*CD LO O o NtjJCO IOOO NThCD lOOO N^CD ■* to O i-- 00 O 05 H H •pe ^Buitun III 9UBI J 9AOqt3 !»9aj ui sclraci 3 o ^qSta B electrical tables and e Height of lamp in feet above plane to be illuminated. tololco !2| O H O IT 1 g zn TABLE XXXV rn Table Showing Illumination in Foot Candles from 25, 40 and 3 Tungsten Lamps Arranged in 3 Eows at Heights and Distances as Given in Table. Bowl Frosted Lamps Equipped with Holo Clear High Efficiency Reflectors Nos. 106,125 r 106,130 and a*, to OOOI C5*-tO OOOI C5*-tO OOOI 03*- tO OOOI 05*. to OOOI 03*-tO 03*-tO OOOI o Ol 8» CD OOOI CO oobb Mp*. Mb© 'o' 01 CO pi biia'cc -q O p bbb *.00pl ppp bbb 00M<1 OOM ctopo V CD ? 05*. tO CDM05 00 Or CO cobM OOl*. bbb op*. CO bibih COOICO wmw OOCTCO *■«*■ *.tOM bb*» *.tOM bb^ bb^i *.tOM bbb OlCOtO WMH p*>to b^ib 3c? d •31? 3 COMM COtOM MCDtO OTMCO COtOM 1 COtOM bbb I ' COtOM bb*. COtOM b*>b *-COM § cd"? 1 1 on 3 6 ^ M H 3 2* w-*co *cot- W_g^ odd* odd AND *©© do" i-5 DATA ddi-5 CD 05 CO do r-5 CDO-* \6rlrl ©OiTj< ddi-5 III i-IOt- oicdid «35 r-5o3CO oox 05 COCO dr-5oi C0rH05 drHi-5 C-OCD OlHrH ©©lO ddi-5 . lOCOi-l ddi-5 t>©* ©t-5t-5 C0O3J> drHi-5 cqcxjq 05-* i-l 1 XCO-i Oi-5oi 1 dr-5oi cooj© di-5oi P-aS T-JCC35 03*lQ cqcoq r-5 03* «coo r-5 r-5 CO OLO!> T-5r-5oJ 0*10 i-5 r-5 oi q*o) di-5oi cqcoiH diHoi X ill 03 l>© *©© IO 03 CO •rUNlO «*!-UO COr-OJ rHrH03 r-lrlCO tHCNJCO r-.CQCO rHCQCO rHCNtCO rH-ICO *coco oi*d 05t-IQO r-5 CO* 10 Tjjq rHOJ^H TjHcoq iHOJCO *CQlO r-5oico *0^ I OJC005 r-5oico i-5i-5oi pq ^ S 1O03* t>1000 i-5 oioo i-5oicd cot>co r-i « •& t-t>'N r-5 oi-* t-iqoi r-5 oi* 10*0 r-5 oi* *coi> r-5oico 03 ft 3 03 H O t>C0© oi*d 03 CO* oi CO id ooq oicoTji cqi>iq cqt>* rHoi-^' r-5oi-* 1.0 qq **oq r-5 oi* i-5oicd £ $&3 ID GO CO oicdid t>03lO oi*d CDCOtJ* ojco'd IO CO 1-1 oicdd *CD05 oicdid *C0* | 03050} r-5cdid i-ioi»d || 03 CO 01 C0ldf> coocq oi*d 10 1>© oicod CO CD 03 cicdid coiqi> oico'id ©coco oicdid r5oi* oj $ a wis CO CD 05 CO 10 GO ©q© co id co co id co co-#t> C0*i> coco© oi*j> oicdd 52! PJ5 qt~© *©05 1>C0J> co' id o6 tJ*C01O co'idcd 0*050 CO* CO r-jcqq co*t> l>C0i-l oi*'i> •CO 00 CO oicdd p * HOQO iddoi H 05 CO** *j>oi ©i-JW •*b5rH -*qcq H r-jiqq qi>o» CO id 05 ©00 0? co*co ,2 ^ P* l>03© id oi CO *C0r-l id co co 05 CO CO IOiHJ> Tj5t-rH iqt-O *dr-5 cod© r-l©C0 CO* 00 jk § * 03 0303 05* CO T-iCN *cq© odoid tH03 qqq i>i-5d C0 050 ddcd ojqcq r4C0O idco* 03©© *©'tH ,2 a p3 O3 03© 05" id co" r-lCDCD codt> *cqcq <6oiz£ qq* *cocd ©*© 1 1000 1000 CQ*© 03*© 1000 1000 0*Ttm© M 00rf^ *^b»H *t0M 1 OTC0M 05 co to . 05*05 C05-3 COWM *>h*k> *t0M ©** CI COM CTCOm b*b ©*-W bob 00* to biio'cc l_i©W W CD to 3 COtOM *-WM *t0M CTtOM CTTOm CTCOM CTTOM il* *Ot0 bco^ 1 w u N H * CO £ O <{ S H i-i >- tr 1 w a.gp > !zj ^ C^ !_l n ^ g OS: V, > tei H o O 3 3 £ o w o H Q rr! tn r H M r/2 M C72 b (J K > 2 Q M O O C/J h- 1 > o > § Oi 114 02 EH ^ !z *: o > to C Ph ^ w o o o £ rH h a o 03 ©©•* colox odd CO©© ddtH ©©o ©OH CO 03© TfXX ©rH03* 03OTt- X"*tH ©rH03 »OrHt> co CO d CO 03 D- CO LO o oi^co t- w © ocd^h oicdcd LO lO t- ©©03 rHoiid C3TjO ThTHLO rH03T)i" ©03L0 rHOOlfi rnVx «■* LO 03 ©_ © OrHX CO • fl ft O '. ' X ©r^© ©-*© L-CO^ ©©© co©x X©© ©J>rH XO-+ ©©X OC3X 03©^ ©X© 03 ©1< OHH ©i-HCM OrHW ©rHCO HriCO rH03M rHrHX ©© iO03© cod© 01 CO © L-L-CO oi-^cd CD!.- CO rHi>© CQcdcd t- CO © t-rHlO rHCO id 03 -Ht- IQt-X r n03'* ©©rH C3HO rH03Tti HCH rHOOlQ rHrHX £ «^3 co coo t-LOX diHW OQOCQ qcocq drHcd iHtH.X rHOJCO © © 03 03C0--' rHCJ'* ©X© tH03^1 CO©'* XIOH1 TH03-* O3X03 X"#X rH03'* 02 COLO CDCOrH CO'cOrH ^C0i> C0©L0 oj-^cd ©i-HCO «©© 03^© ©OLO x-^© thcoio rHcnco t-©C3 HOJIO ©03X rHO*^ HiC-CO X 03 03 rH03X 03 p8J| CO L0 LO rHCi'-tf ©XTff O©03 rHOJid CD"*-HH CD « © rHCO'ld tJ t-C0lO HfflOO 03 CO© ^03tH C©03 03 X© 03X© QOHCO ricoid 10 03 LO © © X rHCQ-* £ o tJ<-*© ©©CQ L-XlO oJ-*cd U0-<#-^ ©©© ci'*© CO©'* MXiO 03-*X 03 rH© t-t>03 oi^x ^00© Tt*C3L0 •*©03 rHt-X 03 CO© 05 CO HC005 iocs rJH©© co cod' ©C0H< cd »d© 03 ICt- £-X-* 03 -#X 03©X ©■H^X 03T|5l> loox 03 O© 03-*© WHO r-JCDCO 03 CO© £ CO c 5 coco CDiHO H -f CD COOl> ^cdco 0?C0 ©03 • OC-31C ^1>03 Xt>!> COdrH rH ©-* 03X03 cd id© 03 03 03 rHCO 031OX pi ©CO-* id co id lOOJ ■*j>ed TfCO r-oi; ■* J> 03 t>© t--*q CdcdrH 0310X LO©© cod© ©©lO HfflCO x' >C 00 oat- io x©x 03-rJHx" CD CO COrHOI rHCNt CO r-J©C0 rHCM © © © 03 CD r-* O rHOi © ©©X co ©od X -f ©© id ©d 03© iO©X ^eded XX X©t> XdrH CO ©coco £>CQtH H« CO io^co ©r-3d THrH OIOC3 coded © HHi>X idd© 03© rH©© LO ©J id rH ©X tJU-IO rtit>co ©© xt-t- CO t£j ©©© © lO 1.0 rHrHCNf ©©© OlOiO o©© OlOLO ©©© ©i.OiO rHrH03 ©O© ~ 1.0 10 rHrH03 o©o ©LOIO rHrHOl ©o© ©LOIO rHrH 03 T« II? e^rei tJ 9Aoqc © ^»aj nt snrnry rH o uriSp 3 ELECTRICAL TABLES AND DATA 115 the opposite will be the case. See Table XXXIX for approximate effects. The efficiency of all lamps decreases with use. In- candescent lamps will not give good results with fre- quencies lower than 40 ; for outdoor illumination they have, however, been used with 25 cycles. The fluctua- tions are less noticeable with heavy filaments. Circuit Limitations. — Not more than 660 watts are generally allowed on circuits, but where small fixture- wire and fiber lined sockets and flexible cords are not used there is no serious objection to 1320 watts per circuit, or 32 lights instead of the usual 16. Frosting. — Lamps are frosted to reduce the intrinsic brilliancy and through it become less harmful to the eye. Ordinary frosting reduces the c.p. from 5 to 10 per cent, but shortens the life from 25 to 50 per cent. Bowl frosting has no appreciable effect upon the life. The effect of coloring upon the life of the lamp is. about the same as that of frosting. The effect upon the c. p. varies with the color and its density. Amber,, opal and yellow absorb the least ; blue, green and pur- ple the most; blue and red are the most used colors. Not much illumination can be expected from colored, lamps. In some cases lamps are merely bowl colored. The efficiency of incandescent lamps increases with the voltage, but the length of life decreases. To a certain extent, therefore, what is gained on the one hand is lost on the other. Table XXXIX is prepared to facilitate the calcula- tions necessary to be made in order to determine the- most economical voltage at which to operate lamps. In the column "K. "W*. wasted" we give the K. W- wasted by the use of the middle or bottom voltage during the length of life corresponding to top voltage, which is considered the standard. In the column- headed "Saving in lamp renewals" we give the per- centage of lamp renewals avoided by the use of lamps 116 ELECTRICAL TABLES AND DATA at the lower voltages. In order to find the money value of the watts wasted by any lamp we must multiply the figure given in the table by the c. p. of the lamp and the rate per K. W. In order to find how much the same combination will save us in lamp renewals we must multiply the cost of lamp by the figure in the column on "Saving in lamp renewals." If our calcu- lation shows a net saving it will be more profitable to use the lower voltage, otherwise use the higher. Ex- ample: With energy at 5 cents per K. W. and 25 watt tungsten lamps costing 20 cents each, is it more economical to use the middle voltage than the top volt- age? A 25 watt lamp gives 20 c.p. and the K. W. wasted at middle voltage is 0.050; we have therefore 20x0.050x0.05, which equals 0.05, or 5 cents wasted during 1,000 hours. On the other hand, we save 0.23 x 0.20, which equals 0.046. The saving in cost of lamp renewals does not quite offset the loss by the lower voltage, hence the higher voltage is more economical. In many cases such a calculation has merely an academic value. As long as the parties using the light are satisfied with that obtainable from the use of the lower voltage there is no economy in using the higher. Smashing Point.- — The useful life of a lamp is gen- erally considered to be over when its c. p. has dropped to 80 per cent of its original value. The following table is based on average values. The improvement in lamps is at times very rapid and in case great accuracy is required the manufacturers" guaranteed data should be obtained and used instead of values here given. Inductance. — This is that property of an electric circuit which causes a current in it to create lines of force and thus produce a counter e. m. f . proportional to the rate of change of that current. ELECTRICAL TABLES AND DATA TABLE XXXIX Comparative cost of illumination and lamp re- newals. Name of Lamp Mazda or Tungsten Tungsten Gas Filled Tantulum Gem or Graphitized Filament Carbon Carbon Saving Voltage Watts Hours of K.W. in Lamp Eating Per C.P. Life Wasted Renewals Top 1.22 1,000 Middle 1.27 1,300 0.050 0.23 Bottom 1.33 1,700 0.110 0.41 Top In large units the type " C ' ' or Middle gas filled lamp is fully twice as Bottom efficient as the common tungsten lamp but in connection with small units there is no saving, but a whiter light is obtained. Top 1.84 800 Middle 1.91 1,075 0.056 0.26 Bottom 2.00 1,350 0.128 0.41 Top 2.50 500 Middle 2.65 700 0.075 0.28 Bottom 2.83 1,000 0.165 0.50 Less Than 50 Watts Top 3.16 750 Middle 3.40 1,100 0.180 0.68 Bottom 3.61 1,600 0.337 0.47 50 Watts and Over. Top 2.97 650 Middle 3.18 925 0.136 0.30 Bottom 3.39 1,425 0.273 0.54 W ELECTRICAL TABLES AND DATA M X i/5 n u8 H .fl kJ

££* £ OOOOOOO ro ^ pq O £ S S -^ J^h 3 OICOTHM ©OOOOOOO H +?QQ c3 »-i ooioooiooo t*V2 i-* o ^ ©Ol w to o O GO CO 6T0H JO V.CD vffl SSO ©^ >*N c-1^ £ JLQ%dmvi(i h hh him Ncq ^ .S fl +j bf; tn fl £ rC ro Eh ^ ELECTRICAL TABLES AND DATA TABLE : xxxxi Tables showing dimensions of porcelain insulators. See Fig. 7. Wire of Approximately Over all Diam. Same Diam. No. Height Diam. of Hole Groove as Groove 21 3 If 1 350,000 1 3 21 ft f 0000 2 o 2 1 1 2 3 H 2 ft ft 4 3WG If 2 £ f 0000 31 2 2 ft ft 4 4 HI H § t 6 41 11 11 f ft " 4 51 1ft 1 1 ft 8 6 1 11 A 1 10 7 f 1 1 ft 4 8 H 1 1 ft 8 9 it f ft ft 12 10 if If ft § 6 11 11 It 1 1 2 12 11 If ft ft 1 13 f 11 1 f 00 15 1ft If ft 1 2 20 •2 2 ft 1 00 21 21 2 1 ft 1 22 If 21 l ft 350,000 23 H H I 1 350,000 24 If 11 ft s 00 25 11 11 11 1ft 400,000 26 2 21 - f ft 1 29 2| ■2J 1 If 450,000 36 If If 1 f 0000 39 If 21 f If 450,000 Split knobs are made only for wires from 14 to 8. ELECTRICAL TABLES AND DATA wills t» 3 Figure 7. — Porcelain Insulators. ELECTRICAL TABLES AND DATA TABLE XXXXII One Wire Cleats. Smallest Size of" Wire to Fill Out Groove [eight Width Length Groove B. & S. li f 2 I 8 Hi f 2 § 8 if 1 2| 1 3 2* 1 21 J 3 If u 2| f 1 2i l* 2+ f 1 n 1A 2f f 000 2* 1A 2f f ooo- 21 1A 3 tt 250,000 2H 1A 3 11 250,000 3i if 3| u 6,000,000 3f 1A 3« if 750,000 3f If 4f 2 2,000,000 4 2 '5 11 1,750,000 4 2 5 1* 1,000,000 Two Wire Cleats I' li I 3| A M Three Wire Cleats 1* I 3| A 14 * The wire sizes given are thought to be the smallest the cleats will grip well. Diameters of wires, however, vary considerable and some single braid wires may be too small for the cleats with which they are supposed to go. See tables giving diameters of insulated wires. Insulating Materials. — The standard insulating materials are glass, porcelain, slate (without metal veins), marble, clay and certain compositions. The general requirement is that materials to be used for 122 ELECTRICAL TABLES AND DATA insulation shall be incombustible, shall not absorb moisture and shall not soften from heat. Wood and fiber are not approved, but are tolerated in some cases. The dimensions and other data concerning insu- lators, cleats and tubes are given in Tables XXXX to XXXXII. In buildings insulators must provide \ inch separa- tion between supports and wires and in damp places 1 inch is required. Below are given sizes of bushings constructed ac- cording to the N. E. Code standard. Also the largest sizes of wire that can be used in them. The diameters of wires vary somewhat, and while it is believed that trie wires given can be readily drawn through the bushings, it is advisable to use a larger bushing where it is necessary to draw wires through many of them, as in concealed knob and tube work. Logarithms. — Logarithms are used for multiplica- tion and division of large numbers, for raising num- bers to any power or extracting roots. Every log- arithm of 'the number 10 or greater than 10 consists of two parts. — a whole number, which is known as the characteristic, and a decimal fraction known as the mantissa. The mantissa of all numbers consisting of the same digits is the same ; thus in the table (which gives only the mantissa) we see that 0.8, 8, and 80 each have the same mantissa, viz., .903 09, and this mantissa would still be the same for 800 or 8000. The characteristics of these numbers, however, are not the same, but always 1 less than the number of integers or whole numbers ; thus for 8 it would be 0, for 80 it would be 1, making the logarithm of 8 = 0.903 09 and that of 80=1.903 09. If the number of which the logarithm is to be taken is less than unity, the charac- teristic is 1 greater than the number of ciphers which follow the decimal point. The characteristics of vari- ous numbers are given below. The characteristic of ELECTRICAL TABLES AND DATA 123 a number does not change unless that number be in- creased or decreased by one decimal place. 1 000 000 = 6 100 000 = 5 10 000 = 4 1 000 = 3 100 = 2 10 = 1 1 = 0.1 = 1 0.01 = 2 0.001 = 3 0.0001 = 4 The characteristics of logarithms of numbers less than 1 are treated as minus quantities and usually designated by drawing a line above them. The characteristics serve merely to determine the location of the decimal point. Whether they are added, subtracted or multiplied, if they are positive we must add to the number (found as hereafter described) ciphers enough so that the whole number will contain one more integer than the characteristic indicates. If the characteristic is minus, we must prefix one cipher less than the characteristic indicates. How to Find the Logarithm of a N 'umber. — Trace along first column at the left until the first two digits of the desired number are found; next follow along the same horizontal line until the third digit is found. At this place the mantissa required will be found. Put this down, prefixing it with a decimal point, and in front of it place a number equal to one less than the number of digits composing the original number. Example : find the logarithm of 676. Tracing down the left hand column, we come to the number 67 and in this horizontal line until we come to the third num- ber, 6, we find 829 95. As 676 contains 3 digits our 124 ELECTRICAL TABLES AND DATA characteristic is 2 and we have 2.829 95, which is the logarithm of 676. How to Find a Number Corresponding to a Certain Logarithm. — This is accomplished by the reverse proc- ess. Suppose we wish to find the number whose log- arithm is 1.421 60 ; we first look for the mantissa part of it and find it in the horizontal line with 26 and under 4, giving us 264 as the required number; since the characteristic is 1 we locate our decimal point 2 places from the left and the actual number now is 26.4. To Use Logarithms for Multiplication. — Find the logarithms of the two numbers; add them and find the number corresponding thereto. Example : What is the product of 36 x 88 ? log. 36 = 1.556 30 log. 88 = 1.944 48 3.500 78 The mantissa nearest equal to 500 78 is 499 69, which corresponds to 316. Since our characteristic is 3 we point off 4 from the left, giving us the number 3160. To Divide by Logarithms. — Find the logarithms of the two numbers as before and subtract one from the other and find the number corresponding to the remainder. To Raise a Number to Any Power.— Find the log- arithm and multiply it by the index of the power. Example : "What is the cube of 9 ? Log 9 = .954 24; this multiplied by 3 = 2.862 72; looking to the table we find 862 73 as the nearest and this corresponds to 729, and as our characteristic is 2 we point off 3 from the left, which shows us that the desired number is 729. To Extract Roots. — Find the logarithm of the num- ber as before and divide by the index. Example: What is the cube root of 1331 ? The number 1331 is ELECTRICAL TABLES AND DATA 125 not tabulated, but the mantissa of 133 will be the same and it is 123 85 with a characteristic of 3, mak- ing it 3.123 85; this divided by 3 = 1.041 28, and the number corresponding to this is 11 ; since our char- acteristic is 1 we point off 2 from the left. The method of dealing with quantities less than unitv is explained by the following example : What is the product of 0.079x0.87? The log of 0.079 is 897 63 and as there is one cipher following the decimal point our characteristic is 2; the log of 0.87 is 939 52 and as there is no cipher after the decimal point the characteristic is 1. We now add the man- tissae and the characteristics separately, and as the- only characteristics are minus quantities, we subtract the positive characteristic found by adding the man- tissae from the sum of the negative characteristics, with the net result as given below: 2 .897 63 1 .939 52 3 1.837 15 1 2.837 15 The nearest number in the tables to 837 15 is 836 96 and this we see corresponds to the number 688. As our characteristic is now 2 we prefix this, number with one cipher, giving us 0.0688 as our product. In case the mantissa is not tabulated and the near- est one to it is not considered accurate enough, the- approximate value of the corresponding number can, be found by taking the numbers corresponding to the nearest two mantissae and noting their difference. Multiply this difference by -r- where a is the difference o between the lowest mantissa and the one under con- 126 ELECTRICAL TABLES AND DATA -^ >o o co o >o 10 co a ^ co waHos Ooowoio N L^ ^ O CJ CO OO CD CO O '^lOWOH tF CO CO TfH CO .OS rtlCOIMHO O CO t>- OS LO t> WOMCO T-H b- C\l CO 00 ION50 05 05 SHO^Ol M S H ^ |> O O] W S Ol OS CM xH LO CO t>OOOOCSQ OOtHi— lr-1 oq cq cq oq oq GNCDOO^ CO r-H Ol CO CO N QO H 00 © CO O N lO tO O CM r-H b- oq ^fHlOO^cq rtlOONOON CO CO ^ r-t CO CO CO LO b- OS t— I CO (M Ol ^ r- 1 COH (>QO O0 l.O O tH © O W ^ •> 00 CO CO OS -^ OS COt^OMN OS CM LO b- OS OS C\l Tfl LO CO t» 00 00 C5 Q OOHHH H (M CM (M (M OlOOOO b- b- OS Oq b- CO Cl O 00 CO O r-H b- -rfH CO H^COOQrt COO^IOt> COH00INCO Ol b- Ol 00 -* b- »0 O i— I CO CO lOCOCDffitD O3 00COCOt> lO(Mt>r- i tH rf< CO CO © l> LO CO CO CO CO N © O CO CO OS CO 'f b- OS CO CO Ttl LO CO NO0O0O5O5 OOrHrHi— I i— i CM CM CM CO co ^ oo «ra co h h lo in oq O CO ^cH ^ ^0 CO OOOO^CQ lO rt* O CO ^ CO O IO Ol CXI K O H lO © ^HCBCOCO W tO O CO CO © (M ^ C Q »2 b- CO ^H LO CO NW00G3O5 O O r- 1 H r- 1 r-H CO CO Ol CO s f— ( <^ b- OS -^ b- rH ©H©CT Ol OlOHCOS CO 00 CO 1> CO 4— I C^OOJOO] COCiO^O- r-l b» OS CO CO MtPOHO M'ti lo C" O S ^ CO O (M lO O) S t— I O CO O rH ONCOSO ° CS b- OS ^ lO <*H K(Ml> CI © C5 CO © QH^OCS £> OHCO W© NOOCOQOi OOOi-ti-i tH CO CO Ol CO a § CO O W O CD CO rtf rtf r- I O OOl^HCO LO CO LO 00 CO t- CO CO t^ CO b-THOr^b- i— l lo O CO H O0 CO |>H©Hr0 TH r-i CO LO CO rtl Ol CO OS CO Ol CI © H © ^COrHLOTfH OS CO T^ >0 LO GO O OS CO CO COrHOTTiLO Ol CO OS CO CO ^ CI Q0 01 1(0 i— I LO CO CM LO OOHCO©CO OOOt— li— i tH CO CO CJ CO COCOCMLOiO 05Wr4 05 O CO CD t- OS t)H Ol CO b- O OH-^Hcg OCOCOcOb- CO CO CO LO OS OOLOLOOCO Hdoqioco © c>T> co co co cs co o co h oi lo o co O b- •* O oq HO'Or- 1 CO O rtl CO CI LO ■ CO O CO CD 00 eoOcoLoco b- b- co os os o o o r- 1 i— i rHoqoqoqoq o cs 01 co co t- co co 01 -* oqoqost^rH b-coosb-co O CO O] CO l> LO CO CO Tt< O CO CO b- CO CO oscooscoo O H Ol H CQ N IO H CO Ol ■* IO Ol N Ol CO CD Ol b- r- 1 O "* O] Ol H O 00 LO O lO OTtlCOr-T+l l> O CO LO 00 OOCO'*© b- b- 00 OS OS OOOrHtH H N Ol N CQ OCOCMCO b-LOOOS-H O CS 00 tH CO CS CO LO b- LO OOrHo OHHOW O CO H Ol H O t-l r)i OJ t-> o r-i b- co oocoLOcooq ohoico© co^oloco OOt>0 Ol N -tj O lO OrttS H^H • SOCOWN oco-^co ©scooioi o o o r- 1 i— i l— i oq oq oq oq jr- 1 01 CO t*I LOOb-oOOS OHOICO^ W © S 00 Ol ELECTRICAL TABLES AND DATA tO X> -1 OJ Ol 4^ W tO I- ci 01 01 01 01 01 01 ci ^ rf^ ^ ^ ^ ^ w wwwojoj a rf^ tOWClClO CO i4-^ OS O O HOOClWCl o ClClClClCl ClClCirf^M^ rf^^^^t^ wwwww 3 !> tOOOSOl^ COtOOOCO OOIWMO COOrf^tOO 3 l_i ^WHiOS Ol I>0 tO Ol I— ' OMOICW ClSXOKI W g W W tO Cl ^ to M O OS W O OS LO CO W —J ^ ^ -q tO O O tO "^ P Pj WCOOOMO Cl S Cl O DO MWSfflGO W tO tO 4^ OS M- P] ' O W -3 O O Cli4-l4^W-q I^HClOCO (O M (^ h w «£ p> £* ClClClClCl ClClCl^^ hf^rf^Mx^rfx wwwww tu jOS C5C1 CO LO M to CO S Cl ^ tO O tO -q Cl W M S Ol Ol CO M tO O) CO tO Cl H ffi O f)» CO oton-^co OS •lClH-»rf^^ OUIOfflS to CO to CO to tOtOK-irf^CO OtOtOCOCl SWH ' CO tO tO OS O CO H- COHOOlff) ClClClClCl Ol Cl Cl Ol tfi. rfx^^tfx^ wwwww tDCOo o -q 4^ i-^ -q to -q to os to to tf^ as os oi "^ -IS CO Ol ff) W OS C< O I— i —ICO^CltO QvlO^tO OH^SS WWhf^ClW OICOCOH W tO rf^ tO OS -<1 ClClClClCl Ol Ol Ol Ol rf^ rfi.^rf^rf^rf^ COWWWCO tO CO — 1 Oi CI tf^tOMOCO s ci^ to m to-qoiw^-» tO CO - OOCOh^COCO Ol tO CO 4*. Ol tOWOMCJ rf^OltOrf^O CO W tO Cl -CO S M Ol rf^ ^^' to CO -q Ol tOOSWtO OlOOltOW OS CO tO O O I. .128 ELECTRICAL TABLES AND DATA CI H O © lO HhiHO Ql I- ^) O) l> HHOONCfl t^ Ol Hi Hi Ol 00HCOC0H l^ rt ■* lO m TtfHC- 1 rt* OS H (M (M - - .t^t^t-l>. ffi'+COOOH Ol Ol Ol CO CO rH Ol rH t^ C5> CO CO CO Hi t~ lO i— I Hi Hi CO Ol CO LO LO CO O rH CO Ol Ol CO W H 5D a b» Oioooo 01 ci co t- co 10 co rH 01 1>- 10 co h k it. O Ol CO Hi "O W CD l> 00 05 OHCIC-JCO t(< Ifl O © O CD CO CD CD CD CD CO CO CO CO t^t^t-t~t-~ t~ t~ t~ »>- l> CO Ol rH Ol CO CO Ol rH Hi CO lO LO Ol CO Ol S (M N O lO m lOOTf^M OICOCD©^ HC2G3HH O CO Hi Ol Ol • rr-t in CD 000)050501 CO CO t~ CD LO t)KMOO>I> 1C N O t> >0 ^? ^ O H (M CO •* O CD S CO a O rH Ol CI CO r(< O CD CO l> ~ rQ CO CO CO CO CO CD CD CO CD CO t^t^t^t^t» (>- t- t~ L~ t>- I I "S fe CDIOC5 05© H W O) TH H Ol rH CO lO O Ql LO t^ CD Ol O Hi O CO Hi CO O Hi CD t^ CO NCOHCOtJ* oj O CD h LO ' O t) in NCOCOCOCO CO N CO W H COHOCOCD tH C3 Ol t~ Hi O OHNCO^ ID CD K CO o O H ci cq CO Hi LO LO CO !>. co cd co co cd co co co co co t- t- t- t~ i>- t^t-t-t^t^ h*j tS CO O t~ Ol CO CO CM CO W CO CO CD CO ■* O H CO H H Ol M .m CO O CO Tf* CO O LO t> CO N Hi H< CO LO CO lOCMCTi^t^ .tx! IJ crt -m CD t- t- t^ b- t^COlO-^CO Ol O OS S W CO H 00 CD CO {Xj £v ^ OH01C0"t LO CD N CO O OrHrHcMCO H< lO LO CO t^ jj £U co cd co co cd CDCJCOCDCD t-t-L-t^t- t- L— t~ t~ » C£l rH LO H< Ol O O CO CD LC W SNOCOO CO H O S W " *j £ CO Ol CO Hi Hi rH LO CO Ol CO O H lO t> CO SIOHCOO £? 5 CO lOOCOCOCD CO >0 Hi CO Ol rH O CO CO Hi Ol O CO LO CO M-l fl OHOICOH LO CDSCOQ O H H Ol CO TH L.i lO CO t> <| 2 CO CO CD CD CO CDCDCOCDCO t~ b- t~ t^ t>- t- t~ t~ t~ t>. €" g CO O H CO Ol Hi Hi Hi 1<^ t-- Ot^b-rHO ^ rH O Ol Ol Ol Ol CO 'Hi Hi HH050Q h Ol CD Q O Ol b- Hi CI CO Ol Hi t+I LO LO LO WHCOCOH O 05 l> lO -H rH Ol t- Hi Ol OHC1COH lO CD N CO C5 O O H CI CO ■* H ID CO N CD CD CO CO CO COCOCOCDCO t- t— b- L- t- t- t~ L>- t- t- ^HCOCOH CO O Ol W CO H Ol -H Q O LO CO Hi CO Ql HaOOlHH ri t- O ri O CO ^ GO O Ol H 05 CO nio rH COCOHHH H CO CO Ol H 05 CO CD LO CO HCOCDH< H O rH Ol CO Hi lO CD t- CO OS Ol O rH Ol CO ^ H IO CO N CO CO CO CO CO COCOCOCDCO CO L^ N t- t> t- t- t- t~ f- Ol Ol CO CO CO CO CI Ol rH O CO N CD H CM O OO LO CO O O H CM CO H LO CO t- CO Ol C5 O H Ol CO H H ID C t- COCOCOCDCO COCOCOCDCO CO L- N l^ t> b- l>- t- t- f. ELECTRICAL TABLES AND DATA ^1~q^^l~q ^^-l^I^q^J 03 OJ 05 OlCl O OS CT1 OS OS ^ CO GO ■-> O ^ O0O00000O0 00 00 00 00 GO 00 CO COOOOO OO N N N "<1 ffiffiGoccvi a q ci m 4 s - w w 10 m m o cotooos NMQOOl ©W^WOI 00 LO Q CO CO C5 CO tO Ol 00 O •CiO^OOO tow WMO OOOlOOl© M W W WM tOOCHOl OJtOOJOlCD axi-'^IM^t-' 00 rf^ CD CO Ol GO GO OO 00 GO GO 00 00 00 OO 00 00 00 00 00 GO GO N S -3 •CO ^ 00 GO N Oi Gi Ol Ol rf^ CO M LO b5 M O O CD 00 S CO tO S M CJl to W s H Oi CDWQOW OiOCOCSOO M HfflOWCS OOOCDOOS ^MS tOOl 0000000 S ^ Ol 00 ^ I— i I— ' CO N I— ' O) Ol LO O 00 Ci CO CO >£«. N ■GOOOOOOOOO GOOOOOOOOO COO0O0000O 00 CO ~-l S N CO©GOGOS S CI C'l Ol ^ tf^ CO tO tO I— ' OOO00S CO CON Mffl Ott-CCtOQ OWSO*> S O CO Ol CO tO -1 to OJ CO to ^ Ol Cn rf^ W MS WOO to Ol N N N Oi tO O H Qi M OHCOOOW MQOSfflOl rfi. tO CO Ol O commoco s^oaico to^rf^^co •^ GOOOOOOOOO 0000000000 00 00 00 00 00 0OCCSS ■CD CO CO CO N <|C)0I01^ |(i. CO to tO M OOCOOOOO H Ix) CO WCOtOQ OOtCOCOffl OlMJOH^ OOh-»^~qOCO V~ f Ci) --j r— ui ^1 cc l- 1 ^ O r 4J N Hi U W( yj Ki ^ tR (R UJ ^ u N Oi CC tO CO 00 O CO CO Ol WtOtOMM MOCOOitO KJ •CO 00 CO 00 CO 0000COQO00 OOCOOOOOCO COOO^KIS CO CO 00 00 S S CS Ul Oi rfi rfi CO tO tO H OOCDOOCO M *^ \^ ^> L*J ^* — ^l u; >~>\ Wl H-* H-* V^ LV L^l r— ( J ^ — ' >^-> Kf~i ^ ■CO (fi CO CO O HOlCOWS h-i Ol CO to Ol 00 tO Cl CO I- GO CO ~3 O CO OlOJ^IGOl WOOIHOI COOMMO - MHtf'COS SCOWCDS O5OJO5S00 CO CO 00 Ol 00 H Ol ^ Q ■CO oo CO OS CO MtO W WM CO CI CO CO tO Ol N CO 00 <1 2 OsOOli^ Ol 00 CO O 00 COCOOtOrf^ C5N0OQOC35 ^ g. I I' ■CO CO CO CO CO GOOOOOOOOO OO0O00QOO0 00 00 ~3 N -3 r- S CO CO CO S N C3 OJ Ol ^ ^ CO lO tO M M O CO » CO X £? OOlCO^OO bO O O rf^ 00 tO CI SO CO O oCOOiCOtOO hj >-" 'CO rf^ 00 tO Ol SCOCOCOCO Oi CO CO rf^ CO to^oioi^ m l-i tO Ci CO tO WNWMO H LO CJ1S O CO Oi -■ CO 01 O Ol CO tO ^OXl SO) rf^tOOOrf^OO CO 0< Oi C5 Ol >fi. ^ CO CO rf». OOrf^-tOtOrf*- OOtOSWCO hfiOOl CO to 130 ELECTRICAL TABLES AND DATA Hi QO lO «0 O os cxj in b- os OS t~ CO CO CO CO OHHNIM OS OS OS OS OS OS CXI QO O CO OS O OS OS t^ CO OS CO CO CO CO CO Hi Hi m OS OS OS OS OS OHHOtO mmocDN CO CO CO CXJ b- WCO©Nt> OS OS OS OS OS Htoomoi QO QO OS OS OS- OS OS OS OS OS rH lO CO Hi OS Hi b- O CXI CO 00 b- CXI QO CO CO O iH rH CXI CXI OS OS OS OS OS CO CO CO CO CO CO CO Hi H* to OS OS OS OS OS CO CXI t- CXI CO os os os os os HWO^OS GO CO OS OS OS OS OS OS OS OS t- cxj o cxj co CO CXJ in b- 00 b- CD cq b- cxj b- O iH rH CXI CXJ OS OS OS OS OS CXJ GO CO b- CXJ CO CO tH Hi lO OS OS OS OS OS OCDM^W CD CO O b- CO ' b- CXJ b- rH CO WCD(OI>N os os os os os o m OS -h CO GO QO GO OS OS OS OS OS OS OS CD CO i— I CD CXJ b- O rH rH CXJ CXJ OS OS OS OS OS CI b- CXJ b- CXJ fOCOHHHlo os os os os os CXJ OS rH b- OS tH GO CO CXJ QO bHCOHW lOOCObN os os os os os IO >> lO b w Hi OS Hi CO CXI O "* OS CO 00 GO QO GO OS OS OS OS OS OS OS a s 1-3 £1 s o os in io co to NHH ©CO lO in rH CD rH «0 O rH rH CXJ CXJ OS OS OS OS OS in cxj cxj co -* CXJ CD OS i— I CO O rH rH CXJ CXI os os Os os os rH OS O HH CXJ bOHOOO co -* o in o in O rH rH CXJ CXJ OS-OS OS OS OS b- in b- CXJ rH rH m CO rH CO n os os os os os CD rH rH in CO hh in in hh co rH CD rH CD rH CO CO tH H< m os os os os os in rH rH CD in os o o os co O CD rH in O co co Hi Hi in OS OS OS OS OS OIOOIOO co co Hi Hi in OS OS OS OS OS Hi CXJ Hi rH CO CD Hi rH 00 Hi CD rH CD O m moobb OS OS OS OS OS ©HNHN rH OS CD CO OS «o o m o Hi in CO CD b- b- OS OS OS OS OS OOSOOOH CD Hi CXJ GO lO in o in os Hi in CD CO CD b- OS OS OS OS OS o cxj o co cxi O W O Hi 00 O ^ OS CO b- GO CO CO OS OS os os os os os Hi fc- in os co in o in os co OS ^ 00 CXI b- t- CO CO OS OS os os os os os OS CXJ rH in H* O CO rH in OS OS CO CO CXJ CD b- GO GO OS OS OS OS OS OS OS O OS CO rH m CXJ OS b- Hi O >0 OS Hi OS Hi in m co co b- os os os os os CO b- CD rH rH CD rH CD rH in GO CO b- CXJ CD b- GO CO OS OS OS OS OS OS OS CO OS Hi OS Hi OOHHN OS OS OS OS OS os in o Hi os CXI CO Hi Hi Hi OS OS OS OS OS Hi OS Hi CO CO io in co co b- os os os os os CO CXJ b- rH CD b- GO CO OS OS OS OS OS OS OS OS CO rH b- b- O Hi CO O CXJ O CO 00 CO OS Hi O O rH rH CXI os os os os os rH OS rH CO OS Hi Hi lO Hi CO OS Hi OS Hi OS CXJ CO CO Hi Hi os os os os os Hi tH CO CO CXJ CXJ O b- Hi rH Hi OS CO 00 CO in m co co b- os os os os os CXJ b- t~ CXJ CO b- CXJ ,t- CXJ CO b- CXJ CO rH »0 b- CO CO OS OS OS OS OS OS OS ELECTRICAL TABLES AND DATA 131 sideration, and h the difference between the two man- tissae; next add this number to the lower number. Example : Our mantissa is 2.851 60, and looking into our table, we find that it is not tabulated. The next lower is .851 26, which corresponds to the number 700 ; the next higher is 2.851 87, which corresponds to 710. Now, .851 60- .851 26 leaves us 34, and the difference between 851 26 and 851 87 is 61. We have now 34 -^ x 10, which equals 5.57, and this added to 700 gives oJ us the approximate value of the number correspond- ing to the mantissa of 2.851 60, viz., 705.57. Magnetic Blowout. — A strong magnetic field repels an arc and is often used to break it. It is made use of in lightning arresters, and at other places where the arc is troublesome. TABLE XXXXIV Melting Points of Various Substances in Degrees Centigrade and Fahrenheit C. F. v C. F. Aluminum 659 1218 Mercury —38.7—37.7 Antimony 630 1166 Nickel 1452 2645 Bismuth 271 520 Paraffin 52 126 Brass 900 1652 Photo emulsion . . 32 90 Bronze 900 1652 Platinum 1755 3191 Carbon 3600 6512 Eubber 100 212 Chronium 510 950 Silenium 218 424 Cobalt 1490 3714 Silicon 1420 2588 German Silver. -1100 2012 Silver 960 1760 Glass 1300 2372 Steel, Av. ... . . .1400 2552 Gold 1063 1945 Sulphur 110 230 Gutta Percha... 100 212 Tantalum 2850 5162 Iridium 2300 4140 Tin 232 449 Iron 1520 2768 Tungsten 3000 5432 Lead 327 620 Vanadium 1730 3146 Manganese 1225 2237 Wax, Bees 62' 143 Marble 2500 4532 Zinc 419 787 Bureau of Standards as authority for the majority. 132 ELECTRICAL TABLES AND DATA Mains. — This term properly used applies only to the last set of wires feeding the final distribution point. Primary mains are those which feed the individual transformers. The wires leading from transformers are usually spoken of as secondary mains, although *\l Figure 8. — Measurement of Heights and Distances. there may be conditions in which they would be sec- ondary feeders. Measurement of Heights and Distances. The measurement of heights and distances requires first of all the use of right angles. Where no instruments or squares are available, a right angle can be laid out as in G, Figure 8, setting stakes or stretching lines so ELECTRICAL TABLES AND DATA 13£ that the dimensions given, or multiples of them, obtain on the three sides. A square or rectangle can be proved by stretchings diagonals from the corners. When both diagonals are the same length we have a perfect rectangle. See H, Figure 8. The height of a pole or other object can be found by the method shown in 7, Figure 8. Set up two stakes, A and B, a known distance apart and of a height so that their tops form a straight line with top of pole. When this is done the length of pole C above B is to E as D is to F, hence C = — Er . If the total length r ofD + Fis made equal to 27J feet and F-2\ feet, then C = 10xi£. Add distance below line D to this to ob- tain total height of pole. The distance between two points, one of which is accessible, can be found by means of the construction: shown in J, Figure 8. Similarly to the foregoing, if B is made 10 times C, then A will be made 10' times D. The distance between two inaccessible points may be measured by the methods shown in K, Figure 8.. If two stakes, C and D, be set up with reference to A and B, so as to be at right angles to each other and with diagonals pointing to A and B, also forming the same angles, the distance between C and D will be: equal to that between A and B. Another method consists in setting up two stakes,, E and F, and parallel to them drawing a line or lay- ing a tape line upon the ground and setting up stakes: as indicated at S. Measure distances between the various stakes and draw a plan of them to any con- venient scale as indicated. Measure the distance be- tween A and B on this plan. This method does not require that E and F be parallel or centered with reference to A and B. 134 ELECTRICAL TABLES AND DATA Mensuration. — Area of a triangle = base x \ altitude. Area of a parallelogram = base x altitude. Area of a trapezoid = altitude x \ the sum of parallel sides. Area of trapezium: divide into two triangles and find area of the triangles and add together. Area of circle = diameter 2 x 0.7854 = radius 2 x 3.1416. Area of sector of circle = length of arc x \ the radius. Area of segment of circle = area of sector of equal radius -area of triangle, when the segment is less, and + area of triangle when the segment is greater than the semi-circle. Area of circular ring = diameters of the two circles x difference of diameters x 0.7854. Area of an ellipse = product of the two diameters x 0.7854. Area of a parabola . = base x f altitude. Area of regular polygon = sum of its sides x perpen- dicular from its center to one of its sides -r- 2. REGULAR POLYGONS Length Radius of Length of side when Area of circum- radius when side Perpen- scribed of dia. of Area when dicular circle circum- No inscribed when perpen- when when scribed of circle side dicular side side circle i Sides =1 =1 =1 =1 =1 =1 3 Triangle ..1.299 0.433 3.464 0.289 0.577 1.732 4 Square .. ..1.000 1.000 2.000 0.500 0.707 1.414 5 P'entag. . ..0.908 1.720 1.453 0.688 0.851 1.176 6 Hexag. .. ..0.866 2.598 1.155 0.866 1.000 1.000 7 Heptag. . ..0.843 3.634 0.963 1.039 1.152 0.868 8 Octag. . . ..0.828 4.828 0.828 1.207 1.307 0.765 9 Nonag. . . ..0.819 6.182 0.728 1.374 1.462 0.684 10 Decag. . . ..0.812 7.694 0.650 1.539 1.618 0.618 11 Unclecag. ..0.807 9.366 0.587 1.703 1.775 0.563 12 Dodecag. ..0.804 11.192 0.536 1.866 1.932 0.518 ELECTRICAL TABLES AND DATA 135 Surface of cylinder or prism = area of both ends-f length x circumference. Surface of sphere = diameter x circumference. Convex surface of segment of sphere = height of seg- ment x circumference of the sphere of which it is a part. Surface of pyramid or cone = circumference of basex -| of the slant height + area of the base. Surface of frustrum of cone or pyramid = sum of cir- cumference at both ends x | of slant height + area of both ends. Contents of sphere = cube of diameter x 0.5236. Contents of cylinder or prism = area of end x length. Contents of segment of sphere = (height + three times the square of radius of base) x (height x 0.5236). Contents of frustrum of cone or pyramid: Multiply areas of two ends together and extract square root. Add to this root the two areas x -J altitude. Contents of a wedge = area of base x \ altitude. Circumference of circle = diameter x 3.1416. Circumference of circle- radius x 6.2832. Circumference of circle = 3.5446 x square root of area of circle. Circumference of circle x 0.159155 = radius. Circumference of circle x 0.31831 = diameter. Circumference of circle x 0.225 = side of inscribed square. Circumference of circle x 0.282 = side of an equal square. Half the circumference of circle x half its diameter— its area. Square of circumference of circle x 0.7958 = area. Diameter of circle x 0.86 = side of inscribed equilateral triangle. Diameter of circle x 0.7071 = side of an inscribed square. Diameter of circle x 0.8862 = side of an equal square. 136 ELECTRICAL TABLES AND DATA Diameter = 1.1283 V square roo ^ f area f circle. Length of arc = number of degrees x 0.017453. Degrees in arc whose length equals radius, 57.2958°. Length of arc of 1° = radius x 0.017453. Meter Capacity. — It is a general rule to install meters of about one-half the capacity of the connected load in residences ; three-fourths this capacity in small stores, offices, etc., and full capacity for elevator motor service and similar installations where exces- sive starting currents are the rule. For more exact determinations, see Demand Factors. The d. c. meter is essentially a shunt motor, and its direction of rotation is independent of the polarity, but if fed from the wrong side, it will run backwards. On a. c. circuits wattmeter readings will not check with volt and ammeter reading; the latter must be multiplied by the power factor. Current transform- ers are used in connection with large capacity a. c. meters. Meter Location. — Meters must always be* accessi- ble, never in places that are locked or where meter readers would cause annoyance to occupants. The location selected must be free from moisture and vibration. Meters should not be placed on curb walls of streets on which cars operate nor on thin partitions. If meters are placed in cabinets, these should be fire- proofed and no magnetic material should be brought close to the meter. Meters must be set level and level- ing can be accomplished by placing a small weight upon disk, and shifting meter until disk remains at rest in any position. In order that meters may be properly set, meter boards must be provided. The necessary dimensions of such boards vary with the service to be rendered and are given on Figures 9 and 10. These are the requirements in force in the City of Chicago. ELECTRICAL TABLES AND DATA A o ALTERNATING ~\& 22 WATT HOUR METER 34 r { \ i ' ;::5L.. ; i i ' ! • i • i i i ; i ^ / x , { 34^ LJ lJ N/ k— »e* — » Figure 9. — Meter Fittings and Meter Boards. Figure 9. — Showing Proper Location of Meter Fittings and Size of Meter Boards Kequired for Different Installations. A. C. Eesidence or Apartment Lighting. 30 sockets or 1500 watts, or under, sketch A. 31 to 48 sockets or 1501 to 2640 watts, sketch B or D. Above 48 sockets or 2640 watts, sketch C or E. ELECTRICAL TABLES AND DATA A. C. Business Lighting. 24 sockets or 1320 watts, or under, sketch A. Above 24 sockets or 1320 watts, sketch C or E. A.. C. Power. 5 H. P., and under, single-phase, sketch A. Above 5 H. P., and all three-phase, sketch C. P i Q > ^ < -, 22 ■ i : K ) ^J V r-"f — i '^-w — > DIRECT CURRENT /< i -i f ; r""""i i .2 '! i ' u Uf~-\ • i >/ rn k — — **- * Figure 10. — Meter Fittings and Meter Boards. ELECTRICAL TABLES AND DATA 139' Figure 10. — Showing Proper Location of Meter Fittings and Size of Meter Boards Eequired for Different Installations. D. C. Eesidence or Apartment Lighting. 30 sockets or 1500 watts, or under, sketch F. 31 to 48 sockets or 1501-2640 watts, sketch G or I. Above 48 sockets or 2640 watts, sketch E or J. D. C. Business Lighting. 24 sockets or 1320 watts, or under, sketch F. Above 24 sockets or 1320 watts, sketch H or J. D. C. Power. 1500 watts, or under, sketch F. Above 1500 watts: 2 -wire, sketch G or I. 3-wire, sketch H or J. If the meter is located at service entrance, the meas- ured energy will exceed the delivered energy by the percentage of loss occurring in the feed wires. If it is located at some distance from this point the service company will stand part or all of this loss. The per cent loss per 100 feet ran with . different voltages, wires assumed to be loaded to full capacity 7 is given in Table XXXXV. TABLE XXXXV B. & S. Amperes 110 v. 220 v. 440 v. 550 v. 1000 i 14 15 4.80 2.40 1.20 0.96 0.53 12 20 5.80 2.90 1.45 1.16 0.64 10 25 4.50 2.25 1.13 0.90 0.50 8 .35 4.00 2.00 1.00 0.80 0.44 6 50 3.60 1.80 0.90 0.72 0.40 5 55 3.10 1.55 0.77 0.62 0.34 4 70 3.10 ' 1.55 0.77 0.62 0.34 3 80 2.90 1.45 -0.73 0.58 0.32 2 90 2.60 1.30 0.65 0.52 0.29 1 100 2.20 1.10 0.55 0.44 0.24 125 2.20 1.10 0.55 0.44 0.24 00 150 2.10 1.05 .0.53 0.42 0.23 000 175 1.90 0.95 0.47 0.38 0.21 0000 225 1.90 0.95 0.47 0.38 0.21 300 000 275 1.90 0.95 0.47 0.38 0.21 140 ELECTRICAL TABLES AND DATA Reactances are not taken into consideration. Meters, Maximum Demand. — The cost of supply- ing electrical energy is properly divided into two parts: One of these consists in charges to be made for meter reading, bookkeeping, and investment of capital ; the other in the cost of energy consumed by the customer. The capital investment depends largely upon the maximum demand of the customer and also upon the time at which this demand occurs. A given trans- former, for instance, will serve perhaps twice as many families in which the ironing is done during the day, as it will where an iron is used at the same time with the lights. In order to obtain compensation for un- necessarily high demands for short times, maximum meters are installed, or a certain fixed charge per month is made against every customer whether cur- rent is used or not. The maximum demand meter may be any arrange- ment which will indicate the highest amperage, or rate of power consumption, during any month or other convenient term. The method of computing Dills where these meters are installed is somewhat con- fusing to one who does not make a business of it, and to show the influence of max. meters the following table is presented : This table shows the average rate per K. W. hour brought about by different maximum demands and total K. W. consumption per month. TABLE XXXXVI Max. Amp. Total K.W. Hours 25 50 75 100 125 150 200 300 25 11. 11. 11. 10.1 9.3 8.7 7.7 6.4 .20 11. 11. 10.4 9.3 8.6 8.0 7.0 6.0 15 11. 11'. 9.3 8.4 7.9 6.9 6.2 5.5 ' 10 11. 9.3 8. 7. 6.4 6. 5.5 5. .5 9.3 7. 6. 5.5 5.2 5. 4.7 4.4 ELECTRICAL TABLES AND DATA This table is based on a charge of 11 cents per K. W. hour for the first thirty hours of the maximum used ; 6 cents per K. W. hour for the next thirty hours of the maximum, and 4 cents per hour for the balance. The maximum load is found by multiplying the high- est amperage during the month by the volts. If we have a maximum of 10 amperes our first charge will be 10 x 110x30x0.11 = $3.63; the next will be 10 x 110x30x0.06 = $1.98, and for the remaining K.W. hours we charge 4 cents, which equals $1.60, giving us n-xrxn "12x33,000xe where P =pull in pounds which must be applied at periphery of pulley to move it ; r = radius of pulley in inches; n- number of revolutions per. minute; e = the efficiency of a direct current motor or the product of efficiency and power factor in an alternating current motor or circuit. If the- machinery to be started is equipped with heavy flywheels, or possesses considerable inertia of any kind, the size of the motor needed is governed by the starting requirements which depend largely upon the rate of acceleration demanded. In connection with other machinery, such as ventilating fans for instance, the power required increases faster than the speed and can be measured only when the device is operating at full speed. For such motors the above formula cannot be used and it is necessary to obtain data from manufacturers or other users. ELECTRICAL TABLES AND DATA oooooooooo hj oooooooooo • oooooooooo ^300f^tDOll-'s^^(»l^ ^coooocacoo~auico oooooooooo OWOllfiCOCOBI-'h'O OWOSMOOClOSW •CD ^ oooooooooo OOSffiOlUl^WtOI-iO ^CftOOCHti^ClNlOO 00|>00)O^O^OOI CD ■ (-OOOOOOOOOO OtOOOSOlOI^WtOM (SOl^^WWMHMO OlMXJMOOlMXKiCS MMOOOOOOO l-'OGO-qOG-lCOCOl-' rf^l-iQOC5COOOOClt>0 W05«OKIOl(/)HOlS MMMMOOOOOO rfxWMOOOSUllf'.MI-' rf*-?0^<©^S0rf^Otf^ oKiaw^oiasosci 3^ MMMMMOOOOO CftWWMOOOfflOlWH CSGOOtOOGOOOOOO MM-MMMOOOOO tO^OlCOM<©~qCHWI-i OOCOOMCS^OlOMO tOMMMMI-'OOOO ooooiiMooooai^M tocoi-»i-»i-'i-»©ooo WOMOWMffiCS^K) K)00)h'tOOlW©SW K) M M M Ol Kl O vl ^ oo CO s O OS to GO ^ o as to o *>■ 160 ELECTRICAL TABLES AND DATA LiTT X f* X 'Yh In the table below the values of ^ — tttttu^ — 12x33,000x6 (e being assumed as of about .75) are given wherever the horizontal line pertaining to speed crosses with a vertical line pertaining to radius of pulley. Care must be exercised in determining P; it must not be more than just enough to cause motion, and at best can be only an approximation. P may be deter- mined by a spring balance, or by a weight and lever. If the latter is used and attached to rim of pulley, multiply weight by distance from center of pulley and divide by radius of pulley. Group vs. Individual Drive. — The total H, P. ca- pacity of motors for individual drive must be equal to the H. P. demands of all the machinery. The H. P. capacity for group drive may be con- siderably less, because not all of the driven machinery is used at the same time. How much of saving there is in any given case depends upon circumstances. Very often the shafting necessary with group drive requires as much additional H. P. capacity as is saved by the other consideration above. The total H. P. required for group drive can be found by the formula: H p = (h.p.xf)+s e where h. p. is the horsepower demanded by the total machinery if run all at the same time; / is the load factor ; s the H. P. required to drive shafting, and e the efficiency of the motor. The large motors used for group drive are more efficient at full load than the smaller ones, but a group drive motor is seldom run at full load. If it is properly chosen it will be over- loaded part of the time and inevitably be running with no other load than the shafting part of the time. ELECTRICAL TABLES AND DATA 161 The nearer it can be kept running with full load the more efficient it will be. The total H. P. required for individual drive is equal to the sum of the H. P. of all the machines divided by the efficiency. The full load efficiency of the small motors is lower, but there is never any idle machinery or shafting to be moved, and if properly selected the motors may operate at full load efficiency most of the time. In most cases individual drive is the most economical where a per- manent installation is considered, but the cost of installation is generally somewhat higher. In addi- tion to the above advantages, which can be figured out in dollars and cents, the following considerations should be of interest and duly noted: With indi- vidual drive the fire and life hazard are somewhat increased, but the shafting and belting accidents are greatly decreased. In connection with low voltage (110 or 220) the life hazard is small, and the advan- tage is on the side of the individual drive. With high voltage group drive is probably safer. With individual drive the facilities for speed regulation are better and motor troubles cannot throw a whole shop out of order. There is no shafting to cause dirt and noise and interfere with illumination, and there is less vibration in the workroom. Individual drive, however, requires somewhat more care and atten- tion. Where we have the choice of motors of different efficiencies we can afford to expend for the motor of the better efficiency a sum of money upon which the annual interest charge will be equal to the saving in the cost of energy effected by the better motor. We must, however, select the rate of interest so as to cover all depreciation, and if we assume that the motor will be a dead loss at the end of the time it is to be used, we shall obtain the following rates of interest, using a 6 per cent basis: B2 ELECTRICAL TABLES AND DATA Motor to be used 1 year only, 106 per cent 2 years, 56 " 3 vears. 40 " 3 years, 40 4 years, 32 5 years, 27 6 years, 24 7 years, 21i 8 years, 20 9 years, 18f 2 For longer periods of time the interest rate decreases slowly and the above will cover all ordinary cases. According to the above principles we can determine the amount of money we may economically invest in order to substitute a motor of higher efficiency for another with lower efficiency by the formula, ~_K.W. xrxkxdxe per cent interest where C = capital to be invested; K. "W. = the number of watts used; r=the rate per K. W. hour; h=the number of hours K. W. is used per day; d = the num- ber of days per year ; e = the difference in efficiency of the two motors; per cent interest = the rate of interest governed by the number of years motor is to remain in use as given above. In the following table it is assumed that the motor will be used 300 days per year, and on this basis the numbers given represent the capital which could prof- itably be invested with K. W., r, and h equal to unity, and e and the rate of interest as given in the table. To use the table for determining how much can prof- itably be invested to substitute a more efficient motor in place of a poorer one, it is but necessary to find the product of K.W.xrxh, and with this multiply the number found where the horizontal line pertaining to the difference in efficiency in favor of the better motor ELECTRICAL TABLES AND DATA oo as tf^ to o © oo '.'. '.'.'.'.' 5" p : : : : : : j j : : : : : : : «3 hi Cn ">P- CO CO tO tO M m M h-» M O O O i_i M 01 o cuto to oo 01 to to a ^m oo 01 to 5^ w «o to © co w ^ © oo to i— ' to ^ a oo r 4 O £» 00 CO OS O ^ ^ M OO M M O Q W u) ' o «o 00 S S3 S Ol Ul Ol rf^ to t^. s o w 00 os ^ to K) Kl H M O %«i O) M O M Ol Ol |5 00 ^ o vi w oa 5 o ^ 00 to OS w w to o «o o or o 01 o 00000 00 OS rfs. C-wi M vl 00 co .-to tf*. OS to to rf*. O Ol O Oi o co 00 -; o cm 10 t>; CM* CO* CO* CO* CO* fn b» ^ ^ oo oo co >^cq »hh o co o co ^ rJH CD 00 rH CO S CO lO ■* t}( CO rH CM O 00 rH s q to iq rH' rH* id id id o o o o o o >o o io o q n iq i> q Tj" rj* rJH rH* id CM CM O O O CD rH CM O CO IO CD CO CD CD o o o o o io o io O IO CCJ IO b~ O CM id »d id co* cd CM rH CO CM IO b- Oi CM IO b- Ci CM CM 00 H OO IO CD CO r- 1 CM IO CD 00 rH CO IO DO CO CO ^ ^ rH rH IO IO IO OO 0O CM o OO Ci 00 b~ CD rH Ci rH CO IO b~ CM* co" CO* CO* CO* CD CM O CO IO CO CM CM Oi CO Oi r-j CO rH CD CO rJH rH rH rH ■3 .9 .1 n-H © Jh W S ""^ O Tj T3 fe|§"S HH _Q el's S-P © fn o "+3 © rQ « r>> | 2 fl cJDfl © d 3 2 -O O CD O O O • O O IO CD IO CD CO Ci rH CM CM CM* O O O O O o IO o io o rH iq b-; CO CD CM* CM* CM* CM* CO* £ CO CJ CD HH H CO k* IO t^ 00 Oi o o ^* rH CM CO IO CO CM ^ ^ ,_J ,_} pH ,_< CD CM CO rH O CM Ci IO CM Oi CM I- CO Ci ' IO cm Ci co rH rH CM CM CO rH b- 00 Ci CD rH CM CM* O O O O O io o >o o IO T-i CO rH CO b~ co* co* co* co' co* rH CO CO CM O IO IO CO b- CO CM CO rH IO CD CM* CM* CM* CM* CM* ■ b- t- 00 Ci Ci O O ■ CO IO CM CO IO CO O0 rH O IO r-i rH CM CO CO rH 5 * © S Cl> S :£ „ .2 cq m 3 © 2.2 5 M 2 © • O S £►»£■§ © o w £ *P S ® JH '3 $ g .2 co q3 h >h .2 c8 -gj h >h •rH O O ei_i Si =H o3 H © © ® <2 ca © S^ O $H rH > ELECTRICAL TABLES AND DATA 165 crosses with the rate of interest applicable to the problem. The result will be the sum in dollars and cents which can with profit be expended to procure the better motor. Rule of Tables — Find the difference in efficiency between the motors considered and the number of years the motor is to be used. Select the number found in the longitudinal line where the correspond- ing efficiency (given in vertical column at the left) crosses with the proper rate of interest (given at top) ; multiply this number by the K. W. hours per day, and by the rate per K. W. The result will give the amount of money which may be invested to procure the motor of higher efficiency. If this sum will make up the difference in cost, the better motor should be provided. Nails. — Use cut nails for driving into brickwork. TABLE XXXXIX Dimensions of Nails Common Nails Fi nishing 1 Nails Diam. Approx. Diam. Approx. Nearest in number Nearest in number Size Length B. &S. inches per lb. B. &S. inches per lb. 2d 1 13 %28 876 14 %28 1351 3d 1% 12 %4 568 13 %28 807 4d iy 2 10 %4 316 13 9 /(28 584 5d i% 10 Vu 271 13 %28 500 6d 2 9 %4 181 11 %2 309 7d 2% 9 7 /64 161 11 %2 238 8d 2y 2 8 17 /i28 106 10 %4 189 9d 2% 8 17 /i28 96 10 7 /64 172 lOd 3 7 19 A28 69 9 7 /64 121 12d 3% 6 19 /i28 63 9 %4 113 16d 3y 2 6 %2 49 8 17 /i28 90 20d 4 4 2 %28 31 8 17 /i28 62 30d 4y 2 4 2 %28 24 40d 5 3 2 %28 18 50d 5% 2 31 /i28 14 6oa 6 2 3 %28 11 166 ELECTRICAL TABLES AND DATA National Electrical Code (Abbreviated N.E.C ;. — The N. E. C. contains the recommendations of the National Fire Protection Association in reference to electrical installations. It is revised every two years, and its recommendations are generally accepted as standard throughout the United States. Most mu- nicipalities pattern their regulations after this code, but introduce a few variations which local conditions seem to warrant. The National Board of Fire Under- writers issue ' ' The List of Electrical Fittings. ' ' This contains a list of appliances which have been tested and are considered safe. Those engaged in electrical construction work are advised to keep in touch with the N. E. C, the List of Electrical Fittings, and local requirements. Nernst Lamp. — This lamp is not as much used as formerly. It has a high intrinsic brilliancy; requires no reflectors; should be hung high. It requires con- siderable attention to keep in repair and cannot be used in theatres or similar places where quick changes are necessary. Neutral Wire. — This term describes one of the three wires used in connection with the three-wire system. Normally this wire carries no current and is, therefore, often smaller than either of the outside wires. In case an outside fuse blows, it may, however, be called upon to carry the full load current. It is always fused higher than the outside wires, and often is not fused at all. Blowing of the neutral fuse may do much damage. Ordinarily this wire is also grounded. In a star connected polyphase system, the point at which all of the wires connect is also spoken of as neutral. The fourth wire in a three-phase system may also be so termed. Non-inductive Load. — A non-inductive load is dis- tinguished from an inductive load by the fact that ELECTRICAL TABLES AND DATA 167 the current is in phase with the voltage. Circuits supplying only incandescent lamps are very nearly non-inductive; arc lamps .and motors make up a strongly inductive load. Office Lighting. — Desk lights are very common, but they are also a nuisance. They cause constant annoyance, and increase the fire hazard. Inverted lighting is very favorably received in many offices and deserves extended trials. The newer high efficiency lamps have done much to make it econom- ical. Where all employes are constantly at their desks there can be no difference of opinion regarding the superiority of a good general illumination in every respect. Local illumination can appear advisable only in such places where most of the desks are occupied for a short time per day only. Avoid large spreading chandeliers carrying many lamps. These often cause a multiplicity of shadows. If clusters are used, lamps should be close together. Do not run wires in any but the main walls or parti- tions; use three-fourths inch conduit so as to have plenty of capacity for changes which are always tak- ing place. Arrange lighting to harmonize with win- dows, so that furniture placed correctly for daylight will also fit the artificial illumination. Ohm. — The international ohm has been legalized in this country and is defined as the resistance which a column of mercury of a uniform cross section, at the temperature of melting ice, and 106.3 centimeters in length, and of a mass of 14.4521 grams, offers to anV unvarying electric current. TP J? Ohms Law.—/—; IxR = E; B=~ li i Ohmic Loss or Drop. — The loss in e. m. f . or drop in p. d. caused by the resistance as distinguished from that caused by reactance. 168 ELECTRICAL TABLES AND DATA Overhead Construction. — The timbers most in use for poles are : Michigan cedar, Western cedar, chest- nut, pine and cypress. Of these the cedars and chestnut are the most used. The cedars are easier to climb and the taper is greater so that the tops of cedar poles are smaller in proportion to the butts than chestnut poles. On account of the variable nature of the wood and the fact that they soon begin to rot at the ground line, which is the point of greatest strain, the strength of poles must be calculated with a large factor of safety. In the tables following the breaking strain of the wood has been taken as 7,000 pounds per square inch and a factor of safety of 10 has been used. Poles are usually designated by their length in feet arid diameter at top in inches; thus a pole 40 feet long and 8 inches in diameter at top is spoken of as a 40-8 pole. The standard or most used pole is 35 feet long and has a 7-inch top. In swampy places poles are often set in concrete. Poles should be set with the sweep in the line so that the wires may be straight. Use no iron poles where lines must be worked on while alive. Set pole steps 32 inches apart and stagger them. In cities place poles on lot lines. Avoid placing poles near lamp posts, hydrants or catch basins. Give corner poles a slight rake outward. Use the heaviest poles for transformers. Special attention should be given to tamping at bottom and top of holes, and the earth should be piled up a little around pole to keep water from running in. Keep one side of pole free for climbing. Double arm all poles subject to unusual strains. The lowest cross arm should be at least 18 feet above ground and 22 feet above railway tracks. Allow at least 2 feet between cross arms ; more if pos- sible. Insulate guy wires. Make cross arms of uni- form length. ELECTRICAL TABLES AND DATA 169 Standard cross arms are rounded on top ; 3J inches wide by 4J inches high ; allow- 24 inches between pole pins, and at least 12 inches between other pins; this distance varies with number of pins, length of span and voltage. Junction arms usually have a wider spacing between inside pins. The high tension wires should be carried on the top arms; secondary wires are usually run below them, and the lowest arms are left for signal wires if any are to be run on same line. There should be a space of about five feet between the signal and the lighting and power wires. The lowest voltage wires are usually run next to poles; circuit wires should be kept together, and neutral of three- wire system should be run in center. The fourth wire of a three-phase system is also carried next to pole. Pole Line Calculations. — The first step in laying out a pole line must be to decide upon height of poles and maximum span lengths. The next step will be to calculate the strains to which poles may be sub- ject. The main body of a pole line is subject only to wind pressure, and this can be determined by use of Table LIL End poles are subject to half of this wind pressure and strain from the wires as well. Poles from which taps are taken have the full wind pressure and strain of wires leading off. Corner poles must be considered as subject to 1.41 times the strain on end poles. The wire strains upon poles can be found by the use of Table LI. The strains upon poles having been determined, the proper diameter at ground line can be determined by Table LIU. When the strains on a pole are found to be greater than a pole of desirable diameter can well bear, it must be reinforced by guying or bracing. The proper diameter of guy cables can be found from Tables LV to LVII. If the pole is light compared to the strain put upon it, it will be best to provide a guy cable to take care of the total strains. ELECTRICAL TABLES AND DATA TABLE L It is common practice to string electric power wires in accordance with the following tabulation, which gives the sa g in inches : Length of Temperature in Fahrenheit span 20° 30° 40° 50° 60° 70° 80° 90° 50.. . 8 8 9 9 10 11 11 12 60.. . 9 10 11 11 12 13 14 14 70.. . 10 11 12 13 14 15 16 17 80.. . 12 13 14 15 16 17 18 19 90.. . 14 14 16 17 18 19 20 21 100.. . 16 16 17 19 20 21 23 24 110.. . 18 18 19 21 22 24 25 26 120.. . 18 19 21 23 24 26 27 28 130.. . 20 22 24 26 28 30 32 33 140.. . 22 23 26 28 30 32 34 35 160.. . 24 26 28 30 32 34 36 38 With wires strung according to the above tabula- tion each wire at the lowest temperature given will cause a strain on poles as given below. To find total strain on pole multiply proper number in table below by number of wires. By allowing a greater sag the strain will be proportionately reduced. TABLE LI Bare Copper Length of B. & S. Gauge 'Span 14 12 10 8 6 5 4 3 2 1 00 000 0000 80 10 16 2G 47 03 so 101 127 160 202 255 321 405 512 100 13 22 34 62 85 107 135 171 215 272 343 432 545 688 120 15 24 39 70 95 120 151 190 240 303 382 481 607 768 140 18 29 47 85 116 147 182 230 294 371 470 592 740 942 160 19 32 52 1)4 120 160 202 254 320 404 510 642 810 1024 Breaking Strains B. & S. Gauge Hard Drawn — 14 12 10 8 6 5 4 3 2 1 00 000 0000 219 343 546 843 1300 1580 1900 2380 2970 3680 4530 5440 6530 8260 Annealed — 110 174 277 441 700 884 1050 1323 1670 2100 2650 3310 4270 5320 Insulation and sleet may easily treble the strains. ELECTRICAL TABLES AND DATA 171 The Maximum wind pressure upon the pole alone will range from 125 to 250 lbs., according to length and diameter of pole. The side strain on a straight pole line (125 ft. span ) can be found by use of the table below. Multi- ply number of wires on pole by number found under size of wire and in proper horizontal line. TABLE LII Wind Pressure B. &S. 14 12 30 8 6 5 4 3 2 1 00 000 0000 Bare wire.. 8 11 13 19 22 20 29 32 36 40 45 50 55 60 Insulated ..35 38 41 46 50 53 56 60 65 70 80 90 100 110 Sleet may easily treble these strains, but sleet seldom exists in stormy weather. TABLE LILT Table showing maximum strains (applied at top) to which poles of various heights above ground, and of various diameters at ground line, should be subject. 1=3 O C o Height of Poles Above Ground in Feet t 3 C (SO-'- 5 60.5 20 25 30 35 40 45 50 55 60 65 70 8.. 147 118 98 84 74 66 58 53 49 46 42 9.. 209 168 138 120 •105 93 83 76 70 65 60 10.. 286 228 191 164 143 127 115 104 95 88 81 11.. 381 304 254 218 191 169 152 138 127 117 109 12.. 495 396 330 284 247 220 198 180 165 121 141 13.. 624 500 416 356 312 278 250 226 208 192 178 14.. 786 628 524 450 393 350 314 287 262 242 224 15.. 960 768 640 548 480 427 384 349 320 296 274 16.. 1176 940 784 672 588 524 470 428 392 362 336 17.. 1407 1124 938 804 704 625 563 572 469 433 402 18.. 1658 1328 1106 948 828 756 664 604 553 510 474 19.. 1964 1572 1310 1120 982 872 786 716 655 604 562 20.. 2288 1831 1526 1284 H44 916 915 832 763 704 652 21.. 2665 2132 1764 1524 1333 1144 1066 968 885 820 762 22.. 3048 2440 2032 1740 1524 1356 1209 1108 1016 938 870 ELECTRICAL TABLES AND DATA Depth of Setting Earth 5 Bock 4 5i 6 6 6| 6i 7 5 5 5£ 5^ 6 71 6i 8 7 81 7 9 9* When erected along a curved line it is best to set somewhat deeper. TABLE LIV The following table probably shows the average of poles used for general telegraph and telephone purposes : Butt Top Wt. Butt Top Wt. Length Dia. Dia. App. Length Dia. Dia. App. 25... 9 to 10 6 to 8 350 50... 9 to 15 6 to 8 1350 30... 9 to 11 6 to 8 450 55... 16 to 17 6 to 8 1700 35... 9 to 12 6 to 8 600 60... 16 to 18 6 to 8 2200 40... 9 to 13 6 to 8 850 65... 16 to 19 6 to 8 2500 45... 9 to 14 6 to 8 1100 70... 16 to 20 6 to 8 3000 Guys. — Guys should be fastened to pole at point of strain and when so fastened the strain upon the guy can be found by the formula 8 = V D^ xp where D - horizontal distance at ground of guy from pole; H= the height of guy, and P = the pull upon the pole. TABLE LV Table for Calculating Strength of Guys. — To find the proper size of wire or wire rope for guying, mul- tiply total strain upon pole by number found at point where line pertaining to height of guy fastening on pole crosses with line pertaining to horizontal dis- tance of guy at ground from pole. The product will equal the breaking strain of the proper cable or wire to be used. The table is calculated for a safety factor of 5. ELECTRICAL TABLES AND DATA Height Horizontal distance in feet from pole to where of guy guy or its support leaves ground on pole 5 10 11 15 16 20 21 30 31 40 40 50 50 60 ..... . 60 70 70 the 10 15 20 30 40 50 7.0 6.2 5.5 o.3 5.2 5.1 9.0 7.0 6.2 5.6 5.3 5.2 11 8.3 7.0 6.0 5.6 5.5 16 11 9.0 7.0 6.3 5.8 21 15 11 8.3 7.0 6.5 26 18 14 9.5 8.0 7.0 31 21 16 11 9.0 7.6 36 24 TABLE 18 LVI 13 10 8.5 Table Showing Breaking Strain of Cables and "Wires. — Standard Steel Strand. American Steel and Wire Company. Seven steel galvanized wires twisted into a single strand. Galvanized or extra galvanized. Approx. Weight Approx. i Galvanized Steel Wire \ Dia per Strength Break- in 1000 in A. S. & ing . Nearest inches feet pounds W. G. Dia. Strain B. & S. Dia. I 800 14000 12 .106 510 10 .102 & 650 11000 10 .135 774 8 .128 * 510 8500 9 .148 942 7 .144 & 415 6500 8 .162 1170 6 .162 1 295 5000 6 .192 1770 5 .182 & 210 3800 5 .207 2079 4 .204 i 125 2300 4 .222 2433 3 .229 & 95 1800 The American Steel and Wire & 75 1400 gauge is commonly used for & 55 900 iron wire. TABLE LVII "When a pole or mast is held in place by several guys equally spaced the figures obtained by the above calculation may be divided by the following guy fac- tors taken from publication of the American Steel and "Wire Company: ELECTRICAL TABLES AND DATA £ Min. Max. s value bfi „ ^ factor Corresponding line of action of force value of guy factor 3 0.866 30° from 1 guy 1.000 4 1.000 5 1.538 Opposite 1 guy 18° from 1 guy 1.414 1.618 6 1.732 30° from 1 guy Corresponding line of action of force Opposite 1 guy or half way between two Half way between 2 guys Opposite 1 guy or half way between two 2.000 Opposite 1 guy Telephone Wires. — The tables below give the prac- tice of the A. T.' & T. Co. No. 12 hard drawn copper wires are strung according to the following table : TABLE Lvin Temp. in Degrees Length of Span in Feet F. 75 100 115 130 Sag in 150 Inches 175 200 250 300 — 30 1 2 21 3| 41 6 8 14 22 — 10 U 21 3 4 5 7 9 16 251 + 10 H 3 31 4| 6 8 101 181 291 + 30 2 3| 4 5i 7 9| 12 21 33 + 60 21 41 Si 7 9 12 16 261 421 + 80 3 51 7 8* 111 15 19 31 49 +100 41 7 9 11 14 18 221 36 55 The same sag is also allowed for iron wire. Messenger Cables. — The standard messenger strands used are the following: Size of Cable Strength No. 22 Gauge No. 19 Gauge of Strand 100 pair or smaller 100 to 200 pair Larger than 200 pair 50 pair or smaller 6000 lbs. 55 to 100 pair 10000 lbs. Larger than 100 pair 16000 lbs. ELECTRICAL TABLES AND DATA 175 The above strands are about equivalent to f 7 ^? t% and f inch diameters of good quality steel and used for spans not exceeding 200 feet. The sag allowed is the following : Sag in inches Sag in when not more than inches for 50 pair No. 22 gauge in in feet heavy cables wire will 1 80 16 10 90 20 12 100 22 16 110 26 18 120 30 20 130 34 22 140 40 26 150 44 30 175 62 42 200 82 58 Panel Boards. — The panel board is a small switch- board, but circuits supplying more than 660 watts are seldom fed through it. Those described in the following figures and tables are designed for 660-watt branch circuits. Main bars have a capacity of 6 amperes per branch circuit at 110 volts, but only 3 amperes if designed for 220 volts. The figures in the tables are those furnished by the Cuthbert Electric Mfg. Co. Wherever the depth of cabinet required is the same for all numbers of circuits, it has been given in the fourth column from the left. In other cases the special designations at each height will serve as a guide. Where no special mark is placed and no depth given, the required depth is 3J inches. When ordering boxes, see points to be noted under Cabinets. ELECTRICAL TABLES AND DATA Type 'A-9» Figure 12. — Types of Panel Boards. cap cap Kae crap I E3i °3 23! "31 23 nasn c^ap = = 3 KaE: '"31 CS|§ = = 31 g # p .-31 1 1 1 C2 s r rj 3 S^3 IP Figure 13. — Types of Panel Boards. ELECTRICAL TABLES AND DATA 177 - - :•:: ■ :: ■:: :*-:■.;. :■=.::- ::j: US Si : :&. i e i i I 1 ■ G •■■■ O ■ :8 ' : ■ G *' ©=■ 8 5 8 Figure 14. — Types of Panel Boards. 8 8 1 5 &2 1 Type'E.5' Type'E-6' Type 'F-1' Type 'F-2' Figure 15. — Types of Panel Boards. ! 1 1 I 3 3 Type 'F-3* Type 'P-4' Type 'F-5' Type 'F-6' Figure 16. — Types of Panel Boards. © too 03 . © © ELECTRICAL TABLES AND DATA + +++<<<]<] < < + + <<++ <3 + »DOHfflt> N Si ^ c3 rHt^OOCOCOLO^^^^aDCOcO SO©CJ'OONW^O©OJ Afi + +++ < + OCTHHWONNH^hHO IM NH OOMhtO^ M H O + +++ < + <.% > ooonooh^oh^Otjooo CicTiooiOTtioqiHcoo^^co ;-. i-ic>qcoOit(MHTj(00O HNH0QNH"*WhIO(»CS HQ * rHoacMoacaoacocacococooJco ©qcacqcocqcocqcocococaoo ++++ + + 3 005DN M^OOS^mHOQHtOL' icqcocaco i-ioQi-icacMcgoacocvjcocao' £ + + + "-H(MHCTN(M(M(M HHH(MH(MH(MC]CKQOq + + + 1H1— IHr lrHiHt-li-lo C3 LO CI O CI LO C] 10 cq 10 cq »o OrHC\| 1 -lcqi-lcqrH(M'Hoqi-ICNJ rt(MHNH(MH(MHC3HOq r?» ^rH K CO tO M^ MMtOH COMM l- l fOMMh-i en co en to en to en to en to en to ocnocnccnocnocnocn tO |_i to >_i en to en co o en o en to h-i to i-j to i- _. cntooitoentoentoi-j ocnowooiowj + <1 5" OOGOOOOOOOOOOOQOOO OOOOOSOSOOGOOSOSQOODOSOSpj vH ^ vM ^M M vj-* vM m ti^ tc^ tF- k£-^ ks-<. ir^ kS^ k5^ co co eo co g > • rf^co rf^ eo„ ^ w |_l 00 c rfx CO v£< ^ 00 OS K^ o en rf^ en [£ >. + + + > en 4^ en >£"• to &■ en -^ + + + > cs 4^ en #>> CO OS CO co + + + > os o< os en co o eo co + + + + ' 9% ^< S-^ 5°2 i O & ' O CO_g X 3M 2^ > rf^COrfxCO^tOCOtOI- ■ ■ o rf^ •— ' co -a to c + »- >t>- encocn^^e^^eo en co o to to eo en en + cn^cn^eneorfxco cotorf^cncoosco^ + as^en^eneoen^c os^osenosrf^en^t SSHOl-'HOlt5C + + + + p - I S go 0Q 8? E£ 1_J ° arcs" co ,_, •^ to 180 ELECTRICAL TABLES AND DATA <3<1«5©lOl>tOI>OQO 10lOO«5©ffi»OI>©t>tOl> COHNOKjOoocOiOr^NOlHOS HlOOJH00Hl(5l>(M©HN « <]<++ <<•+ + CM ^tf kO ^ <£> iq CO lO CO LO ^ ^ t^ ^lo^ioioioiocoiocoio^ « <+++ <]+++ 8 0 rd £ <] + + + <] + + + © " OOOIMSOlOOOCOtOnCOSO CO H SWIONM Hq H SW -I & <+++ <]+++ 90« <<++ <+++ I . "KHOOWOHtDCOM^NS 0000 O ■* ON © S 00 O N H « ^ 'HOST'S <]+++ <+++ jO O *-> r} rHCMCOCMCOcOCOCOCOCO - 1 ^^ (MOCqnCOMITOCOCOOjfO^ «"TJ*-H ++++ ++++ ;i © 5 en ° N ■* N tH (M O H S LO to >C r- I OS ^O^OJOOSMLO^OH 'Kfl^if, H(M(M(MOOCOCOO]COCOCOCOCO CMCMCMCMCOCOCMCOCOCOCOiro 3£«£j ++++ ++++ ■Cj 1~_ d OHtHHNNIOtJIOHhQOlo HCOHIONO^COHOIMOO °S™£ ++++ ++++ H 3 ^-t W HHHNNNH(NNNCQ(M HHHNCQ(MHCqN(MCXlcX| a '^ * ++++ ++++ d „ , n m©r|(NM«©0)(MOO)N WW*0(»l>©>i»0 CM lO CM »0 CM to CM >0 CM lO lO CM := .°H(MH(MH(MH(MHIMH(M 1HCM1— ICMrHCMT— ICMiH^MCgtH -a > ^ gj-S .S „ ~ ~ ~ ^ P;tH CMCOT^lrp«D tHCMCOtJHIO Efficiency Altitud'e Theoretical Practical Sea level 33.95 25 75 65 50 45 40 35 1,320 ft. above 32.38 24 70 52 46 35 32 28 24 2,640 ft. above 30.79 23 75 56 48 38 34 30 26 3,960 ft. above 29.24 21 80 60 52 40 36 32 28 5,280 ft. above 27.76 20 85 64 56 43 38 34 30 10,560 ft. above 22.82 17 Reactive Coils. — This term describes coils intro- duced- into a circuit to produce a certain reactance. They are also known as reactors. They are used to* limit short-circuiting currents. Reactors are usually designed for a high temperature rise, and should be treated as sources of heat. When used in connection with lightning arresters they are often spoken of as " choke coils." Rectifiers. — The mercury-arc rectifier is the one most used for arc lamp operation and is very common in motion picture theaters. Other types are the elec- trolytic and rotary. The mercury-arc type is also much used for storage battery work in connection with automobile charging. It is usually fed through autotransformers, but sometimes through constant current transformers, and then delivers a constant current. Most rectifiers are operated on single-phase circuits, but they can be arranged for two-phase and three-phase circuits and operate more advantageously. They may also be operated in parallel. Rectifiers de- signed for 40 to 50 amperes usually have glass tubes, but if larger capacities are required, the tubes are metallic. The power factor is ordinarily about 0.90. The drop in voltage is always about the same, hence 186 ELECTRICAL TABLES AND DATA the lower the voltage the lower the efficiency. The average efficiency is about 75 or 80 per cent. If the vacuum is good, shaking the tube will cause a metallic sound ; if tube is dirty on inside, the vacuum is usually poor. Reciprocals of Numbers. — The reciprocal of any number is equal to 1 divided by that number. The reciprocal gives by multiplication what the number would give by division, and vice versa. The prin- ciple involved is made use of in many formulae and is much used to facilitate calculations. The recipro- cals have been given only for whole numbers and up to the number 100. The reciprocal of any number larger or smaller may, however, easily be found by adding a decimal point to the reciprocal for each num- ber added to its integer or subtracting one for each integer taken from the whole number. The larger the number, the more decimal places the reciprocal will contain. The smaller the number, the greater wall be its reciprocal. Thus the reciprocal of 7.3 0.13698 73 0.013698 730 0.0013698 7300 0.00013698 0.73 1.3698 0.073 13.698 0.0073 136.98 To find the reciprocal of a number trace along until this number is found. Thus the reciprocal of 21.7 is 0.04608. To find the number pertaining to any reciprocal find the reciprocal and take the number. Thus the whole number of which 0.2710 is the reciprocal is 36.9. ELECTRICAL TABLES AND DATA tf*. 00 bO M © JO 00 _■.o>ocnwoo MWWSOMOlOoMOI-CRWOOMailSGlOOWOO O CR^^ffiOffiOlQOOlOl^CWOOMOOOQOOWO HOCOW©OClMWH ELECTRICAL TABLES AND DATA HN^O^tD'OClOWIOOOOHOWNHCOSfflNS'Q^ OHOOO^MKMLOCiCOHNNO^aMNNNmQO'tO Ci COS10\HMOJH00500t>t>©1010-*MM(M(MH-iOOO m n m co m ro cc co ci N ci ijj ci w ci (M eg ci ci ci ca CI -Cg©I^L0©©rhlC0l^l0l^C0rHCC]©C0 0;)C0t~Cga;a0 1>C005I>10^^-#1^NC5H^I>HIOC1COCCCOOOC003-+0 -_ 00 C- lO ^ CO CJ H O a 00 N N © LO LO ^ CO CO CO CO r-j ,— t o o o °o co co co oo co co co co ci on ci ci ci c! ci ci ci ci ci ct ci ci eg eg eg ooooooooooooooooooooooooo HIOOTtiSl>WOOl>HHlO(M^Oil>OOCQQCl>CCHOCO(M a^HOOOlOLOLO^OOOCHOOOnlOO^CCcOOC^OJlOH K, CO O © •* CO CI H O O OO QO N O LO LO •+ CO CO CI CI H H O O O CO CO CO CO CO CO CO CO CI C] CI CI O CI C] CI CJC1C1 CI CI ci co ci eg ooooooooooooooooooooooooo 00>COOOOOOIOI>0001(MOH10CC^STHC1COOOOOCO OLOWQhOOtONfflCCOfflQOIOO^ffi^ffi^OIOH ^ fflt-tD^COClrtOffiOOCONCO'OLO^^COClCXIHHHOO <0 co co co co co co co co ci ci ci ci ci ci co ci cm eg CI CI CI 03 eg C] eg © © © © © © © # © © © > © © © © < © o © © o © © © © © © CTcO©Oi05ffilOt-W05l>Ot>S(MOiOCOOt>OOOLONO Cl|>COOOONSS»QH^tOQCO©HIOffi^CIOOffi(M lO 05S©lOC0ClHO0i00C0t>OWI0'f'tC0C]C]HHHOO co co co co co co co co cq cm eg (m c] ci ci c-] ci ci ci ci ci eg eg eg eg ooooooooooooooooooooooooo b- 00 OH H05l0 50^t>Wb-^^OOU5lOOO^(NMiOO«OrH J. *H COOOIONOOOOOCOCJlOCM^hOCOOHlOOlOOlOHtON n ° rtf OJhOlO^ClHOroaoOhOffilOrti^COCOCICqHHOO □ co co co co co co co co eg eg ci eg eg co eg eg .eg eg eg cm ci eg eg eg eg k3 co ooooooooo < oooooooooooooooo J 1 O COdCOTHCO. OLOtDCOlOCOIOHH^HH^OlNNO^OQO E2 fn lOOOrOHOOlOlOHMIOCOH^QOClOOlOOtOH^N H Ph M©OOtDIOTtlCOHOOO)CCll>OtD'C-T-f CO CO CI CO r-l — I © © H *r! co co co co co co co co co eg ei eg eg ei ci c i c i c i c i eg eg c] eg eg eg pq g OOOOOOOOOOOOOOOOOOOOOOOOO C" 1 00N©©IOHWIOC]^HM00O0H00NO11O«CXItHC11O(M tOHNTf(MHOOHC]Tl<©(»HIOOOC^OH©H(DHSCO CCJ QCCCLO^COClHOaoONffltDlO^^McOCllMHHOO co co co co co co co co co ci eg eg cm ei ei ei eg eg cm eg eg eg cm eg eg © © # © © © © © © o © © o < © © © © © © © © © © © © © ^THOaCCllOWHCOOlOlOION^COmOCONffiCOOt- GOC0O0IOC0C]HHdC0Tf(|>ffi(M!Oa)C0l>Cl©H5OC]NCO _i acOOLO^COMHOQOOt-tOtOLO^iiCOCOCKMHHOO co co co co co co co co co co eg co ci cj ci ci o] ci co co c;i eg ci ci co o o o o o o # o o o o o o # o o o o o o o o O o o o o OCDr)OOCOCqrt(OGHCCOC3rt-*COC]ClCO-tHOO-* O OOOI>lO^COO]HOO»l>t>©OlO^COcOCI(NIHHOO th co co co co co co co co ci c] w ci ci c] ci (m cj eg eg ci eg eg eg eg ooooooooooooooooooooooooo (OOlXXlffiOHCKO^IOtOSOOOOHnMTtllOffiSCOO o cgeieqcgcacocococooocococococo^TtH^Tt*"*"^^-^^-^ A ELECTRICAL TABLES AND DATA ^WLOMO'OOOSQOThliWMMCCOM^OlOljfiWKiHO © o o © o © © o o o o o o o o o © o o o o o "o o © W CO W *• t(^ ^ ^ ^ O Ol CT Oi Cl Q Ci C; -1 -1 -1 00 00 CB © C O O 1 Ol3^SOI- J WGQoMWGCO[OtlQOHaiOODOG30 HO^OOO©OHb50lOOtO— 'I— '►— »l— »l— ih-»l— 'H-» , ooooooooooooooooooooooooo (— if— 'I— ' t— ' t— i t— ' I— 'I— 'Ml- ' t— 'I— » I— 'I— 'I— 'I— ' t- 1 t— 'I— ' t— ' t— ' t— 'I— ' t— 'I— » 0:C0C0i^rfi^rfirfi0l0lOlCiQOQC35SS<10000(ZH0(0© CO sow^^oioooHifooDON^HoaiaotooiOQWto -, W |> ooooooooooooooooooooooooo § ^; Ott^WbODOW^WOOMOilOOlHCCiffiOlOlOGOtOCltSOOO ooooooooooooooooooooooooo HMHf- 'I— it- 1 !— i M t-» I— » 1— 'I— 'Ml— 'h » I— 'I— ' I — ' I — ' t— 'I- 1 !— 'Ml- ' M WWW^^^!^!^Ul0lOlOlO5OJOlfflSS.ffi00Ot0^Cl00OK)0-|SOt0 0\00H!^0'*N(M50H(0(MCO'*HOOW(MOQO«5inTtlcniMHHHH HOQOOlOMIMOOSSOIOmOOHOWIXDlC^CONHOO „C> MnNNNNNNHHHHHHHHOOOOOOOOOO) i— ti— It— li— I i— It— IHr- It— It— It- It— I t— I t— It- It— It— IHriHHr I r- lr li— I O o © o © © oooooooooo © © © © © © © © o © o ©100COOtf3C<10©Tt T— It— Ii-Ht-It— It— It-it— ItHt-It-It-It-It— It— It— IHHr ItHt— It— ItHt— ItHO oooooooooooooooooooooooooo HT}ii>HiooiTt*ainHScoot>io«oois?DiO'^«iM«o: NOC0N10MNOOi00«0l0^lMHO©t>» COMNN(M(M(MNriHHriHHHHOOOOOOOOOffl t— It— |i— It— It— It— It— It— It— It— It— It— It— It— It— It— I r-l i— It— It— It— It— It— It— It— IO © © o © © © o o o © o o o © © o o © © © © o © © o o C0W0lN?DHWH©NC01Ceq0H0-*NOC0N^il0W-*'*T)l (MOC0Nl0Tt*«HO300iXllOTj» tHt— IT- It— It-It-It— It-It— It— It-It-It- It-It— ItHtHt-ItHt— ItHtHt- IHHO oooooooooooooooooooooooooo 'In OQ T^NOTtlOONS(MOOWOCOMOI>infOH0500l>«0«DtOlOm S *i (MOOiNW^NHOlQONlOrtirOHOOlOOCIOTtlMWHOO) Z o o o os ..iHHHHHO M m oooooooooooooooooooooooooo 3 ^ O QOOCOt-T— llOOlOOCOOCIOSOCvJot-lOCOcqOOSOOOOb-b-t- H *-j (MHOSI>iOTjlfOHOCOI>lC^M(M005GOt>O^CO(MH005 3 P^CO «Mnn(MNIMNIMHHHHHHHOOOOOOOOOO t? *r} THrHTHTHTHi-lr-lT-lT-lT-lTHTHTHrHrHr-lT-lT-lT-lTHTHT-lTHT-lTHO PQ S oooooooooooooooooooooooooo ■S w ONi0aMSHCD©^a5HO«)l>«DTilCOMOO)(»NOincONHOO> CDlOTf oooooooo MCOONOOTtlOWOtOMOHCi^HaNiOTllMCQHOOO WH05C0C0l0MHOaiN©^M0JH0)C0r>fflinTtXOOr l(MCOTtllO«Ot^aOOSOr-lcqcO"*100t>-OOOSO O t>.t-t^t^t^COGOOOGOOOODOOG00000050SOSOSOSOSOSOS050SO ELECTRICAL TABLES AND DATA 191 Reflectors. — Perfect prismatic glass makes the very best reflector. The following table gives approxi- mately the percentage of light reflected by. various materials : TABLE LXIV Per Cent Light Kefiected Well polished silver 92 Silvered mirror 70 to 90 Highly polished brass 70 to 85 Mirror backed with amalgam .• 70 Well polished copper 60 to 70 Well polished steel 60 Burnished copper 40 to 50- Chrome yellow paper 60 Orange paper 50 Yellow paper or painted wall 40 Pink paper 35 Blue wall paper 25 Emerald green paper 1& Dark brown paper 13- Vermilion paper 1& Bluish green paper 12 Cobalt blue paper 12 Deep chocolate colored paper 4 Black cloth 1.2 Black velvet 0.4 Refrigeration. — Refrigeration by machinery is much more reliable, effective and cleanly than that produced by the use of ice. Electric power compares favorably with steam power in large installations, but more especially so in the smaller plants. Its main advantages are : lower first cost, less space required ; less attendance and operation ; can be made automatic. For direct current, compound- wound motors are pref- erable, and where variable speed is desired, the speed control should be by means of field regulation. For alternating current, the squirrel cage type of arma- 192 ' ELECTRICAL TABLES AND DATA ture may be used, but if speed control is desired, a wound armature should be provided. The latter is much preferable for automatic control. The horse- power required for refrigeration can be determined by means of the curves in Figure 17, due to Westing- house Electric & Mfg. Co. The upper curve is for compressors of 50 H. P. and smaller; the lower curve Figure 17. for larger machines. For example: a 30-ton com- pressor requires a 52 H.P. motor; a 300-ton com- pressor requires a 470 H.P. motor. When the ice- making capacity of compressor is given, the motor H.P. required will in general be about double the figure given in the curve. Refrigerators. — All refrigerators are at times very damp. As long as they are kept cold, ice forms, and as soon as they are empty the ice melts and all parts become wet. No very bright illumination is required, and in many of them workmen are required to s^et ELECTRICAL TABLES AND DATA 193 along with lanterns. Weatherproof construction is preferable to conduit in all places except where heavy coatings of ice form on the wires. This frost is scraped off from time to time, and open wires are likely to be torn loose. Porcelain sockets break easily and should not be used. Circuits should not enter or leave too close to entrances; the meeting of the cold and warm air at such places cause the deposit of much moisture. Lamps are usually placed only in runways, and in large refrigerators the circuits are apt to be long. In some of the large refrigerators watchmen are regu- larly making rounds ; in such places three-way switches at doors are useful. Keep cut-outs and switches out- side of damp rooms and avoid the use of the common fiber-lined brass shell socket. Residence Wiring. — As a general rule a total wattage capacity. of about \ watt per sq. ft. should be provided for the whole building, including cellar and attic. If these latter are not to be illuminated, 1 watt per sq. ft. will be ample for the balance of house. The best place for service switch and meters is in the basement. Select a location easily accessible to meter readers. If not too much economy is neces- sary, let two circuits enter each room that contains more than one outlet. Place all switches at doors where room is most likely to be entered, and if there are two entrances two-way switches will be a great convenience. In some elaborate residences circuits are sometimes so arranged that lights in all rooms may be thrown on by a master switch, even if turned off in rooms. This is useful as burglar protection and also in case of fires. A measure of protection against intruders can be obtained by placing lights above doors so that an intruder must show himself in the light before he can enter a room. The bright light will prevent him from seeing what is inside the door. 194 ELECTRICAL TABLES AND DATA Attics. — No part of residence requires light more than the attic. The use of matches is exceedingly dangerous in such places. Run wires where they will not be molested. Bathroom. — A center light in a bathroom is an abomination. Place a light at each side of shaving mirror if practicable, but locate them so that person in tub cannot reach socket. An outlet for heater will be a great convenience. If possible place or shade lamps so they will not cast shadows of persons on window. Place a switch at door. If expense is no object, inverted lighting will be very useful. Basement. — The wiring of the basement depends upon the use to which it may be put. Two or three- way switches, one at each entrance, will be very con- venient. Plenty of light will be an inducement for servants to keep basement cleaner than the average. Provisions should be made for motors to operate ice cream freezers, washing machines, mangels, or vacuum cleaning motors. It is much preferable to place the motor for this purpose in the basement rather than to bother with portable machines. Fan motor outlets will assist in drying clothes. If part of basement is used as laundry and likely to be damp, use weather- proof construction and avoid placing sockets where one standing on wet floor will be likely to touch them. Provide outlet for flatiron. Bedrooms. — A center fixture should never be in- stalled in a bedroom unless it is intended also as a sort of living room. Lights should be arranged to suit the various positions in which a bed can advantage- ously be placed, and so that one can use the light for reading in bed or make easy connections for heating pads. Special outlets along baseboard for flatiroif heaters, sewing machine motors, etc., will be found very useful. One light on each side of dresser mirror is a great convenience. Avoid placing lights so that ELECTRICAL TABLES AND DATA 195 they will cast shadows of occupants on windows. For protection against burglars, a switch by which lights in other rooms may be turned on is very effectual. See "Modern Wiring Diagrams and Descriptions' ' for circuits. Such a switch might be placed in each bedroom. Inverted lighting is very useful if only one light can be installed and if ceilings are light enough. Cellars. — A cellar is usually damp, and weather- proof construction should be used. Keep switch out- side at door. Closets. — The use of matches in closets is very dan- gerous and will be entirely eliminated by good illum- ination. Place a light at ceiling and control by switch if closet is small. In large closets a pendant light may be advisable, but there is usually too much chance of clothing coming in contact with it and the cord. Dining Rooms. — Beam lighting is used to some ex- tent in dining rooms. Special illumination of buffet and china closet is also often practiced. Small lamps are used for the latter and should be located to show off cut glass, etc., to the best advantage. It is well to study the effect of such lights carefully before finally locating them. To show off silverware, fine table linen, etc., to the best advantage it is advisable to concentrate a strong light upon the table and leave balance of room somewhat dark. Side outlets for fan motors, and floor sockets for chafing dishes, are very useful. The low hanging fixtures often seen in dining rooms should not be recommended. They will soon become obnoxious. Halls. — Halls ordinarily require only a perfunc- tory illumination unless a showy appearance is de- sired. These lights are often combined with stair lights and fitted with two or three-way switches. Place switch for hall light close to the door. Ice Boxes or Chambers. — A light placed opposite door will be very useful. 196 ELECTRICAL TABLES AND DATA Kitchen. — If kitchen walls are of light color, a cen- ter light will give good illumination. With dark col- ored walls a light should be placed over sink and near range, but a little to one side, so as to avoid the cook- ing fumes as much as possible. A small motor to drive steam out will be of great use. Ozonators to destroy odors will also be much appreciated. As ironing is often done in the kitchen, an outlet for irons should always be provided. If electric cooking is indulged in this must be provided for. Laundry. — There should be a light directly over wash tubs and another arranged to be directly over ironing board. If clothes are dried in laundry a fan or ventilating motor will be of great service. Pro- visions should be made for washing machine motors, mangels and flatiron. Locate sockets so persons will not be likely to touch them while standing on wet floor. Lavatory. — One light controlled by door-switch is very useful here. Library. — Inverted lighting of sufficient c.p. to allow the reading of titles of books in cases is the best means of illumination here. In addition to this there should be outlets for reading lamps and brackets con- veniently located on walls to give a brighter light for those that need it. A direct light with strong reflector under inverted light is useful for reading purposes. Nursery. — The lighting of the nursery should be ample, but precautions should be taken to guard against the possibility of outlets being short circuited by children. Avoid placing sockets within easy reach. Electric toys should be confined to battery current, or a low- voltage transformer, to which children have no access, might be used. The lighting voltage is too dangerous for them. Control all lights by switches and keep them high. ELECTRICAL TABLES AND DATA 197 Pantry. — Provide bright illumination to show up dust and dirt and induce cleanliness. Parlor. — The illumination of the parlor is usually effected by means of quite elaborate chandeliers. Out- lets for piano and reading lamps should be provided. The center light does not illuminate pictures very well, and for this reason inverted lighting is often useful. Really good pictures, however, deserve spe- cial illumination. Porch. — A light should be arranged close to main entrance and so located as to reveal features of per- sons applying for admission without making the party inside of house visible. The light should be controlled by a switch inside and should be out of reach from the outside. If porch is to be enclosed, other outlets for lamps or fan motors will be useful, but they should be arranged at ceiling so as to avoid moisture. Use no fiber lined sockets outside. Resuscitation from Electric Shock. — Rules recom- mended by commission on resuscitation from electric shock, representing The American Medical Associa- tion, The National Electric Light Association, The American Institute of Electrical Engineers. Issued and copyrighted by National Electric Light Associa- tion. Reprinted by permission. Follow these instructions even if victim appears dead. /. Immediately Break the Circuit. — With a single quick motion, free the victim from the current. Use any dry non-conductor (clothing, rope, board) to move either the victim or the wire. Beware of using metal or any moist material. While freeing the vic- tim from the live conductor have every effort also made to shut off the current quickly. II. Instantly Attend to the Victim' 's Breathing. — (1) As soon as the victim is clear of the conductor, rapidly feel with your finger in his mouth and throat 198 ELECTRICAL TABLES AND DATA and remove any foreign body (tobacco, false teeth, etc.). Then begin artificial respiration at once. Do not stop to loosen the victim's clothing now; every moment of delay is serious. Proceed as follows: a. Lay the subject on his belly, with arms extended as straightforward as possible and with face to one side, so that nose and mouth are free for breathing. Figure 18. Inspiration — Pressure Off. See Figure 18. Let an assistant draw forward the subject's tongue. b. Kneel straddling the subject's thighs and facing his head; rest the palms of your hands on the loins (on the muscles of the small of the back), with fingers spread over the lowest ribs, as in Figure 18. c. With arms held straight, swing forward slowly so that the weight of your body is gradually, but not violently, brought to bear upon the subject. See Fig- ure 19. This act should take from two to three seconds. Immediately swing backward so as to remove the ELECTRICAL TABLES AND DATA 199 pressure, thus returning to the position shown in Figure 18. d. Repeat deliberately twelve to fifteen times a min- ute the swinging forward and back — a complete res- piration in four or five seconds. e. As soon as this artificial respiration has been started, and while it is being continued, an assistant Figure 19. Expiration — Pressure On. should loosen any tight clothing about the subject's neck, chest or waist. (2) Continue the artificial respiration (if neces- sary, at least an hour), without interruption, until natural breathing is restored, or until a physician arrives. If natural breathing stops after being re- stored, use artificial respiration again. (3) Do not give any liquid by month until the sub- ject is fully conscious. (4) Give the subject fresh air, but keep him warm. 777. Send for Nearest Doctor as Soon as Accident Is Discovered. .200 ELECTRICAL TABLES AND DATA Ropes. — TABLE LXV iStandard Iron Hoisting Eope, 6 Strands — 19 Wires to the Strand — 1 Hemp Eope. American Steel & Wire Co. 1>R OS M S.S o.2 g-SR < 9 154 10 15% 11 21 R 10 10 10 154 10 154 12 15% 12 21 S 8 10 8 154 8 154 10 15% 10 21 T 6 10 6 is 1 .; 6 154 7 15% 8 21 U 8 10 8 154 9 154 10 15% 10 21 V 7 10 7 154 154 9 15% 9 21 W 12 12% 12 ' 15i:; 13 194 15 19% 15 25 X 8 10 8 154 9 154 9 15% 9 21 Y 6 10 6 154 6 154 7 154 8 21 Z 8 10 8 154 8 1514 9 15% 11 21 & 8 10 8 154 9 154 9 154 10 21 1 4 10 4 is 1 ; 4 3514 5 21 2 9 10 8 154 8 15*4 11 21 3 9 10 7 154 7 154 9 21 4 7 10 7 154 7 15% 11 21 5 10 10 10 154 10 15% 12 21 6 9 10 8 154 9 154 11 21 7 6 10 6 154 G 15% 8 21 8 11 10 11 154 8 154 10 21 9 9 10 8 154 9 154 11 21 $ 8 10 8 154 154 8 15% 154 8 21 The supporting cable is usually attached to the electric sign somewhat back of its outer end, and it may be assumed that the cable carries about 60 per cent of the wezght of sign. Y7 ith this assumption and 208 ELECTRICAL TABLES AND DATA using a safety factor of 5, the strength of the cables necessary to support it can be found by the formula : S - 5 x .60 x W- II where W = weight of sign; II = height of attachment to wall above sign, and D = the distance from attach- ment on sign to a point vertically under sign support. Table LXVIII is calculated according to this for- mula (omitting W), and to find the proper cable to support a given sign it is but necessary to multiply number found at intersection of line pertaining to height of support and that pertaining to distance of sign attachment from wall, by the weight of sign. The result will give the breaking strain of the neces- sary cable. TABLE LXVIII Supports for Weight of Sign. Distance from Wall to Attachment on Height of Cable Fastening Above Sign in Feet Sign in Feet 3 4 5 6 8 10 12 14 16 IS 20 4 5 4 4 3.6 3.4 3.2 3.0 3 3 3 3 5 6 5 4.2 3.7 3.5 3.3 . 3.2 3 3 3 3 6 7 5.4 5.0 4.2 .3.8 3.5 3.4 3.2 3 3 3 7 8' 6.0 5.1 4.7 4.0 3.7 3.5 3.4 3.3 3 3 8 8.6 6.8 o.7 5.0 4.2 4.0 3.6 3,5 3.4 3.3 3 10 10.5 8.1 6.9 6.0 5.0 4.4 3.9 3.8 3.6 3.4 3.3 12 12.4 9.4 7.8 6.7 5.4 4.6 4.3 4.0 3.7 3.5 3.4 14 14.6 11.1 9.0 7.8 6.0 5.2 4.8 4.1 4.0 3.9 3.7 SIDE GUYS FOR SIGNS The wind pressure on the ordinary sign must be calculated on the basis of 20 lbs. per square foot and requires much better supports to withstand it than are necessary to support the weight of sign, although they are never so provided. ELECTRICAL TABLES AND DATA 209' The table below has been calculated according to the same general formula as the one above. To find the proper size of cable for side guys, multiply the num- ber of square feet in sign by number found where lines pertaining to the two fastenings of side guys* cross. TABLE LXIX Distance of Attachment on Distance c f Guy Attachment on Wall from> Sign from Wall Sigr l in Feet 3 4 5 6 7 8 10 12 14 16 2 17 17 16 15 15 14 14 14 14 14 3 21 18 18 17 16 15 14 14 14 14 4 24 20 18 17 16 16 15 15 14 14 5 27 22 20 19 18 17 16 16 15 14 6 31 25 22 20 19 18 17 16 15 15 7 34 28 24 22 20 19 18 17 16 15 8 38 32 27 24 21 19 18 17 17 16 9 44 35 29 26 22 21 19 18 18 17 10 48 3S 32 28 24 23 20 19 18 17 12 57 45 37 33 27 25 22 21 19 18 For signs hung at corners the distance of guy attachment on wall must be taken as the point at right angles to sign where the guy would strike wall if it were at right angles to sign. TABLE LXX Table showing approximate strength in pounds of Standard Steel Strand — American Steel & Wire Co. Diameter Approximate D^ ameter Approximate in Inches Strength in Inches Strength § 8,500 lbs. 3 7 2 1,800 lbs. ts 6,500 lbs. ft 1,400 lbs. § 5,000 lbs. 3 5 2 900 lbs. - 5 -v i 3,S00 lbs. 2,300 lbs. 1 8 500 lbs. 400 lbs. 210 ELECTRICAL TABLES AND DATA Cable Supports for Signs Over Streets. — Signs of this kind are usually supported from steel cables swung across street, or other open place, from the tops of buildings or suitable poles. The table below gives the stresses caused by various loads per foot evenly dis- tributed, and also for loads suspended from center. The arrangement of sign is usually such that neither case exactly applies, so that an approximate mean of the two must be taken. The calculations are for a 100-foot span and a sag of 4 feet. TABLE LXXI Diam- Stress eter Wt. Approxi- Caused by of per imate Cable Distributed Load Load ir Center Cable Foot Strength Alone Poun ds Stress Pounds Stress If 4.85 84,000 1,500 50 17,140 2,500 15,625 1+ 3.55 60,000 1,109 30 10,484 1,500 9,375 U 2.45 46,000 766 20 7,015 1,000 6,250 1 1.58 28,000 493 15 5,181 750 4,687 1 1.20 22,200 375 12 4,125 600 3,750 t 0.89 15,600 278 9 3,090 500 3,125 The above figures represent the maximum loads which should be suspended by such cables unless a greater sag is allowed, and do not take wind pressure into consideration. See "Side Guys." The above figures are based on the following for- mulae used by American Steel and Wire Co. : S x = -Q-j- giving stress for evenly distributed load, and oCl Wl S 9 = -rr- for stress due to load in center. 2 4d S = stress on cable W = weight per foot of cable and load if evenly dis- tributed, or load in center I- length of span <2= sag in feet. ELECTRICAL TABLES AND DATA 211' To find total stress those due to cable and load must be added. Slide Rule. — Figure 22 is an illustration of the ordinary slide rule. The numbers on the top, or A, scale, may be read naturally as 1, 2, 3, 4, etc., ending with the last figure 1 at the right, which would then be called 100, or these values may be considered in- creased or decreased to any extent by adding or prefixing the necessary number of ciphers. Thus if the 2 is called 20 or 200 the 3 would be called 30 or 300, etc. The same also hclds true of the upper half of the slide, or B scale. The divisions between the main figures are of various dimensions, but serve only Figure 22. — The Slide Rule. to designate fractional values of the figures. The- principle of operation can easiest be made clear by examples. Multiplication. — Set the 1 on upper half of slide under one of the factors on scale A. Find the other factor on the slide and directly above it you have the product. Multiply 4 by 2. Setting the slide as directed we find 8. This same setting might be used to multiply 40 by 20, or 4000 by 2 or 200. "We have but to note as we go along by how much we increased the value of either of the factors, and add the cor- responding number of ciphers. Different settings could also be used for the same problem. Consid- erable practice is necessary before one can become; really proficient in these calculations. Division. — In division the above process is reversed. Place the divisor on the slide under the dividend on 212 ELECTRICAL TABLES AND DATA scale A and the 1 on slide will be directly below the quotient. Multiplication and Division Combined. — ^ , 7x3x4 Sample: — ^ Set 1 on slide under 7, note product above 3 ; next Key Keyless Max. Max. Amp. Amp. at any at any Nominal Volt- Volt- Class Diam. Watts Volts age Watts Volts age Candelabra i in. 75 125 f 75 125 1 Medium 1 " 250 250 2* 660 250 6 (a)660 250 6 660 600 Mogul 1^ in. 1,500 250 (b) 1,500 600 214 ELECTRICAL TABLES AND DATA (a) This rating may be given only to sockets having a switch mechanism which produces both a quick "make" and a quick "break" action. (b) Eatings to be assigned later, pending further discus- sion with manufacturers. Miniature sockets and receptacles having screw shells smaller than the candelabra size may be used for decorative lighting systems, Christmas tree light- ing outfits, and similar purposes. Double-ended Sockets. — Each lamp holder to be rated as specified above, the device being marked with a single marking applying to each end. In addition to these there is the Edi-Swan base, which is f inch diameter, and has bayonet-type con- nections and is sometimes used on automobiles and other places where there is much jarring. The Edison miniature base is f inch in diameter and is used only for low voltages. Some very small lamps are made without bases, the wires connecting direct to lamp terminals. The mogul socket is used for series in- candescent lighting and often fitted with automatic cut-out. It is also used for gas-filled lamps of 300 watts or over. Fiber lined or brass shell sockets should not be used in damp places, or where corrosive vapors exist. Key sockets should also be avoided in damp places, or where inflammable gases may exist. Sparking Distances. — Very high-test voltages are often measured by their sparking distance. The fol- lowing table gives the sparking distances between sharp points corresponding to different alternating current voltages, when the ratio between maximum and mean effective voltages is equal to 1.41, or the square root of two. The values given were derived from a long series of careful and accurate tests. ELECTRICAL TABLES AND DATA TABLE LXXII (Copyright, 1906, by Standard Underground Cable Co.) Spark Spark Spark Volts Distance Volts — Dist ance — Volts — Distance — A. or B. A. B. A. B. 1,000 0.028 18,000 0.945 0.945 35,000 1.840 1.895 2,000 0.098 19,000 0.995 0.995 36,000 1.900 1.958 3,000 0.159 20,000 1.042 1.042 37,000 1.945 2.020 4,000 0.216 21,000 1.092 1.097 38,000 2.012 2.085 5,000 0.270 22,000 1.143 1.150 39,000 2.062 2.153 6,000 0.324 23,000 1.195 1.206 40,000 2.127 2.220 7,000 0.378 24,000 1.247 1.260 41,000 2.190 2.290 8,000 0.432 25,000 1.300 1.314 42,000 2.247 2.360 9,000 0.487 26,000 1.353 1.373 43,000 2.308 2.434 10,000 0.540 27,000 1.405 1.427 44,000 2.370 2.506 11,000 0.595 28,000 1.460 1.485 45,000 2.432 2.580 12,000 0.644 29,000 1.512 1.540 46,000 2.495 2.660 13,000 0.695 30,000 1.566 1.600 47,000 2.560 14,000 0,746 31,000 1.620 1.655 48,000 2.625 15,000 0.797 32,000 1.675 1.712 49,000 2.692 16,000 0.845 33,000 1.728 1.772 50,000 2.760 17,000 0.897 34,000 1.785 1.833 SPARKING DISTANCES IN INCHES. Column A gives spark distances with 10 inch con- cave metal shields, the plane of whose edges was 1 inch "back of the needle points. Column B gives the spark distances without shields. Sharp needles are essential for uniform spark dis- tances, as points measuring from 0.001 inch to 0.002 inch gave in many instances spark distances that were from 20 to 45 per cent greater than those ob- tained with sharp points. See also table of A. I. E. E. in Standardization Recommendations. Specific Gravity (Solids). — The specific gravity of a substance is defined as the ratio of the weight of that substance to the weight of an equal volume of water or air. Water is used as the standard of liquids and solids. Air at the temperature 0°, C. (32° F.) and 766 mm. mercury pressure for gases. By multiplying the specific gravity of any substance by the weight 216 ELECTRICAL TABLES AND DATA of an equal volume of water we find the weight of that volume of the material. The weight of a cubic foot of water is approximately 62.5 lbs. The weight of a gallon is approximately 8.33 lbs. To find the specific gravity of a body heavier than water approx- imately by experiment, weigh it in air and then weigh it in pure water. Divide the weight in air by the loss of weight (buoyancy) in water and the quotient will give the specific gravity. If the body is lighter than water load it down with a substance heavy enough to sink it. Then weigh the two submerged together. Also weigh both separately in air and the heavy body in water. Subtract the buoyancy of the heavy body from the buoyancy of the two bodies to- gether. The remainder will be the buoyancy of the lighter body by which its weight in air is to be divided as before. Specifications. — In many cases preliminary specifi- cations, setting forth what the purchaser desires, are made out. Unless these are quite broad many dealers or manufacturers may not be able to comply with them and for this reason often submit specifications of their own, and thus the final specifications which form the basis of contracts must be somewhat modi- fied. In general, specifications may be divided into two parts: one part which deals with machinery and materials, and another which deals with the installa- tion work and results to be obtained. If certain materials are specified, and at the same time require- ments as to certain results are made, there is always a chance for disputes as to who is responsible in case the installation does not fulfill requirements. Unless the work is to be carried on under the supervision of a consulting engineer, it is best to give the contractor free choice of materials and hold him entirely re- sponsible for the final result. ELECTRICAL TABLES AND DATA 21? All specifications should be based upon the stand- ards of the engineering societies governing the par- ticular kind of work. The A. I. E. E. have standard- ization rules which govern everything electrical, but these do not largely concern themselves with safety rules. In this regard the National Electrical Code should be adopted as the standard and all material and workmanship should be specified to conform with its requirements. This is a reliable guide in every respect except that of economy and efficiency and suitability of systems, etc. It deals only with safety and reliability. It is best always to have some sort of a plan show- ing location of cut-out centers, switches, lights and motors, or any other parts about which there may afterwards be disputes. If there are no plans the location of cut-outs and other conspicuous elements should be mentioned in the specifications. They should also mention how much conduit, open or mold- ing work is to be used. Every item mentioned should form a clause and these should be numbered for reference. Where accurate calculations are to be made, all circuits and runs of wire should be measured and the specifications thoroughly read and considered. The estimator should take plenty of time to understand every phase of his job. As a reminder of the many items so easily overlooked, he should have prepared an estimate sheet on the order of that following which is furnished by courtesy of the National Electrical Contractors ' Association. Large apartments, hotels, etc., usually have many floors and rooms which are exact duplicates, and very careful measurements of one floor or room will answer for the whole building or that part of it which is typical. Table LXXIII shows approximate quantities of" material used for rough wiring in average flats. ELECTRICAL TABLES AND DATA P?3 »>a 3 XS™, n K " ?BB B 8.-« cog ssrs I °EL 1 s-l fen g.g-s ^jf 3 * &^ i-sg- as& l»s. ° 3 S" 65 B-g* ££££ ££ rfc£ >££ ^ 1 KWWW £?£?£?£? c?c?c?*>•; ts3N »»: 8 g^s Ft. Single Wire. • to " ■ : *" : : : s Ft. Twin Wiee. • N 00- • Is &■■ ! isooo Ft. Loom. ~i '• • U>; ; • 00; ; Ft. Moulding. 5C t-i' 'a -^: - C/J w r| w o u H i— i rrt M £ O] Ph u C£ ^ y 1 «H £ £ OQ © .4 pq <^ E-i © m H S h>0 J "*o Ho : § ■<) ^ rjH ^ • O S h S OO 00 00 WNOOCO^rtHlO^WWtD u*^ rt CJ CO rH TJH CO CO t- r* O J Hw Hfcio i-if* i-w t-iH< hW hn ihH« g.-p^LOLOCOCOt^t-OOOOOOCS f>r HN Hft mH< rift ctM< CO CO CO Ttl LO LO > .u rnh- H» r-iM «M< H)M ecHf L- c-i CI CO CO CO T^ "«* LO > C4 ■') WW Hoo HW wHt HIS T+« c* U .J rH Oi CJ CO CO "«* rJH LO .-oooo fc§«* lOONOONMNM^IO ftCi, o o o cS g CO CD O o o o o o o o o o o O 3 OUlOOOC^MCOtOM —J* £"0 OOOOOOOOOOiCOciSO ooooooooooo «s MHOOCOOOOlOll^ -3 Or m i-i O GO -3 M © CO 00 ffl CO ~3 M CO >§egl ^< K) M H «0 • CO CJ M M iMca M w «M #>l» • Wh' Oo|-^ «H Mi- 1 to CO CO tO • MM tO SO CD O • tO O Ci U« tO tO tO M MM Ul to tO CO • Ux to CO MM ifMl- 1 00|C0 • 05|C0 aicc Hi 9< 1-3 w t- 1 M M M I o tOtOtOtO 'MMMM CO Ol ^ M • S ^ M O iMt- 1 Hh tiM oojoi . Co]-} Wh hL i 228 ELECTRICAL TABLES AND DATA r-ft - F=" i*-^- -*ri -v-i 1" •8 ^ fe^ _ HPn ®-.l • — ° 'Ife O R - !. n ELECTRICAL TABLES AND DATA 3- ELECTRICAL TABLES AND DATA fecoco^^-^^Ttiioio _to into .to into "H Hto # HH ^H t* r+H e# CD CO GO GO CO CO O C5 CqtMCO^WWlO© 1 W o pj .2* «h Hi H fr 2 pq CD < QQ EH H P ft rtilOtOCDCOt^t^COGOCOC^CiO co t- t- oo =3 lO ^ H|* eob* „;-, kH rW CO cc CO -h o o CO >\.-o tHh» tH|m H|M nh< Cv CI CM CO CO CO «tf -tH o >o >d ^d ■ «H i^^u^d ?flo<^ > -o 0,2 §H«j ^ h„ hod «*» H to -a -a gO^-co co Ci rH co £2 -2 £2 HS Hh hS hS HH Tt< in ^ CO CO CO Gi G5 cS C O rH rH OrjO . rfl ^ (•» r# rHfcO £^g- t- i-H rH i— 1 r-H rH rH i— 1 l— 1 P.P, ooooooooooooo rid COCOOOOOOOOOOOO U5 **— rHClCO-HHCOCOOlOC^OO ELECTRICAL TABLES AND DATA 231 4^ CO CO M M * t^o ooomoooOhKcocoM -+ tTp OOOOOOCDOOOOCiCO gw ooooooooooooow- 3^2: CD O ° • a o a 3 >i.°gl P Q<3 ^ W tO O • 00 05 « K) ^oPSl • • • • S CS Ol to ■ O 00 Ol Ol .^o ^2 • • • • iW» W hL o*- • **» «(oi M M MM Q 1 ^ ^ tO 00 OO Ol • Ol rfi M m : O do, ,ms hH tKH iH» • ,Hca oh cdco **j o -> j raw H O-d .^ tO M H © • OOOirf^rf^ t^oUo i^u Mh 1 oc|m Woo • W-* OH «H M-» -. 1 " O CO W OJ tO • m M M g w It* ■K £. tO M M M M !» _ H ta- O QO — 1 rf^ • tO © Q rfi • °. W W #+-> M,„ H , <*H • a*-' iH" hL, a(ai Q ^ © tO tO tO M MM MHOS' rf^ M <£> WM 9» Sh aM * " Q d^ to O • - maxwell Magnetic density B gauss Magnetic force II gilbert per cm. Length L, 1, cm. or inch Mass M, m, gm. or lb. Time . . . T, t, second or hour Em, Im and Bm should be used for maximum cyclic values, e, i and p for instantaneous values, E and I for r. m. s. values, and P for the average value or effective power. These distinctions are not necessary in dealing with continuous current circuits. Vector quantities are preferably represented by bold face capitals. Testing. — It is assumed that the reader of this work is familiar with the general principles employed in testing, and therefore no attempt will be made to explain methods of using the various instruments. The list given in the following pages is intended as a reminder of the various instruments available for different purposes. Those about to undertake testing work with which they are not entirely familiar are advised to consult this list, and select those instm^ ments needed. Consult Standardization Rules of A. I. E. E. and N. E. C. and make tests in conformity with their standards. 234 ELECTRICAL TABLES AND DATA STANDARD SYMBOLS FOR WIRING PLANS AB adopted and recommended by the National Electrical Contractohs Association of the United States. y^K Ceiling Outlet; electric only. Numeral in center indicates x£/ number of standard 16 c. p. incandescent lamps. 4 Ceiling Outlet; combination. 4-2 indicates 4-16 c. p. stand- HU IT ard incandescent lamps and 2 gas burners, Bracket Outlet; electric only. Numeral in center indicates number of standard 16 c. p. incandescent lamps. 4 Bracket Outlet; combination. 4-2 indicates 4-16 c. p. stand* 7T ard incandescent lamps and 2 gas burners. Wall or Baseboard Receptacle Outlet. Numeral in center indicates number of standard 16 c. p. incandescent lamps. Floor Outlet. _ Numeral in center indicates number of stand- ard 16 c. p. incandescent lamps. 6 Outlet for Outdoor Standard or Pedestal; electric only. Numeral indicates number of stand. 16 c. p. incan. lamps. B Outlet for Outdoor Standard or Pedestal; combination. yQff "#• 6-6 indicates 6-16 c. p. stand, incan. lamps; 6 gas burners. )J3f Drop Cord Outlet. m 3 One Light Outlet, for lamp receptacle. Arc Lamp Outlet, Special Outlet, for lighting heating and power current, as described in specifications. ^^^"^^QCeiling Fan Outlet. 2 ' S. P. Switch Outlet. Q2 D. P. Switch Outlet. Q 3 3-Way Switch Outlet. O 4 4-Way Switch Outlet. Show as many symbols as there are switches. Or in case of a very large group of switches, indicate number of switches by a Roman numeral, thus: SI XII; meaning 12 single pole switches. Describe type of switch in specifi- cations, that is, Flush or surface push button or snap. Copyright 1906 by the National Electrical Contractors' Association of to© United States, Published by permission. ELECTRICAL TABLES AND DATA 235 STANDARD SYMBOLS FOR WIRING PLANS As adopted and recommended by the National Electrical Contractors Association of the United States. S Automatic Door Switch Outlet. 2 Electrolier Switch Outlet. ^m Meter Outlet. ; H| Distribution Panel. J Junction or Pull Box. \j5jf Motor Outlet; numeral in center indicates horsepower ] Motor Control Outlet. ^T"|^ Transformer. ■«^— ^ «^B™^™»Main or feeder run concealed under floor. •■^■■■■■■■■■■■■m Main or feeder run concealed under floor above* ■» ■» ■■» ■» ■»••■• Main or feeder run exposed. Ife ■ Branch circuit run concealed under floor. "- ' ■ Branch circuit run concealed under floor above. «■■" — "■ — — — — "■"• Branch circuit run exposed. b* -•• — — — — ♦ — — Pole line. • Riser. Suggestions in Connection with Standard Symbols for Wiring Plans. Indicate on plan, or describe in specifications, the height of all outlets located on side walls. It is important that ample space be allowed for the installation of mains. feeders, branches and distribution panels. It i3 desirable that a key to the symbols used accompany all plans. If mains, feeders, branches and distribution panels are shown on thia plans, it is desirable that they be designated by letters or numbers. 236 ELECTRICAL TABLES AND DATA STANDARD SYMBOLS FOR WIRING PLANS As adopted and recommended by the National Electrical Contbactojw Association of the United States. Kj Telephone Outlet; private service. 8 Telephone Outlet; public service. BeU Outlet f~V Buzzer Outlet. I ©1,2' Push Button Outlet; numeral indicates number of pushes* m- i^qS Annunciator; numeral indicates number of points, i — M Speaking Tube. *&~/q\ Watchman Clock Outlet. — i T Watchman Station Outlet. *— (fc) Master Time Clock Outlet. —In Secondary Time Clock Outlet I f I Door Opener. RFj Special Outlet; for signal systems, as described in specifications J | I | I |Battery Outlet. ( Circuit for clock, telephone, bell or other service, 1 run unde- floor, concealed. I Kind of service wanted ascertained by symbol to which line connects. Circuit for clock, telephone, bell or other service, run under floor above concealed. Kind of service wanted ascertained by symbol t / / / A Y * ') X/ < s \ k; \ o <3 / / / / o 6 / A/ A s / /\ O A s o c »* / / / / / A ( / / VJ A A s> A A s X R / / / / / / / A o 'A X \ ^ \ \ / / / / / / X N / \ \ \ / / / / / / / / / / / y \/ \ / \ \ \ \ / ) / Ti me / A Figure 31. — Train Sheet. it may be cut in sections, each section being fed by f its own feeder. Alternating current systems do not usually have any secondary feeders. The drop allowed in d-c. systems ranges from 10 to 25 per cent ; for a-c. systems it is 5 to 10 per cent. The current used at any point can be approximately determined by use of the "train sheet" illustrated in Figure 31. The height of the figure represents the length of the road or of any part of it to be considered. The width of it may represent the length of time during which the load is to be determined. For each car, or train, entering a section of trolley, draw a line beginning with the time the car enters ELECTRICAL TABLES AND DATA the section at the bottom and to meet the time point at the top at which it leaves that section. Draw lines beginning at the top. of the figure in the same manner for all cars moving in the opposite direction. These lines will then cross, and to find the load on this section at any desired time, it is only necessary to draw an ordinate such as 1 at that point and count the number of car lines this crosses. This will give the number of cars fed over this section of trolley at that time, and the maximum current used can be easily determined. TABLE LXXXIX Table Showing Drop in Voltage Per 100 Amperes for Distance Given. Feet 1,000 2,000 3,000 4,000 11.9 23.8 35.7 47.6 9.44 18.9 28.3 37.8 7.48 15.0 22.4 29.9 5.94 11.9 17.8 23.8 Miles 12 3 4 62.8 125.6 188.4 251 49.8 99.6 149. 199 39.5 79.0 118. 158 31.4 62.8 71.4 126 5 314 249 198 157 B.&S. 00 000 0000 CM. 500000 2.513 5.0 7.5 10.5 13.26 26.5 39.8 53.0 66.3 1000000 1.256 2.51 3.7 5.0 6.63 13.3 19.9 26.6 33.2 2000000 0.628 1.26 1.88 2.51 3.31 6.6 10.0 13.2 16.6 3000000 0.419 0.84 1.26 1.67 2.21 4.4 4000000 0.315 0.63 0.95 1.26 1.65 3.3 D. C. Only. 6.6 5.0 5000000 0.251 0.50 0.75 1.00 1.33 2.65 4.0 6.6 5.3 11.0 8.3 6.6 TABLE LXXXX Table Showing P.D. on Eeturn for Distances Above. Wt. of Rails Per Yard. 2 Rails Used. 40 45 50 60 70 80 90 100 110 1.23 2.46 3.69 4.92 ( 1.09 2.18 3.27 4.36 5.8 11, 0.98 1.96 2.94 3.92 5.2 10, 0.81 1.62 2.43 3.24 4.3 0.70 1.40 2.10 2.80 3.7 0.61 1.22 1.83 2.44 3.2 0.55 1.10 1.65 2:20 2.9 0.49 0.98 1.47 1.96 2.6 0.45 0.90 1.35 1.80 2.4 13.0 19.5 26.0 32.5 L1.6 17.4 23.2 29.0 L0.4 15.6 20.8 26.0 8.6 12.9 17.2 ■21.5 7.4 11.1 14.8 18.5 6.4 9.6 12.8 16.0 5.8 8.7 11.6 14.5 5.2 7.8 10.4 13.0 4.8 7.2 9.6 12.0 ELECTRICAL TABLES AND DATA 261 The copper loss calculations are based on resistivity of hard drawn copper at 65° C 149° F. Eails are supposed to be standard and of specific resistance of 10 times that of copper. The losses in return circuit will be less than indicated because part of current returns through piping and earth. The combined drop in conductors and rails in parallel is equal to — +-tj- + -p- where d, d*, d2, etc., represent the- drop in the different conductors. The impedance of the rails at 25 cycles is said to be from 6 to 7 times as high as the ohmic resistance. Impedance of trolley=1.5 times ohmic resistance. Tables LXXXIX and LXXXX have been especially prepared to facilitate calculations concerning drop in trolley circuits. Every trolley circuit consists of three elements: trolley proper, its feeders and the track return, and in order to effect distribution econom- ically, it is necessary to consider all of these sepa- rately. The upper part of table LXXXIX gives the drop- in voltage caused by the trolley proper, and the lower part that caused by feeders, either overhead to rein- force trolley or underground to help out track rails,, and table LXXXX the drop caused by the iron rails. The calculations have not been carried out for a-c. be- cause the circuits used for this method of transmission differ materially from d-c. systems. In a-c. systems the ground return may be considered as made up of a number of comparatively short sections, the current returning not to the central station but to its trans- former. This is also true of the trolley. With energy distributed at 25 cycles, the drop caused by the rails, will be about 6.5 times as great as for d-c. and that in the trolley about 1.5 times. The drop caused by 262 ELECTRICAL TABLES AND DATA trolley and feeders, when they are in parallel, is equal to the reciprocal of the sum of the reciprocals of their lines. This is also the case with track rails and their reinforcement. As far as these are used in series the various losses must be added. The use of the tables can perhaps be best made clear by an example. Example : The train sheet shows that 1,200 am- peres will be required on a certain section of trolley one mile long and fed in the center by a feeder two miles long. The loss at far end of trolley must not exceed 15 per cent of the voltage, which is 600. The rails weigh 100 lbs. per yard, and the difference in potential between any two points must not exceed 5 volts. What size of feeder and reinforcement of track rails will be necessary? Table LXXXIX shows that a 0000 trolley wire will cause a drop of 31.4 volts in one mile per 100 amperes. Our trolley is fed in the center and must be con- sidered one-half mile long; each half carries half of the current, viz., 600 amperes; therefore, the drop caused by a 0000 trolley will be six times the drop in half a mile, or, according to our table, 94.2 volts. This alone is more than 15 per cent of our voltage, 600, hence we must divide our trolley into shorter sections. Making two sections out of the same length, or feeding it in two places, will give us a loss equal to 300 amperes for one-fourth mile, or just one- fourth of what we had before, viz., 23.6 volts lost in trolley. We have next to deal with the size of feeder, and are allowed a loss of slightly over 60 volts in it. The loss in feeders two miles long is given in table LXXXX, and we may use any feeder the loss of ; which, multiplied by 12, does not exceed 67 volts. ELECTRICAL TABLES AND DATA 263 12 times 6.6 equals 79.2, and is the loss caused by a 2,000,000-cm. cable. This we must not use, but the next larger one will give us a loss of only 52.8, and this, added to the trolley loss, makes a total of 76.4 volts. If it is desired to lose the full 90 volts a smaller trolley wire may now be considered. The loss in one mile of 100-lb. track is 2.6 volts per 100 amperes, which makes 31.2 for 1200; a 5,000,000-cm. cable causes a drop of twelve times 1.33, or 15.96 volts. The drop caused by both in parallel will be the reciprocal of the sum of the reciprocals. By the table of reciprocals we find the reciprocal of 31.2 is, roughly, 0.032051, and that of 15.96 is 0.062500. Adding these, we have 0.094, ap- proximately. The number corresponding to this from the same table is 10.6, which is more than two times too high. Let us now consider the use of two 5,000,- 000 cables. The drop in the cables will be just half of what it was before, or about 8. The reciprocal of 8 is 0.01250; this added to 0.032 gives us 0.157, and the number corresponding to it is about 6.4. This is still above what we require, but it must be borne in mind that not all of the current returns over the rails and negative feeders, hence, this will give us about the right p.d. The loss in trolley lines, track, and feeders can be lessened very much by increasing the number of substations from which they are fed, and the most economical arrangement can be determined by the same calculations laid out for locating trans- formers. Underground Construction. — Underground con- ductors are usually lead encased and as the lead is not very strong it is best to run the conductors in some form of conduit which protects them and facilitates removal in case of trouble. These conduits usually consist of some kind of clay, concrete or fiber, and their heat conductivity is generally not as good as 264 ELECTRICAL TABLES AND DATA that of moist earth. Conduits arranged as shown in Figure 32 carry away more heat than those shown at Figure 33, but if there are many of them they also require more trench area. All conduits should be arranged to drain, and at suitable intervals should be provided with splicing chambers. If space between them is to be filled with concrete they must be anchored to prevent floating. The following tables and information is taken from Handbook No. 17 of the Standard Underground Cable Co. (Copyright by Standard Underground Cable Co., 1906). Recommended Current Carrying Capacities for Cables, and Watts Lost per Foot, for each of four equally loaded single conductor paper insulated lead covered cables, installed in adjacent ducts in the usual type of conduit system where the initial tem- perature does not exceed 70° F. (21.1° C), the maximum safe temperature for continuous operation being taken as 150° F. (65.5° C). ELECTRICAL TABLES AND DATA 265 TABLE LXXXXI Size B. &S. Safe Cur- rent in Amp. Watts Lost Per Ft. at 150° F, Size B. &S. or , C. M. Safe Cur- rent in Amp. Watts Lost Per Ft. at 150° F. Size Circular Mils. Safe Cur- rent in Amp. Watts Lost Per Ft. at 150° F. 14 18 0.97 2 125 2.77 900000 650 5.71 13 21 1.03 7 146 3.00 1000000 695 5.86 12 24 1.09 168 3.23 1100000 740 6.01 11 29 1.15 00 195 3.46 1200000 780 6.13 10 33 1.25 000 225 3.69 1300000 820 6.25 9 38 1.39 0000 260 3.92 1400000 857 6.37 8 45 1.53 300000 323 4.22 1500000 895 6.49 7 53 1.67 400000 390 4.61 1600000 933 6.61 6 64 1.85 500000 450 4.91 1700000 970 6.73 5 76 2.08 600000 505 5.16 1800000 1010 6.85 4 91 2.31 700000 558 5.36 1900000 1045 6.97 3 108 2.54 800000 607 5.56 2000000 1085 7.09 Assuming that unity (1.00) represents the carrying capacity of single-conductor cables, the capacity of multi-conductor cables would be given by the fol- lowing : 2 Cond., flat or round form, 0.87 ; concentric form, 0.79. 3 Cond., triplex form, 0.75; concentric form, 0.60. The following experiment on duplex concentric cable of 525,000 cm. indicates clearly the danger in subjecting this type of cable to heavy overloads of even short duration. The cable was first heated up by a current of 440 amperes for five hours. An over- load of 50 per cent was then applied, the results in degrees Fahrenheit above the surrounding air being as follows : Time from start min. 15 min. 30 min. 45 min. 60 min. 90 min. Inner condr.. . 70° 84° 98° 111 123° 142° Outer condr... 55° 65° 76° 85° 94° 108° Lead cover... 31° 35° 40° 45° 49° 57° 266 ELECTRICAL TABLES AND DATA As it is the final temperature reached which really affects the carrying capacity, the initial temperature of surrounding media must be taken into account. If, for instance, the conduit system parallels steam or hot water mains, the temperature of 150 F., which we have assumed in the table to be the maximum for safe continuous work on cables, will be reached with lower values of current than would otherwise be the case; and as 70 is the actual temperature we have assumed to exist in the surrounding medium prior to loading the cables, any increase over 70 must be compensated for by reducing the current. For rough calculations it will be safe to use the following multipliers to reduce the current carrying capacity given in table LXXXXI to the proper value for the corresponding initial temperatures. Initial temp. F. 70° 80° 90° 100° 110° 120° 130° 140° 150° Multipliers ...1.00 0.93 0.86 0.78 0.70 0.60 0.48 0.34 0.00 When a number of loaded cables are operating in close proximity to one another, the heat from one radiates, or is carried by conduction, to each of the others, and all are raised in temperature beyond what would have resulted had only a single cable been in operation. And if the cables occupy adjacent ducts in a conduit system of approximately square cross- section laid in the usual way, the centrally located cable or the one just above the center in large installa- tions (A in Figure 32) will reach the highest tem- perature. This is equivalent to saying that its cur- rent carrying capacity is reduced and while this re- duction does not amount to more than 12 per cent (as compared with the cable most favorably located, D, Figure 32) in the duct arrangement given it may easily assume much greater proportions where a large number of cables are massed together. ELECTRICAL TABLES AND DATA Assuming that not more than twelve cables, ar- ranged as shown in Figure 32, can be used, the aver- age carrying capacity may be taken as the criterion for proper size of conductor, and for cables of a given type and size the carrying capacities of all cables, even though placed in adjacent ducts, will be represented by the following figures, taking unity as the average carrying capacity of four cables. (See Table LXXXXI.) Number of cables 2 4 6 8 10 12 Multiplier 1.16 1.00 0.88 0.79 0.71 0.63 Recommended Power Carrying Capacity in Kilo- watts of Delivered Energy. — The tables below are based on the carrying capacities of cables as given in Table LXXXXI. A power factor of unity was used in the calculations and hence the values found in the lower table are correct for direct current. For alter- nating current the kilowatts given must be multiplied by the power factor of the delivered load. Units. — Synopsis of units and symbols in general use. Defining Equation Unit Name Sym- bol Direct Current Alternating Current Electromotiv force Current e Volt Ampere E, e I, i IE E--R IZ E-hZ Resistance Power Ohm Watt R, r P E-f-I EI VZ2 — X2 E I X p. f . Impedance Ohm Z, z VR 2 +X2 Reactance Inductance Capacity Quantity Ohm Henry Farad Coulomb X, x L, 1 C, c Q, q fc + I Q-s-E I X time VZ2 — R2 I X time Admittance Mho Y, y I _ z = V G2 -f B2 Conductance Mho <*, g I-r-B R-^-Z2= VY2 — B Su'sceptance Mho B, b X — Z2 = y Y2 — G2 ELECTRICAL TABLES AND DATA TABLE LXXXXTI Size in inn >e v_/on<_ lUCLUIj xnum- riiase ^auies £. &S. Volts. 1100 2 200 330C L3200 22000 Kilo-Watts 6 92 183 275 333 549 915 1098 1831 5 109 217 326 395 652 1087 1304 2174 4 130 260 390 473 781 1301 1562 2603 3 154 309 463 562 927 1544 1854 3089 2 179 358 536 650 1073 1788 2145 3575 1 209 418 626 759 1253 2088 2506 4176 240 481 721 874 1442 2402 2884 4805 00 279 558 836 1014 1674 2788 3347 5577 000 322 644 965 1172 1931 3217 3862 6435 0000 372 744 1115 1352 2 231 3717 4462 7435 :250000 413 827 ] 240 1 .503 2 480 4132 4960 8264 Single Conductor Cables, A. C. or D. C. Volts. 125 250 500 1100 2200 3300 6600 11000 Kilo-Watts . 6 8.0 16.0 32 70 141 211 422 704 5 9.5 19.0 38 84 167 251 502 836 4 11.4 22.8 45 100 200 300 601 •1001 3 13.5 27.0 54 119 238 356 713 1188 2 15.6 31.2 62 138 275 413 825 1375 1 18.3 36.5 73 161 321 482 964 1606 21.0 42.0 84 185 370 554 1109 1848 00 24.4 48.8 97 215 429 644 1287 2145 000 28.1 56.3 113 248 495 743 1485 2475 0000 32.5 65.0 130 286 572 858 1716 2860 300000 40.4 80.8 162 355 711 1066 2132 3553 400000 48.8 97.5 195 429 858 1287 2574 4290 500000 56.3 112.5 225 495 990 1485 2970 4950 600000 63.1 126.3 253 556 1111 1667 3333 5555 700000 69.8 139.5 279 614 1228 1841 3683 6138 800000 75.9 151.8 304 668 1335 2003 4006 6677 900000 81.3 162.5 325 715 1430 2145 4290 . 7150 1000000 86.9 173.8 348 764 1529 2294 4587 7645 1100000 92.5 185.0 370 814 1628 2442 4884 8140 1200000 97.5 195.0 390 858 1716 2574 5148 8580 1400000 107.1 214.3 429 943 1S85 2828 5656 9427 1500000 111.9 223.8 448 985 1969 2954 5907 9845 1600000 116.6 233.3 467 1026 2053 3079 6158 10263 1700000 121.3 242.5 485 1067 2134 3201 6402 10670 1800000 126.3 252.5 505 1111 2222 3333 6666 11110 2000000 135.6 271.3 543 1194 2387 3581 7161 11935 ELECTRICAL TABLES AND DATA 269 Ventilation. — Ventilation for the purpose of pro- viding a certain quantity of fresh air to occupants of rooms or shops requires the apparatus to be in use continuously while the rooms are occupied, regardless of temperature. Where it is provided mainly to carry off surplus heat, it is used only in warm weather. The capacity in such cases must be sufficient to take care of the hottest weather. The quantity of air moved by any fan varies directly as the speed, but the power required to run the fan varies as the cube of the speed. The net result is that the cost of moving different volumes of air by any given fan varies about as the square of the speed at which the fan must operate to move it. This is the theoretical relation, but this is somewhat dis- turbed by the difference in efficiency of large and small motors operating at various speeds. Owing to the above facts it is often a difficult task to decide whether it is more profitable to install a small, cheap fan and run it at a high rate of speed, or to provide a more expensive one and operate it at a lower cost per unit of air moved. Which is the more profitable in the long run depends upon the number of hours per year the fan is to be used at its various speeds. In any case the most economical ventilator will be the one in connection with which the cost of energy saved per year will equal the interest charge upon the in- vestment of capital necessary to provide it in place of the cheapest fan which can do the work. The follow- ing tables are taken from publications of the American Blower Co. and give all the necessary data for com- parison of various fans. In order to find the most economical fan select the smallest fan capable of mov- ing the requisite amount of air and note the K. W. necessary to run it (divide H. P. given by 1.3). Next select some larger fan and note the K. W. necessary to move the same volume of air with this fan and sub- 270 ELECTRICAL TABLES AND DATA tract it from the first. The next step is to find the value of the annual saving, by multiplying the number of hours per year this power is used by the rate per K. W. Having found this, if we divide it by the rate of interest applicable, we shall obtain the sum of money which we can afford to spend to substitute this fan in place of the smallest one we were consid- ering. The rate of interest by which we must divide is determined by the number of years the installation is to remain in use and is as follows : One year, 1.06 per cent ; 2 years, .57 ; 3 years, .40 ; 4 years, .32 ; 5 years, .27 ; 6 years, .24 ; 7 years, .21J ; 8 years, .20; and 9 years, .18J. "We have now the following formula by which we can determine the amount of capital which can with profit be invested in a larger fan: n K. W. -k.w.xhxr c= % "~ where C = capital to be invested; K. "W. - k. w. - the saving in energy per hour, and h and r = the number of hours per year and rate per K. W. hour of energy. In case the fan is used intermittently at various speeds the calculations should be made accordingly, since tlfe power required at high speeds is much greater than at low speeds. The capacity of a fan used only to provide a sufficient quantity of fresh air is best determined by allowing from 30 to 50 cubic feet of air per minute for each adult, and from 20 to 35 for each child. In special places such as hos- pitals this quantity is often doubled. The maximum quantities given will secure ample ventilation for all ordinary persons. In public places such as toilet rooms, waiting rooms, etc., it is customary to require from three to six changes of air per hour. ELECTRICAL TABLES AND DATA 271 TABLE LXXXXIII t( Ventura' ' Disc Ventilating Fans. General Capacity Table. — American Blower Co. Capacities, Speeds and Horse Powers with Unobstructed Inlet and Discharge. No. of Velocity of Air in Feet per Minute. Fan 600 900 1200 1500 1800 2100 Cu. Ft. Per Min.. 950 1420 1895 2370 2840 3320 3 Pres. Ins. W. G.. .0225 .055 .09 .1406 .2025 .2755 E. P. M 625 980 1255 1565 1880 2190 H. P 0097 .036 .079 .153 .265 .42 C. F. M 1620 2430 3240 4050 4860 5670 4 Pres. ins 0225 .055 .09 .1406 .2025 .2755 E. P. M 470 735 945 1175 1410 1645 H. P 0168 .062 .13 .262 .455 .72 C. F. M 2500 3750 5000 6250 7500 8750 5 Press. Ins 0225 .055 .09 .1406 .2025 .2755 E. P. M 375 585 755 938 1125 1310 H. P 026 .095 .207 .405 .701 1.10 C. F. M 3560 5350 7125 8900 10700 12500 6 Press. Ins 0225 .055 .09 .1406 .2025 .2755 R. P. M 315 492 632 786 945 1100 H. P 037 .136 .295 .575 1.00 1.59 C. F. M 4S00 7200 9600 12000 14400 16800 7 Press. Ins 0225 .055 .09 .1406 .2025 .2755 E. P. M 288 419 537 669 803 936 H. P 05 .182 .398 .776 1.345 2.13 C. F. M 6250 9375 12500 15600 18750 21850 8 Press. Ins 0225 .055 .09 .1406 .2025 .2755 E. P. M 234 366 470 584 702 817 H. P 065 .237 .516 1.01 1.75 2.77 C. F. M 7875 11800 15700 19650 23600 27500 9 Press. Ins 0225 .055 .09 .1406 .2025 .2755 E. P. M... 209' 326 419 521 626 730 H. P 082 .30 .65 1.27 2.20 3.48 272 ELECTRICAL TABLES AND DATA TABLE LXXXXIV Capacities, Speeds and Horse Powers with Eesistance of Average Piping System. No. of Velocity of Air in Feet per Minute. Pan 600 900 1200 1500 1800 2100 Cu. Ft. Per Min.. 950 1420 1895 2370 2840 3320 8 Press. Ins. W. G.. .06 .15 .24 .37 .53 .73 E. P. M 716 1075 1435 1790 2150 2510 H. P 022 .085 .18 .34 .59 .93 C. F. M 1620 2430 3240 4050 4860 5670 4 Press. Ins 06 .15 .24 .37 .53 .73 E. P. M 540 808 1075 1345 1615 1885 H. P. 037 .14 .30 .58 1.00 1.59 C. F. M 2500 3750 5000 6250 7500 8750 5 Press. Ins...."... .06 .15 .24 .37 .53 .73 E. P. M 430 644 860 1075 1288 1500 H. P 057 .21 .46 .90 1.54 2.45 C. F. M 3560 5350 7125 8900 10700 12500 6 Press. Ins 06 .15 .24 .37 .53 .73 E. P. M 361 540 720 900 10S0 1260 H. P 082 .30 .65 1.27 2.20 3.50 C. F. M 4800 7200 9600 12000 14400 16800 7 Press. Ins 06 .15 .24 .37 .53 .73 E. P. M 307 460 614 767 920 1075 H. P 11 .40 .88 1.71 2.96 4.69 C. F. M 6250 9375 12500 15600 18750 21850 8 Press. Ins 06 .15 .24 .37 .53 .73 E. P. M 268 402 535 670 803 940 H. P 143 .53 1.14 2.23 3.85 6.10 C. F. M 7875 11800 15700 19650 23600 27500 9 Press. Ins 06 .15 .24 .37 .53 .73 E. P. M 239 358 477 597 716 835 II. P 18 .67 1.43 2.80 4.84 7.68 Pressures noted are static pressures. ELECTRICAL TABLES AND DATA 273: Where it is desired to reduce temperature or remove: steam, etc., we must proceed to find the necessary capacity in another way. If we remove all of the heated air in a room and replace it with air from the outside in the same length of time required to heat it, we shall reduce the temperature by one-half the dif- ference between that of the air in the room and the air brought in. From this fact we can deduce the fol- lowing method for determining the amount of air which must be taken out of a room in order to lower its temperature by any desired amount. Before the room has attained its full temperature place one or more thermometers at representative locations and note the temperature rise for any convenient length of time, but be sure that you are observing the maximum or general temperature rise which is to be ventilated for. By providing ventilator capacity to exhaust alL of the air in the room one or more times in the same length of time in which the rise took place we shall, reduce it according to the following tabulation whick shows the number of degrees F. which the room tem- perature will be above the outside temperature with, the number of changes taking place as given at the left in column 0. The column is correct only when the room is so tightly closed that there is no natural ventilation. Under the other columns, headed by 1, 2, 3, 4, and 5, are given the number of times the air must be changed to limit the temperature rise in room to the increases above the outside air as given in right hand section of table. Thus, if the increase in temperature allowed over the outside air is 30 degrees and the air is naturally changing three times we must change it twelve times to limit the rise to 5 degrees. ELECx'RICAL TABLES AND DATA TABLE LXXXXV Number of natural changes of air Increase in degrees F. assumed. above outside air. 5 4 3 2 1 5 10 15 20 25 30 35 40 10 8 6 4 2 1 2| 5 7* 10 122 15 m 20 15 12 9 6 3 2 U 2i 3| 5 6* 71 81 10 20 16 12 8 4 3 f if U H 4i 5 5f 6§ 25 20 15 10 5 4 f li 1| 2* 3* 3| 4| 5 JKwZe. — Determine difference in temperature be- tween outer and inner air which is to be ventilated for, and trace down column headed by this temperature until the allowable temperature of inner over outer air is reached. Next estimate number of natural changes taking place during the time of previous test and in section of table at left headed by this number trace down to same horizontal line in which the per- missible temperature was found. At this point the necessary number of changes in air will be found. These changes must take place in the same length of time in which the temperature rise took place. If there is a temperature rise accompanied by nat- ural ventilation the reductions in temperature given in Table LXXXXV, column 0, can be obtained only by doubling the number of changes taking place dur- ing the time that the rise in temperature was going on. Suppose, for instance, that a certain temperature rise takes place in an hour while during the same time the air is naturally changing ten times. The starting of the ventilator, if of sufficient capacity, immediately ELECTRICAL TABLES AND DATA 275- ends all natural ventilation because every former out- let for air now becomes an inlet and all air passes through the fan. The number of changes which were naturally taking place now count for nothing and to reduce the temperature by one-half we must provide ten more changes per hour, i.e., change the air by means of the fan twenty times to obtain the effect of one change as given in column 0. Thus to find the number of changes necessary to obtain the effects given in the table in column we must use the formula c=(axb)+a, where c=the number of changes that must be made ; a = the number of natural changes tak- ing place, and b = the figure in column which corre- sponds to the desired rise above the outside air at the difference in temperature. Example. — The increase in temperature in a certain room is 10 degrees above that of the outside air and is to be limited to 2-J degrees; the dimensions of the room are 100 x 20 x 12, while the natural change of air is assumed to be about three times per hour. What must be the capacity of the ventilating fan ? Tracing down in Table LXXXXV under 10 degrees to where 2J is found, and then in the horizontal line to the left, to column pertaining to three changes of air per hour, we find the number 9, which signifies that we must have capacity to change the air nine times per hour,, and since the room contains 24,000 cubic feet we must select a fan which can move 3,600 cubic feet per minute. Practical Hints. — Place ventilators at end of room opposite to where most of the air enters or so that all disagreeable air is nearest to the fan. Protect fan against wind blowing into it. Avoid noise by selecting large fans to operate at low speeds. Air in motion does not feel as warm as stationary air. It is best to provide a separate fan for kitchen ranges, etc., an& attach it directly to hoods placed over such apparatus.. '276 ELECTRICAL TABLES AND DATA In wide or square rooms provide several ventilators so as to secure a more uniform movement of air over the whole space. If fan capacity is small compared to size of room and cooling is the only consideration it is best to blow air into the room. An exhaust fan which does not change the air oftener than it is naturally changing has little effect. Even in well constructed places the air is supposed to change itself once per I hour at least. Voltage Regrdation. — In a network of wiring the regulation is always fairly good because a heavy de- mand at any point immediately causes current from all sides to rush in. The drop at feeder ends can be easily compensated for if they are all of the same length. If they are not of the same length they should be divided into groups of the same length and each group separately regulated. For d. c. work individual feeder regulators waste too much energy to be con- sidered except with very short lines. In long lines a booster is often installed. To deter- mine whether it is profitable to install a booster we must compare its cost and the losses due to its opera- tion, with the cost of increasing the size of conductors proportionately and the losses incident to the im- proved lines. Obviously this depends upon the length of the line, and the drop which may be allowed. De- termine investment for booster, interest and deprecia- tion and cost of operation and losses. This amount can be saved by the installation of proper feeders, and if we can obtain the larger feeders by an invest- ment of capital upon which the above sum will be the proper interest it will not be profitable to install the booster. For a. c. work individual feeder regulators are much used, and as they waste comparatively little energy, they may be used in each feeder and all feeders con- nected to a common line. Such regulators may be ELECTRICAL TABLES AND DATA 27? arranged either to boost or choke. For low tension work, either a. c. or d. c, pressure wires are often run from the end of feeder back to switchboard to indicate the pressure at feeder end. The same object is also attainable by line drop compensators, or if the size and length of line be known the drop at the far end or any other point may be calculated from the number of amperes. The^ following table (LXXXXVI) is provided to assist in making the necessary calculations for the set- ting of a. c. line drop compensators, and also to deter- mine the drop in voltage occurring at any part of the line so that the voltage at the station may be raised correspondingly. To find the drop in voltage we may use the formula IZxd; in which / is the current in amperes; Z the impedance as given in the table for various sizes of wire and separation, and d the number of 1,000 feet of line. For line compensators it is necessary to find the percentage of the reactive, and ohmic drop. The same formula may be used substituting X or R for Z and dividing the result by the transmission voltage. This will give the percentage according to which the two sections of the compensator must be set. See detail instructions sent out with compensators. The values of Z, R and X are for 1,000 feet of wire. A single phase installation can be served by a single compen- sator, but then the drop will be double that given, or for 2,000 feet instead of 1,000 feet of wire. The same may be said of a two phase installation which is served by two compensators, but in two phase three wire, or in three phase systems, a compensator must be in- stalled in each wire, and a four wire three phase sys- tem requires four, so that in connection with these systems the value given in the table need not be doubled. ELECTRICAL TABLES AND DATA TABLE LXXXXVI Table Showing Resistance, Eeactance and Impedance of 1,000 Feet of Wire of Sizes Given and at Various Separations. B. & S. R 12 X Z Separation of Wires in Inches. 24 36 48 60 x z xzxz xz X z 8 .627 .126 .640 .142 .640 .151 .640 .157 .640 .163 .640 .167 .640 6 .397 .120 .415 .136 .415 .145 .420 .152 .420 .157 .420 .161 .420 5 .314 .118 .345 .134 .350 .143 .355 .150 .357 .155 .360 .159 .362 4 .250 .115 .275 .131 .2S0 .140 .285 .147 .290 .152 .292 .156 .294 3 .198 .112 .230 .128 .235 .137 .240 .144 .245 .150 .248 .153 .251 z .157 .110 .190 .126 .200 .135 .205 .141 .212 .147 .215 .151 .217 1 .126 .107 .165 .123 .175 .132 .180 .139 .187 .144 .191 .148 .194 .100 .104 .145 .120 .155 .129 .165 .136 .169 .141 .173 .145 .176 00 .079 .102 .130 .118 .140 .127 .150 .133 .156 .139 .159 .143 .162 000 .063 .099 .120 .115 .130 .124 .140 .131 .145 .136 .149 .140 .153 0000 .050 .096 .110 .112 .125 .122 .135 .128 .138 .133 .140 .137 .146 Weights of Materials in Pounds (Approximate). — Aluminum, cu. ft., 167 ; cu. in., 0.095. For wires, see tables. Antimony, cu. ft., 418; cu. in., 0.242. Asphaltum, cu. ft, 84; gal., 11.2. Bismuth, cu. ft., 612; cu. in., 0.354. Brass, cu. ft, 522 ; cu. in., 0.302. Brick, cu. ft., 119 ; per thousand, 4500. Bronze, cu. ft, 537; cu. in., 0.311. Cement, loose, cu. ft, 88 ; bu., 95. Charcoal; cu. ft., 25 ; bu., 27. Coal, anthracite, piled loose, cu. ft., 52 ; bu., 56. " bituminous, piled loose, cu. ft., 50; bu., 54. Coke, piled loose, cu. ft., 27 ; bu., 29. ELECTRICAL TABLES AND DATA 279 Concrete, eu. ft., 150 ; cu. yd., 4050. Copper, cu. ft, 555; cu. in., 0.321. For wires, see tables. Cork, cu. ft., 15.6. Crushed Stone, cu. yd., 2700. Earth, cu. ft., 109; cu. yd., 2943. Glass, cu. ft., 165. Gold, cu. ft, 1225 ; cu. in., 0.709. Gravel, cu. ft., 119 ; cu. yd., 3213. Ice, cu. ft, 56; cu. yd., 1512. Iridium, cu. ft., 1400; cu. in., 0.81. Iron, cu. ft., 490 ; cu. in., 0.225. For wires, see tables. Lead, cu. ft., 709; cu. in., 0.41. Limestone, cu. ft., 165 ; cu. yd., loose, 2700. Loam, cu. ft, 78; cu. yd., 2106. Mercury, cu. ft, 850; cu. in., 0.492. Nickel, cu. ft., 540; cu. in., 0.312. Oils, olive, gal., 7.6. " cottonseed, gal., 8.0. 11 linseed, gal., 7.8. " turpentine, gal., 7.2. " lard, gal., 7.9. " whale, gal., 7.8. " gasoline, gal., 5.7. " petroleum, gal., 7.3. " mineral lubricating, gal., 7.8. Paper, cu. ft., 56. Paraffine, cu. ft., 56 ; gal., 7.41. Pitch, cu. ft., 67 ; gal., 8.9. 2S0 ELECTRICAL TABLES AND DATA Platinum, cu, ft., 1340 ; eu. in., 0.718. Porcelain, cu. ft., 150; en. in., 0.087. Salt, cu. ft., 60; gal., 8.04. Sand, cu. ft., 105; cu. yd., 2835. Silver, cu. ft., 653 ; cu. in., 0.377. Slate, cu. ft., 184; cu. in., 0.109. Sulphur, cu. ft., 125. Tantalum, cu, ft., 1040; cu. in., 0.60. Tar, cu. ft., 62.5 ; gal., 8.33. Tin, cu. ft., 455; cu. in., 0.263. Tungsten, cu. ft, 1175; cu. in., 0.68. Water, plain, cu. ft., 62.5; gal., 8.33. sea, cu. ft., 79 ; gal., 10.3. Wood, ash, cu. : it, 46 per 1000 ft., 3850. ' ' butternut, ' 1 28 2330. 1 ' cedar, 1 38 3165. ' ' chestnut, 1 39 3250. 1 1 cypress, 1 35 2915. ' ' elm, 1 36 3000. "fir, 1 35 2915. 1 ' hemlock, 1 27 2250. 1 ' hickory, ' 55 4600. 1 ' lignum vitae, ' ' 81 6750. 1 ' mahogany ' 1 36 3000. 1 ' maple, 1 50 4560. ' ' oak, 1 47 3915. " pine, white, ' 1 25 2275. 11 pine, yellow, l 1 45 3750. 1 1 poplar, 4 24 2200. 1 ' redwood, 1 30 2740. 1 ' spruce, 1 28 2330. ' ' walnut, 4 41 3400. Zinc, cu. ft., 420; cu. in., 0.243. ELECTRICAL TABLES AND DATA 281 Contents of Barrels or Round Containers = average diameter squared x height x 0.7854. If measurements are taken in inches D 2 xHx 0.000454 = cu. ft. D 2 xHx 0.0034 =gal. D 2 x H x 0.000425 = bu. If cubic contents are known in feet, multiply by 7.58 to obtain gallons, and by 0.936 to obtain bushels. To obtain cubic yards divide by 27. Welding. — From 30 to 60 H. P. per square inch area of weld to be made are used. This is the power required to be delivered to welder. The greater the capacity the shorter will be the time required to make a weld. In some cases only a few seconds are required. Wire Calculations. — This division contains the following tables: A table of carrying capacities of copper and alumi- num wires. A table showing carrying capacities of different combinations of wires. Table for determining the total wattage of groups of lamps or other devices usually rated in watts. Tables for calculating the amperage per H. P. of motors at various efficiencies and power factors. Tables showing maximum H. P. allowed on wires according to N. E. C. rules and carrying capacities. Tables for determining proper size of wire for a certain loss in voltage; copper and aluminum wires, direct current, and 60 and 25 cycles. Tables to facilitate determining the most economical conductors. Various tables showing physical properties of cop- per, aluminum, copper clad, german silver and steel wires. Tables showing outside diameters of wires and cables. 282 ELECTRICAL TABLES AND DATA TABLE LXXXXVIII Table of Allowable Carrying Capacity of Wires. ^B. & S. Bubber Insulation Other [nsulations 'Gauge Copper Aluminum Copper Aluminum 18 3 2 5 4 16 6 5 10 8 14 15 12 20 17 12 20 17 25 21 .10 25 21 30 25 8 35 29 50 42 6 50 42 70 59 5 55 46 80 67 4 70 59 90 76 3 80 67 100 84 2 90 76 125 105 1 100 84 150 126 125 105 200 168 00 150 126 225 189 000 175 147 • 275 231 0000 225 189 325 273 ^Circular Mils 200000 200 168 300 252 300000 275 231 400 336 400000 325 273 500 420 500000 400 336 600 504 600000 450 378 680 571 700000 500 420 760 639 800000 550 462 840 705 900000 600 504 920 773 1000000 650 546 1000 840 1100000 690 580 1080 901 1200000 730 613 1150 966 1300000 770 646 1220 1024 1400000 810 680 1290 1083 1500000 850 714 1360 1142 1600000 890 748 1430 1201 1700000 930 781 1490 1251 1800000 970 815 1550 1301 1900000 1010 848 1610 1352 .2000000 1050 882 1670 1402 ELECTRICAL TABLES AND DATA 283 Carrying Capacities of Different Combinations of Wires. — Owing to the relatively different radiating surface of wires of different sizes the carrying capacity per circular mil is not the same for all wires, and where wires of different gauge number are to be con- nected in parallel this must be taken into account. In the following table this is done and the carrying ca- pacity of smaller wires at the current density allowed for the larger wires is given wherever the horizontal and vertical lines pertaining to any two wires cross. The number found at this place indicates the am- perage the smaller wire will have with the larger wire fully loaded. The figures are based on the carrying capacities given by the National Electrical Code. To find the proper wire to reinforce another which has been overloaded: Select the horizontal line pertain- ing to the larger wire and follow along this line until a number about equal to the necessary additional amperes is found. At the head of the vertical column in which this number is found will be found the gauge number of the proper wire to be used. ELECTRICAL TABLES AND DATA TABLE LXXXXIX Table Showing Combined Carrying Capacity of Different Wires — Eubber Insulation Amps. B.&S. 15 14 20 25 35 50 55 70 80 90 100 125 150 175 225 5 4 3 2 1 00 000 0000 14*12 10 15 12 20 10 15 25 8 13 22 8 6 5 4 3 2 00 000 0000 275 300000 325 400000 400 500000 12 20 11 17 11 18 10 16 9 14 8 12 7 12 7 11 6 10 7 11 6 9 35 31 50 27 44 55 28 45 55 70 25 39 50 64 80 22 35 45 56 71 90 19 31 39 49 63 80 19 31 39 49 62 77 18 30 37 47 59 74 17 27 34 43 54 69 17 28 35 44 56 76 15 24 30 38 48 61 13 21 26 33 43 54 13 21 26 33 42 53 Other Insulations 100 98 125 94 118 150 87 108 138 175 89 112 141 178 225 77 96 122 154 194 68 85 109 137 172 67 84 106 134 169 Amps. B&S. 14 20 14 20 12 10 8 6 5 4 3 2 1 00 000 0000 25 30 50 70 80 90 100 125 150 200 225 275 325 12 15 10 11 8 12 6 10 5 10 4 10 3 7 2 1 00 000 0000 400 300000 500 400000 600 500000 25 19 30 19 31 17 27 16 25 16 25 12 19 12 19 11 18 12 19 11 17 10 17 10 16 8 14 8 13 8 12 50 44 70 40 64 40 64 31 50 31 50 29 47 31 49 28 44 27 43 25 40 22 35 20 33 20 31 80 80 90 63 80 63 78 59 74 62 79 56 70 54 68 51 64 44 55 41 52 40 50 100 99 125 94 118 150 99 125 157 200 89 112 141178 225 86 109 137 173 218 275 81 102 128 162 204 258 325 70 88 112 140 177 223 282 66 83 104 132 166 209 264 63 80100127160 202 255 ELECTRICAL TABLES AND DATA 285 TABLE C Table for determining total wattage required for incandescent lamps or other devices usually rated in watts. To find total wattage add all numbers found where lines pertaining to number of lamps and wattage of same cross. Number of Watts lamps 1000 750 500 250 150 100 m 40 25 2 2000 1500 1000 500 300 200 120 80 50 3 3000 2250 1500 750 450 300 180 120 75 4 4000 3000 2000 1000 600 400 240 160 100 5 5000 3750 2500 1250 750 500 300 200 125 6 6000 4500 3000 1500 900 600 360 240 150 7 7000 5250 3500 1750 1050 700 420 280 175 8 8000 6000 4000 2000 1200 800 480 320 200 9 9000 6750 4500 2250 2700 900 540 360 225 10 10000 7500 5000 2500 1500 1000 600 400 250 15 15000 11250 7500 3750 2250 1500 900 600 375 20 20000 15000 10000 5000 3000 2000 1200 800 500 25 25000 18750 12500 6250 3750 2500 1500 1000 625 30 30000 22500 15000 7500 4500 3000 1800 1200 750 35 35000 26250 17500 8750 5250 3500 2100 1400 875 40 40000 30000 20000 10000 6000 4000 2400 1600 1000 45 45000 33750 22500 11250 6750 4500 2700 1800 1125 50 50000 37500 25000 12500 7500 5000 3000 2000 1250 55 55000 41250 27500 13750 8250 5500 3300 2200 1375 60 60000 45000 30000 15000 9000 6000 3600 2400 1500 65 65000 48750 32500 16250 9750 6500 3900 2600 1625 70 70000 52500 35000 17500 10500 7000 4200 2800 1750 75 75000 56250 37500 18750 11250 7500 4500 3000 1875 80 80000 60000 40000 20000 12000 8000 4800 3200 2000 85 85000 63750 42500 21250 12750 8500 5100 3400 2125 90 90000 67500 45000 22500 13500 9000 5400 3600 2025 100 100000 75000 50000 25000 15000 10000 6000 4000 2500 110 110000 82500 55000 27500 16500 11000 6600 4400 2750 120 120000 90000 60000 30000 18000 12000 7200 4800 3000 130 130000 92500 65000 32500 19500 13000 7800 5200 3250 140 140000 105000 70000 35000 21000 14000 8400 5600 3500 150 150000 112500 75000 37500 22500 15000 9000 6000 3750 ELECTRICAL TABLES AND DATA TABLE CI Table showing wattage capacity of different wires. —110 Volts— —220 Volts— —440 Volts— Eubber Other Eubber Other Eubber Other Ins. Ins. Ins. Ins. Ins. Ins. 14 1650 2200 3300 4400 6600 8800 12 2200 2750 4400 5500 8800 11000 10 2750 3300 5500 6600 11000 13200 8 3850 5500 7700 11000 15400 22000 6 5500 7700 11000 15400 22000 30800 5 6050 8800 12100 17600 24200 35200 4 7700 9900 15400 19800 30800 39600 3 8800 11000 17600 22000 35200 44000 2 9900 13750 19800 27500 39600 55000 1 11000 16500 22000 33000 44000 66000 13750 22000 27500 44000 55000 88000 00 16500 24750 33000 49500 66000 99000 000 19250 30250 38500 60500 77000 121000 0000 24750 35750 49500 71500 99000 143000 200000 22000 33000 44000 66000 88000 132000 300000 30250 44000 60500 88000 121000 176000 400000 35750 55000 71500 110000 143000 220000 500000 44000 66000 88000 132000 176000 264000 If system is balanced use columns 220 volts for 3-wire 110-volt systems and column 440 volts for 3-wire 220 volt systems or for such voltages direct. Tables for calculating amperage of motors with various efficiencies, power factors systems and voltages. RULE FOR FINDING AMPERES In top part of table select numbers found where lines pertaining to efficiency and power factors cross and find same number in middle table. In same line under proper system will be found the number of amperes required for 1 H. P. at 110 volts. In bottom table select divisor pertaining to higher voltages, di- vide amperes by this and multiply by number of H. P. The result will give the total number of amperes re- quired. The efficiency of small motors is always much less than that of larger motors. ELECTRICAL TABLES AND DATA TABLE CII to Efficiency O c8 PMfa .95 .90 .87£ .85 .82* .80 .75 .70 .65 .60 .55 .95 .90 .86 .83 .81 .78 .76 .71 .67 .62 .57 .53 .90 .86 .81 .79 .77 .74 .72 .68 .63 .59 .54 .50 .85 .81 .77 .74 .72 .70 .68 .64 .60 .55 .51 .47 .80 .76 .72 .70 .68 M .64 .60 .56 .52 .48 .44 .75 .71 .68 .66 .64 .62 .60 .56 .53 .49 .45 .41 .70 .67 .63 .61 .59 .58 .56 .53 .49 .46 .42 .39 Amperes for 1 H. P. at 110 Volts Direct Direct current Two Three current Two Three or s. phase phase phase or s. phase phase phase .39 17.4 12.5 10.0 .66 10.3 7.3 5.9 .41 16.5 11.9 9.6 .67 10.1 7.2 5.9 .42 16.1 11.6 9.3 .68 9.9 7.1 5.8 .44 15.4 11.1 8.9 .70 9.7 7.0 5.6 .45 15.1 10.8 8.7 .71 9.6 6.9 5.5 .46 14.7 10.5 8.6 .72 9.5 6.8 5.4 .47 14.4 10.3 8.4 .74 9.2 6.6 5.3 .48 14.1 10.2 8.2 .76 8.9 6.4 5.1 .49 13.8 9.9 8.0 .77 8.8 6.3 5.1 .50 13.6 9.7 7.8 .78 8.7 6.2 5.0 .51 13.3 9.5 7.6 .79 8.6 6.1 5.0 .52 13.0 9.4 7.5 .81 8.4 6.0 4.8 .53 12.8 9.2 7.4 .83 8.2 5.9 4.7 .54 12.6 9.0 7.3 .84 8.1 5.8 4.6 .55 12.4 8.8 7.1 .85 8.0 5.7 4.6 .56 12.1 8.7 7.0 .86 7.9 5.7 4.5 .57 11.9 8.5 6.8 .90 7.5 5.4 4.3 .58 11.7 8.4 6.7 .92 7.4 5.3 4.3 .59 11.5 8.3 6.6 .93 7.3 5.2 4.2 .60 11.3 8.1 6.5 .94 7.2 5.2 4.2 .61 11.1 8.0 6.4 .95 7.1 5.1 4.1 .62 10.9 7.8 6.3 .96 7.0 5.1 4.1 .63 10.7 7.7 6.2 .97 7.0 5.0 4.0 .64 10.6 7.6 6.1 .98 6.9 4.9 4.0 Voltages 110 220 440 550 650 1100 2080 2200 Divisor 1 2 4 5 5.9 11 18.9 20 ELECTRICAL TABLES AND DATA e a 6>D - („ . ^ ci 01 co rH S x cm vz °o «H ^ •gO {l| i-H t-H 08 r}1 a rH CD LO iq rH l-H O Cl rH GO rr} .5 d d oi go' tjh 10 10 co t- ci IO* rH* CXJ* t»* GO* CXI -* t^ O GO rH rH rH CXI rH as 1 01 **■< FH o § 01 M gi-T *# "* ^ °°. °^ cq b- rH t- iq • O tJH t- CD b- bc° ±! CQ rd d c^ ^ rH * '""* O ^ rH rH CM CO rj" co' d d cxi co ^*i 10 10 CD t-H cq iq 10 co' rH d 7-^ id b- Cl O TH CXJ t— 1 rH rH iq »q iq iojV i "Ci CO ^ ' G rH r-t ^ ro •o si (_; 00 Oi iq co os Qj _J LO d l^' GO* | w r-i r-t rH CM CO co" d go' go" go" CD t- t^ Cl rH rH Cl rH GO iq CO* TH co' d GO* rtl lO CD t^ b- b-* b-' d id d IONHIOCO rH rH CXJ q ^"3 d* > oi >>* oi co co* CXI CO Tfi ^ IO d d co' d d CD GO Cl CXI rH rH % 1 © h'W 10 .© '°. »°. «?.S°;2rHCMCOrH g m iq iq iq o iq iq iq co' d d co* d 10 CO CD GO rH iq 10 iq iq iq iq iq co' d co d d CO LO GO t— 1 rH rH rH CXI CXI iq iq rrjj qj la bO=H 2 ° p4 d m ^ <** ^ ^ W £3 rH rH CM CO d d co" d d CO ^ UO CD CD co' d d d co* CO O r-t IQ CO rH rH rH rH "Sf" . 'f >» r * d r-H* XH t-' d rH* rH rH rH rH Ol d cxi b-* 00' cxi cxi co co tH rH S3 ** s s3 s o M © h? tH CD O rH CD TtH O CD tH O tH O tH CD O el 2 O *d ^ °° ^ °°' is f -1 rH § ^ O rH CD rH CXJ rH tHH d CO* O CXI CXI CXI CO -^ CD CD tH O CD co* d co' d d LO CD b- GO GO rH O CD > O CXJ CX 7J c3 O O CO L Ph th" 10 d d co TjH GO rH -H* d rH rH CXJ Ol CXI co d d d co CO rH rH CD LO O r -1 f" gH-H rH b- CM rH b- IO CD CO CO O CXI Cl CO CO 3 "S r-H O 1 c co" d d co" d rH rH rH rA co' d rH cxi CXI Cxi Cxi CO CO ri a 2 £j 2 M l CD r-t b- b- CO CO r}H UO CO CD CO O CD O CO '§1 ^S3 ■3 K ft r-i cm' cm* CO lq* O ^i-J SMON CO 1 « id t>* go' d d t^ O CO t>; O d cxi co d d HHHHOJ CO d GO* ^H* rA rH rH rH CXI CXI b q s « q v~> d, <6 crj d cxi co co rH rH bO S3 o Ml ONCON© CO CO b- co # b- # CO CD ■+3 ,rH ® g **5 •? d *^°o o'43 Eh c« L Ph cd cq co* rH' d W eg -rH CM O GO CO M t^ d d cxi co IQ -tf CO CXI rH r£ ci ci d di r-t CXI CXI CO CXI 00000 0000 000 CXI r=3 .£ "•<-. x cm cxi co 10 b- O O O LO O GO Cl O CM "O r-i r-{ rH O LO LO LO O O CXI t^ CM O CM CM CM CO CO 1 Eh d a H " 10 10 10 ^ooi rH ^ ^ M "^ IO O O O O lO b- GO Cl O rH IO O LO LO O CM LO b- CM O rH r-t r-t CM CM 5E ELECTRICAL TABLES AND DATA H 03 £ 3 S'c? CO CO e-t- o ^ 3 (X> O CO CD 00 oo 01 M N CO to Ol o o o o o o O0 -q -q © © © MS WOWO o o o o o o © © en tf^ i-h co — CO CO OS o o o J Cn C o o o tO M M O CO 00 o o o O O O o o o o o o o o o -q as en o o o o o o o o o o o o o o o fcO-CO M O co to en oo o o o o I— i |_ i m i— i ^ W K) M o o o o CD O O O o o o o CD O O O o o o o O CO o to © © O CO o o o o o o o o o o Ol O Ol O M S • <^ X? pq H- © go © © © • — o? oooooo. M g oo ^q as en tf^ co _ o o o o o o O o o o o © o J?" © © © © © © © © © © © CD fa" ©©©©©© s © © CD © GO OO — q © © Cn hH oo to ^i to as © to os © co co w - © as "co © as o co as © co co as - M ^ S3 © OS CO © OS CO bO bO'bO M M M tO M © CO CO 00 to ^ os co © h» bs as as © as co © as co © co as © co as © as io f o 3 ;. ~q rf^ to © ~q rf*. ~& ^^) rr 1 "^ "^ c 2 "^ M c oo oo ~q ~q © as en en ^ rt*. co to m m2. qmswow po co -q to rf^ co «° ^ j+ to co ^q tf^ h- 1 bo en bo co "en If*, to . M gj M Hi M l-i M £ :> ~q © en fH n^T its wu to y is © to to to GO © © © to to to i>o en rf^ co to oo oo --q © ^ ^ co co co 3 HCOOOCJ 3 CO 00 M tO tO CO CO to X © to ^ "co © hH co kh bo "co bo to en - M b2b5HMMM h» © co oo ~q as © en en ^ co © to co co to to to hH tO © GO © hH ^ en © oo © en to to to © i-H to i_i m i_i t_i C s oo © co o m w M © CO © ' S?3 02 S. tO tO K) H M (J tOMOOQOGO co en © go co h* co co co co co to en *^ co i— ' o co en to © -q ^ © i- 1 © © oo © en m S 2. --q © © en oo go • £ *■ hb as •CTQ rt eg 2 © -3 o co M © CO CO en en en co oo ~q © © en ai hMOiOOS © © co © © © co co co © en © co en co © en rf^ ^ tf* © en co to oo go oo ^q ^q ^i oo en to © os to oo © en to © en to to to to to i— « ^q en ^ co i— i co ^ co en © co © en en hH rf^ ^ ^ fH (-J oo © co © © co © © co CD CO 00 -q -q © © © I-* © tO © Hi © co as © © co ^ hH CO CO CO CO CO © GO © kH I— I i— ' © oo -H H- © en cri a o\ ux oi Oi CO O 0O GT CO 'CO tf^ © rf^ © CO © © CO © ~q en u\ Ox Ox \P* ~q *^ h- ' -q 1^. CO Hi tO 5 © 00 ~q -q q © en oo to 3 hH © © co en ^ © GO © co ^ rf^ rf^ CO en co © -i oo co oo as 5. S ©©©©oooo >-i 5 rf-* h ' -o co © en oPj Go©cocn~qen oo --q -q © © en © © to - 1 t '^ 1 i © en i— » oo oo oo S H O < eocotototoi-iWWS. (M-JOOOIOS'h"? en hH co t-i co to • en vH vH co co to o% to -q to ^q m en • « ^q -q ^q © hH Hi • , 290 ELECTRICAL TABLES AND DATA ' m • © 10 10 © © iq 2xoi tH eo co" eg co ■gO rH rH CM CO CO rt^-cq o 10 q 10 o 03 0}©' C5 iH © CM id ' rH CM CM £«*« • o o o o iq o S baH H* t-' od ©' id 10 fiO H rH rH CM CO rH Sm'W O O 00 CM O oioqwqw |H LO t-" CO rH CM ■^^ lO«DOO © 10 © in © © CM* CO rA 10" b-" CO CO CO "* rH 10 CO 10 10 10 O IO o oowioqiq IO l- CO rH t-* CM CM ^H CO CO CM «>- HH HHIMCq iqqqqmq Oi CM* !-" IO O-' CM* b- O © CM ^ CO © q q 10 co' d JO CO CO iq © iq 10 iq iq ©s id d co' d rH CO rH 10 10 t- co iq o iq lb" oq oo CM CO CO CM CM CO q q iq id co' id »o CO CM ■ ' H CM 0,0 > B -Ph *u CD -1 02 » cscAh pi M E- O 'rS cT O > "O Sh OS O ' H CD «-j 0Q H rt ^ a d J »T ^ w W P-i CD '0 Ah < •££ ^ FH ^W £ a ri -73 £ O CD CD 3 fs S "5 .. OQ k.2 M as la ■ mmCM cm 00 hh q cm oq rH © co oq © 2 At> o" ©' 06 id os — ■go HHCqcxi c ojhht^ cm cm oq q q m ps'io" t>* os' cm' 06 © WHH rH iH CM h'oo cm q rH q q « rjCO* rH* co' cm' i-i CO B U rH rH CM CO CO § r-j co 00 cm oq q oq cd co' co' th" id cm" h* rH rH CM CM g m CO CO t^ CM CO CO ■C o co" rH* id Os cm" h" « £ m t>- co co ^ q q o^Wcm' co" n" d os" d © M'rH q oq cm oq q CM W QHH* IO CO rH id 00' q q cm cm co q O* CO* OS* id rH* 00* © rH O HH CO r-t rH rH rH rH rH CM © CM 00 HH © rH © © 00 © © © , rH H r ~ l td ,° HH COCO W( H rH cm_ rH q q q q rH cm rH q oq hh" co' co" d id d *& cp 1— I rH rH rH rH CM CM Cp; 5 o hh cm hh co oq © © © rH rH ^Z3 ■hh cxi oq rH hh © © 00* cm" S CO H rH rH CM CM CO HH oq q hh cm oq cm cm' hh d co" cm" t>* rH rH rH rH CM CM CM CO CM © © O0 g^rH rH q os co H^ PhCO* HH* id b-* rH* CM* ' «h» co t- q hh co ^OrH CM* CM* H* ©*l>* o -S •» 2 2 M .co oq co cm >q q O W Ph rH* rH CM* CO* H* id © i-icq oq rH q q © rH c Ocm" cm" co' id t-' os" ^^scxjoqqcocxi Ph rH* cm' cm co* id d or) %*# CM © 00 © IO J?0)i-h'©IO©©©© -XJqCM CM CO 10 t- 00 oq © cm q cm 00 id 00" © cm' 00" co" rH rH CM CM CM CO rH CO rH © iq rH ©' rH* rH t>-' CM* id rH rH rH rH CM CM OS © rH CO rH q t>* OS" ©" rH H* d © q q © 00 © d os* h" cm' © os* IOIOWI>050 , rH oq oq hh q q oq rH* © d © os' cm" CO HH CO IO IO t*. © cm q cm oq rH , CM" CO* t>" © CM' rH* CDOCD05HM rH oq © © CM cm ©' d id cm" co' d , CO IO rH © fc» © © iq co co rH iq ' id OS* t-" ©' id rH* ! CM CM CM CO HH JO © rH CM © IO rH >d ©" 06 id os © rH CM rH CM CM CO © © CO rH rH l>- rH* © CO IO ©' b-* . CO CO CO HH 10 © t-; rH iq © © rH • d id ci rH* ©' id rH CM CM CO CO HH 1 2=8 o . CSJD0 c3 © Ph2 CD I "vfr rH CO CM rH © © © ©©©©©© © © © O O CO © © © O © © © © © © © CM © © © CO rH IO © © IO © © >o © O CM IO © CM rH rH rH CM CM IO IO © © © © t~ CM © © © O CM CO CO rH IO © © © © © IO © t~ 00 © © CM IO rH rH rH IO IO © IO in © t~ CM © t>- CM © rH CM CM CM CO rH S ^ s .si ELECTRICAL TABLES AND DATA 291 otosotos O OX V\ © OX OX o G> 3 3 © OX © o o o en ^ © o o o o o o o o o ^ co co co O O CO ~q OOOlO] co co o o o o o o o o o o o o © o o o o COtOHMM CO O OX CO o © Ox © O OX © o O O M tO CO ^ OlOJOOOKJ^f CO CO © © 00 tf* CO CO © CO © 00 Cn i£* CO CO CO CO © OX .1^ 00 CO p bo © © CO © CO i CO tf^ 00 CO C5 CO O ^ ~q OX OX CO n> CO ,^ CO JO © © © H-» bo b o tJ^ bo bo 2R N GO O m; O © -q cn cn cn ■ p p p 2 © 00 OS "© © © £cd ^ Ha f-> O t-i M M M 00 rf^ CO © © ~3 © © h£- © M 00 M-Hj CD p P CfQ rt* "rf^ © © bs bo MtOHHHM © CO GO CO rf^ CO 00 OX © OX © tf* &2" bo bs k> 'co fe. © cn 00 © CO 1— I CO WS OS © © 00 OS OS • o 02 _ t© I — i I — i I — i ! — i 1 — k HOOrf^OHO 00 |— i ox © oo © © OS CO CO © © * o si P 2. &■ CO CO CO M CO h-i 0)fflfM»OOI © co po © co ^q bo bo © © co bs cp CD Pj OX (j> CO CO CO CO ** ox © © © ^ M h-» © OS CO GO p • bs "co bo >£. bo "© CO CO CO 1— ' l-» ;-» © co © ^ as to M os © cn co ^q co o © bs "co co CD Qj ^ CO CO CO CO CO CO OS © h-» oo © OS CO © 00 OS © © CO ]p- '$>■ © © CfQ I-* P P ^ rf^ CO CO CO CO 1— ' cn os m co cn © h-* © © cn rf^ -q © © © © © © >T3 p 2 p ^ © cn ^ co co co SOiOl WC3M M-i 00 Q o 2 <3 © ©" CD S- CO CO CO M CO M © © cn oo © cn ri^ cn © co rfi- © &® © © © © © © Hs tu «r* P P-P cn ^ co co co co i£» cn © ~q © cn cn ^ co co cn © CD Pj © © © © o o tO tO M M M M ^l CO 00 © M^ CO to bo co °rf>> bs bo *>Wt0tOHM J- 1 © ~q CO 00 OS © rfi. 'rfx bo co rf»» © cn rf^ rf^ co co ^i os cn © © j-» bs rfi- co 1^. © bs CO M ^q Cn rf^ CO Jjj ?£■ co bo bs "^ I(u, j^g ^^^ ' I po cn m ps cn p» p | © bo to bo bs !)!» m M © © os rfs> co co td td © © rfi. bs bs ^ ■ ■"■ M^ co © cn tfi. co OS" bs bo co rf^ bs bs w m co co i-» i-» [P>. CO cn M GO OS JjJ bo bs bo to bo bo ng B 35 < 2. sw CO CO CO M M _. © H co co h-» oo O CD • 00 CD P Pj B o bs © © rf^ "co '^ © bs rf*. bs co bo ^ © rf^ oo to © 00 -q cn (^ CO CO co co ms> cn os co © bo bo bs if*, bo i— ' i—i CO M © 00 ^1 © p( CO © © CO CO co bo rf^ bo © co tOHU < © go to © ^q cn td w S © © go co to rf^ m ^ f co co ^~ © cn go co bs rf^ o © -.©©j-i^ to © © bo tf^ bo © to bo co tf 5 ' bs i ©> © ~q © cn cn oo m co cn oo i-i bo "co bo bs V co © © © co oo © © M^ I— © © • co © © © © b © J t- 1 . ,ljO 05 ©oscnoo^©tdws b © bs rfs» Ij^. bo « 3 ra ' © m oo rf^> P^„ if» co bo bs 'n^ hf^ t-'w © cn co co co m M co ps © oo co ^q rO © °^ bs © © © t -1 § © ^q Oi co co CO ri 5' p © © rf^ oo CO y w „ © © © © © © t* ° Cq CO in in >n © iq ©' rH ©' ©' od rH CX) 2 '-' ""So 4 rH © # cq cxi cq ■; CXJ* in* GO* i-H 02 til PQ s ^ P5 -J cq oq rH cq oq -> ©" b-' © id i-h* rH CXI cq cq co © cq rH CO b-' rH id ; cq co oq cq rfl \ b- © i— i © »» ' iH i— I CXJ oq cq cq co cq id b-' ©" cd © oMtf co th © iq cq cxj co* co* id fc» .So c 2 .< o >o in m o lOOOlOO © iq iq cq © rH" GO oo* od od IO CO t> CO © CD rH rH © CD ©' co' cq' go" cd w m co b- © cq rH rH © cd cq' o* oo' go' t>* CO b- t^ © rH r-i cq oo cq rH rH CO rH Cd" ©' 00* rH LO CO b- i>- q q q q io co' cd rH rH' rH lONHlOOO i— i r-i cq cq cq iq qqioo t-' b-' co" id co OHCONIO r-i r-i r-i r-i cq in iq iq © cd o* ©' go" rH © cq CO r-i Ci t-n oq oq co oq in © iq io o cq* b-" r-i o" cd cq rH b- ci © T-H rH rH C] r-i oq rH © cq © ^H* ©" rA CO b-* cq rH t- o co r-i r^ rH Cq r-i © © CXI rH GO CO* CO cd ©* -HH t^ © © -Hi cq oq rH © cq cq © co" >n rH' «d IO b- rH IO CO rH ^h cq cq cq © © cq th go " o" co" ©* r& CD §3 bo° c$ h > a S a £ bo Ph 3 ""1 w'l OS r CO L iri © cq cq © oo rH cq oq © oo id OO* rH* O* ©" cq cq co co th cq oq © cq cq l>* r-i LO O0* r-* rH cq cq cq co «# cxi cq © cq _5 id ©* ©' od co co co ^h io co th rH cq cq _H l>* rH id © cq cq co co co iq r-j © > iq rH eg' -h" id ©' co" Jl" rH r-i rH CI CO © IO r-i^ CD on' ©" cq' rH id r-i r-i r-i r-i © co ©. CT rH rH cq cq ^h cq CO* GO* t-' b-' b-^ t>00C(MH © GO ©_ C3 rH ©' GO' GO* GO* GO rH lO © GO b- C\I r-i © GO © o . Sffl I? bc3 c3 a> CD ^ si K SI t» .r-1 'a I 03 s o3 t^ cq © iq rH oq rH © b- cq cp ir" b-' ©' rH* © ©* rH* CO* CO* GO* .£ . hHH(M(M COrHlO©lO > O0 b- b- © CD o co" id b-" © IO rH CO r-i cq a3rHCq©00© i^rHfOCXlrH _k> i—t r-i r-i © © © © © © O O O © O © O © '£~o (-, o © io © 5q o © cq m O ID IO IO © cd cq t^ cq © cq cq cq co co in © io io © cq in b- cq © rH rH rH CM Cq £ 2 g £ » o"^5 Eh rt 1-8 .2'S ELECTRICAL TABLES AND DATA 293 o ts OQ •slfflOlOlOt WtOOlOCl o © © o o I Hd hO MMM , _ HOOCQO .th. Cn 00 © tO rf*. ' 3 © © © © © co i-* © © oo © © © © © © © o © © © © © © © © © © © © © © © © © 3 5 P |_i M |_i |_i |_i Cn tf^ t^- CO CO W0-, © en © to ^ M £ 5* © © © en en « q -q ci © en rf*> P^3 ©OO©©© M^jq © © © © © ©©©©<© M. © © © © © r* © © © o © ^ © © © © © g © © © © © ~- 09 © 00 ~q © Cn hj - oo oo oo rfi. ^ •_; CO l-> © O0 © £us M © © -q © OP © © ^ oo to [_,<£ to to to to to 0DHO1 WM © © HM rf^ © rfi ^ W Oi w en co © © to © to to © oo tO tO tO M M to i— ' © oo ~q 00 © rf^ oo to CO CO co to to Ol CO I— i oo © oo oo to © to en en en rf*. £» ~3 rfi. © © CO to © oo oo to © 00 ■ © to 00 © tf>> -■ to tf^ ■ tS W ifl It 1 a H > o (73 m ^ QQ DOOOOOCD OOOOOO 0>00O0*O OOMMWCIIOtBH' P" SOOOOOO O O O O I— ' ha M LO tO CO ^ Ol OGOWOtOH^f+^ O CO tO tO CO CO rf^ Ol Q M CO O W Ol O OT tO H M CI LO O W M M "" g tu S Mrf^<)00O0i03 (^hUOOStOCO M^CO^ CO CO CO OS P M- SOOOOCOOM Offl <•>- P OO OOOOOO OOOOOO ^ M O O OOOOOO) CDOMh-il— 'I— '^ rf^d OlClQS-lCO CD O O h-* CO CO QtO -3 CO CO rf^ CO C7| O CJt Gi CJ ~3 CO 5000000 oooopo p p p p p p p p p p p p o DOOOOOO OOOOOO OOOOOO OOOOOO ® D O O P- 'I— 'I— ' »— l MHMMHl-i Ml— i I— 'I— i l-i I— » MMMMMbOW ., O CO CD O O O O I— i I— i LO tO tO CO M^OimoO -q. rf^M^OlOTOCi ^soooooto ootowt^ci p £• 3> ~C| O CO tf^ " |_i LO LO tO tO LO LO tO LO IO LO CO C5tOHjS"° hj ^OlOlOffiOiS <)QOOOOO©CO O O H to LO CO CO r^ Ol Q S CO P _ << £S S^tO^Ol© CO ©HOHOW50 ^tO^OQM Q H H tO W tO ^1 ^ ^ o P] p p p p o o p p p p p o o p p p p p o o p p p p p S T3 QO SO s& <& m r —J ^ CD I— « I— ' L\J i>~> CO UJK^K^utCJlcrs 05 N W ^ O M C f» h-^ (DOWffiCOHOl OOWSHOlO UlOOMStO «<| 00 00 CO Ql Ol P r* M 3 o o o o p p p oooopo p o o p p p p p O O O O P bbbbbbb o b b b o o bbbbbb o b b b b b co £. to CO CO CO CO CO CO CO to CO LO to lo to to to to to to to to CO OO CO CO m <=T OOHMHMtO tO CO CO CO ^ h^ Cl Ol Oi O S CO 00 CD O P- 1 CO CO £> go co co rf^ cji co rf^. go co 01 co co go ri^ co p^ co en o whiowwi^ wi ooooooo pop poo op op op op poop h> 'g c^ '<=> ' a> oboobo ' 'q 'cz> '<=> '<^> h> 'o g> 'o cd '<=> o d±. to CO CO CO CO co to to to to to CO CO to to to to CO LO CO OO CO CO OO 00 no tO tO tO tO CO CO CO p^ hP- hP- CJT C7I C5 QSNCOOOO CO O I— ' tO CO tfx HtOOlCOOCOS HW©WSCO - b b boo o b o boo o b b b b "o bbbbbb^, hn O CO CO CO CO CO CO LO tO LO LO CO CO tO tO OO CO CO CO CO CO CO CO CO ^ c-h Wifi^rfi^cnoi Oioo-o-aao co co co o o h-» h to w ^ en a k^ hj • WH^OKIHOI OlfSHOlO Ul P-» C5 P- 1 - h C5 W00WO5COSCO Oi 00 CJ» 00 GO CO HS?O^OlH O^ P CD 298 ELECTRICAL TABLES AND DATA © d rH o r- iwrHto^^rHOoocoiococoost^ocDcooo o 2<£>rHooooo S o o* ©' o © © o' © o o* o" © o' o' ©' o" o" o" © © o" ©' © ©* S CD *"2 =.pC3 i— I b- CM 00 rH r- I 05t>l0«OC0 CO rH CM O CO t» CO rH CO CM © © "*H "SO , CO CM CM rH rH r- I OOOOOC5 0050500000 CO CO CO OO 00 l> rHPjrHrHi— Ii— IrHrHrH HrtHr I i— I O OOOOOO OOOOOO- WrH [n ©M CN, ©©©©0© OOOOOO OOOOOO © © © O © © < Q ^Q^i>. ©'©'©'©"©'©" oo'ooo'o oooooo ©©'©©'©©< to 'To 9 H £ i>» ® rj © O ri c! S^OIOOOO CD rH CM © b- m f0O00l>10C0 (MOOJOONCOl Sb> S O HHHOOOl O5O5O5COCOG0 OO CO l> t- t- l> b- b~ CD CD CD CO < n r , rt 43.rtlNHHHHHO OOOOOO OOOOOO OOOOOO' g 2 oo'ooo'o oo'ooo'o o'oo'o'o'o o'o'ooo'oc c$ Ph Z* ■+* ST m o n cxi i> in cohooco^cnj © t- 10 rH cm © cistow^coc NI> CD CO CD CD CO lO lO 10 « Ifl H tH ^ ^ ^h ^ ,^ ^ c w cooooooo oooooo oooooo OOOOOOC _ OOOOOO o. o o O O O O O © © o o # © © © © © © c o © ©' o* o' o" o" o' o* o o' © ©' ©'©'©'©'©'©* o' o" o" o" ©* ©' c ^ !>. CO CO rH 05 t- CD CO rH t- CD r}4 CO Oi C3 UOlO-rHrtiCOCO COCOCO CM CI CXI CM rH oi ^?o ooooc> o>ooooo OO B rt o o o o o o oooooo o > o Ph o'oo'oooo'ooo'o'oo'o a S _ ^j ^ _^ CD O CMOCOCOOO«I .S CJ,* CDCO CMOO rttCOrHC^OOCxjCOCMr-iHHeOCOOOOt^THr fe m S^HCOCOOCXllO rH rH CM lO O CD CMOCOl^om rHCOCOCMCMCMC S uISmHCQOCOCO© LO -H CO CM CM rH i-Ht-hOOOO CD000C50C 2 -H m O W CO Cl H o q o o o < O O O oooooo o o o o o o C ^ ^ *TO h> o* o" o o" o" o o o o o o o o o' o o' o" o o o o' o" O O* C -HHCMOOOCDkO ^CONHOO OOOOOO OOOOOOC SPh\ m f CI O »J » « 'T w t,\i nu U C3C^O<0 OOOOOOC V* rH rH rH OC500000000000C e» OOOOOOOOOOOOC ^^ ( — > < — i ( — i <— > <— > ( — l i — ii — ii — i (~i r— l £ OOOOO OOOOOOC • OOIOO OOOIOOOC CM CO CO rH IOCONNCOCSC ELECTRICAL TABLES AND DATA TABLE CXI Power and Eeactive Factors for Different Angles of Lag or Lead o3 l-e ©02 > 00 o3 l-e ©02 ci l-e ©02 > 03 *H © © a £*5 o3 o 2 © © rt o3 © Jh © © rt 03 © 2 s- O O © o3 2 u O O © oj i? ^H © o © oj P o PhQ tfft P O PhO , Mfe P o PhQ Mfr 1 .999 .017 31 .857 .515 61 .485 .875 2 .999 .035 32 .848 .530 62 .469 .883 3 .998 .052 33 .839 .545 63 .454 .891 4 .997 .070 34 .829 .559 64 .438 .899 5 .996 .087 35 .819 .574 65 .423 .906 6 .994 .105 36 .809 .588 66 .407 .914 7 .992 .122 37 .798 .602 67 .391 .921 8 .990 .139 38 .788 .616 68 .375 .927 9 .988 .156 39 .777 .629 69 .358 .934 10 .985 .174 40 .766 .643 70 .342 .940 11 .982 .191 41 .755 .656 71 .326 .946 12 .978 .208 42 .743 .669 72 .309 .951 13 .974 .225 43 .731 .682 73 .292 .956 14 .970 .242 44 .719 .695 74 .276 .961 15 .966 .259 45 .707 .707 75 .259 .966 16 .961 .276 46 .695 .719 76 .242 .970 17 .956 .292 47 .682 .731 77 .225 .974 18 .951 .309 48 .669 .743 78 .208 .978 19 .946 .326 49 .656 .755 79 .191 .982 20 .940 .342 50 .643 .767 80 .174 .985 21 .934 .358 51 .629 .777 81 .156 .988 22 .927 .375 52 .616 .788 82 .139 .990 23 .920 .391 53 .602 .799 83 .122 .992 24 .914 ,407 54 .588 .809 84 .105 .994 25 .906 .423 55 .574 .819 85 .087 .996 26 .899 .438 56 .560 .829 86 .070 .997 27 .891 .454 57 .545 .839 87 .052 .998 28 .883 .470 58 .530 .848 88 .035 .999 29- .875 .485 59 .515 .857 89 .017 .999 30 .866 .500 60 .500 ,866 SOO ELECTRICAL TABLES AND DATA ; W N H r}l ft O M tO Ol (M CO OHCXlTf*«Oft * CO ■*' N H O N CO ® M ft O ^r^COO^S J w ^ N " W CO © rH CO TtJ b- co o © lH CXI co # H jj4 co CO* rH rH © O N ■* CO W 05 OrflCCtDOO w ■ O ft CO CO HH CO O^CONtDO fl fc Tj< ^ ^ ^ "^ ^ ."S ^ coM'2" 003 "" 11-1 ^ OOOOOO Ot-HHCOOOW •CQ « * o i— i oi ^ io o o-dHftcococo % _, OHIM^tDO COOOrHCXjTtl d " O " • m I 3 " 1 ft! b~ CO ft CO ft tj ON-^COCKl OOOOlOrH C3 PH'sMHHd & O CM rH 0O OJ rH O lO O O Ol LO TO ^t»Ci3HrlO Qj ^ gg ^ ^ ^ CXI © rH CX] CXI T* *" EH S * * * 'rH (M ^rj O +■> C? o co co cxi co oajtowato "S 0>. O 05 l> O H W O LO O rH O b- * ~£^ftC000 .2 00 -J -OCOaftOrHCXICOlO 3 M^ 3 ^ -£ •••rH'r4«rH " h O si i-^. ,* n. »r> co ^ r^ r"^ <"=><=> ° ° *J? © -h cxi tH rH co a>° ^ ^ ^ "^ ^ ^ *^P ooj^cooo Pococm^coio r "* t- CO CX) rH lOCXJTjHGOCOO CO O H CXI M W bJO W OWOO OUOOOCMCO £ £< ot-oocoo oococococo CD V n 2 -^ CXI lO rH CO lO t- O i— I C] CO >o ft E'd" © ifj oq oq cxi .2 ' 'rtrioi ^ <1 hL,T ~ l q ot-'+i oftcooom i -1 oOMNSrjH O 19 CO N O (M O O0CONHHCO CO O rH CM TtH CO ^ ' '*<** ^ G fe" "^ "^ "^ °*"! ^ & O © CO CO Q rH ■£ JH © O ft t- Tt< r}i r* > • 3 OrHCXJ-HHlOO O N lO H © H J*. ^^ CS ^ rH Cxi ^' CO O "2J °. ""I M . "*. ^ <1 be OS "ooooo -MOOOOO 7J rH CXI r* tO O ^r-HCXlTtllOO PrHCXJ^CDO ^HN^tOO ELECTRICAL TABLES AND DATA 301 *£.COC0b0tN3tOMl-»l-»l— i hHO «H,m>3<| otoo^^to^oitoocooo^oocoi--if u af ^ 2 >° » 2. OClOOiOOlOloaiOOOOWOOlOlOOl u 4 o £ B ^ £ r— 1m o^Sp^^S* cooiouiKKitooaiKiotoai^ciWKitoys ^^J° m^® ooooocnmatoooxooooooaio , .crs r^ 5 r»^S'"J'+ r 1 b w tr^gs «p Ut rf^ CO CO tO wpy ^.sp O^ 01 o o ui o en . ^ a> ^so^^o 1 ooooooo K 3 o . r+:TH3P!» w k» w b w b m 's b mmi-» g^™ <%!'£ b q oj h b b w w bi w '^ b m to ^ ^S^ H tJ2- rf^ CO O OS l_i B' ^^ZfD^ra 00 00■ m _ « w w b b b co b b t b bo '^ b b w b h b co <-+■ » p a> g p ° p 2. t? -qosososmm^tf^cocototoh-'i-ii-i 3 Kw'g J oS J B°3 G p ^q rf^ o ^ co oo to ~q h p to oo jm-i s jf>. w _M q P b | p o ^ (W cL ~£ ^ o ©CIHS^M^I^WM M 1 ^ OS ~ B & « *m co h-i \o b\ co co *«© !■£- bo bs rf^ bs ox bo to co m to to £ ° p o S 3 p ™ GOrf-COGO £ ^ «£ %3 £--S % „, ^ to bs m to bs m bs m m H^ ^ "to to bs b b h b ^ M . k^ b- <■ £.« 5 ° tf- CO CO OO a^O B P ** ££ a> £ c+ O pj t^.|^rfi.Hfi.|^.COCOCOCOtOtOtO!— 'I— 'I— » B B! £ W ® 2 "< Pi 'i ln-' s^/ r- '^-^ — tO tO tO QO ~3 3 o t^.rf^^hfi.h^.cocococotototoi— 'i— 'i— » a 1 ^ b p ^ w to w p p co o s w o a ^ m s rf^ co m co o a P r- co "to I— ' o o o - m. © crq £,® c ^ ^(^rfiCOO:COWOOtOtOtOMHI-'M B Bp MMOfflOOS pi tO OOWpp*.MS^WM ^ l "U o & g bo bs b> co bs "to m ^ bo ^q bs 'co '-q o bx to \o U co Q° 9 b 2- 3 2 OMtOOO ^B 1 ^ 3 t-S CD C . B 2 CO l4^rf^COCOCOCOCOCOtOtOtOI->t-'l-'l-' H 5^ a, 3- £ 5* HOppsp^MOpfOpp WMS^MM ffl ^ (^ _ ^ B: W 3 I-i to m*. t. b b b b b b b s b b '^ m b h b o ^ a ■ m^^ " oomgd & b§ • p o § ® 2 ^B g rfi-COCOCOCOCOCOCOtOtOtOI— il— i (— i I— ' r^!=m B^B^ o p co p s p p W M OO Ol to © ffi CO H -d ((»■ CO P — P — r* o co m co tfi. b> 'co to bi '-q ^ b\ b\ bo rf^ h-» bo i-i 5o ^ vq ®° u-%% o" o©mco o* 1 Pa aift B 302 ELECTRICAL TABLES AND DATA c',5 2 *§ **3^ N OCO-OSS CM CM 00 rtf rH rH CM O rH CD r-j N W OS H £ =2 ft -~ i2 ^ Hm'tj!|> CM* id 00 CO OS* lO CM* O OO* id CO* l>" rH rt" iH c „ o £ o O 5rim m "^ OO O O CM ° j-j N M 00 ■* h W tH ■* OS Q l> O] 00 Tt| r)i c 2} 3 cH y r* ^ h fo w" i> oi in oo' co" os id cm* o oo' co" rt* ci co* i>* co ** -fi 2o £ HHHWWm^lOWCONNOOOOO s > 3 n ©2 ^ ,2 imC _ £ £ OOOOCO oo^ >> « £ oo 05ooqt>NM05inq^ffi»inwN^C5 £ G to ^ 4 rHi— lrHCMC\IC0''#ininCDt^0000OSOS 1 l&S "o rfS OOrHOrH •0 fi w ^ 2 -w •' -l -C ^ ^ CO O fc- CM CO O 50CON(NSOHW?oq CO l>; . ^h~ ~'&'S CO T-iccfioiyri co' th* © ©' os' co" os' tj* th" p ^ » ® Oaj h C HHHNWfO-*intDNI>Q000050 o £ a ^ -g b r-j -- 1 th cj m q i> co co h s w h h p s « in oo © q a „> — *5 — >- ^ fl N hco wVoiio'oico'dtDTji co" cxi cxi cm' t>* rf* o l>" 2 ^^c (» >> CD .2 HHHGSKMCO^in©NOOCOOOO ^ , cg^s : H'«'§ rHrH 5> d c c *3 a O eS 2 °* °5 ® •> ^ ^ ^ °° °. «*ft '"I *> *q W °°. °o »q eo tH ft tj £ £ s? f^*™ 1 rH co" id t>° cm* id os' co' o* cd id hh* id h* os' id ■*' cxi co •* co h "t © co q ?0 rH oo % in os in os Ph" tuo v «S o ^ nn f- c3 rH* CO* id l>* CM id OS* rt* ©' t>" CD CD OO* CM* id Tf" rt* id o 1-3 C^i«2m „° 13 rH rH rH CM CO CO T* in CO 00 OS © rH CM CO w z%<>«>*%2« § HHHH -d S-*.*o2 >?- £ M COHCX1H H *3 d o 2 ° S m m 5 n q co q m ^ w q co oo h in h n q co h h » io w +j -m *• g •" u S o rH co' id t>* oa* id os' -*' o oo' t>* oo' tH «d t** Tt* t>-' oo' oi cC«,-u03— HHHIMCOCOxlllOt-OOOHIMCOlO •-^SxaJ^gC+a HHHHH aJ^^S 14 - O) „ 00 H CO CO « 2" g > * J 2 .fti ^qcoooowt>i>inqi>oqi>oocxi (m § ■ w ® *fe Q rH* CO* id t>* CM* id OS* HH* rH* OS* OS* CM* 00* GO u > H HHHCMCOCO^tONQ O C cu " CM* id OS* tJH O CO* OS rH CO* GO* O GO* CM* id rH 5 « 5 ® DQ Q rH rH rH CM CO CO TjH CD t>- OS rH CO CD CO CO ii:1«il«s Ic'ggiS DO 3 to C .2 !3 C m2 rC-^r/3 ^NOOOClO^CONHOOOOoOOOO - ri > "« H H H OOOOOOOO 3 »*S ffl A • in o in o o ^SQ ^** gv1 m CQCOCO^IO „ o s R S cd Pn m - in o in o o %** %2 %z o - + J « , .;<2' M S* J ^ O be . omooooooinooLominooooo (i;t;ii^ot3^. n CACqo]MIOt>OOOlO(MIOOMN(MIOOIOOO ^S?®* 1 o °? T 1 rH rH rH CM CM CM CO CO Tfl ^tl m CD 2 hSj a? ■ *3 M . mommoinooooinommo>oomo > S *© <» "ftj HoqHsoNo P P.0KH O Q HH rH rH rH rH CM CM CM CO CO ■* ELECTRICAL TABLES AND DATA 3 COCOCOCOCOI->H->l->l-i HO , d H,rt>w s j ObosM^swooajtoooosaw^tstoM rs t_. tr-^rto r?» ooooooo>_ &> g 3 r+tr» ' 'is;" 00000000 „ . i-* m v-*_ ., 2. tr p u £ 3 3 2 oooooooooi-'tNOCorf^oiooootorf^ ^S-^J Si»^£a>r..n-3 cm ^HOOOHOIWWWMMMM C? £ 2 »' _, 5 P 2 tf». os co os CO W O CO H w p w to JO ~q J^ OJ M M ' £ o 3 -,=• *© co © © *m^ co to bo bx *m bo s "^ co bo b h cd b P ™ g o o 2 2* £ 3 oooooooooooooocncai— 'Oico >-- '-0 p ^ 3 » o„^ 3 3,_,pa. ..... Ci^tOWtflMHMM ,_, Sro •%»:, I I '. . ! J_i J-i bi co m © bo b bo b b h b to tf! £" d 2 s. s 5 o w OTOrf^COO CD H.ct^^jCffl ~£ CP J?o m ^ wpp^^s.^* p>- 2 "^ S " ° ° ©£ W OS OS Ol Ol rf^ ^ CO CO CO CO M M l-> s b b b h to He po-s- « r OlOl^^^^COWtOtOHMM CD ° r5 " "~ c £" tf^ CO © OS CO O OJ O OS CO 00 p" CO © -O ^ CO M l-J 43 O O. ~ 3 & © m bi en m tf^ bs bo rf*. i-» m bo m s 'o b m b io co ^ v* 2 - £ 3 B moo^coco© £^ g «> g l^rfi.rfi.^WOiCOtOtOtOHI-'l-i q\ £ -• o f? & SOUWMOOpWCOaiMS^MCOS^MHM j- hj |> £ ^ ^%~- *^ rf^ b» Jf* bSHb'H^Sffi © OS <5!flM*COlo ^ u S h." p „ -■ cocooscocoo E" cd »> <- <-*■£ & p g » O JO 1 " ^^^WWWWtOCOCOMMM M* P p £ aa - M GO rf^ p^^^p^^WMh" w g rt; p _^ b b bi b ut b s h rfx b If^ '^ co b s b m b to os P*" 1 5" ""' £" ® M 3 osoaicocoo cD(jq g-° ^»g p OO S OJ ^ to o a M p S rf^ M CO <1 rf^ W M H _ ^ to ^° S w 3 o bs "^ © to bs © © bi co bo co bs bi bs © U © to o ^ cd 9 r «' - _. cs o © co co co © g. ^oo ^Pg" o COMWCOWMtOtStOtOHMM n c tf -S d> m 00 S p W M M p p W O S rf^ H p -q (^ W |_i M ^- O 3" 2, ^ 3 ,-. S- bo ffs. co m rf^ © *^ bi b i- 1 h to ai If^ b b h b to to bo » o _- ^ o 5- ELECTRICAL TABLES AND DATA ° £> O® £f CO Ci "-J Oi OS O i; r)J iM O © H t(| o CO N LO 00 CD S ^ ! oi d LO d -^' ® ® w h i> m' oo oi d ^ ^ 'fe ■" 5i 1— lrHC\!C\lC\lCOH^LOLOCDCDb-GO ■2 ojorj 00 ^ ^ LO >o co r>l t! '-S °8 . rt bC r-i r-i « "* l> O «' LO O rjH Cl' d (TO H t>.' CO* C* "d" Cd* O fl • & ™ ^ H H H C] C3 « W "* W LO © O N 00 "£ S Sh m S 5 „ tH LO W O M H .2 CD C cj g ™ COQHGlQOiUDnN 1 * ^ rH rH b- t>- rH LO CXI £ "£ 3 ~ ° ^ rH rH* CO HH l>* O oi LO* O HH ^ "^ "*t* 01 ' CO H* rH* CD H* .Q u 3 ^ H HHHNN(MCQ^lOLOtOI>t>CO 3 > cu ! o Cvf LO* O -f* C3 CD -H CO O* CO CM* CO* t>* £, £ S ^g, f^fl I-irHi-ICslCQC^CO'NH^O'-OCOL—t-OO CO S ^ P " ^ ■3 an, ''.S wh ui miioiosiom > u ° >, °^ dot m . °. H . °i c; q lo t> ^ i; m w co co iq ^ t-j cxj b- 3*^ "2 -<-> ' § rl H f0 ^ Ls! d oi LO* O* -rj" O b- >d Ttf" rH CO* CO* CM* rH ^3. > o """"^ ." HHHWwMW^iniOtOSCOa •2 S3 3 £, tf o3 cS ?h -H LO ^ CO co LO 3 -o -4J cijq co q H . q q q lo n lo co ^ ^ w w q co h t> h ^ 6D g & 1 TH rH CO rJH t^.' * CM LO O* HH <=* b^ CO CO* H* CM rH CO rH f" 1 U -2 3 - .^3 Z, r%- THrHrHCMcqCOCO-HLOCDL-OOOOO M , 3. £ .2 y ""cOO'lcidOOOOCOO'iqN^THOHNN pq 60 o g S ^ w "g H* H w h" l>* d ci 10 d H H " ^ >> OT " t>" *& o* LO* o [j .So in3 5v? ™ © rHrHrHCq^COCO-HLOCOL-OOCTirH j?j "cd d o 2 I g £ i? W Mch'lqQHOOOOKM^^OOMqaHSW m -m -^ -^ w fl H rt W W l> O N LO O I.O ^ °°' C°* °' C?" C5 rH rH O* .SS m x .a "S <2 ° £ W O w q H . q q q h t- q h w oq *^ ^ S =2 ,„ t, 0> • H H W ^' t> O Ol LO* Oi* LO ^ CJi" CD co' C\j CD O-T CO HH* S ^ 3 -2 S " . P HHHCqWCOLOCONOOOH^ irj^gO fl^^ 5) rHrHrH ^•^'Purt 53 "^ ^."S^ rHOqqoO{OLOHCO(MH 00 0000000 a Jl !s« t. ^ S^^ 0000000 ^t:2o-T'^'3a' 000000 „3CBoSi.tJ 2 CvTPQ LO O LO O O ^UQ° M gjSg .S Q^ CMCOCOHHLO ^O J 5 „ £ 60 S "^ScJ^^-^^S rS ^ M SHLOcMffib-O-rhiOCOWOlHCOrtlCOCOOTH ®.2-- ( -2 +j ^h -r^.^r^ Hcqcq^i 0col ^ COOClJ cococoi>Qcoi'-oJo £33§" O^^-rlO rHrH<-lrHCN]CXlCxlCOCOHHLO fH PHr-C-^fe CD P . .« frlS. 3 2 CS .Cqt-^C^oqCDC^L^COH^^^^CJiGXIrHCXlCOCO & a cd <£ S, OD5 hhNw^^locoixjoOw^coocolooco [> mcd Crf ?j oooooooooo • S £3 c £? ooooooooooo *- a *- i '- 1 r/5 ^ 3 £ 2. ° OOOOooooooooMtocotf^.tnOiooofco^r-' g Boa Mp cm 3 OOOOOOOOOOOOOOOOOOh- 'K-iCOht -oooooooooh-ii— 'i— 'torocorf^or^ii— noooo K)K)tOMUWOl030M^OOWOSS©OlQOOMO OM0l00W?0ON^CDCD00SC50:b0CnO«i53WO o "o o o o o o o 00000000000000 K ~ S> 2, 2 E £ oooooooooooooooooooooo 1 ^ OOOOOOOOOOOOOOOOOOOOOO^ OOOOOOOOOOOOOOOOMMtOOOUiOcD M ~ 3 a OOOOOOOMHtOMW^OlNtBMlJltaasS jB ^pi2o? o:^^^^olOis^D^3'<^t^tXlO(OlQOOtoMWOoQo £5 *■* » B 3 OOOOOOOOOOOOOOOOOOOOOO co K ,^li OOOOOOOOOOOOOOOOOOOOOO o-i g B"<< » P IBOOOlOOOHaSOOlOlOOOlOOSSOlOUlO 02 3 ~ o-'O c»2rc£- OOOOOOOOOOOOOOOOOOOOOO d*. OOOOOOOOOOOOOOOOOOOOOO.. OOOOOOOOOOOOOOOOOOOOOO- i" OOOOOOOOOOOOOOMHHtSCOOHOOl £> OSOOCMWCil'OMCDOtOCOQOWQSOOHOOOOO £ OlOlHWOtOOltStSa^OlSHOOMHOOOOMS w O O O "O O O O O O O O b> O O O O © © O © © © [.,; OOOOOOOOOOOOOOOOOOOOOO w< 00>0>OOOOOOOOOOOOOOOOOt-»l-' t o OMHHMHIOtO^OlGOOOtOQOffiWtOlf'WM fi3 fLS-B^P QOOOM^^U5«Dl- l tOMWC T lWaCOK)MK)0000 "-i £ B 2 BI © o © o o o © © o o © © oooooooooo ^, g* 3* rt 3 3 OOOOOOOOOOOOOOOOOOOOOO. ° m ^ OOOOOOOOOOOOOOOOOOOOI— 'tO^ C >1 w JL £ C>OOOOOOOOOOOI— » K-> I— ' K) tO W OlO Ol U CD en CO 05 — A- OMMMPHK)WfrUlSOM^COWOO)OOW ffi H IO W O © *. CO O CO OJ OJ S O 1^ tO W O W <1 0O 1^ H P' So £ n- 0" SHMffiWOlGOOlOl^OIOOtOCTWStOaOlffl » ■-£•£. rt- *§,»*<> OOOOOOOOOOOOOOOOOOOOOO oo ^ 2 ~. OtOWOlSHClOlOWCOM■ GMMHQtOMOOOlOiaODOOTOCHOIOiWPMO <» £ 3 B B-^'F^ OOOOOOOOOOOOOOOOOOOOOO CO << ^ ~- m OOOOOOOOOOOOOOOOOOOOOO,. . 2 ^ ©OOOOOOOOOOOOOOOOOOI— 'h^tO^ S3ffi"- OOOOOOOOOOOH- > I— 'HtOtOCO^OiO^Kl ^ b 2 MMMWHtOtOWOiQOOOWCHQCObSSSOM P m £ P to Ht010ffiOOtOiCOSCO-s ~ 3 n> Mi»©os^w!fl^woi©* rH rH CO* id cm* a" CO CO o id o* o HNNCO^hhio?DI>0-*H rH iH CXI OOOOOOOOOOOOO co cd cxi co" h* ©' cd od 06 rH o" o o* o" OOOOOOOOOOOOO »- id ©' uo ©° >d o" 10 o* id ow'od __ -©LO £ ft HH ° 05 . M 2 ■£ R 1 OOOOOOOOOOOOO M n^ 2 k> '* od cxj cd ©' rH go cm' co o o o" ©" k> fl . Ph ""I "H CKI CXI CM CO CO rH CO GO Cd a fi M o Q n r« H «H 'C •>» w ooooooooooooo t3 5 *n » M © ffi N W DO H il s o' w d d PQ j. ^® CU rH rH rH CM CnJ CXI CO rH CO Ci ^~ l 2 grj cu> ^ * lo q in o w o in q o o in o q 6X1 cxj id i>* o* cxI id t-' ©' cxi id t-' o id rHiHi-irHCX|CXlCXlCOlOt>. OOOOOOOOOOOOO P« rt cxi rJH co' CO* ©' CXI rH CO od o" o o o _ rHrHrHrHrHCXICOrHCO 2»h ^inqinqinqiqqiqqinqq so S? rH th co* rH* co t>* © © cxi cd id cxi ©' id _rO rH rH TH rH CXI CO rH II rt fl © © © © o © © © © O © o © E"* k^ *"• tH* oi CO rH »d co' t> co' oi o" id o* © £» rH rH * ©' id rrj -4 r-4 a „ S OOOOOOOOOOOOO £ ^ OOOOOOOOOOOOO rt • > >HMco^mtoi>ooooinoo O t~< rH rH CXI CO Ph ELECTRICAL TABLES AND DATA TABLE CXX Copper Wire Table Bureau of Standards, Washington, D. C. Working Table, International Standard Annealed Copper American Wire Gauge (B. & S.) Diam Gauge in No. Mils . , Cross Circular Mils Section * Square Inches /—Ohms per 25° C (=77° F) 1000 Feet-^ 65° C (=149° F) Pounds per 1000 Feet 0000 460. 212 000. 0.166 0.0500 0.0577 641. 000 410. 168 000. .132 .0630 .0727 508. 00 365. 133 000. .105 .0795 .0917 403. 325. 106 000. .0829 .100 .116 319. 1 289. 83 700. .0657 .126 .146 253. 2 258. 66 400. .0521 .159 .184 201. 3 229. 52 600. .0413 .201 .232 159. 4 204. 41 700. .0328 .253 .292 126. 5 182. 33 100. .0260 .319 .369 100. 6 162. 26 300. .0206 .403 .465 79.5 7 144. 20 800. .0164 .508 .586 63.0 8 128. 16 500. .0130 .641 .739 50.0 9 114. 13 100. .0103 .808 .932 39.6 10 102. 10 400. .008 15 1.02 1.18 31.4 11 91. 8230. .006 47 1.28 1.48 24.9 12 81. 6530. .005 13 1.62 1.87 19.8 13 72. 5180. .004 07 2.04 2.36 15.7 14 64. 4110. .003 23 2.58 2.97 12.4 15 57. 3260. .002 56 3.25 3.75 9.86 16 51. 2580. .002 03 4.09 4.73 7.82 17 45. 2050. .001 61 5.16 5.96 6.20 18 40. 1620. .001 28 6.51 7.51 4.92 19 36. 1290. .00101 8.21 9.48 3.90 20 32. 1020. .000 802 10.4 11.9 3.09 21 28.5 810. .000 636 13.1 15.1 2.45 ELECTRICAL TABLES AND DATA TABLE CXX— Continued Diam. , Cross Section , r- Ohms per 1000 Feet-^ Pounds luge in Circular Square 25° C 65° C per «Io. Mils Mils Inches (=77° F) (=149° F) 1000 Feet 22 25.3 642. .000 505 16.5 19.0 1.94 23 22.6 509. .000 400 20.S 24.0 1.54 24 20.1 404. .000 317 26.2 30.2 1.22 25 17.9 320. .000 252 33.0 38.1 0.970 26 15.9 254. .000 200 41.6 48.0 .769 27 14.2 202. .000 158 52.5 . 60.6 .610 28 12.6 160. .000 126 66.2 76.4 .484 29 11.3 127. .000 099 5 83.4 96.3 .384 30 10.0 101. .000 078 9 105. 121. .304 31 8.9 79.7 .000 062 6 133. 153. .241 32 8.0 63.2 .000 049 6 167. 193. .191 33 7.1 50.1 .000 039 4 211. 243. .152 34 6.3 39.8 .000 031 2 266*. 307. .120 35 5.6 31.5 .000 024 8 335. 387. .0954 36 5.0 25.0 .000 019 6 423. 488. .0757 37 4.5 19.8 .000 015 6 533. 616. .0600 38 4.0 15.7 .000 012 3 673. 776. .0476 39 3.5 12.5 .000 009 8 848. 979. .0377 40 3.1 9.9 .000 007 8 1070. 1230. .0299 Note. 1. — The table is based on the international standard of resistance for copper, which takes the fundamental mass resistivity = 0.15328 ohm (meter, gram) at 20° C, the corre- sponding temperature coefficient = 0.00393 at 20° C, and the density = 8.89 grams per cc at 20° C. The temperature coefficient is proportional to the conductivity, whence the change of mass resistivity per degree C is a constant, 0.000597 ohm (meter, gram). Note 2. — The values given in the table are only for an- nealed copper of the standard resistivity. The user of the table must apply the proper correction for copper of any other resistivity. Hard-drawn copper may be taken as about 2.7 per cent higher resistivity than annealed copper. Note 3. — Ohms per mile, or pounds per mile, may be ob- tained by multiplying the respective values above by 5.28. Note 4. — For complete tables and other data see Circular No. 31 of the Bureau of Standards. Bureau of Standards, Washington, D. C, 1914 ELECTRICAL TABLES AND DATA ^1 CO CO © © © © © o o o o o o o © o o o o CD o o o CO Ol o © o o CD Cl O o o o © o to o o w o o M o o Ol o o OS o o o o o o o o o o © o o o o o © o o o o o o o o © o o o o o o O 5] CD ' b o © © © o o o o o o o © © © II to° O M o CD o o o o o © © © to to O CD CO CO -1 ^1 © OS Ol Ol en Q -q o rf*. CO CO CD CO ^1 M ^1 CO CO © CO 3°; o CD M CD o © CD tf^ M CD CO © 1 tri © ? 8 CD P Pi © o © © © O © © © *o © ■© ©> © £§§ H h-» CD o o o o © © © a>" rf*> CO CO to o CD 00 CO -J © © © CO °w © CO I— 1 M ** (4- Ol CO CO ^1 CO CD Cl to t" 1 CO CD o CO bo to oi to o p ^ Hi ^ to to to CO CO co ^ M^ ^ hfk Ol Ol at © o ^ W © ~l CD o M- ^1 o CO © CD to Ol CO ©ts g P Q 10 CO CO CD o 10 CO M CI © -i CO , p o o O o o o o o o o © © © ©> pj c^ © © © © bd P jn © H g" g ^ ■ • QD ^ ^ K a | g- >4 . , . - ,-i.stc b^-r 00 M rfx CO CD p> CO ^ 00 tO Ol O JO Ol g m! g £ Q © bi bo © cd bo oi © tf^ to s "h w bi ^ o r" g - § M M tO O M M » IO M H M U U b^r, i — l lJ^ rv-t fo lL^ p^ ili*. rv-i r\^ era <— * t *\ rn pai ,_? H M M M M-pUO © © CD CO lO 10 IO tO LO © I— 'MMM^^1^^1~a© M O -< a}" MM M l-» M . MMMMP^MSr* ocooooooooooooo ^s^pffl © CD tO ^ W S M OT CO S O W Cj CO 5 S P 13 Q © rf^ to bo *m to to © ^ bo bo DO o bo g-'S 3 £2 )-l \-l \-l \-l y-L \-l i-L \-l \-i h-L h-l h-i >-i h-i Z'UW 2. ©©Ml— iMtOWW^^OiDlOlffl*- c O atDWClHO)MOJM050^«5Wg£J w^^wo^oiciwo^ooomP-3- o © ©> i— i m to to co co rf^ rfx ai oi Oi os ^.rt-v. " ,-, ©©tOOl©©M©MCl©MOCO^££" Q tO CO CO tO © CO C71 ■*- tO © R* CO CD M C P o ELECTRICAL TABLES AND DATA ™ E 9 T-HOLOOCOlOlOCOOi(Mi-ICOCOT-IOr^(rO«OCO o PnflOaOJOJOOOOMt«S»©IOIOT|tTllMW«N ^(■■-ooooswiM^inaosHOCMO^fflri© 5p£ c O c « £ § co o" t>." ^* r-i t-.* o irj i-i 10 o Tt? 10 b-* o eo t-' ci cq ~ Cut. 1— IrHrHr-lT-li-tr-lrHr- IHHHSNSSNOOl >7 P ■sShHOO^OMIO^NOOHoWWOMCCNNO ^i«i^COffitO(M(»CONIMSHSMO)tO c * S t ~ *°. . *"! ^ °^ ^ °^ °°. °. °°' °. •*? w . °. ^ "5 "* "* *> 5 u£«s£ I aj .Q d) M § "* O* b-" CO ffi IO ffi O rH l> O M lO rfi M \. . -OJOHHOOJOOOOOOOSOfflCO o 5 £ OOOO»-0OOOOOCD~lTHCMCCI Z P «*"*■ ""V B m ft ~ p CO 2- B N H • I CD t. C+- O CO yjf e+ 4 I -1 hg Hs B CT5 p OOl ' poo ^ft^-BftawB . * O |^CDCDO MC -ihHQocD J?" ^^ct-ceM-CDCDCD^B rf^ CO o to OS ox CO 3°i ^1 ox rf^ CO CO ox CO ~3 ^1 CO OX co CO OS CO l"3 > F ox OS oo o CO Q 1^ CO CO is 3 o "co o M ^ XT CO i ^1 -^ -^ ^1 ^J o o B rf^ ox os OS <1 a B* Pi oo $» M 00 ^ O O hi bx to bo CO o 3 P-> g'Jo 5 £ P' p ^ ^ CD g ^ OS ^ jfx p CO gg 2 a P^^^ 5, O K)£ fj> O CD B? ° 2- Qffl" o u s m a g H OB 05 O ^ §3 S-^ c ^- 1^3 H ^ CD 5- S OJ ft ffi ftS 5 ^^ g. «3. g b" m ^ m to CO ' ft ET. CD ^ It 5^S- f^OSOOOCO S 2 *t S' o ft ft ft cd ,s a » w jf. ELECTRICAL TABLES AND DATA TABLE CXXII Aluminum Company of America Stranded Aluminum Wire Diameter and Properties Conductivity at 62 in the Matthiessen Standard Scale Number B. & S. Circular Gauge Mils. DIAMETERS WEIGHT IN POUNDS Triple Braid Resistance Decimal Nearest BARE Insulated in Ohms. Parts 32nd Per Per at 70° F of an of an 1000 Per 1000 per Inch. Inch. Feet. Mile. Feet. 1000 Ft . 1000000 1.152 1A 920. 4858. 1406. .016726 950000 1.125 li 874. \ 4617. 1337. .017606 900000 1.092 1A 828. 4374. 1268. .018585 850000 1.062 ift 782. 4131. 1199. .019679 800000 1.035 1A 736. 3888. 1129. .020907 750000 .996 l 690. 3645. 1060. .022301 700000 963 U 644. 3402. 990. .023894 650000 .928 IS 598. 3159. 921. .025734 600000 .891 M 552. 2916. 852. .027878 550000 .854 11 506. 2673. 782. .030411 500000 .814 \l 460. 2430. 713. .033450 450000 .772 M 414. 2187. 644. .037170 400000 .725 If 368. 1944. 575. .041818 350000 .679 tt 322. 1701. 506. .047789 300000 .621 f 276. 1458. 436. .055755 250000 .567 A 230. 12.15 366. .066905 000( ) 211600 .522 U 195. 1028. 313. .079045 00( ) 167805 .464 U 155. 816. 253. .099675 oc 133079 .414 II 123. 647. 204. .12569 ( ) 105534 .368 i 97. 513. 165. .15849 ] I 83694 .328 u 77. 407. 135. .19984 i 5 66373 .291 A 61. 323. 112. .25200 I I 52634 .261 i 48.5 256. 93.5 .31779 4 [ 41742 .231 & 38.5 203. 76.5 .40069 i > 33102 .206 3i 30.2 161. 56.0 .50530 ( 5 26250 .180 & 24.1 128. 47.0 .63720 ELECTRICAL TABLES AND DATA TABLE CXXIII Aluminum Company of America Weight of Aluminum, Wrought Iron, Steel, Copper and Brass Wire. Diameters determined by American (Brown & Sharpe) Gauge. Water at 62° Fahrenheit, 62.355 lbs. per cubic foot. Drawn Wrought Steel " Copper " Brass Iron is 2.8724 times heavier than Drawn Aluminum. " 2.9322 " " 3.3321 " " 3.1900 " No. Size of of each Gauge No. Inch Weight of Wire per Ft. per lb. Alumi- Alumi- Wro't num num Iron Steel Feet Lbs. Lbs. Lbs. L000 Lineal Feet Copper Brass Lbs. Lbs. 3000 .46000 . 5.185 192.86 553.97 565.50 642.68 615.21 000 .40964 6.539 152.94 439.33 448.45 509.32 487.92 00 .36480 8.246 121.28 348.40 355.65 404.20 386.94 .32486 10.396 96.18 276.30 282.02 320.50 306.83 1 .28930 13.108 76.29 219.11 223.68 254.20 243.35 2 .25763 16.529 60.50 173.78 177.38 201.60 192.98: 3 .22942 20.846 47.97 137.80 140.67 159.86 153.02 4 .20431 26.281 38.05 109.28 111.57 126.78 121.37 5 .18194 33.146 30.17 86.68 88.46 100.54 96.26 6 .16202 41.789 23.93 68.73 70.15 79.72 76.32 7 .14428 52.687 18.98 54.43 55.56 63.23 60.53- 8 .12849 66.445 15.05 43.23 44.12 50.14 48.00 9 .11443 83.822 11.93 34.28 34.99 39.77 38.07 10 .10189 105.68 9.462 27.18 27.74 31.53 30.181 11 .090742 133.24 7.505 21.56 22.01 25.01 23.94 12 .080808 168.01 5.952 17.10 17.46 19.83 18.99 13 .071961 211.86 4,720 13.56 13.84 15.73 15.06 14 .064084 267.17 3.74 3 10.75 10.98 12.47 11.94 318 ELECTRICAL TABLES AND DATA Size of No. each of No. Gauge Inch Ft. per lb. Alumi- num Feet r-Weight of Wire per 1000 Lineal Feet-^ Alumi- Wro't num Iron Steel Copper Brass Lbs. Lbs. Lbs. Lbs. LbSi. 15 .057068 336.93 2.968 8.526 8.704 9.890 9.468 16 .050820 424.81 2.354 6.761 6.903 7.843 7.508 17 .045257 535.62 1.867 5.362 5.474 6.220 5.955 18 .040303 675.67 1.480 4.252 4.342 4.933 4.723 19 .035890 851.79 1.174 3.372 3.443 3.912 3.755 20 .031961 1074.11 .9310 2.672 2.730 3.102 2.970 21 .028462 1356. .7382 2.121 2.165 2.460 2.355 22 .025347 1707.94 .5855 1.682 1.717 1.951 1.868 23 .022571 2153.78 .4643 1.333 1.361 .547 1.481 24 .020100 2715.91 .3682 1.058 1.080 1.227 1.175 25 .017900 3424.66 .2920 .8388 .8563 .9731 .9316 26 .015940 4317.78 .2316 .6652 .6791 .7716 .7387 27 .014195 5446.63 .1836 .5276 .5385 .6120 .5858 28 .012641 6868.13 .1456 .4183 .4270 .4853 .4645 29 .011257 8657.5 .1155 .3317 .3386 .3849 .3683 30 .010025 10917.0 .0916 .2631 .2686 .3052 .2922 31 .008928 13762.8 .0727 .2087 .2130 .2421 .2318 32 .007950 17361.1 .0576 .1655 .1693 .1919 .1837 33 .007080 21886.7 .0457 .1312 .1340 .1522 .1457 34 .006304 27622. .0362 .1040 .1062 .1207 .1155 35 .005614 34807.3 .0287 .0825 .0842 .0957 .0916^ 36 .005000 43878.9 .0228 .0655 .0668 .0759 .0727 37 .004453 55245. .0181 .0519 .0530 .0602 .0577 38 .003965 69783.7 .0143 .0413 .0420 .0478 .0457 39 .003531 88028.2 .0114 .0326 .0333 .0379 .0363 40 .003144 110980. .0090 .0259 .0264 .0300 .0287 Specific gravity Wire... 2.680 7.698 7.858 8.930 8.549 Wt., per cu. ft., Wire. . 167.111 480.000 490.000 556.830 533.073 ELECTRICAL TABLES AND DATA Cn tf* CO tO M O o e m to to QO O tO tO tf*. © tO tO CO CO rfx rfi. en oo to cs i— ' os co © en en o o ol i__i l_i i_i to sr£ r co ►£>. en OS no o CO © co to OS CO © CO uo to M ■ o © © o o © 3 to CO ^ en © OO CO OS OS to to en K> en to ffi *» © CO CO -^ © M« p (73 B C71 tf*. CO tO tO M ■ M • M &,* erg - M © tO tf*. oo co en o os a u m to CO o oo o *> »*i M ^ pf M M © tj W CO CO ^ © -q © tO en CO §«g org © CO CO M OS ^1 to ^ en 8p ^ ri^» tf^ © © © (D CO ■ o O o a en © en © ^ p to to to co © w »q o oo © to M to © en ^ en to to -a © © M to CO CO rfs» as ~-a © to © ** © © © NO CO no ^ en en © © to © ro © o © © © © © © © © © > ELECTRICAL TABLES AND DATA £ . m # W >l>. © O O O O © O* *# Tl? T}J rH ri CM* © id id ©" U ^ CM b- S H OO 00 O ri CilOOl © t» » 0) lO (M O) b- CD ri M M N ri ri H o b- rfl 1-4 CO O b- CO CI CO ^ !D N ^ CO lO CO Cd rri m o CO CO o co o CS to o CO o CO CO to OS M Ol CO to to o oi o to CO -3 HI w t" 1 -3 •Oltf*.COtOtOI-'l-iM U CO Ol 00 rf^tOCO OS M OS W O 00 O) Oi ^ S rN O CO l-i OCOCO CO CO CO rfi.05^ S W M § o M rf* b M M ©^ V <1 2- Q 5«| b b bob bob bob m m m to to w ^c Ol— ' (-» l-» fcO M W ft* Ol > CO W CO CS OS OOCOtO S S Cfl lf>. W H rt ■t-» Ol Ol tO O O Ol M M W(^ o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o b o o o to o o CO o o o o CO w fcs" o o Ol o o CO o CO o to o CO CO o Ol CO o CO Ol CO OS to M CS CO CO Ol o CO OS CO CO CO co CO Ol Ol CO to t>0 tf^ rf^ to CO ^1 rf^ £ M to to CO ^ Ol ~q CO M rf^ CO to CO CO Ol CO CO Ol -3 to OS CO CO .Ol CO CO CO CO CO -^ 3 ELECTRICAL TABLES AND DATA bSTHM^oitoaswootfiiaaoiooHT)* p, oq co ■* 10 co oq q co t> r-j t- Ttj co tp ci t>- o g> ft r-J r-i r-I H t> ■* CO "* OJ ! * * r-i r-H rA C\l" J W § ft OCOCOOOSCONNCOOCOCOO ^ !i7 $ u O © >^ CSH^OOMOOCOIONNNCOCO t- -tf O £ '-'.£?

(D _i ,_; ,_j oq (jg* co" tH id «o oo" o co" co" o »o" co o" r-i HHHOQtMCO^lO aOOCDOOtONOS&t-OOOSCiCO^^CO QH00WWTtiost^ i X'-^cococai-i UCX)©10^M«NHHH ?nfenH < ^ > '^ ,00 '^ :, OOOOOOOlOOOOOO -a^ooiooooooootooo-om-- ih00O0CH0(M00rHCM0500«0l0^M £ OO OCOCDlOT^rfrlCOCOCMr-Hr-lr-l y ^ ©oooooooooooooooooo ftSCS^NW^COWCMHCOCDHCOcOOCjOCO ftKHl>m(MO00?DW-*C0(MNHHH .-> ° CM IM H H H H P.H dfs* OOOOOOOOOOOOOOIOOOIO omfiwoooooocgoxooiiiooio OT-tTjHOOTtiO<©COr-tOSl>- © « CO .fl- CCS*; , © O I** •£ ft'O'S * ' O 3 w © ; u HWN t}( © OS 00 CO N N O M J OO CO "?H lO CO OS O CD 00* OS co" CO* 00* id r-J rH co lO •9, „, Ht>^(MOOCOW^©CMHCOtOOtOCOOOOCO (J ,2 fl«©H©C0O00C010^C0NCNHHH «S ° COOQWHHH ^©V (DCLSTiCiOlOOOlOOOHOailO^THtMSNH kftd^OSt-t-THOOCOCOOSOSO^OSlOCOOSt^CD *> Ar-? H^05lO(M0Jt'50Tj(C0MNrtHH OUCONHHH o go OOOOHNCO^WOt-OOOOHNCO^ — °« O O O r-lr-li-li-lr-t ELECTRICAL TABLES AND DATA 323 MM M OOO^S tfw tO O © 00 04 C* ^ 00 MMO © O © ^N t> *' B ^j M M M tO M W 1^ Ol O Q O p jo oo oo p to ^.cn to^oiosi^-^o^-'oo p,^ CD Cd ^ t-« O H a y Pj 5u . O ft 0 <59/ 64 3%^ X «%4 5 27/ 64 30/ 64 32/ 64 35/ 64 185 % X 5%4 32/ 64 X 5% 4 6 26/ 64 29/ 64 27/ 64 30/ 64 150 2 %4 X 54/ 64 30/ 64 X 56/ 64 8 23 /k 26/ 64 24/ 64 . 27/ 64 100 27/ 64 < X 4% 4 28/ 64 X 52/ 64 10 2 %4 25/ 64 22/ 64 24/ 64 7 5 2 %4 X 4% 4 2^ X 4%^ 12 20/ 64 23/ 64 21/ 64 24/ 64 60 24/ 64X 43/ 64 2$fe X 4fo 14 1%4 2 %4 2 %4 2 %4 45 23/ 64 X41/ 64 23/ 64 X 41/ 64 Weights given are thought to be average weights; duplex wires weigh nearly double the amounts given. ELECTRICAL TABLES AND DATA TABLE CXXXI Approximate Weight and Diameters of Rubber Covered Lead Encased Cables Single Conductor to 600 Volts Duplex Conductor Wt. per Wt. per B. &S. Diameter 1000 ft. Diameter 1000 ft. 0000 5% 4 1600 5% 4 x H%4 2900 000 5i^ 4 1400 5% 4 x 9% 4 2600 00 49/ 64 1250 47/ 64 x 9% 4 2300 45/ 64 1100 44/ 64 X 78/ 64 2000 1 38/ 64 900 39/ 64 X 68/ 64 1700 2 34/ 64 750 38/ 64 x 6% 4 1400 4 29/ fi4 500 3% 4 x 56/ 64 1100 6 26/ fi4 400 28/ 64 x so/ 64 800 8 22/ fi4 300 2 %4 x 4 %4 600 10 2i/ 64 275 2i/ 64 x 3% 4 500 12 i% 4 175 i% 4 X sy 64 350 14 l%4 150 %X 3% 4 300 ELECTRICAL TABLES AND DATA TABLE CXXXII 329 8ths. leths. 32nds. 64ths. Mils. 8ths. 16ths. 32nds. 64ths. Mils. 1 2 3 4 5 6 7 8 9 10 11 12 .. 13 15.6 31.2 46.9 62.5 78.1 93.7 109.3 125. 140.6 156.2 171.8 187.5 203.1 218.7 234.3 250. 265.6 281.2 296.8 312.5 328.1 343.7 359.3 375. 390.6 406.2 421.8 437.5 453.1 468.7 484.3 500. 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 515.6 1 17 531.2 546.8 l 2 9 18 562.5 578.1 3 19 593 7 609.3 1 2 4 5 10 20 625. 640.6 5 21 656.2 671.8 3 6 11 22 687.5 703.1 7 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 23 718.7 734.3 2 4 8 6 12 24 750. 765.5 9 25 781.2 796.8 5 13 26 812.5 828.1 ..11.. 27 843.7 859.3 3 6 12 7 14 28 875. 890 6 ..13.. 29 906.2 921 8 7 15 30 937.5 953.1 ..15.. 31 968.7 9S4.3 4 8 16 8 16 32 1000. CARRYING CAPACITIES OF WIRES FOR SHORT PERI- ODS AND INTERMITTENT LOADS. The following tables of carrying capacities were prepared by the use of formulae deduced by the authors from heating curves of a large number of conductors experimentally determined in the labora- tories of the Commonwealth Edison Co. of Chicago. The tests were made at the suggestion of the Depart- ment of Gas and Electricity of the City of Chicago and in some of these tests the engineers of the above company were assisted by engineers of the city de- partment. A full description of these tests was given in the Electrical "World during 191$. The data used in compiling the figures given were obtainable only in the form of "curves." It is well known that such curves are to a large extent an inter- polation of values, and it is therefore quite unlikely that many of the values given would produce exactly the temperature assigned to them if subject to a test. A study of the curves showed that in a general way the temperature rise in any given conductor was pro- portional to the square of the current used, but there were also some exceptions, due probably to errors of observation and interpolation as well as to a variety of causes. In order to eliminate these errors as much as pos- sible, and at the same time provide a simple means of 330 ELECTRICAL. TABLES AND DATA 331 interpolation to determine the carrying capacity of such wires as were not tested, the amperage necessary to bring each size of wire to a certain temperature was first computed. After this had been done, the circu- lar mils of the conductor were divided by the amper- age found, thus giving the circular mils per ampere. The circular mils per ampere of all the conductors tested were then plotted vertically, while the copper contents were laid out horizontally, and the whole combined in the form of a curve in the well known way. The. final carrying capacity was then deter- mined by dividing the circular mils in the conductor by the circular mils per ampere indicated by the curve. It is believed that, in this manner, fairly ac- curate average values have been obtained. The current which will cause a given temperature rise in a conductor can be found by the following; formula : I=xi JT~ in which T is the desired temperature ; t the tempera- ture attained in the conductor by the current i and I is the current to be found. This formula does not take into account the fact that the resistance of the conductor increases with the temperature, as this is considered negligible for all practical purposes. The values of t and i are given in the tables for rubber covered wires. Those conductors, in connection with which no temperature rises are given, were not tested,. but the current values given were obtained by interpo- lation as before explained. The tables applying to conduits also give the di- mensions of the conduits used in the tests. Under the heading, "N. E. Code," we give the amperage 332 ELECTRICAL TABLES AND DATA allowed by the code. Under the heading, ' ' Calculated Carrying Capacities," we give those calculated as described above. These values must not be used in conflict with the official figures given by the code, as they are not yet sanctioned) thereby. The amper- ages given under, ' ' Short Time in Minutes, ' ' are those which it is believed the various conductors can safely carry for the length of time given, provided no appre- ciable heating has been caused before this load is ap- plied. Four tables are given. Two of them are calculated for a temperature rise of 72 degrees Fahrenheit, and the other for 36 degrees Fahrenheit. They are also arranged for open and concealed wires, the latter in conduit. The three wires run in conduit were all carrying the same current and the heating effect there obtained will be exceeded only in cases where the four wires of a two-phase system are run in the same pipe. With the ordinary three-wire lighting system, the heating will be considerably less. The temperature of rubber covered wire should not exceed 120 degrees F. but that covered with other insulations may rise to 150 degrees, and asbestos cov- ered wires may be carried to higher temperatures than this. The following tables are intended to assist in the selection of the smallest conductor that may be used to carry an intermittent load. The ultimate tempera- ture rise of a conductor subject to an intermittent load depends upon the ratio between the "on" and "off" time of the current. Unless the current is off long enough to allow the loss of the heat accumulated -during the "on" time, the temperature will rise. At low temperatures the dissipation of heat pro- ELECTRICAL TABLES AND DATA 333 ceeds slowly, but at higher temperatures it is much more rapid. For this reason, the relative time in which a given quantity of heat can be dissipated varies greatly with the temperature permitted. A separate table is provided for each size of wire considered; in conduit as well as for open wiring. Each table is divided into two parts. In the left hand portion of the tables is given the time in seconds re- quired for the currents given at the top, under the heading, "Heating Load; Amperes," to raise the tem- perature of the wire 5 degrees F. within the range of temperature given under the heading, "Temperature Range," in conduit or open wires as the case may be. Thus, referring to the table for No. 14 wire in con- duit, we see that a current of 25 amperes will produce a rise of 5 degrees, between the range of 47 and 52, in 220 seconds, but also that it will require 1,350 seconds to effect a temperature rise from 67 to 72 in the same conductor by the same 1 current. In this connection we need not pay any attention to the lower temperatures, as we are interested only as the critical temperatures are approached. If an intermittent load is continued long enough, there will be a steady rise in temperature until the point is reached at which the dissipation of heat equals the supply. Therefore, if we allow sufficient cooling time, we can keep the temperature within bounds. In the right hand portion of the tables we give the time in seconds required to dissipate the heat gen- erated during the time given in the same horizontal lines. Thus, again referring to the table for No. 14 wire, we see that with a temperature range of 22-27 degrees, the heat produced in 110 seconds requires 300 seconds 334 ELECTRICAL TABLES AND DATA to cool off, while if we allow the temperature to go to 57-62, that generated in 400 seconds will be lost in 40 seconds. Cooling times are given with zero load as well as with continued loads of the amperages given. The temperature of rubber covered wire should not be allowed to rise above 120 degrees Fahrenheit, and that of ' ' Other Insulations ' ' should not go above 150 degrees F. Asbestos covered wires, however, may be allowed to run much hotter. In order to facilitate the selection of the proper conductor there is provided a column "Limiting Outer Temperature." A sepa- rate column is provided for rubber covered and other insulation covered wires. The figures there given in- dicate that, in locations where the temperature of the air does not rise above the values given, the tempera- ture of the conductor may be allowed to rise to the value of the highest figure given in the same horizontal line under the heading "Temperature Range,' ' either in conduit or open wires. The simplest method of using the tables consists of first determining the limiting outer temperature. Next find the peak number of amperes and the length of time in seconds during which this amperage is used. Then proceed to find the minimum amperage and the length of time during which it is in use. Make notes of these values and always estimate them with a view to obtaining the hardest operating condi- tions likely to occur. Now proceed to find the small- est wire under which the amperage in question is given and, selecting the horizontal line in which the limiting temperature is found, see whether the ratio of the on and off times corresponding to the temperature given is the same as that in the problem. ELECTRICAL, TABLES AND DATA 335 Example: "We have a peak load of 80 amperes which lasts for 60 seconds and is then reduced to 25 amperes for 200 seconds ; this being the estimated regular cycle of operation of the circuit. Wires are in conduit. The smallest wire under which an amperage of 80 or more is found is a No. 8. Here we find, in the horizontal line pertaining to 83 degrees P., that 105 amperes will cause a temperature rise of 5 degrees in 21 seconds and that this heat, even with only ITV^ amperes in continued use, requires 285 seconds for its dissipation. This will not do, and we proceed to the next size of wire. Here we find, in the correspond- ing horizonal line, that 80 amperes will require 100 seconds to raise the temperature of the wire 5 degrees, and that this heat will be lost in 300 seconds, even with 25 amperes in continued use. Furthermore, as the cooling time is three times as long in this case, while in our problem it was three and one-third times as long, the wire thus found will not heat quite as much as indicated and will therefore be safe to use. 336 ELECTRICAL, TABLES AND DATA Table CXXXII Wires in Conduit Table of Carrying Capacities; three conductors in conduit, each carrying same current. 20° C; 36° F. temperature rise above surrounding air. Use this table for rubber covered wires in conduit where temperature of air does not exceed 85° F., and for other insulations at temperatures from 85° F. to 125° F. Size N. E. CODE Calculated Carrying Capacities 36° F. rise B. & S. $** la 1 sajrmtin ui eon} Jaoqs gauge. :onduit S-cl |*1 30 15 10 5 14 y 2 " 15 27.0 17 19 22 24 30 12 %" 20 31.0 22 24 26 29 35 10 %" 25 27.9 27 30 35 40 45 8 i " 35 29.9 36 43 50 60 65 6 i " 50 33.1 52 60 73 80 105 5 55 56 69 88 100 125 4 ivi" 70 4*0.7 64 77 97 110 140 3 1V4" 80 34.9 82 93 113 135 165 2 iy 2 " 90 34.7 90 106 130 155 195 1 iy 2 " 100 39.1 96 126 154 180 225 2 " 125 41.2 110 147 182 210 275 2/0 2 " 150 41.8 130 179 220 260 340 3/0 2 " 175 39.4 150 213 270 320 420 200000 200 175 247 310 355 480 4/0 2y 2 ; ' 225 57.6 180 256 325 395 515 250000 240 205 297 375 455 585 300000 3* ' " 275 45.2 238 345 435 535 690 350000 300 265 395 500 605 790 400000 %'"" 325 4*2*1 290 440 555 690 850 500000 3 " 400 48.1 345 529 660 800 1090 600000 450 390 610 750 915 1225 700000 500 430 680 830 1025 1400 750000 4 "'' 525 44.8 450 710 870 1080 1450 800000 550 465 745 905 1120 1525 900000 600 495 810 975 1210 1665 1000000 4V 2 ' ; 650 55.2 525 870 1040 1295 1800 ELECTRICAL. TABLES AND DATA 337 Table CXXXIII Wires in Conduit Table of Carrying Capacities; three conductors in conduit, each carrying same current. 40° C; 72° F. temperature rise above surrounding air. Use this table for "Other insulations" in conduit where temperature does not exceed 80° F., and for rubber covered wire where temperature of air does not exceed 50° F. Size N. E. CODE Calculated Carrying Capacities 72° F. rise B. &S. « ^ to gauge. conduit '3 °? £ is a Short time in minutes 30 15 10 5 14 w 15 27.0 24 26 31 34 42 12 %" 20 31.0 30 33 37 41 50 10 %" 25 27.9 38 43 50 55 65 8 1 " 35 29.9 50 60 70 85 95 6 1 " 50 33.1 70 86 105 115 150 5 55 80 95 125 140 , isa 4 ivi" 70 40*7 90 110 140 155 200 3 VA." 80 34.9 110 130 150 190 235 2 iy 2 " 90 34.7 125 150 175 220 275 1 1%" 100 39.1 135 175 215 250 31& 2 " 125 41.2 140 205 255 290 385 2/0 2 " 150 41.8 185 245 310 360 440 3/0 2 " 175 39.4 215 300 380 430 565 200000 200 240 350 430 520 675 4/0 2W f 225 57.6 250 360 455 550 720 250000 240 280 420 525 640 820 300000 3 '" 275 45.2 335 485 610 750 965 350000 300 375 560 700 845 1105 40000C z"» 325 42.1 415 630 775 965 1190 500000 3 " 400 48.1 480 750 925 1130 1520 600000 450 545 860 1050 1280 1700 700000 500 600 950 1160 1435 1960 750000 4"// 525 44.8 630 1020 1220 1510 2030 800000 550 660 1050 1260 1560 2135 900000 600 700 1140 1365 1690 2330 1000000 W 650 55.2 1 740 1215 1460 1840 2520 338 ELECTRICAL TABLES AND DATA Table CXXXIV Open Wires Table of Carrying Capacities; open wires. 20° C; 36° F. temperature rise above surrounding air. Use this table for rubber covered wires where tempera- ture does not exceed 85° F., and for "Other insulations" where temperature is between 85° F. and 125° F. N. E. CODE Calculated Carrying Capacities 36 F. rise B& S. £58 1 14 £ 2 1 Short time in minutes gauge I'll III •05*^ oo* a 30 15 10 5 14 20 21.6 25 25 29 33 37 12 25 19.1 31 31 39 42 47 10 30 18.0 41 41 47 53 60 8 50 27.9 52 52 60 66 75 6 70 29.5 67 67 80 87 95 5 80 80 80 90 100 112 4 90 32.6 90 90 105 120 137 3 100 26.1 100 100 125 145 168 2 125 30.6 120 120 150 175 210 1 150 32.4 140 145 180 220 265 200 40.0 160 165 215 260 330 2/0 225 41.2 186 210 250 310 380 3/0 275 45.7 215 250 300 380 465 200000 300 240 290 345 440 535 4/0 325 56.6 250 300 360 450 560 250000 350 285 335 410 520 660 300000 400 38.6 325 400 475 620 765 350000 450 360 450 545 700 895 400000 500 4*7^6 400 500 600 790 1020 500000 600 51.4 480 600 730 950 1220 600000 680 560 690 860 1110 1565 700000 760 625 775 970 1260 1785 750000 800 57.6 650 800 1025 1340 1910 800000 840 680 850 1090 1400 2040 900000 920 730 930 1190 1550 2300 1000000 1000 54.6 775 1000 1285 1665 2500 ELECTRICAL TABLES AND DATA 332 Table CXXXV Open Wires Table of Carrying Capacities; open wires. 40° C; 72° F. temperature rise above surrounding air. Use this table for "Other insulations" where temperature does not exceed 80° F., and for rubber covered wires where temperature does not exceed 50° F. N. E. CODE Calculated Carrying Capacities 72 ° F. rise B&S. M£3 i> ■So" short time in minutes gauge fll 33« si* a * l.gi 30 15 10 5 14 20 21.6 34 34 40 46 52 12 25 19.1 43 43 54 59 65 10 30 18.0 57 57 67 74 83 8 50 27.9 72 72 84 92 103 6 70 29.5 94 94 109 122 134 5 80 110 110 127 141 157 4 90 32.0 125 125 145 165 190 3 100 26.1 145 i45 175 202 234 2 125 30.6 168 170 205 245 295 1 150 32.4 195 205 250 309 372 200 40.0 225 235 300 360 460 2/0 225 41.2 260 290 350 430 530 3/0 275 45.7 300 345 410 520 645 200000 300 335 400 480 610 750 4/0 325 56.0 350 410 500 630 785 250000 350 400 470 575 730 9<>5 300000 400 38.0 450 550 660 860 1070 350000 450 500 630 760 980 1250 400000 500 47.0 560 700 840 1100 1425 500000 600 51.4 670 840 1025 1330 1785 600000 680 780 965 1200 1550 2190 700000 760 870 1080 1370 1760 2500 750000 800 57.6 910 1110 1435 1860 2675 800000 840 950 1190 1525 1960 2855 900000 920 1020 1300 1665 2150 3215 1000000 1000 54.6 1085 1400 1800 2330 3500 ELECTRICAL TABLES AND DATA Table CXXXVI Wires in Conduit Limiting Outer | Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 14 TV ires in Heating load 15 20 25 2280 250 110 y 2 " Conduit amperes 45 15 Cooling Load; Amperes 7% 300 180 118 88 27-32 300 120 15 210 130 113 83 32-37 450 160 15 195 100 108 78 37-42 660 180 15 125 80 103 73 42-47 1560 210 15 95 70 98 68 47-52 220 15 80 60 93 63 52-57 350 15 60 60 88 58 57-62 400 15 40 40 83 53 62-67 540 15 40 40 78 48 67-72 1350 15 40 40 Limiting Outer Temp. Oth- Rub- er ber Ins: Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 12 "Wires in Heating load 20 25 35 840 200 50 %" Conduit Cooling Load; amperes Amperes 60 10 13 230 200 118 88 27-32 270 50 13 200 150 113 83 32-37 500 60 13 170 100 108 78 37-42 660 80 13 120 100 103 73 42-47 2000 100 13 100 100 98 68 47-52 100 13 100 90 93 63 52-57 120 13 80 80 88 58 57-62 200 13 50 50 83 53 62-67 200 13 50 50 78 48 67-72 220 13 50 50 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 10 Wires in Heating load 25 35 50 1380 210 60 %" Conduit amperes 75 21 Cooling Load; Amperes 12i/ 2 360 270 118 88 27-32 210 60 21 250 225 113 83 32-37 270 65 21 200 150 108 78 37-42 300 70 21 150 130 103 73 42-47 540 75 21 90 115 98 68 47-52 1440 80 21 90 85 93 63 52-57 90 21 90 75 88 58 57-62 120 21 90 75 83 53 62-57 140 21 90 75 83 53 62-67 140 21 90 75 78 48 67-72 160 21 90 75 ELECTRICAL TABLES AND DATA Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 118 88 113 83 108 78 103 73 98 68 93 63 88 58 83 53 78 48 limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 118 88 113 83 108 78 103 73 98 68 93 63 88 58 83 53 78 48 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 118 88 113 83 108 78 103 73 93 63 88 58 83 53 78 48 22-27 27-32 32-37 37-42 42-47 47-52 52-57 57-62 62-67 67-72 Temper- ature Range in Conduit F. 22-27 27-32 32-37 37-42 42-47 47-52 52-57 57-62 62-67 67-72 Temper- ature Range in Conduit F. 22-27 27-32 32-37 37-42 42-47 <±7-52 52-57 57-62 62-67 67-72 Table CXXXVII Wires in Conduit 3 No. 8 Wires in Conduit Heating load; amperes 105 1380 210 240 270 350 540 70 60 60 70 80 90 900 100 1360 105 110 115 120 21 21 21 21 21 21 21 21 21 21 3 No. 6 Wires in Conduit Heating load; amperes 100 150 50 70 80 1000 120 100 1920 180 100 200 100 220 120 300 140 360 160 450 180 630 220 840 240 1260 260 45 19 50 19 60 19 80 19 80 19 90 19 90 19 90 19 90 19 £0 19 Cooling Load; Amperes 17% 510 420 345 290 285 210 240 160 180 120 120 100 100 100 90 90 90 90 90 90 Cooling Load; Amperes 25 600 330 420 240 300 225 220 200 180 120 120 100 100 100 100 100 100 100 100 100 3 No. 4 Wires in Conduit Heating load; amperes 70 80 90 100 140 600 360 240 135 50 900 450 270 150 50 1260 510 300 160 60 2400 630, 390 200 70 1080 480 240 70 600 360 70 950 450 75 1800 510 75 570 75 780 80 Cooling Load; Amperes 210 35 22 720 300 22 480 270 22 480 210 22 320 150 22 220 120 22 180 110 22 150 90 22 130 80 22 130 60 22 130 60 ELECTRICAL TABLES AND DATA Table CX XXV] [II Wires in Conduit Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 3 Wires in Heating load, 80 90 100 780 480 240 1 \i " Conduit amperes 160 240 60 28 Cooling Load; Amperes 40 600 420 118 88 27-32 1500 645 300 60 28 400 300 113 83 32-37 900 400 70 28 330 175 108 78 37-42 1300 570 72 28 300 100 103 73 42-47 780 74 28 250 100 98 68 47-52 76 28 240 100 93 63 52-57 80 28 200 75 88 58 57-62 85 28 150 75 83 53 » 62-67 85 28 150 75 78 48 67-72 85 28 150 75 Limiting Outer Temp. Oth- Rub- er .ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 2 Wires in Heating load 90 125 180 840 240 65 1%" Conduit amperes 270 25 Cooling Load; Amperes 45 660 480 118 88 27-32 1560 260 70 25 450 350 113 83 32-37 320 75 25 345 240 108 78 37-42 360 85 25 270 200 103 73 42-47 570 95 25 165 150 98 68 47-52 720 95 25 155 110 93 63 52-57 1000 95 25 155 110 88 58 57-62 1900 95 25 155 110 83 53 62-67 100 25 155 110 78 48 67-72 100 25 155 100 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 1 Wires in 1%" Conduit Heating load; amperes 100 125 150 200 300 840 310 170 90 29 Cooling Load; Amperes 50 750 480 118 88 27-32 1020 330 180 90 29 580 360 113 83 32-37 1560 420 200 100 29 420 300 108 78 37-42 600 220 100 29 360 270 103 73 42-47 810 240 110 29 270 195 98 68 47-52 1000 270 110 29 220 165 93 63 52-57 1560 390 125 29 180 135 88 58 57-62 450 135 29 150 135 83 53 62-67 480 135 29 150 135 78 48 67-72 720 140 29 150 135 ELECTRICAL, TABLES AND DATA Table CXXXIX WlEES IN DONDUIT Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. Wires in Conduit Heating load; amperes 125 175. 250 375 550 190 85 32 Cooling Load; Amperes 62 y 2 840 525 118 88 27-32 800 210 85 32 600 390 113 83 32-37 1140 230 85 32 480 -300 108 78 37-42 2000 250 85 32 420 225 103 73 42-47 300 85 32 350 200 98 68 47-52 400 95 32 300 190 93 63 52-57 480 115 32 270 180 88 58 57-62 540 135 32 190 140 83 53 62-67 700 135 32 190 140 78 48 67-72 1140 135 32 190 140 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 00 Wires Heating load; 150 225 300 700 180 60 n Conduit amperes 450 31 Cooling Load; Amperes 75 900 500 118 88 27-32 960 190 60 31 720 360 113 83 32-37 1680 210 60 31 570 330 108 78 37-42 4000 220 90 31 435 315 103 73 42-47 230 90 31 360 240 98 68 47-52 250 90 31 250 210 93 63 52-57 265 105 31 195 160 88 58 57-62 285 105 31 160 130 83 53 62-67 315 105 31 160 130 78 48 67-72 400 105 31 160 130 Limiting Outer- Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 000 Wires in Conduit Heating load; amperes 175 262% 350 525 1100 200 100 38 Cooling Load; Amperes 87 V 2 960 540 118 88 27-32 1470 210 100 38 660 480 113 83 32-37 2300 220 100 38 560 450 108 78 37-42 240 110 38 500 350 103 73 42-47 270 110 38 480 310 98 68 47-52 300 110 38 360 270 93 63 52-57 360 120 38 315 180 88 58 57-62 420 135 38 210 120 83 53 62-67 480 135 38 180 120 78 48 67-72 660 135 38 180 120 ELECTRICAL TABLES AND DATA Table CXL Wires in Conduit Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 200,000 C. M. Cables estimated i Heating load; amperes 212 265 318 380 424 636 420 180 135 100 72 29 Cooling Load; Amperes 106 2040 660 118 88 27-32 495 220 135 100 72 29 1320 540 113 83 32^37 600 240 140 100 72 29 780 450 108 78 37-42 780 250 140 100 72 29 570 300 103 73 42-47 1200 270 150 100 72 29 450 300 98 68 47-52 1980 300 150 100 72 29 390 240 93 63 52-57 3300 340 165 100 72 29 270 180 88 58 57-62 380 165 100 72 29 170 150 83 53 62-67 400 240 100 72 29 170 150 78 48 67-72 480 240 100 72 29 170 150 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 Temper- ature Range in Conduit F. 22-27 3 No.400 Cables in Heating load 225 281 337 420 180 135 2y 2 " Conduit Cooling Load; ; amperes Amperes 393 450 675 112y 2 100 72 29 2040 660 118 27-32 495 220 135 100 72 29 1320 540 113 32-37 600 240 140 100 72 29 780 450 108 37-42 780 250 140 100 72 29 570 300 103 42-47 1200 270 150 100 72 29 450 300 98 47-52 1980 300 150 100 72 29 390 240 93 52-57 3300 340 165 100 72 29 270 180 88 57-62 380 165 100 72 29 170 150 83 62-67 400 240 100 72 29 170 150 78 67-72 480 240 100 72 29 170 150 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 S No. 250,000 C. M. Cables estimated Cooling Load; Heating load; amperes Amperes 250 312 375 437 500 750 125 420 180 135 100 72 29 2040 660 118 88 27-32 495 220 135 100 72 29 1320 540 113 83 32-37 600 240 140 100 72 29 780 450 108 78 37-42 780 250 140 100 72 29 570 360 103 73 42-47 1200 270 150 100 72 29 450 300 98 68 47-52 1980 300 150 100 72 29 390 240 93 63 52-57 3300 340 165 100 72 29 270 180 88 58 57-62 380 165 100 72 29 170 150 83 53 62-67 400 240 100 72 29 170 150 78 48 67-72 480 240 100 72 29 170 150 ELECTRICAL TABLES AND DATA Table CXLI Wires in Conduit Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 300,000 C. M. Cables in 3" Conduit Heating load; amperes 275 343 412 550 825 720 360 120 100 33 Cooling Load; Amperes 137 1140 480 118 88 27-32 840 370 150 100 33 690 400 113 83 32-37 1320 400 160 100 33 600 360 108 78 37-42 1980 420 170 100 33 480 260 103 73 42-47 450 180 100 33 360 240 98 68 47-52 540 190 100 33 300 220 93 63 52-57 810 250 100 33 280 180 88 58 57-62 1080 300 100 33 210 150 83 53 62-67 2040 350 100 33 210 150 78 48 67-72 400 100 33 210 150 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit P. 22-27 3 No. 350,000 C. M. Cables in Conduit, estimated Heating load; amperes 300 375 450 600 900 840 370 165 105 40 Cooling Load; Amperes 150 1070 600 118 88 27-32 1000 400 185 105 40 780 485 113 83 32-37 3000 455 200 105 40 660 435 108 78 37-42 480 210 105 40 600 370 103 73 42-47 540 225 105 40 480' 320 98 68 47-52 630 240 105 40 400 260 93 63 52-57 825 315 105 40 315 210 88 58 57-62 1080 350 105 40 300 200 83 53 62-67 1900 415 105 40 250 175 78 48 67-72 470 105 40 220 165 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 400,000 C. M. Cables in 3" Conduit Heating load; amperes 325 406 487 650 975 960 390 210 110 46 Cooling Load;, Amperes 162% 990 720 118 88 27-32 1170 430 225 110 46 870 570 113 83 32-37 1800 510 235 110 46 720 510 108 78 37-42 4000 540 250 110 46 615 480 103 73 42-47 630 265 110 46 600 400 98 68 47-52 720 290 110 46 510 300 93 63 52-57 840 330 110 46 480 270 88 58 57-62 1080 400 110 46 330 250 83 53 62-67 1740 480 110 46 300 200 78 48 67-72 4000 540 110 46 240 180 346 ELECTRICAL. TABLES AND DATA Limiting Outer Temp. Oth- Rub- ber Ins. 123 118 113 108 Ins. 93 88 83 78 103 73 98 68 93 63 88 58 83 53 78 48 Temper- ature Range in Conduit P. 22-27 27-32 32-37 37-42 42-47 47-52 52-57 57-62 62-67 67-72 Table CXLII Wiees in Conduit 3 No. 500,000 C. M. Cables in 3" Conduit C« Heating load; amperes 400 500 600 700 800 1200 1050 360 250 165 122 42 1140 400 270 165 122 42 1440 430 300 175 122 42 1860 480 330 175 122 42 2700 560 360 195 122 42 650 390 195 122 42 750 420 210 122 42 870 450 210 122 42 960 465 225 122 42 1260 480 225 122 42 oling Load; Amperes 200 3500 1080 1620 950 1200 720 900 540 870 450 600 360 500 300 440 240 280 160 200 110 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 118 113 88 83 108 78 103 73 98 68 93 63 88 58 83 53 78 48 Temper- ature Range in Conduit F. 22-27 27-32 32-37 37-42 42-47 47-52 52-57 57-62 62-67 67-72 450 1000 1110 1440 2340 3500 3 No. 600,000 C. M. Cables in Conduit, estimated Heating load; amperes 562 420 450 480 580 660 720 780 1020 1500 675 240 250 260 270 290 320 360 410 420 430 785 900 1350 160 122 42 160 122 42 160 122 42 160 122 42 160 122 42 160 122 42 160 122 42 160 122 42 160 122 42 160 122 42 Cooling Load; Amperes 230 2280 1500 1150 900 750 660 600 510 420 270 o 900 720 600 500 480 420 390 360 300 250 Temp. Oth- Rub- er ber Ins. Ins. 123 93 ature Range in Conduit 22-21 3 No. 700,000 C. M. Cables in Conduit, estimated Cooling Load; Heating load; amperes Amperes 505 630 757 880 1010 1515 253 1000 420 240 160 130 45 2280 900 118 88 27-32 1110 450 250 160 130 45 1500 720 113 83 32-37 1440 480 260 160 130 45 1150 600 108 78 37-42 2340 600 270 160 130 45 900 500 103 73 42-47 3500 660 300 160 130 45 750 480 98 68 47-52 720 340 160 130 45 660 420 93 63 52-57 780 380 160 130 45 600 390 88 58 57-62 1020 420 160 130 45 510 360 83 53 62-67 1500 460 160 130 45 420 300 78 48 67-72 500 160 130 45 270 250 ELECTRICAL. TABLES AND DATA 347 Table CXLIII Wires in Conduit Limiting Outer Temp. Oth- Rub- er" ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 750,000 C. M. Cables in 4" Conduit Heating load; amperes 525 656 787 1050 1575 900 420 230 150 54 Cooling Load; Amperes 262y 2 2280 900 118 88 27-32 1110 450 240 150 54 1500 720 113 83 32-37 1440 480 250 150 54 1150 600 108 78 37-42 2340 570 270 150 54 900 500 103 73 42-47 3500 660 300 150 54 750 460 98 68 47-52 720 340 150 54 660 420 93 63 52-57 780 370 150 54 600 390 88 58 57-62 1020 410 150 54- 510 360 83 53 62-67 1500 450 150 54 420 300 78 48 67-72 500 150 54 270 250 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 800,000 C. M. Cables in Conduit, estimated Heating load; amperes 550 688 825 1100 1650 900 420 230 150 54 Cooling Load; Amperes 275 2280 900 118 88 27-32 1110 450 240 150 54 1500 720 113 83 32-37 1440 480 250 150 54 1150 600 108 78 37-42 2340 570 270 150 54 900 500 103 73 42-47 3500 660 300 150 54 750 460 98 68 47-52 720 340 150 54 660 420 93 63 52-57 780 370 150 54 ,600 390 88 58 57-62 1020 410 150 54 510 360 83 53 62-67 1500 450 150 54 420 300 78 48 67-72 500 150 54 270 250 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 3 No. 900,000 C. M. Cables in Conduit, estimated Heating load; amperes 600 750 900 1200 1800 920 420 250 100 50 Cooling Load; Amperes 300 2500 930 118 88 27-32 1020 465 260 100 50 1560 780 113 83 "32-37 1200 480 270 100 50 1320 720 108 78 37-42 1350 500 280 100 50 1050 660 103 73 42-47 2250 530 290 100 50 870 600 98 68 47-52 550 300 100 50 780 540 93 63 52-57 600 330 100 50 670 485 88 58 57-62 690 345 100 50 600 450 83 53 62-67 960 370 100 50 400 360 78 48 67-72 1400 450 100 50 330 300 348 ELECTRICAL. TABLES AND DATA Table CXLIV Wires in Conduit Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. Temper- ature Range in Conduit F. 3 No 650 . 1,000,000 C. M. Cables in 4 y 2 " Conduit Heating load; amperes 812 975 1300 1950 Cooling Load; Amperes 325 123 93 22-27 930 420 250 100 50 2500 930 118 88 27-32 1020 465 260 100 50 1560 780 113 83 32-37 1200 480 270 100 50 1320 720 108 78 37-42 1350 500 280 100 50 1050 660 103 73 42-47 2250 530 290 100 50 870 600 98 68 47-52 550 300 100 50 780 540 93 63 52-57 600 330 100 50 670 485 88 58 57*62 690 345 100 50 600 450 83 53 62-67 960 385 100 50 400- 360 78 48 67-72 1400 450 100 50 330 300 ELECTRICAL, TABLES AND DATA 349^ Table ( :XL^ Open Wires Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range of Wire F. 22-27 No. 14 D. B. R. C. Heating load 15 20 25 120 Wire in Air amperes 45 21 Cooling Load; Amperes 21 118 88 27-32 390 21 21 113 83 32-37 21 21 108 78 37-42 21 21 103 73 42-47 21 21 98 68 47-52 21 21 93 63 52-57 21 21 88 58 57-62 21 21 83 53 62-67 21 2L 78 48 67-72 21 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range of Wire F. 22-27 No. 12 D. B. R. C. Heating load 20 25 35 120 Wire in Air ; amperes 60 21 Cooling Load; Amperes 24 118 88 27-32 150 21 24 113 83 32-37 660 21 24 108 78 37-42 21 24 103 73 42-47 21 24 98 68 47-52 21 24 93 63 52-57 21 24 88 58 57-62 21 24 83 53 62-67 21 24 78 48 67-72 21 24 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range of Wire F 22-27 No. 10 D. B. R. C. Heating load 25 35 50 1020 80 Wire in Air ; amperes 75 32 Cooling Load; Amperes 21 118 .88 27-32 90 32 21 113 83 32-37 180 32- - 21 108 78 37-42 300 32 21 103 73 42-47 32 21 98 68 47-52 32 21 93 63 52-57 ' 32 21 88 58 57-62 32 21. 83 53 62-67 32 21 78 48 67-72 32 21 ELECTRICAL, TABLES AND DATA Table CXLVI i Open Wires limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range F. 22-27 No, 35 8 D. B. R. C. " Heating load 50 70 960 60 Wire in Air < ; amperes 105 23 Pooling Load; Amperes 40 118 88 27-32 70 23 40 113 83 32-37 85 23 40 108 78 37-42 100 23 40 103 73 42-47 180 23 40 98 68 47-52 1350 23 40 93 63 52-57 23 40 88 58 57-62 23 40 83 53 62-67 23 40 78 48 67-72 23 40 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range F. 22-27 No 50 . 6 D. B. R. C. Heating load; 70 80 420 150 Wire in Air ; amperes 100 21 Cooling Load; Amperes 80 118 88 27-32 240 21 70 .113 83 32-37 650 21 60 108 78 37-42 21 50 103 73 42-47 21 40 98 68 47-52 21 30 93 63 52-57 21 30 88 58 57-62 21 30 83 53 62-67 21 30 78 48 67-72 21 30 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range F. 22-27 No. 70 4 D. B. R. C. Wire in Air Cooling Load; Heating load; amperes Amperes 80 90 100 140 210 420 200 60 17 85 118 88 27-32 2000 250 60 17 80 113 83 32-37 600 60 17 75 108 78 37-42 70 17 70 103 73 42-47 80 17 60 98 68 47-52 90 17 50 93 63 52-57 120 17 40 88 58 57-62 160 17 40 83 53 62-67 240 17 40 78 48 67-72 500 17 40 ELECTRICAL TABLES AND DATA Table CXLVII Open Wires Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range of Wire F. 22-27 No. 3 D. B. R. C. Wire in Air Heating load; amperes 80 90 100 160 240 1800 70 27 Cooling Load; Amperes 90 118 88 27-32 75 27 80 113 83 32-37 80 27 70 108 78 37-42 85 27 60 103 73 42-47 95 27 50 98 68 47-52 120 27 40 93 63 52-57 180 27 40 88 58 57-62 300 27 40 83 53 62-67 2000 27 40 78 48 67-72 27 40 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range of Wire P. 22-27 No. 2 D. B. R. C. Wire in Air Heating load; amperes 90 125 180 270 780 90 32 Cooling Load; Amperes 45 130 100 118 88 27-32 95 32 90 80 113 83 32-37 100 32 80 60 108 78 37-42 120 32 60 40 103 73 42-47 200 32 52 40 98 68 47-£2 330 32 52 40 93 63 52-57 540 32 52 40 88 58 57-62 32 52 40 83 53 62-67 32 52 40 78 48 67-72 32 52 40 Limiting Cuter Temp. ■ Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range of Wire F. 22-27 No. 1 D. B. R. C. Wire in Air Heating load; amperes 100 125 150 200 300 540 120 41 Cooling Load; Amperes 50 150 100 118 88 27-32 1300 150 41 100 70 113 83 32-37 200 41 60 60 108 78 37-42 250 41 60 60 103 73 42-47 350 41 60 60 98 68 47-52 500 41 60 60 93 63 52-57 800 41 60 60 88 58 57-62 41 60 60 83 53 62-67 41 60 60 78 48 67-72 41 60 60 352 ELECTRICAL TABLES AND DATA Table CXLVII1 Open Wires Limiting Outer Temp. Oth- Rub- er ber ins. Ins. 123 93 Temper- ature Range of Wire F. 22-27 No. D. B. R. C. Cable in Air Heating load; amperes 125 175 250 375 2000 100 29 Cooling Load; Amperes 62V Z 190 72 118 88 27-32 105 29 150 72 113 83 32-37 110 29 110 72 108 78 37-42 115 29 100 72 103 73 42-47 120 29 90 72 98 68 47-52 180 29 80 72 93 63 52-57 300 29 72 60 88 58 57-62 500 29 72 60 83 53 62-67 20U0 29 72 60 78 48 67-72 29 72 60 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range of Wire F. 22-27 No. 00 D. B. R. C. Cable in Air Heating load; amperes 150 225 450 675 375 100 38 Cooling Load; Amperes 75 250 160 118 88 27-32 500 100 38 210 140 113 83 32-37 750 100 38 190 120 108 78 37-42 1620 120 38 120 110 103 73 42-47 140 38 70 80 98 68 47-52 160 38 60 60 93 63 52-57 180 38 60 60 88 58 57-62 200 38 60 60 83 53 62-67 230 38 60 60 78 48 67-72 260 38 60 60 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range of Wire F. 22-27 No. 000 D. B. R. C. Heating load; 175 262% 350 390 85 Cable in Air amperes 525 38 Cooling Load; Amperes 87Yz 120 250 118 88 27-32 465 85 38 120 165 113 83 32-37 690 85 38 120 130 108 78 37-42 2000 100 38 100 120 103 73 42-47 125 38 90 110 98 68 47-52 195 38 80 90 93 63 52-57 300 38 80 80 88 58 57-62 405 38 70 70 83 53 62-67 600 38 70 70 78 48 67-72 930 38 70 70 ELECTRICAL. TABLES AND DATA Table CXLIX Open Wires Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range of Wire F. 22-27 No. 210 200,000 C. M. Heating load 315 420 195 75 Wire in Air amperes 630 29 Cooling Load; Amperes 240 118 88 27-32 195 75 29 200 113 83 32-37 195 75 29 135 108 78 37-42 195 75 29 100 103 73 42-47 240 90 29 80 98 68 47-52 300 105 29 80 93 63 52-57 400 130 29 80 88 58 57-62 540 170 29 80 83 53 62-67 1200 200 29 80 78 48 67-72 250 29 80 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range of Wire F. 22-27 No 225 2000 . 0000 C. M. Cable in Air Heating load; amperes 337 450 675 195 75 29 Cooling Load; Amperes 240 118 88 27-32 195 75 29 200 113 83 32-37 195 75 29 135 108 78 37-42 195 75 29 100 103 73 42-47 240 90 29 80 98 68 47-52 300 105 29 80 93 63 52-57 400 130 29 80 88 58 57-62 540 170 29 80 83 53 62-67 1200 200 29 80 78 48 67-72 250 29 80 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range of Wire F. 22-27 No 250 250,000 C. M. Heating load 375 500 200 100 Cable in Air amperes 750 35 Cooling Load; Amperes 150 118 88 27-32 200 100 35 125 113 83 32-37 220 100 35 110 108 78 37-42 250 100 35 90 103 73 42-47 300 120 35 80 98 68 47-52 400 135 35 70 93 63 52-57 500 160 35 60 88 58 57-62 800 200 35 60 83 53 62-67 1500 300 35 60 78 48 67-72 400 55 60 ELECTRICAL. TABLES AND DATA Table CL Open Wires Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 No. 300,000 C. M. Heating load 275 343 412 1020 285 Cable in Air amperes 550 825 125 42 Cooling Load; Amperes 137 240 240 118 88 27-32 4000 480 135 42 210 210 113 83 32-37 750 150 42 150 150 108 78 37-42 2300 160 42 120 120 103 73 42-47 180 42 100 100 98 68 47-52 250 42 90 90 93 63 52-57 275 42 80 80 88 58 57-62 330 42 80 80 83 53 62-67 375 42 80 80 78 48 67-72 600 42 80 80 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 No. 350,000 C. M. Heating load 300 375 450 960 300 Cable in Air amperes 600 900 110 46 Cooling Load; Amperes 150 360 200 118 88 27-32 3000 450 120 46 240 150 113 83 32-37 720 130 46 180 80 108 78 37-42 1200 165 46 150 80 103 73 42-47 185 46 80 80 98 68 47-52 240 46 80 80 93 63 52-57 290 46 80 80 88 58 57-62 340 46 80 80 83 53 62-67 420 46 80 80 78 48 67-72 500 46 80 80 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 No. 400,000 C. M. Heating load 325 408 487 960 300 Cable in Air amperes 650 975 110 46 Cooling Load; Amperes 162 360 200 118 88 27-32 3000 450 120 46 240 150 113 83 32-37 720 130 46 180 80 108 78 37-42 1200 165 46 150 80 103 73 42-47 185 46 80 80 98 68 47-52 240 46 80 80 93 63 52-57 290 46 80 80 88 58 57-62 340 46 80 80 83 53 62-67 420 46 80 80 78 48 67-72 500 46 80 80 ELECTRICAL TABLES AND DATA Table CLI Open Wires Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 No. 500,000 C. M. Heating load 400 500 600 690 345 Cable in Air Cooling Load; amperes Amperes 700 800 1200 190 180 50 480 400 118 88 27-32 1110 480 200 180 50 300 300 113 83 32-37 4000 750 240 180 50 200 250 108 78 37-42 900 270 180 50 125 200 103 73 42-47 1500 300 180 50 84 150 98 68 47-52 360 180 50 84 84 93 63 52-57 540 180 50 84 84 88 58 57-62 750 180 50 84 84 83 53 62-67 180 50 84 84 78 48 67-72 180 50 84 84 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit P. 22-27 No. 600,000 C. M. Heating load 450 560 675 700 360 Cable in Air Cooling Load ; amperes Amperes 786 900 1350 225 200 185 52 480 400 118 88 27-32 1200 500 210 185 52 300 300 J 113 83 32-37 775 250 185 52 200 250 I 108 78 37-42 950 280 185 52 125 200 103 73 42-47 1600 310 185 52 84 150 98 68 47-52 370 185 52 84 84 93 63 52-57 550 185 52 84 84 88 58 57-62 775 185 52 84 84 83 53 62-67 185 52 84 84 78 48 67-72 185 52 84 84 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range in Conduit F. 22-27 No. 700,000 C. M. Heating load 500 625 750 660 270 Cables in Air Cooling Load; ■ amperes Amperes 1000 1500 262 150 53 660 400 118 88 27-32 840 300 160 53 450 300 113 83 32-37 1410 375 170 53 400 250 lOo 78 37-42 500 180 53 270 220 103 73 42-47 625 195 53 220 200 98 68 47-52 775 210 53 200 200 93 63 52-57 1200 240 53 150 150 88 58 57-62 260 53 150 150 83 53 62-67 280 53 150 150 78 48 67-72 300 53 150 150 . 356 ELECTRICALi TABLES AND DATA Table CLI] Open Wires Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range of Wire F. 22-27 No. 750,000 C. M Heating load 525 656 787 660 270 . Cable in Air .; amperes 1050 1575 150 54 Cooling Load; Amperes 262 660 400 118 88 27-32 840 300 160 54 450 300 113 83 32-37 1410 375 170 54 400 250 108 x78 37-42 500 180 54 270 220 103 73 42-47 625 195 54 220 200 98 68 47-52 775 210 54 200 200 93 63 52-57 1200 240 54 150 150 88 58 57-62 260 54 150 150 83 53 62-67 280 54 150 150 78 48 67-72 300 54 150 150 Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. 123 93 Temper- ature Range of Wire F. 22-27 No. 800,000 C. M. Heating load 550 687 825 660 270 Cable in Air ; amperes 1100 1650 150 56 Cooling Load; Amperes 275 660 400 118 88 27-32 840 300 160 56 450 300 113 83 32-37 1410 275 170 56 400 250 108 78 37-42 500 180 56 270 220 103 73 42-47 625 195 56 220 200 98 68 47-52 775 210 56 200 200 93 63 52-57 1200 240 56 150 150 88 58 57-62 260 56 150- 150 83 53 62-67 280 56 150 150 78 48 67-72 300 56 150 150 Limiting Outer Temp. Oth- Rub- er . ber Ins. Ins. 123 93 Temper- ature Range of Wire F. 22-27 No. 900,000 C. M. Heating load 600 750 900 720 330 Cable in Air ; amperes 1200 1800 120 58 Cooling Load; Amperes 300 ' 660 480 118 88 27-32 1035 400 130 58 500 320 113 83 32-37 2400 525 140 58 I 420 275 108 78 37-42 630 150 58 300 200 103 73 42-47 800 160 58 250 175 98 68 47-52 1100 170 58 200 175 93 63 52-57 180 58 175 175 88 58 57-62 200 58 175 175 83 53 62-67 220 58 175 175 78 48 67-72 250 58 175 175 ELECTRICAL TABLES AND DATA \ Table CLIII Open Wires Limiting Outer Temp. Oth- Rub- er ber Ins. Ins. Temper- ature Range in Conduit F. No. l.OOO.OOOC. M Heating load 650 812 975 Cable in Air amperes 1300 1950 Cooling L.oad; Amperes 325 123 93 22-27 720 330 120 58 660 480 118 88 27-32 1035 400 130 58 500 320 113 83 32-37 2400 525 140 58 420 275 108 78 37-42 630 150 58 300 200 103 73 42-47 800 160 58 250 175 98 68 47-52 1100 170 58 200 175 93 63 52-57 180 58 175 175 88 58 57-62 200 58 175 175 83 53 62-67 220 58 175 175 78 48 67-72 250 58 175 175 INDEX TO TABLES PAGE Aluminum and copper wire comparison 8 Are lamp data 10 Armored cable data 11 Belting data 19 to 23 Bus bar data 27 Centigrade and Fahrenheit comparison 32 to 33 Center of distribution data 30 Conduit size recommendations 35 to 37 Conversion, inch to decimals 329 Cutout locations 25 Cutout dimensions | 44 to 47 Electrolysis 57 to 58 . Economy of conductors 309 to 310 Economy of motors . 163 to 164 Elevator H. P. requirements 67 Fusing currents . 80 Fusing transformers '. 77 Fuse wire 78 to 79 Gauges, comparison of 82 to 83 Guying 172 Heating 97 to 100 Illumination' 105 to 114 Insulator dimensions 118 to 121 Lamp renewals 117 Logarithms 126 Machinery, power determination for 160 Magnet calculations 61 to 65 Melting points 131 Meters, maximum demand 140 Motor speeds, a. c 145 Motor wiring tables... 287 to 293 Nails, dimensions of 165 Overhead const, data 170 to 175 Panel board dimensions 178 to 180 Pumping 183 to 185 Reciprocals of numbers 187 to 190 Reflectors 191 358 ELECTBICAL TABLES AND DATA 359 PAGE Ropes 200 to 201 Screw data 205 Sign hanging 208 to 210 Sign letters 207 Sparking distances 215 Switches, dimensions of 224 to 231 Terminals, dimensions of 237 to 238 Transformer distribution 256 Transformer efficiency 258 Trollev losses 260 Ventilation 271 to 274 Wires, aluminum 316 to 321 " calculations 285 to 309 " carrying capacity N. E. C 282 " " " combined 284 " " " underground 265 to 268 «« " " for snort periods 330 to 357 " copper 311 to 315 ' ' copper clad 322 to 323 ' ' German silver 324 ' ' mains and branches 222 ' ' outside dimensions of 326 to 328 ' ' quantity required 218 " reactances and resistances 278, 297 to 299 * ' sag and breaking strain 170 ' * telegraph and telephone 325