T K 
 3?75 
 
 N 6 
 
 1909 
 
 MAIN 
 
 bO 15=! 
 
19O9 
 
 
 
 RATIONAL ELECTRICAL CODE 
 INSTALLATION RULES 
 
 (Except Marine Work) 
 
 lioqal Board of Fire Underwriters 
 
 RL.ECTRIC WIRING 
 
 AND 
 
 ARPA.RA.TUS 
 
 As Recommended by the 
 >ERWRITERS' NATIONAL ELECTRIC ASSOCIATION 
 
SUPPLEMENT. 
 
 For satisfactory work only approved fittings 
 should be used. The Supplement to the National 
 Electrical Code, containing a list of approved elec- 
 trical fittings, is designed to aid wiremen hy show- 
 ing them in advance just what will fce approved 
 by the Underwriters. Fittings not listed should 
 not be used without special approval, which will 
 be freely given on application, if the device is 
 found to be reliable. 
 
 The Supplement will be revised semi-annually. 
 
19O9 
 
 |"NATIONAL ELECTRICAL CODE 
 INSTALLATION RULES 
 
 (Except Marine Work) 
 
 OF THE 
 
 National Board of Fire Underwriter!) 
 
 <i 
 
 FOR 
 
 HLrBCTRIO \VIRIIVG 
 
 AND 
 
 ARRARATUS 
 
 As Recommended by the 
 UNDERWRITERS' NATIONAL ELECTRIC ASSOCIATION 
 
 EDITION OF 1909 
 
C.-H -a 
 
 The National Electrical Code was originally 
 drawn in 1897 as the result of the united efforts 
 of the various Insurance, Electrical, Architectural] 
 and allied interests which through the National! 
 Conference on Standard Electrical Rules, composed 
 of delegates from various National Associations, 
 unanimously voted to recommend it to their 
 respective associations for approval or adoption ; 
 and is here presented by the National Board of 
 Fire Underwriters with the various amendments 
 and additions which have been made since that 
 time by them. 
 
 The following is a list of the Associations com- 
 posing the National Conference on Standard Elec- 
 trical Rules : 
 
 AMERICAN INSTITUTE OF ARCHITECTS. 
 
 AMERICAN INSTITUTE OF ELECTRICAL ENGINEERS. 
 
 AMERICAN SOCIETY OF MECHANICAL ENGINEERS. 
 
 AMERICAN INSTITUTE OF MINING ENGINEERS. 
 
 AMERICAN STREET AND INTERURBAN RAILWAY ASSO- 
 CIATION. 
 
 ASSOCIATED FACTORY MUTUAL FIRE INS. Go's. 
 
 ASSOCIATION OF EDISON ILLUMINATING COMPANIKS. 
 
 INTERNATIONAL ASSOCIATION OF MUNICIPAL ELEC- 
 TRICIANS. 
 
 NATIONAL BOARD OF FIRE UNDERWRITERS. , 
 
 NATIONAL ELECTRIC LIGHT ASSOCIATION. 
 
 NATIONAL ELECTRICAL CONTRACTORS' ASSOCIATION. 
 
 NATIONAL ELECTRICAL INSPECTORS' ASSOCIATION. 
 
 UNDERWRITERS' NATIONAL ELECTRIC ASSOCIATION. 
 
TO CONTRACTORS. 
 
 This volume contains only the installation rules 
 under Classes A, B, C and E, such as are required by 
 tb.e contractor "on the job," and is for general 
 distribution. 
 
 Another volume is issued in a small edition con- 
 taining requirements for the construction of approved 
 devices and materials (Class D), and rules for 
 Marine Wiring (Class F). This second volume will 
 not be furnished for general distribution, as the semi- 
 annual List of Approved Fittings will give tb.e con- 
 tractor all the information as to approved devices 
 which he may need. 
 
 207754 
 
GENERAL PLAN 
 
 GOVERNING THE ARRANGEMENT OF 
 RULES. 
 
 CLASS A. STATIONS AND DYNAMO ROOMS. 
 Includes Central Stations ; Dynamo, Motor and 
 Storage-Battery Rooms; Transformer Sub-sta- 
 tions, etc. Rules 1 to 11. 
 
 CLASS B. OUTSIDE WORK, all systems and 
 voltages. Rules 12 to 13 A . 
 
 CLASS C. INSIDE WORK : 
 
 General Rules, all systems and -voltages. Rules 14 
 
 to 17. 
 
 Constant-Current Systems. Rules 18 to 20. 
 Constant Potential Systems : 
 
 General Rules, all voltages. Rules 21 to 23. 
 
 Low-Potential Systems, 550 volts or less. Rules 24 
 to 34. 
 
 High. Potential Systems, 550 to 3,500 volit. Rules 
 35 to 37. 
 
 Extra High Potential Systems, over 3,500 volts. 
 Rules 38 and 39. 
 
 CLASS D.-FITTINGS, MATERIALS AND DE- 
 TAILS OF CONSTRUCTION, all systems and 
 
 voltages. Rules 40 to 63. 
 
 NOTE. Class D is omitted from tliis pamphlet. 
 CLASS E. MISCELLANEOUS. Rules 64 to 67 
 CLASS F. MARINE WORK. Rules 68 to 83. 
 NOTE. Class F is omitted from this pamphlet. 
 
GENERAL SUGGESTIONS. 
 
 The following as well as the fine print notes in 
 the rules are simply suggestions and explanations 
 and are in no case to be considered by inspection 
 departments as mandatory. 
 
 In all electric work, conductors, however well 
 insulated, should always be treated as bare, to the 
 end that under no conditions, existing or likely to 
 exist, can a ground or short circuit occur, and 
 so that all leakage from conductor to conductor, 
 or between conductor and ground, may be reduced 
 to the minimum. 
 
 In all wiring special attention should be paid to 
 the mechanical execution of the work. Careful 
 and neat running, connecting, soldering, taping of 
 conductors, and securing and attaching of fittings, 
 are specially conducive to security and efficiency, 
 and are strongly advised. 
 
 In laying out an installation, except for constant 
 current systems, every reasonable effort should be 
 made to secure distribution centers located in 
 easily accessible places, at which points the cut- 
 outs and switches controlling the several branch 
 circuits can be grouped for convenience and safety 
 of operation. The load should be divided as evenly 
 as possible among the branches, and all compli- 
 cated and unnecessary wiring avoided. 
 
 The use of wire-ways for rendering concealed 
 wiring permanently accessible is most heartily 
 endorsed and recommended ; and this method of 
 accessible concealed construction is advised for 
 general use. 
 
 Architects are urged, when drawing plans and 
 specifications, to make provision for the channel- 
 ing and pocketing of buildings for electric light or 
 power wires, and also for telephone, district mes- 
 senger and other signaling system wiring. 
 
CLASS A. 
 
 STATIONS AND DYNAMO 
 ROOMS. 
 
 Includes Central Stations, Dynamo, Motor and 
 Storage-Battery Rooms, Transformer 
 
 Sub-stations, Etc. 
 1. Generators. 
 
 a. Must be located in a dry place. 
 
 It is suggested that water-proof covers be provided, 
 which may be used in case of emergency. 
 
 6. Must never be placed in a room where any 
 hazardous process is carried on, nor in places 
 where they would be exposed to inflammable 
 gases or flyings of combustible materials. 
 
 c. Must, when operating at a potential in excess 
 of 550 volts, have their base frames permanently 
 and effectively grounded. 
 
 Must, when operating at a potential of 550 
 volts or less, be thoroughly insulated from the 
 ground wherever feasible. Wooden base frames 
 used for this purpose, and wooden floors which 
 are depended upon for insulation where, for any 
 reason, it is necessary to omit the base frames, 
 must be kept filled to prevent absorption of 
 moisture, and must be kept clean and dry. 
 
 Where frame insulation is impracticable, the 
 Inspection Department having jurisdiction may, 
 in writing, permit its omission, in which case 
 the frame must be permanently and effectively 
 grounded. 
 
 If desired high potential machines may be surrounded 
 by an insulated platform, made of wood, mounted on 
 insulating supports, and so arranged that a man must 
 always stand upon it in order to touch any part of the 
 machine. 
 
CLASS A. STATIONS 
 
 1. Generators Continued, 
 
 d. Constant potential generators, except alter- 
 nating current machines and their exciters, must 
 be protected from excessive current by safety 
 fuses or equivalent devices of approved design. 
 
 For two-wire, direct-current generators, single 
 pole protection will be considered as satisfying the 
 above rule, provided the safety device is located 
 in the lead not connected to the series winding. 
 When supplying three-wire systems, the genera- 
 tors must be so arranged that these protective 
 devices will come in the outside leads. 
 
 For three-wire, direct-current generators, a 
 safety device must be placed in each armature, 
 direct-current lead, or a double pole, double trip 
 circuit breaker in each outside generator lead and 
 corresponding equalizer connection. 
 
 e. Must each be provided with a name-plate, 
 giving the maker's name, the capacity in volts and 
 amperes, and the normal speed in revolutions per 
 minute. 
 
 /. Terminal blocks when used on generators 
 must be made of approved non-combustible, non- 
 absorptive, insulating material, such as slate, 
 marble or porcelain. 
 
 g. The use of soft rubber bushings to protect the 
 lead wires coming through the frames of genera- 
 tors is permitted, except when installed where 
 oils, grease, oily vapors or other substances known 
 to have rapid deleterious effect on rubber, are 
 present in such quantities and in such proximity 
 with motor or dynamo as may cause such bush- 
 ings to be liable to rapid destruction. In such 
 cases hard wood properly filled, or preferably 
 porcelain or micanite bushings must be used. 
 
 2, Conductors, 
 
 From generators to switchboards, rheostats or 
 other instruments, and thence to outside lines : 
 
AND DYNAMO ROOMS. 
 
 2, Conductors Continued. 
 
 a. Must be in plain sight or readily accessible. 
 
 Wires from generator to switchboard may, how- 
 ever, be placed in a run-way in the brick or cement 
 pier on which the generator stands. When protec- 
 tion against moisture is necessary, lead covered 
 cable or iron conduit must be used. 
 
 6. Must have an approved insulating covering 
 as called for by rules in Class "C" for similar 
 work, except that in central stations, on exposed 
 circuits, the wire which is used must have a heavy 
 braided, non-combustible outer covering. 
 
 Bus bars may be made of bare metal. 
 
 Where a number of wires are brought close to- 
 gether, as is generally the case in dynamo rooms, 
 especially about the switchboard, they must be 
 surrounded with a tight, non-combustible outer 
 cover. 
 
 Flame proofing must be stripped back on all 
 cables a sufficient amount to give the necessary 
 insulation distances for the voltage of the circuit 
 on which the cable is used. 
 
 c. Must, where not in a conduit, be kept so 
 rigidly in place that they cannot come in contact. 
 
 d. Must in all other respects be installed with 
 the same precautions as required by rules in Class 
 " C " for wires carrying a current of the same vol- 
 ume and potential. 
 
 e. In wiring switchboards, the ground detector 
 voltmeter, pilot lights and potential transformers 
 must be connected to a circuit of not less than 
 No. 14 B. & S. gage wire that is protected by an 
 approved fuse, this circuit is not to carry over 660 
 watts. 
 
 For the protection of instruments and pilot 
 lights on switchboards, approved N. E. Code 
 Standard Enclosed Fuses are preferred, but 
 approved enclosed fuses of other designs of not 
 over two (2} amperes capacity, may be used. 
 
 over iwo (z 
 
10 GLASS A. STATIONS 
 
 3, Switchboards. 
 
 a. Must be so placed as to reduce to a minimum 
 the danger of communicating fire to adjacent com- 
 bustible material. 
 
 Switchboards must not be built up to the ceil- 
 ing, a space of ,three feet being left, ir possible, 
 between the ceiling and the board. The space 
 back of the board must be kept clear of rubbish 
 and not used for storage purposes. 
 
 b. Must be made of non-combustible material or 
 of hardwood in skeleton form, filled to prevent 
 absorption of moisture. 
 
 If wood is used all wires and all current carry- 
 ing parts of the apparatus on the switchboard 
 must be separated therefrom by non-combus- 
 tible, non-absorptive, insulating material. 
 
 c. Must be accessible from all sides when the 
 connections are on the back, but may be placed 
 against a brick or stone wall when the wiring is 
 entirely on the face. 
 
 If the wiring is on the back, there must be a 
 clear space of at least eighteen inches between the 
 wall and the apparatus on the board, and even if 
 the wiring is entirely on the face, it is much bet- 
 ter to have the board set out from the wall. 
 
 d. Must be kept free from moisture. 
 
 e. On switchboards the distances between bare 
 live parts of opposite polarity must be made as 
 great as practicable, and must not be less than 
 those given for tablet-boards. 
 
 4, Resistance Boxes and Equalizers, 
 
 a. Must be placed on a switchboard, or at a 
 distance of at least one foot from combustible 
 material, or separated therefrom by a slab or 
 panel of non-combustible, non-absorptive, insulat- 
 ing material such as slate, soapstone or marble, 
 somewhat larger than the rheostat, which must 
 be secured in position independently of the rheo- 
 
AND DYNAMO BOOMS. 11 
 
 
 
 4, Resistance Boxes and Equalizers Continued, 
 stat supports. Bolts for supporting the rheostat 
 shall be countersunk at least 1-8 inch below the 
 surface at the back of the slab and filled. For 
 proper mechanical strength, slab should be of a 
 thickness consistent with the size and weight of 
 the rheostat, and in no case to be less than 1-2 inch. 
 If resistance devices are installed in rooms where 
 dust or combustible flyings would be liable to ac- 
 cumulate on them, they must be equipped with a 
 dust-proof face plate. 
 
 b. Where protective resistances are necessary in 
 connection with automatic rheostats, incandescent 
 lamps may be used, provided that they do not 
 carry or control the main current nor constitute 
 the regulating resistance of the device. 
 
 When so used, lamps must be mounted in porce- 
 lain receptacles upon non-combustible supports, 
 and must be so arranged that they cannot have 
 impressed upon them a voltage greater than that 
 for which they are rated. They must in all cases 
 be provided with a name-plate, which shall be 
 permanently attached beside the porcelain recep- 
 tacle or receptacles and stamped with the candle- 
 power and voltage of the lamp or lamps to be 
 used in each receptacle. 
 
 c. Wherever insulated wire is used for connec- 
 tion between resistances and the contact plate of 
 a rheostat, the insulation must be u slow burning. 1 ' 
 For large field rheostats and similar resistances, 
 where the contact plates are not mounted upon 
 them, the connecting wires may be run together 
 in groups so arranged that the maximum differ- 
 ence of potential between any two wires in a group 
 shall not exceed 75 volts. Each group of wires 
 must either be mounted on non-combustible, non- 
 absorptive insulators giving atleast 1-2 inch separa- 
 tion from surface wired over, or, where it is 
 necessary to protect the wires from mechanical 
 injury or moisture, be run in approved lined con- 
 duit or equivalent. 
 
12 CLASS A. STATIONS 
 
 5, Lightning Arresters. 
 
 a. Must be attached to each wire of every over- 
 head circuit connected with the station. 
 
 b. Must be located in readily accessible places 
 away from combustible materials, and as near as 
 practicable to the point where the wires enter the 
 building. 
 
 In all cases, kinks, coils and sharp bends in the 
 wires between the arresters and the outdoor lines 
 must be avoided as far as possible. 
 
 c. Must be connected with a thoroughly good and 
 permanent ground connection by metallic strips or 
 wires having a conductivity not less than that of a 
 No. 6 B. & S. gage copper wire, which must be run 
 as nearly in a straight line as possible from the 
 arresters to the ground connection. 
 
 Ground wires for lightning arresters must not 
 be attached to gas pipes within the buildings nor 
 be run inside of iron pipes. 
 
 d. All choke coils or other attachments, inherent 
 to the lightning protection equipment, shall have 
 an insulation from the ground or other conductors 
 equal at least to the insulation demanded at other 
 points of the circuit in the station. 
 
 6, Care and Attendance, 
 
 a. A competent man must be kept on duty 
 where generators are operating. 
 
 b. Oily waste must be .kept in approved waste 
 cans and removed daily. 
 
 7, Testing of Insulation Resistance. 
 
 a. All circuits except such as are permanently 
 grounded in accordance with No. 13 A must be 
 provided with reliable ground detectors. Detec- 
 tors which indicate continuously and give an 
 instant and permanent indication of a ground are 
 preferable. Ground wires from detectors must 
 not be attached to gas pipes within the building. 
 
AND DYNAMO ROOMS. 13 
 
 7, Testing of Insulation Resistance Continued. 
 
 ft. Where continuously indicating detectors are 
 not feasible, the circuits should be tested at least 
 once per day, and preferably oftener. 
 
 8, Motors, 
 
 When motors operating at a potential in excess of 
 550 volts are to be installed, it is suggested that plans 
 for such installations should be submitted to the In- 
 spection Department having jurisdiction before any 
 work is begun. 
 
 a. Must, when operating at a potential in ex- 
 cess of 550 volts, have no exposed live metal 
 parts, and have their base frames permanently 
 and effectively grounded. 
 
 Motors operating at a potential of 550 volts or 
 less must be thoroughly insulated from the 
 ground wherever feasible. Wooden base frames 
 used for this purpose, and wooden floors, which 
 are depended upon for insulation where, for any 
 reason, it is necessary to omit the base frames, 
 must be kept filled to prevent absorption of moist- 
 ure, and must be kept clean and dry. Where 
 frame insulation is impracticable, the Inspection 
 Department having jurisdiction may, in writing, 
 permit its omission, in which case the frame 
 must be permanently and effectively grounded. 
 
 If desired, high-potential machines may be sur- 
 rounded with an insulated platform made of wood, 
 mounted on insulating supports, and so arranged that a 
 man must stand upon it in order to touch any part of 
 the machine. 
 
 6. Motors operating at a potential of 550 volts 
 or less must be wired with the same precautions 
 as required by rules in Class "C" for wires 
 carrying a current of the same volume. 
 
 Motors operating at a potential between 550 
 and 3,500 volts must be wired with approved 
 multiple conductor, metal sheathed cable in ap- 
 proved unlined metal conduit firmly secured in 
 
14 CLASS A. STATIONS 
 
 8, Motors Continued. 
 
 place. The metal sheath must be permanently 
 and effectively grounded, and the construction 
 and installation of the conduit must conform 
 to rules for interior conduits (see No. 25), except 
 that at outlets approved outlet bushing shall be 
 used. 
 
 The motor leads or branch circuits must be de- 
 signed to carry a current at least 25 per cent 
 greater than that for which the motor is rated. 
 Where the wires under this rule would be over- 
 fused in order to provide for the starting cur- 
 rent, as in the case of many of the alternating 
 current motors, the wires must be of such size as 
 to be properly protected by these larger fuses. 
 
 The insulation of the several conductors for high 
 potential motors, where leaving the metal sheath 
 at outlets, must be thoroughly protected from 
 moisture and mechanical injury. This may be 
 accomplished by means of a pot head or some 
 equivalent method. The conduit must be sub- 
 stantially bonded to the metal casings of all fittings 
 and apparatus connected to the inside high tension 
 circuit. 
 
 Where outside wires directly enter the motor 
 room the Inspection Department having jurisdic- 
 tion may permit the wire for high potential mo- 
 tors to be installed according to the general rules 
 for high potential systems. 
 
 c. Each motor and resistance box must be pro- 
 tected by a cut-out and controlled by a switch 
 (see No. 17 a), said switch plainly indicating 
 whether "on" or "off" (except as provided for 
 electric cranes, see 34 A-c). With motors of one- 
 fourth horse power or less, on circuits where the 
 voltage does not exceed 300, No. 21 d must be 
 complied with, and single pole switches may be 
 used as allowed in No. 22 c. The switch and rhe- 
 ostat must be located within sight of the motor, 
 except in cases where special permission to locate 
 
AND DYNAMO BOOMS. 15 
 
 8, Motors Continued. 
 
 them elsewhere is given, in writing, by the In- 
 spection Department having jurisdiction. 
 
 Where the circuit-breaking device on the motor- 
 starting rheostat disconnects all wires of the cir- 
 cuit, the switch called for in this section may be 
 omitted. 
 
 Overload-release devices on motor-starting rhe- 
 ostats will not be considered to take the place of 
 the cut-out required by this section if they are in- 
 operative during the starting of the motor. 
 
 An automatic circuit-breaker disconnecting all 
 wires of the circuit may, however, serve as both 
 switch and cut-out. 
 
 d. Rheostats must be so installed as to comply 
 with all the requirements of No. 4. Auto starters 
 must comply with requirements of No. 4 c. 
 
 Auto starters, unless equipped with tight cas- 
 ings enclosing all current-carrying parts, in all 
 wet, dusty or linty places, must be enclosed in 
 dust-tight, fireproof cabinets. Where there is any 
 liability of short circuits across their exposed live 
 parts being caused by accidental contacts, a rail- 
 ing must be erected around them. 
 
 e. Must not be run in series-multiple or multi- 
 ple-series, except on constant-potential systems, 
 and then only by special permission of the Inspec- 
 tion Department having jurisdiction. 
 
 /. Must be covered with a waterproof cover 
 when not in use, and, if deemed necessary by the 
 Inspection Department having jurisdiction, must 
 be enclosed in an approved case. 
 
 Such enclosures must be readily accessible, dust 
 proof and sufficiently ventilated to prevent an ex- 
 cessive rise of temperature. Where practicable the 
 sides should be made largely of glass, so that the 
 motor may be always plainly visible. 
 
 The use of enclosed type motor is recommended 
 in dusty places, being preferable to wooden 
 boxing. 
 
16 CLASS A. STATIONS 
 
 8, Motors Continued, 
 
 g. Must, when combined with ceiling fans, be 
 hung from insulated hooks, or else there must be 
 an insulator interposed between the motor and its 
 support. 
 
 h. Must each be provided with a name-plate, 
 giving the maker's name, the capacity in volts 
 and amperes, and the normal speed in revolutions 
 per minute. 
 
 L Terminal blocks when used on motors must 
 be made of approved non-combustible, non- 
 absorptive, insulating material such as slate, 
 marble or porcelain. 
 
 j. Adjustable speed motors, unless of special 
 and appropriate design, if controlled by means of 
 field regulation, must be so arranged and con- 
 nected that they cannot be started under weakened 
 field. 
 
 9, Railway Power Plants, 
 
 a. Each feed wire before it leaves the power 
 plant must be protected by an approved automatic 
 circuit-breaker or other device, which will imme- 
 diately cut off the current in case of an accidental 
 ground. This device must be mounted on a tire- 
 proof base, and in full view and reach of the 
 attendant. 
 
 10, Storage or Primary Batteries, 
 
 a. When current for light and power is taken 
 from primary or secondary batteries, the same 
 general regulations must be observed as apply to 
 similar apparatus fed from dynamo generators 
 developing the same difference of potential. 
 
 b. Storage battery rooms must be thoroughly 
 ventilated. ; 
 
 c. Special attention is directed to the rules for 
 wiring in rooms where acid fumes exist (see No. 
 24, t and.;). 
 
AND DYNAMO BOOMS. 17 
 
 10, Storage or Primary Batteries Continued. 
 
 d. All secondary batteries must be mounted on 
 non-absorptive, non-combustible insulators, such 
 as glass or thoroughly vitrified and glazed por- 
 celain. 
 
 e. The use of any metal liable to corrosion must 
 be avoided in cell connections of secondary bat- 
 teries. 
 
 11, Transformers.-- 
 
 (See also Nos, 13, 13 A, 36.) 
 
 a. In central or sub-stations the transformers 
 must be so placed that smoke from the burning 
 out of the coils or the boiling over of the oil 
 (where oil filled cases are used) could do no barm. 
 
 b. In central or sub-stations casings of all trans- 
 formers must be permanently and effectively 
 grounded. 
 
 Transformers used exclusively to supply current 
 to switchboard instruments need not be grounded, 
 provided they are thoroughly insulated. 
 
CLASS B. 
 OUTSIDE WORK. 
 
 (Light, Power and Heat. For Signaling Systems, 
 see Class E.) 
 
 ALL SYSTEMS AND VOLTAGES, 
 
 12, Wires, 
 
 a. Line wires must have an approved weather- 
 proof or rubber insulating covering. That por- 
 tion of the service wires between the main cut-out 
 and switch and the first support from the cut-out 
 or switch on outside of the building must have an 
 approved rubber insulating covering, but from 
 the above-mentioned support to the line, except 
 when run in conduit, may have an approved 
 weatherproof insulating covering if kept free from 
 awnings, swinging signs, shutters, etc. 
 
 b. Must be so placed that moisture cannot form 
 a cross connection between them, and except when 
 run in conduit, not less than a foot apart, and not 
 in contact with any substance other than their 
 insulating supports. Wooden blocks to which 
 insulators are attached must be covered over their 
 entire surface with at least two coats of water- 
 proof paint. 
 
 For conduit work, wires must be placed so as 
 to conform to rules for unlined conduit except 
 that conduit system must be waterproof. 
 
 c. Must be at least seven feet above the highest 
 point of flat roofs, and at least one foot above the 
 ridge of pitched roofs over which they pass or to 
 which they are attached and roof structures must 
 be substantially constructed. 
 
CLASS B. OUTSIDE WORK. 19 
 
 12, Wires Continued. 
 
 (Z. (Stricken out.) 
 
 e. Must, where exposed to the weather, be pro- 
 vided with petticoat insulators of glass or porce- 
 lain ; porcelain knobs or cleats and rubber hooks 
 will not be approved. Wires on the exterior walls 
 of buildings must be supported at least every fif- 
 teen feet, the distance between supports to be 
 shortened if wires are liable to be disturbed. 
 
 Where not exposed to the weather, low potential 
 wires may be supported on glass or porcelain 
 knobs which will separate the wires at least one 
 inch from the surface wired over, supports to be 
 placed at least every four an one half feet. 
 
 /. Must be so spliced or joined as to be both me- 
 chanically and electrically secure without solder. 
 The joints must then be soldered, to insure pres- 
 ervation, and covered with an insulation equal to 
 that on the conductors. 
 
 All joints must be soldered, unless made with 
 some form of approved splicing device. 
 
 g. Must, where they enter buildings, have drip 
 loops outside, and the holes through which the 
 conductors pass must be bushed with iion-com- 
 bustible, non-absorptive, insulating tubes slanting 
 upward toward the inside. 
 
 For low potential systems the service wires may 
 be brought into buildings through a single iron 
 conduit. The conduit to be equipped with an 
 approved service-head. The inner end must ex- 
 tend to the service cut-out, and if a cabinet is 
 required by the Code must properly enter the 
 cabinet. 
 
 h. Electric light and power wires must not be 
 placed on the same cross-arm with telegraph, 
 telephone or similar wires, and when placed on 
 the same pole with such wires the distance 
 between the two inside pins of each cross-arm 
 must not be less than twenty-six inches. 
 
 i. The metallic sheaths to cables must be per- 
 manently and effectively connected to u earth." 
 
20 CLASS B. OUTSIDE WORK. 
 
 12, Wires-Continued, 
 Trolley Wires. 
 
 j. Must not be smaller than No. B. & S. gage 
 copper or No. 4 B. & S. gage silicon bronze, and 
 must readily stand the strain put upon them when 
 in use. 
 
 k. Must have a double insulation from the 
 ground. In wooden pole construction the pole 
 will be considered as one insulation. 
 
 L Must be capable of being disconnected at the 
 power plant, or of being divided into sections, so 
 that in case of fire on the railway route, the cur- 
 rent may be shut off from the particular section 
 and riot interfere with the work of the firemen. 
 This rule also applies to feeders. 
 
 :n. Must be safely protected against accidental 
 contact where crossed by other conductors. 
 
 Where guard wires are used they must be insu- 
 lated from the ground and electrically discon- 
 nected in sections of not more than 300 feet in 
 length. 
 
 Ground Return Wires. 
 
 n. For the diminution of electrolytic corrosion 
 of underground metal work, ground return wires 
 must be so arranged that the difference of poten- 
 tial between the grounded dynamo terminal and 
 any point on the return circuit will not exceed 
 twenty-five volts. 
 
 It is suggested that the positive pole of the dynamo 
 be connected to the trolley line, and that whenever 
 pipes or other underground metal work are found to be 
 electrically positive to the rails or surrounding earth, 
 that tbey be connected by conductors arranged so as to 
 prevent as far as possible current flow from the pipes 
 into the ground. 
 
CLASS B. OUTSIDE WORK. 21 
 
 12 A, Constant-Potential Pole Lines, Over 5,000 
 Volts. 
 
 (Overhead lines of this class unless properly ar- 
 ranged may increase the lire loss from the following 
 causes: 
 
 Accidental crosses between such lines and low-po- 
 tential lines may allow the high-voltage current to en- 
 ter buildings over a large section of adjoining country. 
 Moreover, such high-voltage lines, if carried close to 
 buildings, hamper the work of firemen in case of lire in 
 the building. The object of these rules is so to direct 
 this class of construction that no increase in lire hazard 
 will result, while at the same time care has been taken 
 to avoid restrictions which would unreasonably impede 
 progress in electrical development. 
 
 It is fully understood that it is impossible to frame 
 rules which will C9ver all conceivable cases that may 
 arise in construction work of such an extended and 
 varied nature, and it is advised that the Inspection 
 Department having jurisdiction be freely consulted as 
 to any modification of the rules in particular cases.) 
 
 a. Every reasonable precaution must be taken 
 in arranging routes so as to avoid exposure to 
 contacts with other electric circuits. On existing 
 lines, wherfi there is a liability to contact, the 
 route should be changed by mutual agreement 
 between the parties in interest wherever possible. 
 
 6. Such lines should not approach other pole 
 lines nearer than a distance equal to the height of 
 the taller pole line, and such lines should not be 
 on the same poles with other wires, except that 
 signaling wires used by the Company operating 
 the high-pressure system, and which do not enter 
 property other than that owned or occupied by 
 such Company, may be carried over the same 
 poles. 
 
 c. Where such lines must necessarily be carried 
 nearer to other pole lines than is specified in Sec- 
 tion 6 above, or where they must necessarily be 
 carried on the same poles with other wires, extra 
 precautions to reduce the liability of a breakdown 
 to a minimum must be taken, such as the use of 
 wires of ample mechanical strength, widely 
 
22 CLASS B. OUTSIDE WORK. 
 
 12 A, Constant-Potential Pole Lines, over 5,000 volts Continued, 
 
 spaced cross-arms, short spans, double or extra 
 heavy cross-arms, extra heavy pins, insulators, 
 and poles thoroughly supported. If carried on 
 the same poles with other wires, the high-pressure 
 wires must be carried at least three feet above the 
 other wires. 
 
 d. Where such lines cross other lines, the poles 
 of both lines must be of heavy and substantial 
 construction. 
 
 Whenever it is feasible, end-insulator guards 
 should be placed on the cross-arms of the upper 
 line. If the high-pressure wires cross below the 
 other lines, the wires of the upper line should be 
 dead-ended at each end of the span to double- 
 grooved, or to standard transposition insulators, 
 and the line completed by loops. 
 
 One of the following forms of construction must 
 then be adopted : 
 
 1. The height and length of the cross-over 
 
 span may be made such that the shortest 
 distance between the lower cross-arms of 
 the upper line and any wire of the lower 
 line will be greater than the length of the 
 cross-over span, so that a wire breaking 
 near one of the upper pins would not be 
 long enough to reach any wire of the 
 lower line. The high-pressure wires 
 should preferably be above the other 
 wires. 
 
 2. A joint pole may be erected at the crossing 
 
 point, the high-pressure wires being sup- 
 ported on this pole at least three feet 
 above the other wires. Mechanical 
 guards or supports must then be pro- 
 vided, so that in case of the breaking of 
 any upper wire, it will be impossible for 
 it to come into contact with any of the 
 lower wires. 
 
CLASS B. OUTSIDE WORK. 23 
 
 12 A, Constant-Potential Pole Lines, over 5,000 volts Continued, 
 
 Such liability of contact may be prevented 
 by the use of suspension wires, similar to 
 those employed for suspending aerial tele- 
 phone cables, which will prevent the high- 
 pressure wires from falling, in case they 
 break. The suspension wires should be sup- 
 ported on high-potential insulators, should 
 have ample mechanical strength, and should 
 be carried over the high pressure wires for 
 one span on each side of the joint pole, or 
 where suspension wires are not desired guard 
 wires may be carried above and below the 
 lower wires for one span on each side of the 
 joint pole, and so spread that a falling high- 
 pressure wire would be held out of contact 
 with the lower wires./- 
 
 Such guard wires should be supported on 
 high-potential insulators or should be 
 grounded. When grounded, they must be of 
 such size, and so connected and earthed, that 
 they can surely carry to ground any current 
 which may be delivered by any of the high- 
 pressure wires. Further, the construction 
 . must be such that the guard wires will not be 
 destroyed by any arcing at the point of con- 
 tact likely to occur under the conditions 
 existing. 
 
 3. Whenever neither of the above methods is 
 feasible, a screen of wire should be inter- 
 posed between the lines at the cross-over. 
 This screen should be supported on high 
 tension insulators or grounded, and should 
 be of such construction and strength as 
 to prevent the upper wires from coming 
 into contact with the lower ones. 
 
 If the screen is grounded each wire of the 
 screen must be of such size and so connected 
 and earthed that it can surely carry to ground 
 any current which may be delivered by any of 
 the high-pressure wires. Further, the con- 
 struction must be such thatthe wires of screen 
 will not be destroyed by any arcing at the 
 point of contact likely to occur under the con- 
 ditions existing. 
 
 e. When it is necessary to carry such lines near 
 buildings, they must be at such height and dis- 
 
24 CLASS B. OUTSIDE WORK. 
 
 12 A, Constant-Potential Pole Lines, over 5,000 volts Continued. 
 tance from the building as not to interfere with 
 firemen in event of fire ; therefore, if within 25 
 feet of a building, they must be carried at a height 
 not less than that of the front cornice, and the 
 height must be greater than that of the cornice, 
 as the wires come nearer to the building in accor- 
 dance witli the following table : 
 
 Distance of wire Elevation of wire 
 
 from building. above cornice of building. 
 
 Feet. Feet. 
 
 25 
 
 20 2 
 
 15 4 
 
 10 6 
 
 5 8 
 
 2i 9 
 
 It is evident that where the roof of the building con- 
 tinues nearly in line with the walls, as in Mansard 
 roofs, the height and distance of the line must be reck, 
 oned from some part of the roof instead of from the 
 cornice. 
 
 13, Transformers, 
 
 (See also Nos. 11, 13 A and 36.) 
 
 Where transformers are to be connected to high- 
 voltage circuits, it is necessary in many cases, for best 
 protection to life and property, that the secondary sys- 
 tem be permanently grounded, and provision should be 
 made for it when the transformers are built. 
 
 a. Must not be placed inside of any building, 
 excepting central stations and sub-stations (except 
 as provided in No. 30 A) , unless by special per- 
 mission *of the Inspection Department having 
 jurisdiction. 
 
 b. Must not be attached to the outside walls of 
 buildings, unless separated therefrom by substan- 
 tial supports. 
 
 Must not be attached to frame buildings when 
 any other location is practicable. 
 
CLASS B. OUTSIDE WORK. 25 
 
 13 A, Grounding Low-Potentia! Circuits, 
 
 The grounding of low-potential circuits under the fol- 
 lowing regulations'is only allowed when such circuits 
 are so arranged that under normal conditions of service 
 there will be no passage of current over the ground 
 wire. 
 
 IMrect-Current 3- Wire System*. 
 
 . Neutral wire may be grounded and when 
 grounded the following rules nust be complied 
 with: 
 
 1. Must be grounded at the Central Station 
 
 on a metal plate buried in coke beneath 
 permanent moisture level, and also 
 through all available underground water 
 and gas pipe systems. 
 
 2. In underground systems the neutral wire 
 
 must also be grounded at each distribut- 
 ing box through the box. 
 
 3. In overhead systems the neutral wire must 
 
 be grounded every 500 feet, as provided 
 in Sections c to g. 
 
 Inspection Departments having jurisdiction may 
 require grounding if they deem it necessary. 
 
 Two-wire direct-current systems having no accessi- 
 ble neutral point are not to be grounded. 
 
 Alternating-Current Secondary Systems. 
 
 6. Transformer secondaries of distributing sys- 
 tems should preferably be grounded, and when 
 grounded, the following rules must be complied 
 with : 
 
 1. The grounding must be made at the neu- 
 
 tral point or wire, whenever a neutral 
 point or wire is accessible. 
 
 2. When no neutral point or wire is accessi- 
 
 ble one side of the secondary circuit 
 may be grounded, provided the maxi- 
 
26 CLASS B. OUTSIDE WORK. 
 
 ISA. Grounding Low-Potential Circuits Continued, 
 
 mum difference of potential between the 
 grounded point and any other point in 
 the circuit does not exceed 250 volts. 
 3. The ground connection must be at the 
 transformers or on the individual service 
 as provided in sections c to {/, and when 
 transformers feed systems with a neutral 
 wire, the neutral wire must also be 
 grounded at least every 250 feet for over- 
 head systems, and every 500 feet for un- 
 derground systems. 
 
 Inspection Departments haying jurisdiction may 
 require grounding if they deem it necessary. 
 
 Ground Connection*. 
 
 c. When the ground connection is inside of any 
 building, or the ground wire is inside of, or 
 attached to any building (except Central or Sub- 
 stations) the ground wire must be of copper and 
 have an approved rubber insulating covering 
 National Electrical Code Standard, for from to 
 600 volts. 
 
 d. The ground wire in direct-current 3-wire sys- 
 tems must not at Central Stations be smaller than 
 the neutral wire and not smaller than No. 4 B. & 
 S. gage elsewhere. The ground wire in alternat- 
 ing-current systems must never be less than No. 
 4 B. & S. gage. 
 
 On three-phase system, the ground wire must have 
 a carrying capacity equal to that of any one of the three 
 mains. 
 
 e. The ground wire should, except for Central 
 Stations and transformer sub-stations, be kept 
 outside of buildings as far as practicable, but 
 may be directly attached to the building or pole 
 by cleats or straps or on porcelain knobs. Staples 
 must never be used. The wire must be carried 
 in as nearly a straight line as practicable, avoid- 
 
< CLASS B. OUTSIDE WORK. 27 
 
 13 A, Grounding Low-Potential Circuits Continued, 
 
 ing kinks, coils and sharp bends, and must be 
 protected when exposed to mechanical injury. 
 
 This protection can be secured by use of an approved 
 moulding, and as a rule the ground wire on the outside 
 of a building should be in moulding at all places where 
 it is in within seven feet from the ground. 
 
 /. The ground connection for Central Stations, 
 transformer sub-stations, and banks of trans- 
 formers must be made through metal plates buried 
 in coke below permanent moisture level, and con- 
 nection should also be made to all available un- 
 derground piping systems including the lead sheath 
 of underground cables. 
 
 fj. For individual transformers and building 
 services, the ground connection may be made as 
 in Section/, or may be made to water piping sys- 
 tems running into buildings. This connection 
 may be made by carrying the ground wire into 
 the cellar and connecting on the street side of 
 meters, main cocks, etc. 
 
 Where it is necessary to run the ground wire 
 through any part of a building it shall be pro- 
 tected by approved porcelain bushings through 
 walls or partitions and shall be run in approved 
 moulding, except that in basements it may be 
 supported on porcelain. 
 
 In connecting a ground wire to a piping system, the 
 wire should be sweat into a lug attached to an approved 
 clanip, and the clamp firmly bolted to the water pipe 
 after all rust and scale have been removed ; or be sol- 
 dered into a brass plug and the plug forcibly screwed 
 into a pipe-fitting, or where the pipes are cast iron, into 
 a hole tapped into the pipe itself. For large stations, 
 where connecting to underground pipes with bell and 
 spigot joints, it is well to connect to several lengths, as 
 the pipe joints may be of rather high resistance. 
 
 Where ground plates are used^a No 16 Stubbs' gage 
 copper plate, about three by six feet in size, with about 
 two feet of crushed coke or charcoal.about pea size, both 
 under and over it, would make a ground of sufficient 
 capacity for a moderate-sized station, and would prob- 
 ably answer forthe ordinary sub-station or bank of trans- 
 
28 CLASS B. OUTSIDE WORK. 
 
 ISA, Grounding Low-Potential Circuits Continued, 
 
 formers. For a large central station, a plate with con- 
 siderably more area might be necessary, depending 
 upon the other underground connections available. The 
 ground wire should be riveted to the plate in a number 
 of places, and soldered for its whole length. Perhaps 
 even better than a copper plate is a cast-iron plate with 
 projecting forks, the idea of the fork being to distribute 
 the connection to the ground over a fairly broad area, 
 and to give a large surface contact. The ground wire 
 can probably best be connected to such a cast-iron plate 
 by soldering it into brass plugs screwed into holes 
 tapped in the plate. In all cases, the joint between the 
 plate and the ground wire should be thoroughly pro- 
 tected against corrosion by painting it with waterproof 
 paint or some equivalent. 
 
CLASS C. 
 
 INSIDE WORK. 
 
 (Light, Power and Heat. For signaling Systems, 
 see Class E.) 
 
 ALL SYSTEMS AND VOLTAGES. 
 
 GENERAL RUIZES. 
 
 14, Wires, 
 
 a. Must not be of smaller size than No. 14 B. & 
 S. gage, except as allowed for fixture work and 
 pendant cord. 
 
 6. Tie wires must have an insulation equal to 
 that of the conductors they confine. For wire 
 smaller than No. 8 B. & S. gage split knobs or 
 cleats shall be used except at dead ends, and tie 
 wires and knobs will not be approved. 
 
 Screws must be used for fastening all cleats and 
 knobs which are arranged to grip the wire. 
 
 c. Must be so spliced or joined as to be both 
 mechanically and electrically secure without sol- 
 der. The joints must then be soldered unless 
 made wiUi. some form of approved splicing device, 
 and covered with an insulation equal to that on 
 the conductors. 
 
 Stranded Avires (except in flexible cords) must 
 be soldered before being fastened under clamps or 
 binding screws, and whether stranded or solid, 
 when they have a conductivity greater than that 
 of No. 8 B. & S. gage they must be soldered into 
 lugs for all terminal connections, except where an 
 approved solderless terminal connector is used. 
 
30 GENERAL RULES. 
 
 14, Wires Continued, 
 
 d. Must be separated from contact with walls, 
 floors, timbers or partitions through which they 
 may pass by non-combustible, non-absorptive, in- 
 sulating tubes, such as glass or porcelain, except 
 at outlets where approved flexible tubing is re- 
 quired. 
 
 Bushings must be long enough to bush the en- 
 tire length of the hole in one continuous piece, or 
 else the hole must first be bushed by a continuous 
 waterproof tube, This tube may be a conductor, 
 such as iron pipe, but in that case an insulating 
 bushing must be pushed into each end of it, ex- 
 tending far enough to keep the wire absolutely 
 out of contact with the pipe. 
 
 e. Must be kept free from contact with gas, 
 water or other metallic piping, or any other con- 
 ductors or conducting material which they may 
 cross, .by some continuous and firmly fixed non- 
 conductor, creating a permanent separation. 
 Deviations from this rule may sometimes be 
 allowed by special permission. 
 
 Where tubes are used they must be securely 
 fastened at the ends to prevent them from moving 
 along the wire. 
 
 /. Must be so placed in wet places that an air 
 space will be left between conductors and pipes in 
 crossing, and the former must be run in- such a 
 way that they cannot come in contact with the 
 pipe accidentally. Wires should be run over, 
 rather than under, pipes upon which moisture is 
 likely to gather or which, by leaking, might cause 
 trouble on a circuit. 
 
 g. The installation of electrical conductors in 
 wooden moulding, or on insulators, in elevator 
 shafts will not be approved, but conductors may 
 be installed in such shafts if encased in approved 
 metal conduits. 
 
INSIDE WORK. 31 
 
 15, Underground Conductors, 
 
 a. Must be protected against moisture and me- 
 chanical injury where brought into a building, 
 and all combustible material must be kept from 
 the immediate vicinity. 
 
 b. Must not be so arranged as to shunt the cur- 
 rent through a building around any catch-box. 
 
 c. Where underground service enters building 
 through tubes, the tubes shall be tightly closed at 
 outlets with asphaltum or other non-conductor, 
 to prevent gases from entering the building 
 through such channels. 
 
 d. No underground service from a subway to a 
 building shall supply more than one building 
 except by written permission from the Inspection 
 Department having jurisdiction. 
 
 16, Table of Carrying Capacity of Wires, 
 
 a. The following table, showing the allowable 
 carrying capacity of copper wires and cables of 
 ninety-eight per cent conductivity, according to 
 the standard adopted by the American Institute 
 of Electrical Engineers, must be followed in 
 placing interior conductors. 
 
 For insulated aluminum wire the safe carrying 
 capacity is eighty-four per cent of that given in 
 the following tables for copper wire with the same 
 kind of insulation. 
 
32 
 
 GENERAL RTLES. 
 
 16. Table of Carrying Capacity of Wires-Continued, 
 
 TABLE A. TABLE B. 
 Rubber Other 
 Insulation. Insulations. 
 
 B. *&. G. Amperes. Amperes. Circular Mils- 
 
 16 
 
 6 
 
 8. 
 
 
 U 
 
 12 
 
 
 
 12 
 
 17 
 
 23. 
 
 6 530 
 
 10 
 
 24 
 
 32. 
 
 
 8 
 
 
 
 
 6 
 
 46 
 
 
 
 
 
 
 
 4 
 
 G5 
 
 92. 
 
 41 7f) 
 
 3 
 
 
 
 
 2 
 1 
 0..... 
 00 
 
 ooo 
 
 90 
 107 
 127 
 150 
 177 
 
 131. 
 156. 
 185. 
 220. 
 262 
 
 66,370 
 83,690 
 105,500 
 133,100 
 167 goo 
 
 0000 
 rcular Mils. 
 200 000 . . 
 
 210 
 
 200 
 
 312. 
 
 300 
 400 
 
 500 
 
 aii^eoo 
 
 
 
 400.000... 
 
 330... 
 
 500,000 390 590 
 
 600,000 450..., 680 
 
 700,000 500 760 
 
 800,000 550 840 
 
 900,000 COO 920 
 
 1,000,000 650 1,000 
 
 1,100,000 C90 1,080 
 
 1,200,000 730 1,150 
 
 1,300,000 770 1,220 
 
 1,400,000 810 1,290 
 
 1,500,000 850 1 ,360 
 
 1,600,000 890 1,430 
 
 1,700,000 930 1,490 
 
 1,800,000 970 1,550 
 
 1,900,000 1,010 1,610 
 
 2,000,000 1,050 1,670 
 
 The lower limit is specified for rubber-covered -wires 
 to prevent gradual deterioration of the high insulations 
 by the heat of the wires, but not from fear of igniting 
 the insulation. The question of drop is not taken into 
 consideration in the above tables. 
 
 The carrying capacity of Nos. 16 and 18, B. & S. gage 
 wire is given, but no smaller than No. 14 is to be used, 
 except as allowed under rules for fixture wiring. 
 
IXSIDE WORK. 33 
 
 17,' Switches, Cut-outs, Circuit-Breakers, Etc, 
 
 a. On constant potential circuits, all service 
 switches and all switches controlling circuits sup- 
 plying current to motors or heating devices, and 
 all fuses, unless otherwise provided (for excep- 
 tions as to switches see Nos. 8 c, 23 a and 34 A c ; 
 for exceptions as to cuts-outs see No. 21 a and 6) 
 must be so arranged that the fuses will protect 
 and the opening of the switch will disconnect all 
 of the wires ; that is, in the two-wire system the 
 two wires, and the three-wire system the three 
 wires, must be protected by the fuses and discon- 
 nected by the operation of the switch. 
 
 When installed without other automatic over- 
 load protective devices automatic overload circuit 
 breakers must have the poles and trip coils so 
 arranged as to afford complete protection against 
 overloads and short circuits, and if also used in 
 place of the switch must be so arranged that no 
 one pole can be opened manually without discon- 
 necting all the wires. 
 
 This, of course, does not apply to the grounded 
 circuit of street railway systems. 
 
 6. Must not be placed in the immediate vicinity 
 of easily ignitible stuff or where exposed to in- 
 flammable gases or dust or to flyings of combusti- 
 ble material. 
 
 When the occupancy of a building is such that 
 switches, cut-outs, etc., cannot be located so as 
 not to be exposed to dust or flyings of combustible 
 material they must be enclosed in approved dust- 
 proof cabinets with self-closing doors, except oil 
 switches and circuit breakers which have dust- 
 tight casings. 
 
 c. Must, when exposed to dampness, either be 
 enclosed in a moisture-proof box or mounted on 
 porcelain knobs. The cover of the box must be 
 so made that no moisture which may collect on 
 the top or sides of the box can enter it. 
 
 d. Time switches, sign flashers and similar ap- 
 pliances must be of approved design and enclosed 
 in an approved cabinet. 
 
34 CONSTANT-CURRENT. 
 
 CONSTANT-CURRENT SYSTEMS, 
 
 PRINCIPALLY SERIES ARC LIGHTING. 
 
 18, Wires, 
 
 (See also Nos. 14, 15 and 16.) 
 
 a. Must have an approved rubber insulating 
 covering. 
 
 b. Must be arranged to enter and leave the 
 building through an approved double-contact ser- 
 vice switch, mounted in a non-combustible case, 
 kept free from moisture, and easy of access to 
 police or firemen. 
 
 c. Must always be in plain sight, and never 
 encased, except when required by the Inspection 
 Department having jurisdiction. 
 
 t*. Must be supported on glass or porcelain in- 
 sulators, which separate the wire at least one inch 
 from the surface wired over and must be kept 
 rigidly at least eight inches from each other, 
 except within the structure of lamps, on hanger- 
 boards or in cut-out boxes, or like places, where a 
 less distance is necessary. 
 
 e. Must, on side walls be protected from 
 mechanical injury by a substantial boxing, retain- 
 ing an air space of one inch around the conduc- 
 tors, closed at the top (the wires passing through 
 bushed holes) , and extending not less than seven 
 feet from the floor. When crossing floor timbers 
 in cellars, or in rooms where they might be ex- 
 posed to injury, wires must be attached by their 
 insulating supports to the under side of a wooden 
 strip not less than one-half an inch in thickness. 
 Instead of the running-boards, guard strips on 
 
INSIDE WOKK. 35 
 
 18, V/ires-Continued, 
 
 each side of and close to the wires will be 
 accepted. These strips to be not less than seven- 
 eighths of an inch in thickness and at least as high 
 as the insulators. 
 
 19, Series Arc Lamps, 
 
 a. Must be carefully isolated from inflammable 
 material. 
 
 &. Must be provided at all times with a glass 
 globe surrounding the arc, and securely fastened 
 upon a closed base. Broken or cracked globes 
 must not be used. 
 
 c. Must be provided with a wire netting (having 
 a mesh not exceeding one and one-fourth inches) 
 around the globe, and an approved spark arrester 
 when readily inflammable material is in the vicin- 
 ity of the lamps, to prevent escape of sparks of 
 carbon or melted copper. 
 
 Outside arc lamps must be suspended at least 
 eight feet above sidewalks. Inside arc lamps 
 must be placed out of reach or suitably protected. 
 
 Arc lamps, when used in places where they are 
 exposed to flyings of easily inflammable material, 
 must have the carbons enclosed completely in a 
 tight globe in such manner as to avoid the neces- 
 sity for spark arresters. 
 
 "Enclosed arc" lamps, having tight inner 
 
 lobes, may be used, and the requirements of 
 ections 6 and c above would, of course, not apply 
 to them. 
 
 d. Where hanger-boards are not used, lamps 
 must be hung from insulating supports other 
 than their conductors. 
 
 e. Lamps when arranged to be raised arid low- 
 ered, either for carboning or other purposes, shall 
 be connected up with stranded conductors from 
 the last point of support to the lamp, when such 
 conductor is larger than Xd. 14 B. & S. gage. 
 
36 COXSTAXT-CUIIRKXT. 
 
 20, Incandescent Lamps in Series Circuits, 
 
 a. Must have the conductors installed as re- 
 quired in No. 18, and each lamp must be provided 
 with an automatic cut-out. 
 
 6. Must have each lamp suspended from a 
 hanger-board by means of rigid tube. 
 
 c. No electro-magnetic device for switches and 
 no multiple- series or series-multiple system of 
 lighting will be approved. 
 
 d. Must not under any circumstances be attached 
 to gas fixtures. 
 
IX.SIDK WORK. 37 
 
 CONSTANT-POTENTIAL SYSTEMS, 
 
 GENERAL RULES ALL VOLTAGES. 
 
 21, Automatic Cut-OUtS (Fuses and Circuit-Breakers). 
 (See also JS T o. 17.) 
 
 a. Must be placed on all service wires, either 
 overhead or underground, in the nearest access- 
 ible place to the point where they enter the build- 
 ing and inside the walls, and arranged to cut off 
 the entire current from the building. 
 
 Where the switch required by No. 22 a is inside 
 the building, the cut-out required by this section 
 must be placed so as to protect it. 
 
 For three-wire (not three-phase) systems the 
 fuse in the neutral wire may be omitted, provided 
 the neutral wire is of equal carrying capacity to 
 the larger of the outside wires, and is grounded as 
 provided for in No. 13 A. 
 
 In risks having private plants, the yard wires 
 running from building to building are not consid- 
 ered as service wires, so that cut-outs would not 
 be required where the wires enter buildings, pro- 
 vided that the next fuse back is small enough to 
 properly protect the wires inside the building in 
 question. 
 
 b. Must be placed at every point where a change 
 is made in the size of wire [unless the cut-out in 
 the larger wire will protect the smaller (see No. 
 16.)] 
 
 For three-wire (not three-phase) systems the 
 fuse in the neutral wire except that called for 
 under No. 21 d, may be omitted, provided the neu- 
 tral wire is of equal carrying capacity to the larger 
 
38 CONSTANT-POTENTIAL,. 
 
 21, Automatic Cut-outs Continued, 
 
 of the outside wires, and is grounded as provided 
 
 for in No. 13 A. 
 
 c. Must be in plain sight, or enclosed in an ap- 
 proved cabinet, and readily accessible. They must 
 not be placed in the canopies or shells of fixtures. 
 
 Link fuses may be used only when mounted on 
 approved slate or marble bases and must be en- 
 closed in dust-tight, fire-proofed cabinets, except 
 on switchboards. 
 
 d. Must be so placed that no set of incandescent 
 lamps requiring more than 660 watts, whether 
 grouped on one fixture or on several fixtures or 
 pendants, will be dependent upon one cut-out. 
 
 Special permission may be given in writing by 
 the Inspection Department having jurisdiction, for 
 departure from this rule, in the caseof large chan- 
 deliers. (For exceptions, see rule on theatre wir- 
 ing and List of Fittings for rules for electric signs.) 
 All branches or taps from any three-wire system 
 which are directly connected to lamp sockets or 
 other translating devices, must be run as two-wire 
 circuits if the fuses are omitted in the neutral, or 
 if the difference of potential between the two out- 
 side wires is over 250 volts, and both wires of such 
 branch or tap circuits must be protected by proper 
 fuses. 
 
 The above shall also apply to motors when more 
 than one is dependent on a single cut-out. 
 
 The fuses in the branch cut-outs must not have 
 a rated capacity greater than 6 amperes on 110 volt 
 systems, and 3 amperes on 220 volt systems. 
 
 On open work in large mills approvedlink fused 
 rosettes may be used at a voltage of not over 125 
 and approved enclosed fused rosettes at a voltage 
 of not over 250, the fuse in the rosettes not to ex- 
 ceed 3 amperes, and a fuse of over 25 amperes must 
 not be used in the branch circuit. 
 
 e. The rated capacity of fuses must not exceed 
 the allowable carrying capacity of the wire as given 
 
INSIDE WORK. 39 
 
 21, Automatic Cut-outs Continued, 
 
 in No. 16. Circuit-breakers must not be set more 
 than 30 per cent above allowable carrying capacity 
 of the wire, unless a fusible cut-out is also in- 
 stalled on the circuit, in which event the circuit- 
 breaker may be set as high as 100 per cent above 
 such capacity. 
 
 In the arms of fixtures carrying a single socket 
 a No. 18 B. & S. gage wire supplying only one 
 socket will be considered as properly protected by 
 a six ampere fuse. 
 
 /. Each phase of A. C. motor circuits, except 
 on main switchboard or when otherwise subject 
 to expert supervision, must be protected by an 
 approved fuse whether automatic overload cir- 
 cuit breakers are installed or not. Single phase 
 motors may have one side protected by an 
 approved automatic overload circuit breaker only 
 if the other side is protected by an approved fuse. 
 For circuits having a maximum capacity greater 
 than that for which enclosed fuses are approved 
 circuit breakers alone will be approved. 
 
 22, Switches. 
 
 (See No. 17.") 
 
 a. Must be placed on all service wires, either 
 overhead or underground, in the nearest readily 
 accessible place, to the point where the wires enter 
 the building, and arranged to cut off the entire 
 current. 
 
 Service cut-out and switch must be arranged to 
 cut off current from all devices including meters. 
 
 In risks having private plants the yard wires 
 running from building to building are not consid- 
 ered as service wires, so that switches would not 
 be required in each building if there are other 
 switches conveniently located on the mains or if 
 the generators are near at hand. 
 
40 CONSTANT-POTENTIAL. 
 
 22, Switches Continued, 
 
 b. Must always be placed in dry, accessible 
 places, and be grouped as far as possible. (See 
 No. 17 c.) Single-throw knife switches must be 
 so placed that gravity will not tend to close them. 
 Double-throw knife switches may be mounted so 
 that the throw will be either vertical or horizontal 
 as preferred. 
 
 When practicable switches must be so wired 
 that blades will be u dead " when switch is open. 
 
 When switches are used in rooms where com- 
 bustible flyings would be likely to accumulate 
 around them, they must be enclosed in dust-tight 
 cabinets. 
 
 Up to 250 volts and thirty amperes, approved indicating 
 snap switches are suggested in preference to knife 
 switches on lighting circuits. 
 
 c. Single pole switches must never be used as 
 service switches nor placed in the neutral wire of 
 a three-wire system, except in the two-wire 
 branch or tap circuit supplying not more than 
 660 watts. 
 
 This, of course, does not apply to the grounded 
 circuits of Street Railway systems. 
 
 Three- way switches are considered as single pole 
 switches and must be wired so that only one pole 
 of the circuit is carried to either switch. 
 
 d. Where flush switches or receptacles are used, 
 whether with conduit systems or not, they must 
 be enclosed in an approved box constructed of iron 
 or steel, in addition to the porcelain enclosure of 
 the switch or receptacle. No push buttons for 
 bells, gas-lighting circuits, or the like shall be 
 placed in the same wall plate with switches con- 
 trolling electric light or power wiring. 
 
 e. Where possible, at all switch or fixture out- 
 lets, unless outlet boxes which will give proper 
 support for fixtures are used, a 7-8 inch block 
 must be fastened between studs or floor timbers 
 
IXSIDE WORK. 41 
 
 22, Switches Continued, 
 
 flush with the back of lathing to hold tubing, 
 and to support switches or fixtures. When this 
 cannot be done, wooden base blocks, not less than 
 3-4 inch in thickness, securely screwed to lathing, 
 must be provided for switches, and also for fix- 
 tures which are not attached to gas pipes or con- 
 duit. 
 
 /. Sub-bases of non-combustible, non-absorptive, 
 insulating material, which will separate the wires 
 at least 1-2 inch from the surface wired over, must 
 be installed under all snap switches used in ex- 
 posed knob and cleat work. Sub-bases must also 
 be used in moulding work, but they may be made 
 of hardwood or they may be omitted if the switch 
 is approved for mounting directly on the moulding. 
 
 23, Electric Heaters, 
 
 It is often desirable to connect in multiple with the 
 heaters and between the heater and the switch control- 
 ling same, an incandescent lamp of low candle power, 
 as it shows at a glance whether or not the switch is 
 open, and tends to prevent its being left closed through 
 oversight. 
 
 a. Must be protected by a cut-out and controlled 
 by indicating switches. Switches must be double 
 pole except when the device controlled does not 
 require more than 660 watts of energy. 
 
 6. Must never be concealed, but must at all 
 times be in plain sight. Special permission may 
 be given in writing by the Inspection Department 
 having jurisdiction for departure from this rule. 
 
 c. Flexible conductors for smoothing irons and 
 sad irons, and for all devices requiring over 250 
 watts must have an approved insulation and 
 covering. 
 
 d. For portable heating devices the flexible con- 
 ductors must be connected to an approved plug 
 device, so arranged that the plug will pull out 
 
42 CONSTANT-POTENTIAL. 
 
 23, Electric Heaters Continued, 
 
 and open the circuit in case any abnormal strain 
 is put on the flexible conductor. This device may 
 be stationary, or it may be placed in the cord 
 itself. The cable or cord must be attached to the 
 heating apparatus in such manner that it will be 
 protected from kinking, chafing or like injury at 
 or near the point of connection. 
 
 e. Smoothing irons, sad irons, and other heating 
 appliances that are intended to be applied to in- 
 flammable articles, such as clothing, must conform 
 to the above rules so far as they apply. They 
 must also be provided with an approved stand, on 
 which they should be placed when not in use. 
 
 /. Stationary electric heating apparatus, such as 
 radiators, ranges, plate warmers, etc., must be 
 placed in a safe location, isolated from inflam- 
 mable materials, and be treated as sources of heat. 
 
 Devices of this description will often require a suit- 
 able heat-resisting material placed between the device 
 and its surroundings. Such protection may best be 
 secured by installing two or more plates of tin or sheet 
 steel with a one-inch air space between or by alternate 
 layers of sheet steel and asbestos with a similar air 
 space. 
 
 g. Must each be provided with name-plate, giv- 
 ing the maker's name and the normal capacity in 
 volts and amperes. 
 
INSIDE WORK. 43 
 
 LOW-POTENTIAL SYSTEMS, 
 550 VOLTS OK LESS. 
 
 Any circuit attached to any machine, or combina- 
 tion of machines, which develops a difference 
 of potential between any two wires, of over 
 ten volts and less than 550 volts, shall be 
 considered as a low-potential circuit, and as 
 coming under this class, unless an approved 
 transforming device is used, which cuts the 
 difference of potential down to ten volts or 
 less. The primary circuit not to exceed a 
 potential of 3,500 volts unless the primary 
 wires are installed in accordance with the 
 requirements as given in No. '12 A, or are 
 underground. For 550 volt motor equip- 
 ments a margin of ten per cent above the 550 
 volt limit will be allowed at the generator 
 or transformer. 
 
 24, Wires, 
 
 GENERAL RULES. 
 
 (See also Nos. 14, 15 and 16.) 
 
 a. Where entering cabinets must be protected 
 by approved bushings, which fit tightly the holes 
 in the box and are well secured in place. The 
 wires should completely fill the holes in the bush- 
 ings so as to keep out the dust, tape being used 
 to build up the wires if necessary. On concealed 
 knob and tube work approved flexible tubing will 
 be accepted in lieu of bushings, providing it shall 
 extend from the last porcelain support into the 
 cabinet. 
 
 b. Must not be laid in plaster, cement or similar 
 finish, and must never be fastened with staples. 
 
44 LOW CONSTANT-POTENTIAL. 
 
 24, Wires-Continued, 
 
 c. Must not be fished for any great distance, 
 and only in places where the inspector can satisfy 
 himself that the rules have been complied with. 
 
 d. Twin wires must never be used, except in 
 conduits, or where flexible conductors are neces- 
 sary. 
 
 e. Must be protected on side walls from mechani- 
 cal injury. When crossing floor timbers in cel- 
 lars, or in rooms where they might be exposed to 
 injury, wires must be attached by their insulating 
 supports to the under side of a wooden strip, not 
 less than one-half inch in thickness, and not less 
 than three inches in width. Instead of the run- 
 ning-boards, guard strips on each side of and close 
 to the wires will be accepted. These strips to be 
 not less than seven-eighths of an inch in thickness, 
 and at least as high as the insulators. 
 
 Protection on side walls must extend not less 
 than five feet from the floor and must consist of 
 substantial boxing, retaining an air space of one 
 inch around the conductors, closed at the top (the 
 wires passing through bushed holes) or approved 
 metal conduit or pipe of equivalent strength. 
 
 When metal conduit or pipe is used, the insula- 
 tion of each wire must be reinforced by approved 
 flexible tubing extending from the insulator next 
 below the pipe to the one next above it, unless the 
 conduit is installed according to No. 25 (sections 
 c and/ excepted), and the wire is approved for 
 conduit use. The two or more wires of a circuit 
 each with its flexible tubing (when required), if 
 carrying alternating current must, or if direct cur- 
 rent, may be placed within the same pipe. 
 
 In damp places the wooden boxing may be prefer- 
 able because of the precautions which would be neces- 
 sary to secure proper insulation if the pipe were used. 
 With this exception, however, iron piping is considered 
 preferable to the wooden boxing, and its use is strongly 
 urged. It is especially suitable for the protection of 
 wires near belts, pulleys, etc. 
 
IXSIDE WORK. 45 
 
 24, Wires Continued, < 
 
 f. When run in unfinished attics, will be con- 
 sidered as concealed, and when run in close prox- 
 imity to water tanks or pipes, will be considered 
 as exposed to moisture. 
 
 In unfinished attics wires are considered as ex- 
 posed to mechanical injury, and must not be run 
 on knobs on upper edge of joists. 
 
 SPECIAL RULES. 
 
 For Open Work. 
 In dry places. 
 
 g. Must have an approved rubber, slow-burning 
 weatherproof, or slow-burning insulation. 
 
 A slow-burning covering, that is, one that will not 
 carry tire, is considered good enough where the wires 
 are entirely on insulating supports. Its main object is 
 to prevent the copper conductors from coming acciden- 
 tally into contact with each other or anything else. 
 
 h. Must be rigidly supported on non-combus- 
 tible, non-absorptive insulators, which will sepa- 
 rate the wires from each other and from the sur- 
 face wired over in accordance with the following 
 table : 
 
 Voltage. Distance from Distance "between 
 
 Surface. Wires. 
 
 to 300 5 inch 2| inch 
 
 301 to 550 1 inch 4 inch 
 
 Rigid supporting requires under ordinary condi- 
 tions, where wiring along flat surfaces, supports 
 at least every four and one-half feet. If the wires 
 are liable to be disturbed, the distance between 
 supports must be shortened. In buildings of mill 
 construction, mains of not less than No. 8 B. & S., 
 gage, where not liable to be disturbed, may be 
 separated about six inches, and run from timber 
 to timber, not breaking around, and may be sup- 
 ported at each timber only. 
 
 The neutral of an Edison three-wire system may 
 
46 LOW CONSTANT-POTENTIAL. 
 
 24, Wires Continued, 
 
 be placed in the center of a three-wire cleat where 
 the difference of potential between the outside 
 wires is not over 300 volts, provided the outside 
 wires are separated two and one-half inches. 
 
 Must not be ''dead-ended" at a rosette socket 
 or receptacle unless the last support is within 
 twelve inches of the same. 
 
 In damp places, or buildings specially subject to 
 moisture or to acid or other fumes liable to 
 injure the wires or their insulation. 
 
 i. Must have an approved insulating covering. 
 
 For protection against water, rubber insulation 
 must be used. For protection against corrosive 
 vapors, either weatherproof or rubber insulation 
 must be used. 
 
 ,;'. Must be rigidly supported on non-combustible, 
 non-absorptive insulators, which separate the wire 
 at least one inch from the surface wired over, and 
 must be kept apart at least two and one-half 
 inches for voltages up to 300, and four inches for 
 higher voltages. 
 
 Rigid supporting requires under ordinary condi- 
 tions, where wiring over flat surfaces, supports at 
 least every four and one-half feet. If the wires 
 are liable to be disturbed, the distance between 
 supports must be shortened. In buildings of mill 
 construction, mains of not less than No. 8 B. & S. 
 gage, where not liable to be disturbed, may be 
 separated about six inches, and run from timber 
 to timber, not breaking around, and may be sup- 
 ported at each timber only. 
 
 For Moulding Work (Wooden and Metal). 
 (See No. 25 .1.) 
 
 fc. Must have an approved rubber insulating 
 covering, and must be in continuous lengths from 
 outlet to outlet, or from fitting to fitting, no joints 
 
INSIDE WOKK. 47 
 
 24. Wires-Continued. 
 
 or taps to be made in moulding. Where branch 
 taps are necessary in moulding work approved 
 fittings for this purpose must be used. 
 
 I. Must never be placed in either metal or 
 wooden moulding in concealed or damp places, 
 or where the difference of potential between any 
 two wires in the same moulding is over 300 volts. 
 Metal mouldings must not be used for circuits 
 requiring more than 660 watts of energy. 
 
 in. Must for alternating current systems if in 
 metal moulding have the two or more wires of a 
 circuit installed in the same moulding. 
 
 It 'is suggested that this be done for direct current 
 systems also, so that they may be changed to alternat- 
 ing systems at any time, induction troubles preventing 
 such a change if the wires are in separate mouldings. 
 
 For Conduit Work. 
 
 n. Must have an approved rubber insulating 
 covering. 
 
 o. Must not be drawn in until all mechanical 
 work on the building has been, as far as possible, 
 completed. 
 
 Conductors in vertical conduit risers must be 
 supported within the conduit system in accord- 
 ance with the following table : 
 
 No. 14 to every 100 feet. 
 No. 00 to 0000 every 80 feet. 
 0000 to 350,000 C. M. every 60 feet. 
 350,000 C. M. to 500,000 C. M. every 50 feet. 
 500,000 C. M. to 750,000 C. M. every 40 feet. 
 750,000 C. M. every 35 feet. 
 
 The following methods of supporting cables are 
 recommended : 
 
 1. A turn of 90 degrees in the conduit system 
 
 will constitute a satisfactory support. 
 
 2. Junction boxes may be inserted in the con- 
 
 duit system at the required intervals, in 
 
48 LOW CONSTANT-POTENTIAL. 
 
 24. Wires Continued, 
 
 which insulating supports of approved 
 type must be installed and secured in a 
 satisfactory manner so as to withstand 
 the weight of the conductors attached 
 thereto, the boxes to be provided with 
 proper covers. 
 
 3. Cables may be supported in approved junc- 
 tion boxes on two or more insulating sup- 
 ports so placed that the conductors will 
 be deflected at an angle of not less than 
 90 degrees, and carried a distance of not 
 less than twice the diameter of the cable 
 from its vertical position. Cables so sus- 
 pended may be additionally secured to 
 these insulators by tie wires. 
 Other methods, if used, must be approved by 
 the Inspection Departments having juris- 
 diction. 
 p. Must, for alternating systems, have the two 
 
 or more wires of a circuit drawn in the same 
 
 conduit. 
 
 It is suggested that this be clone for direct current 
 systems also, so that they may be changed to alternat- 
 ing systems at any time, induction troubles preventing 
 such a change if the wires are in separate conduits. 
 
 The same conduit must not contain more than 
 four two-wire, or three three-wire circuits of the 
 same system, except by special permission of the 
 Inspection Department having jurisdiction, and 
 must never contain circuits of different systems. 
 
 For Concealed "Knob and Tube" Work. 
 
 q. Must have an approved rubber insulating 
 covering. 
 
 r. Must be rigidly supported on non-combusti- 
 ble, non-absorptive insulators which separate the 
 wire at least one inch from the surface wired 
 over. Should preferably be run singly on sep- 
 
IX SIDE WOKK. 49 
 
 24, Wires Continued, 
 
 arate timbers, or studding, and must be kept at 
 least five inches apart. 
 
 Must be separated from contact with the walls, 
 floor timbers and partitions through which they 
 may pass by non-combustible, non-absorptive, in- 
 sulating tubes, such as glass or porcelain. Wires 
 passing through timbers at the bottom of plas- 
 tered partitions must be protected by an addi- 
 tional tube extending at least four inches above 
 the timber. 
 
 Rigid supporting requires, under ordinary con- 
 ditions, where wiring along flat surface, supports 
 at least every four and one-half feet. If the wires 
 are liable to be disturbed the distance between 
 supports must be shortened. 
 
 At distributing centers, outlets or switches 
 where space is limited and the five-inch separation 
 cannot be maintained, each wire must be. sepa- 
 rately encased in a continuous length of approved 
 flexible tubing. 
 
 s. When in a concealed knob and tube system, 
 it is impracticable to place the whole of a circuit 
 on non-combustible supports of glass or porcelain, 
 that portion of the circuit which cannot be so 
 supported must be installed with approved metal 
 conduit, or approved armored cable, except that if 
 the difference of potential between the wires is 
 not over 300 volts, and if the wires are not exposed 
 to moisture, they may be fished if separately 
 encased in approved flexible tubing, extending in 
 continuous lengths from porcelain support to 
 porcelain support, from porcelain support to out- 
 let, or from outlet to outlet. . 
 
 t. When using either conduit or armored cable 
 in mixed concealed knob and tube work, the 
 requirements for conduit work or armored cable 
 work must be complied with as the case may be. 
 
 u. Must at all outlets, except where conduit is 
 used, be protected by approved flexible tubing, 
 
50 LOW CONSTANT-POTENTIAL. 
 
 24, Wires-Continued, 
 
 extending in continuous lengths from the last 
 porcelain support to at least one inch beyond 
 the outlet. In the case of combination fixtures 
 the tubes must extend at least flush with outer 
 end of gas cap. 
 
 When the surface at any outlet is broken, it 
 must be repaired so as to leave no holes or open 
 spaces at such outlet. 
 
 It is suggested that approved outlet boxes or plates 
 be installed at all outlets in concealed " knob and tube " 
 work, the wires to be protected by approved flexible 
 tubing, extending in continuous lengths from the last 
 porcelain support into the box. 
 
 For Fixture Work. 
 
 v. Must have an approved rubber insulating 
 covering, and be not less in size than No. 18 B. & 
 S. gage. 
 
 In wiring certain designs of show-case fixtures, 
 ceiling bulls-eyes and similar appliances in which 
 the wiring is exposed to temperatures in excess of 
 120 degrees Fahrenheit (49 degrees Centigrade), 
 from the heat .of the lamps, approved slow-burn- 
 ing wire may be used. All such forms of fixtures 
 must be submitted for examination, test and ap- 
 proval before being introduced for use. 
 
 w. Supply conductors, and especially the splices 
 to fixture wires, must be kept clear of the grounded 
 part of gas pipes, and, where shells or outlet boxes 
 are used, they must be made sufficiently large to 
 allow the fulfillment of this requirement. 
 
 x. Must, when fixtures are wired outside, be so 
 secured as not to be cut or abraded by the pres- 
 sure of the fastenings or motion of the fixture. 
 
 y. Wires of different systems must never be 
 contained in or attached to the same fixture and 
 under no circumstances must there be a difference 
 of potential of more than 800 volts between wires 
 contained in or attached to the same fixture. 
 
INSIDE WORK. 51 
 
 24 A, Armored Cables, 
 
 a. Must be continuous from outlet to outlet or 
 to junction boxes, and the armor of the cable 
 must properly enter and be secured to all fittings, 
 and the entire system must be mechanically se- 
 cured in position. 
 
 In case of service connections and main runs, 
 this involves running such armored cable continu- 
 ously into a main cut-out cabinet or gutter sur- 
 rounding the panel board, as the case may be. 
 
 b. Must be equipped at every outlet with an 
 approved outlet box or plate, as required in 
 conduit work. 
 
 Outlet plates must not be used where it is 
 practicable to install outlet boxes. 
 
 The outlet box or plate shall be so installed that 
 it will be flush with the finished surface, and if 
 this surface is broken it shall be repaired so that 
 it will not show any gaps or open spaces around 
 the edge of the outlet box or plate. 
 
 In buildings already constructed where the con- 
 ditions are such that neither outlet box nor plate 
 can be installed, these appliances may be omitted 
 by special permission of the Inspection Depart- 
 ment having jurisdiction, provided the armored 1 
 cable is firmly and rigidly secured in place. 
 
 c. Must have the metal armor of the cable per- 
 manently and effectively grounded. 
 
 Armor of cables and gas pipes must be securely 
 fastened in metal outlet boxes so as to secure 
 good electrical connection. Where boxes used for 
 centers of distribution do not afford good elec- 
 trical connection the armor of the cables must be 
 joined around them by suitable bond wires. 
 Where sections of armored cable are installed 
 without being fastened to the metal structure of 
 buildings or grounded metal piping, they must be 
 bonded together and joined to a permanent and 
 efficient ground connection. 
 
52 LOW COXSTANT-POTEXTIAL. 
 
 24 A, Armored Cables Continued, 
 
 It is suggested that cables, outlet boxes and fittings 
 having conductive coatings be used in order to secure 
 better electi'ical contact at all points throughout the 
 cable system. 
 
 d. When installed in so-called fireproof build- 
 ings in course of constriction or afterwards if 
 exposed to moisture, or .mere it is exposed to the 
 weather, or in damp places such as breweries, 
 stables, etc., the cable must have a lead covering 
 at least one thirty-second inch in thickness placed 
 between the outer braid of the conductors and the 
 steel armor. 
 
 The lead covering is not to be required when 
 the cable is run against brick walls or laid in ordi- 
 nary plaster walls unless same are continuously 
 damp. 
 
 e. Where entering junction boxes, and at all 
 other outlets, etc., must be provided with approved 
 terminal fittings which will protect the insulation 
 of the conductors from abrasion, unless such 
 junction or outlet boxes are specially designed 
 and approved for use with the cable. 
 
 /. Junction boxes must always be installed in 
 such a manner as to be accessible. 
 
 g. For alternating current systems must have 
 the two or more conductors of the cable enclosed 
 in one metal armor. 
 
 li. All bends must be so made that the armor of 
 the cable will not be injured. The radius of the 
 curve of the inner edge of any bend not to be less 
 than 1$ inches. 
 
 25, Interior Conduits, 
 
 (See also No. 24 n to p.] 
 
 a. No conduit tube having an internal diameter 
 of less than five-eighths of an inch shall be used. 
 Measurements to be taken inside of metal conduits. 
 
 6. Must be continuous from outlet to outlet or 
 
INSIDE WORK. 53 
 
 25, Interior Conduits Continued. 
 
 to junction boxes, and the conduit must properly 
 enter, and be secured to all fittings and the entire 
 system must be mechanically secured in position. 
 In case of service connections and main runs, 
 this involves running each conduit continuously 
 into a main cut-out cabinet or gutter surrounding 
 the panel board, as the case may be. 
 
 c. Must be first installed as a complete conduit 
 system, without the conductors. 
 
 d. Must be equipped at every outlet with an 
 approved outlet box or plate. 
 
 Outlet plates must not be used where it is prac- 
 ticable to install outlet boxes. 
 
 The outlet box or plate must be so installed 
 that it will be flush witli the finished surface, and 
 if this surface is broken it shall be repaired so 
 that it will not show any gaps or open spaces 
 around the edge of the outlet box or plate. 
 
 In buildings already constructed where the con- 
 ditions are such that neither outlet box nor plate 
 can be installed, these appliances may be omitted 
 by special permission of the Inspection Depart- 
 ment having jurisdiction, providing the conduit 
 ends are bushed and secured. 
 
 It is suggested that outlet boxes and fittings having 
 conductive coatings be used in order to secure better 
 electrical contact at all points throughout the conduit 
 system. 
 
 e. Metal conduits where they enter junction 
 boxes, and at all other outlets, etc., must be pro- 
 vided with approved bushings or fastening plates 
 fitted so as to protect wire from abrasion, except 
 when such protection is obtained by the use of 
 approved nipples, properly fitted in boxes or 
 devices. 
 
 /. Must have the metal of the conduit perma- 
 nently and effectually grounded. 
 
 Conduits and gas pipes must be securely fas- 
 tened in metal outlet boxes so as to secure good 
 
54 LOW CONSTANT-POTENTIAL. 
 
 25. Interior Conduits Continued, 
 
 electrical connection. If conduit, couplings, out- 
 let boxes or fittings having protective coating of 
 non-conducting material, such as enamel, are 
 used, such coating must be thoroughly removed 
 from threads of both couplings and conduit and 
 from surfaces of boxes and fittings where the con- 
 duit is secured in order to obtain the requisite 
 good connection. Where boxes used for centers 
 of distribution do not afford good electrical con- 
 nection, the conduits must be joined around them 
 by suitable bond wires. Where sections of metal 
 conduit are installed without being fastened to 
 the metal structure of buildings or grounded metal 
 piping, they must be bonded together and joined 
 to a permanent and efficient ground connection. 
 
 g. Junction boxes must always be installed in 
 such a manner as to be accessible. 
 
 h. All elbows or bends must be so made that 
 the conduit or lining of same will not be injured. 
 The radius of the curve of the inner edge of any 
 elbow not to be less than three and one-half 
 inches. Must have not more than the equivalent 
 of four quarter bends from outlet to outlet, the 
 bends at the outlets not being counted. 
 
 25 A. Metal Mouldings, 
 
 (See also No. 24 k to m.) 
 
 a. Must be continuous from outlet to outlet, to 
 junction boxes, or approved fittings designed 
 especially for use with metal mouldings, and 
 must at all outlets be provided with approved 
 terminal fittings which will protect the insula- 
 tion of conductors from abrasion, unless such 
 protection is afforded by the construction of the 
 boxes or fittings. 
 
 b. Such moulding where passing through a floor 
 must be carried through an iron pipe extending 
 
INSIDE WOKK. 55 
 
 25 A, Metal Mouldings Continued, 
 
 from the ceiling below to a point five feet above 
 the floor, which will serve as an additional me- 
 chanical protection and exclude tbe presence of 
 moisture often prevalent in such locations. 
 
 In residences, office buildings and similar loca- 
 tions where appearance is an essential feature, 
 and where the mechanical strength of the mould- 
 ing itself is adequate, this ruling may be modified 
 to require the protecting piping from the ceiling 
 below to a point at least three inches above the 
 flooring. 
 
 c. Backing must be secured in position by 
 screws or bolts, the heads of which must be flush 
 with the metal. 
 
 d. The metal of the moulding must be perma- 
 nently and effectively grounded, and must be so 
 installed that adjacent lengths of moulding will 
 be mechanically and electrically secured at all 
 points. 
 
 Mouldings and gas pipes must be securely fas- 
 tened in metal outlet boxes, so as to secure good 
 electrical connection. Where boxes used for cen- 
 ter of distribution do not afford good electrical 
 connection the metal moulding must be joined 
 around them by suitable bond wires. Where sec- 
 tions are installed without being fastened to the 
 metal structure of the building or grounded metal 
 piping, they must be bonded together or joined to 
 a permanent and effective ground connection. 
 
 It is suggested that outlet boxes and fittings having 
 conductive coatings be used in order to secure better 
 electi'ical contact at all points throughout the conduit 
 system. 
 
 e. Must be installed so that for alternating 
 systems the two or more wires of a circuit will be 
 in the same metal moulding. 
 
 It is suggested that this be done for direct systems 
 also, so that they may be changed to the alternating 
 system at any time, induction troubles preventing such 
 change if the wires are be in separate mouldings. 
 
56 LOW CONSTANT-POTENTIAL. 
 
 26, Fixtures, 
 
 (See also Nos. 22 e, 24 v to y.) 
 
 a. Must when supported from the gas piping or 
 any grounded metal work of a building be insu- 
 lated from such piping or metal work by means of 
 approved insulating joints placed as close as pos- 
 sible to the ceiling or walls. 
 
 In straight electric fixtures where the insulation 
 of conductors and the metal of fixtures are the 
 equivalent of a conduit or armored cable system, 
 or where used with approved wireless clusters or 
 where the double braided wire extends directly 
 into an approved porcelain socket, the insulating 
 joint may be omitted. 
 
 Gas outlet pipes must be protected above the 
 insulating joint by approved insulating tubing, 
 and where outlet tubes are used they must be 
 of sufficient length to extend below the in- 
 sulating joint, and must be so secured that 
 they will not be pushed back when the canopy is 
 put in place. 
 
 Fixture canopies in fireproof buildings must be 
 thoroughly and permanently insulated from walls 
 or ceilings, and in other than fireproof buildings 
 they must be thoroughly and permanently insu- 
 lated from metal walls or ceilings or from plaster 
 walls or ceilings on metal lathing. 
 
 6. Must have all burs or fins removed before 
 the conductors are drawn into the fixture. 
 
 c. Must be free from "contacts" between con- 
 ductors and fixture, "short circuits 1 ' and ground 
 connections, and must be tested for such con- 
 ditions before being connected to the supply 
 conductors. 
 
 d. All fixture arms made of tubing smaller than 
 1-2 inch outside diameter, also the arms of all one- 
 light brackets, must be secured after they are 
 screwed into position by the use of a set-screw 
 properly placed, or by soldering or cementing or 
 
INSIDE WORK. 
 
 5, Fixtures Continued, 
 
 some equally good method to prevent the arms 
 from becoming unscrewed. Arms must not be 
 made of tubing lighter than No. 18 B. & S. gage, 
 and must have at screw joints not less than five 
 threads all engaging. This rule does not apply 
 to fixtures or brackets with cast or heavy arms. 
 
 e. The so-called flat canopy sometimes used on 
 electric and combination fixtures will not be 
 approved except in connection with outlet boxes. 
 
 /. Must, when installed on the outside of frame 
 buildings, be of water-tight construction. 
 
 g. Must not, when wired on the outside, be 
 used in show windows or in the immediate vicinity 
 of especially inflammable stuff. 
 
 27, Sockets, 
 
 a. In rooms where inflammable gases may exist 
 the incandescent lamp and socket must be enclosed 
 in a vapor-tight globe, and supported on a pipe- 
 hanger, wired with approved rubber-covered wire 
 soldered directly to the circuit. 
 
 6. In damp or wet places "waterproof " sockets 
 must be used. Unless made up on fixtures they 
 must be hung by separate stranded rubber-covered 
 wires not smaller than No. 14 B. & S. gage, which, 
 should preferably be twisted together when the 
 pendent is over three feet long. 
 
 These wires must be soldered direct to the cir- 
 cuit wires but supported independently of them. 
 
 c. Key sockets will not be approved if installed 
 over specially inflammable stuff, or where ex- 
 posed to flyings of combustible material. 
 
 28, Flexible Cord, 
 
 a. Must have an approved insulation and cover- 
 ing. 
 
 6. Must not, except in street railway property, 
 be used where the difference of potential be- 
 tween the two wires is over 300 volts. 
 
58 LOW CONSTANT-POTENTIAL. 
 
 23, Flexible Cord Continued, 
 
 c. Must not be used as a support for clusters. 
 
 d. Must not be used except for pendants, wiring 
 of fixtures, portable lamps or motors, and portable 
 heating apparatus. 
 
 For all portable work, including those pendants 
 which are liable to be moved about sufficiently to 
 come in contact with surrounding objects, flexible 
 wires and cables especially designed to withstand 
 this severe service must be used. 
 
 When necessary to prevent portable lamps from 
 coming in contact with inflammable materials, or 
 to protect them from breakage, they must be sur- 
 rounded with a substantial wire guard. 
 
 e. Must not be used in show windows or show 
 cases except when provided with an approved 
 metal armor. 
 
 /. Must be protected by insulating bushings 
 where the cord enters the socket. 
 
 g. Must be so suspended that the entire weight 
 of the socket and lamp will be borne by some 
 approved method under the bushing in the socket, 
 and above the point where the cord comes through 
 the ceiling block or rosette, in order that the strain 
 may be taken from the joints and binding screws. 
 
 29, Arc Lamps on Constant-Potential Circuits. 
 
 a. Must have a cut-out (see No. 17 a) for each 
 lamp or each series of lamps. 
 
 The branch conductors must haye a carrying 
 capacity about fifty per cent in excess of the nor- 
 mal current required by the lamp. 
 
 6. Must only be furnished with such resistances 
 or regulators as are enclosed in non-combustible 
 material, such resistances being treated as sources 
 of heat. Incandescent lamps must not be used for 
 this purpose. 
 
 c. Must be supplied with globes and protected 
 by spark arresters and wire netting around the 
 globe, as in the case of series arc lamps (see No. 
 19). 
 
INSIDE WORK. 59 
 
 29. Arc Lamps on Constant-Potential Circuits Continued, 
 
 Outside arc lamps must be suspended at least 
 eight feet above sidewalks. Inside arc lamps 
 must be placed out of reach or suitably protected. 
 
 d. Lamps when arranged to be raised and 
 lowered, either for carboning or other purposes, 
 shall be connected up with stranded conductors 
 from the last point of support to the lamp, when 
 such conductor is larger than No. 14 B. & S. gage. 
 
 29 A, Mercury Vapor Lamps, 
 Enclosed Mercury Vapor Lamps, 
 
 a. Must have cut-out for each lamp or series of 
 lamps except when contained in single frame and 
 lighted by a single operation, in which case not 
 more than five lamps should be dependent upon 
 single cut-out. 
 
 b. Must only be furnished with such resistances 
 or regulators as are enclosed in non-combustible 
 cases, such resistances to be treated as sources of 
 heat. In locations where these resistances or 
 regulators are subject to flyings of lint or com- 
 bustible material, all openings through cases must 
 be protected by fine wire gauze. 
 
 High Potential Vacuum Tube Systems, 
 
 c. The tube must be so installed as to be free 
 from mechanical injury or liability to contact with 
 inflammable material. 
 
 d. High potential coils and regulating apparatus 
 must be installed in approved steel cabinet not less 
 than 1-10 inch in thickness ; same to be well venti- 
 lated in such a manner as to prevent the escape of 
 any flame or sparks, in case of burnout in the 
 various coils. All apparatus in this box must be 
 mounted on slate base and the enclosing case posi- 
 tively grounded. Supplying conductors leading 
 into this high potential case to be installed in 
 accordance with the standard requirements gov- 
 erning low potential systems, where such wires 
 do not carry a potential of over 300 volts. 
 
60 LOAV CONSTAXT-POTENTIAL. 
 
 30, Economy Coils, 
 
 a. Economy and compensator coils for arc lamps 
 must be mounted on non-combustible, non-absorp- 
 tive, insulating supports, such as glass or porce- 
 lain, allowing an air space of at least one inch 
 between frame and support, and must in general 
 be treated as sources of heat. 
 
 30 A, Transformers, 
 
 Oil transformers : 
 
 a. Must not be placed inside of any building 
 except central stations and sub-stations, unless by 
 special permission of the inspection department 
 having jurisdiction. 
 
 Air cooled transformers : 
 
 The following sections do not apply to 
 apparatus or fittings, the operation of which 
 depends either wholly or in p art upon special 
 transformers embodied in the devices, but all 
 such apparatus or fitting s must be submitted 
 for special examination and cpproval before 
 being used. 
 
 b. Must not be placed inside of any building ex- 
 cepting central stations and sub-stations, if the 
 highest voltage of either primary or secondary 
 exceeds 550 volts. 
 
 c. Must be so mounted that the case shall be at 
 a distance of at least one foot from combustible 
 material or separated therefrom by non-com- 
 bustible, non-absorptive, insulating material, such 
 as slate, marble or soapstone. This will require 
 the use of a slab or panel somewhat larger than 
 the transformer. 
 
 31, Decorative Lighting Systems, 
 
 a. Special permission may be given in writing 
 by the Inspection Department having jurisdiction 
 for the temporary installation of approved Systems 
 
INSIDE WORK. 61 
 
 31, Decorative Lighting Systems Continued, 
 of Decorative Lighting, provided the difference of 
 potential between the wires of any circuit shall 
 not be over 150 volts and also provided that no 
 group of lamps requiring more than 1,320 watts 
 shall be dependent on one cut-out. 
 
 31 A, Theatre Wiring, 
 
 (For rules governing Moving Picture Machine, see 
 
 No. 65 A.} 
 
 All wiring, apparatus, etc., not specifically cov- 
 vwed by special rules herein given must conform to 
 the standard Rules and Requirements of the 
 National Electrical Code, and the term " theatre " 
 shall mean a building or part of a building in which 
 it is designed to make a presentation of dramatic, 
 operatic or other performances or shows for the 
 entertainment of spectators which is capable of 
 seating at least four hundred persons, and which 
 has a stage for such performances that can be used 
 for scenery and other stage appliances. 
 
 a. Services, 
 
 1. Where source of supply is outside of build- 
 ing, there must be at least two separate and dis- 
 tinct services where practicable, fed from separate 
 street mains, one service to be of sufficient 
 capacity to supply current for the entire equip- 
 ment of theatre, while the other service must be 
 at least of sufficient capacity to supply current for 
 all emergency lights. By " emergency lights" 
 are meant exit lights and all lights in lobbies, 
 stairways, corridors and other portions of theatre 
 to which the public have access which are nor- 
 mally kept lighted during the performance. 
 
 This is a matter solely concerning the protection of 
 the person and should therefore be lef.t to the discretion 
 of the assured, so far as the fire risk is concerned. 
 
62 LOW CONSTANT-POTENTIAL. 
 
 31 A, Theatre Wiring-Continued, 
 
 2. Where source of supply is an isolated plant 
 within same building, an auxiliary service of at 
 least sufficient capacity to supply all emergency 
 lights must be installed from some outside source, 
 or a suitable storage battery within the premises 
 may be considered the equivalent of such service. 
 
 This is a matter solely concerning the protection of 
 the person and should therefore be left to the discretion 
 of the assured, so far as the fire risk is concerned. 
 
 b. Stage, 
 
 1. All permanent construction on stage side 
 of proscenium wall must be approved conduit or 
 armored cable, with the exception of border and 
 switchboard wiring. 
 
 2. Switchboards. Must be made of non-com- 
 bustible, non-absorptive material, and where 
 accessible from stage level must be protected by 
 an approved guard-rail to prevent accidental con- 
 tact with live parts on the board. 
 
 3. Footlights: 
 
 a. Must be wired in approved conduit or 
 armored cable, each lamp receptable being 
 enclosed within an approved outlet box, the 
 whole to be enclosed in a steel trough, metal 
 to be of a thickness not less than No. 20 gage, 
 or each lamp receptacle may be mounted on 
 or in an iron or steel box so constructed as 
 to enclose all the wires and live parts of 
 receptacles. 
 
 6. Must be so wired that no set of lamps 
 requiring more than 1,320 watts will be 
 dependent on one cut-out. 
 
 4. Borders: 
 
 a. Must be constructed of steel of a thick- 
 ness not less than No. 20 gage, treated to 
 prevent oxidization, be suitably stayed and 
 
INSIDE WORK. 63 
 
 31 A, Theatre Wiring Continued, 
 
 supported by a metal framework, and so 
 designed that flanges of reflectors will protect 
 lamps. 
 
 6. Must be so wired that no set of lamps 
 requiring more than 1,320 watts will be de- 
 pendent upon one cut-out. 
 
 c. Must be wired in approved conduit or 
 armored cable, each lamp receptacle to be 
 enclosed within an approved outlet box, the 
 whole to be enclosed in a steel trough, or each 
 lamp receptacle may be mounted on or in the 
 cover of a steel box so constructed as to 
 enclose all the wires and the live parts of 
 receptacles, metal to be of a thickness not 
 less than No. 20 gage. 
 
 d. Must be provided with suitable guards 
 to prevent scenery or other combustible 
 material coming in contact with lamps. 
 
 e. Cables must be made up of approved^ 
 stranded rubber-covered wires ; conduit con- 
 struction must be used from switchboard to 
 point where cables must be flexible to per- 
 mit of the raising and lowering of border, and 
 flexible portion must be enclosed in an 
 approved fireproof hose or braid and be suit- 
 ably supported. 
 
 An approved junction box must be in- 
 stalled at the end of the conduit where the 
 flexible cable leaves for the border. 
 
 /. For the wiring of the border proper, 
 wire with approved slow burning insulation 
 should be used. 
 
 g. Must be suspended with wire rope, 
 same to be insulated from border by at least 
 two approved strain insulators properly 
 inserted. 
 
 5. Stage Pockets. Must be of approved type 
 controlled from switchboard, each receptacle to 
 
64 LOW CONSTANT-POTENTIAL. 
 
 31 A, Theatre Wiring Continued, 
 
 be of not less than fifty ampers rating, and each 
 receptacle to be wired with a separate circuit to 
 its full capacity. 
 
 6. Proscenium Side Lights. Must be so in- 
 stalled that they cannot interfere with the opera- 
 tion of or come in contact with curtain. 
 
 7. Scene Docks. Where lamps are installed 
 in Scene Docks, they must be so located and in- 
 stalled that they will not be liable to mechanical 
 injury. 
 
 8. Curtain Motors. Must be of ironclad type 
 and installed so as to conform to the requirements 
 of the National Electrical Code. (See No. 8.) 
 
 9. Control for Stage Flues: 
 
 a. In cases where dampers are released 
 by an electric device, the electric circuit oper- 
 ating same must be normally closed. 
 
 b. Magnet operating damper must be 
 wound to take full voltage of circuit by which 
 it is supplied, using no resistance device, and 
 must not heat more than normal for appara- 
 tus of similar construction. It must be lo- 
 cated in loft above scenery, and be installed 
 in a suitable iron box with a tight self-closing 
 door. ' 
 
 c. Such dampers must be controlled by 
 at least two standard single pole switches 
 mounted within approved iron boxes provided 
 with self-closing doors without lock or latch, 
 and located, one at the Electrician^ station, 
 and others as designated by the Inspection 
 Department having jurisdiction. 
 
 Dressing Rooms, 
 
 1. Must be wired in approved conduit or 
 armored cable. 
 
INSIDE WORK. 65 
 
 31 A, Theatre Wiring-Continued, 
 
 2. All pendent lights must be equipped with 
 approved reinforced cord, armored cable or steel 
 armored flexible cord. 
 
 3. All lamps must be provided with approved 
 guards. 
 
 d. Portable Equipments, 
 
 1. Arc lamps used for stage effects must con- 
 form to the following requirements : 
 
 a. Must be constructed entirely of metal 
 except where the use of approved insulating 
 material is necessary. 
 
 b. Must be substantially constructed, and 
 so designed as to provide for proper ventila- 
 tion, and to prevent sparks being emitted from 
 lamps when same is in operation, and mica 
 must be used for frame insulation. 
 
 c. Front opening must be provided with 
 a self-closing hinged doorframe in which wire 
 gauze or glass must be inserted, excepting 
 lens lamps, where the front may be station- 
 ary, and a solid door be provided on back or 
 side. 
 
 d. Must be provided with a one-sixteenth- 
 inch iron or steel guard having a mesh not 
 larger than one inch, and be substantially 
 placed over top and upper half of sides and 
 back of lamp frame ; this guard to be sub- 
 stantially riveted to frame of lamp, and to be 
 placed at a distance of at least two inches 
 from the lamp frame. 
 
 e. Switch on standard must be so con- 
 structed that accidental contact with any live 
 portion of same will be impossible. 
 
 /. All stranded connections in lamp and 
 at switch and rheostat must be provided with 
 approved lugs, 
 
 g. Rheostat, if mounted on standard, must 
 be raised to a height of at least three inches 
 
66 LOW CONSTANT-POTENTIAL. 
 
 31 A, Theatre Wiring Continued, 
 
 above floor line, and in addition to being 
 properly enclosed must be surrounded with a 
 substantially attached metal guard having a 
 mesh not larger than one square inch, which 
 guard is to be kept at least one inch from 
 outside frame of rheostat. 
 
 h. A competent operator must be in 
 charge of each arc lamp, except that one op- 
 erator may have charge of two lamps when 
 they are not more than ten feet apart, and are 
 so located that he can properly watch and 
 care for both lamps. 
 
 2. Bunches : 
 
 a. Must be substantially constructed of 
 metal, and must not contain any exposed 
 wiring. 
 
 b. The cable feeding samemustbe bushed 
 in an approved manner where passing through 
 the metal, and must be properly secured to 
 prevent any mechanical strain from coming 
 on the connection. 
 
 3. Strips: 
 
 a. Must be constructed of steel of a 
 thickness not less than No. 20 gage, treated 
 to prevent oxidization, and suitably stayed , 
 and supported by metal framework. 
 
 6. Cable feeding must be bushed in an 
 approved manner where passing through the 
 metal, and must be properly secured to pre- 
 vent any mechanical strain from coming on 
 the connections. 
 
 4. Portable Plugging Boxes. Must be con- 
 structed so that no current carrying part will be 
 exposed, and each receptacle must be protected by 
 approved fuses mounted on slate or marble bases 
 and enclosed in a fireproof cabinet equipped with 
 
INSIDE WORK. ' 67 
 
 31 A. Theatre Wiring-Continued, 
 
 self-closing doors. Each receptacle must be con- 
 structed to carry thirty amperes without undue 
 heating, and the bus-bars must have a carrying 
 capacity equivalent to the current required for 
 the total number of receptacles, allowing thirty 
 amperes to each receptacle, and approved lugs 
 must be provided for the connection of the master 
 cable. 
 
 5. Pin Plug Conductors : 
 
 a. When of approved type may be used 
 to connect approved portable lights and ap- 
 pliances. 
 
 b. Must be so installed that the "fe- 
 male " part of plug will be on the live end of 
 cable, and must be so constructed that tension 
 on the cable will not cause any serious me- 
 chanical strain on the connections. 
 
 6. Lights on Scenery. Where brackets are 
 used they must be wired entirely on the inside, 
 fixture stem must come through to the back of 
 the scenery and end of stem be properly bushed. 
 
 7. String or Festooned Lights. Wiring for 
 same should be approved cable, joints where taps 
 are taken from same for lights to be properly made, 
 soldered and taped, and where lamps are used 
 in lanterns or similar devices lamps must be pro- 
 vided with approved guards. Where taps are 
 taken from cable, they should be so staggered that 
 joints of different polarity will not come immedi- 
 ately opposite each other and must be properly 
 protected from strain. 
 
 8. Special Electrical Effects. Where devices 
 are used for producing special effects such as 
 lightning, waterfalls, etc., the apparatus must be 
 so constructed and located that flames, sparks, 
 etc., resulting from the operation cannot come in 
 contact with combustible material. 
 
68 LOW CONSTANT-POTENTIAL. 
 
 31 A, Theatre Wiring Continued, 
 e. Auditorium, 
 
 1. All wiring must be installed in approved 
 conduit or armored cable. 
 
 2. All fuses used in connection with lights 
 illuminating all parts of the house used by the 
 audience must be installed in fireproof enclosures 
 so constructed that there will be a space of at 
 least six inches between the fuses and the sides 
 and face of enclosure. 
 
 3. Exit lights must not have more than one 
 set of fuses between same and service fuses. 
 
 4. Exit lights and all lights in halls, corridors 
 or any other part of the building used by the au- 
 dience, except the general auditorium lighting, 
 must be fed independently of the stage lighting, 
 and must be controlled only from the lobby or 
 other convenient place in front of the house. 
 
 5. Every portion of the theatre devoted to the 
 use or accommodation of the public, also all out- 
 lets leading to the streets and including all open 
 courts, corridors, stairways, exits and emergency 
 exit stairways, should be well and properly lighted 
 during every performance, and the same should 
 remain lighted until the entire audience has left 
 the premises. 
 
 31 B, Outline Lighting, 
 
 Wiring (Other than Signs on Exterior of 
 
 Buildings) : 
 
 a. Must be connected only to low-potential 
 - systems. 
 
 6. Open or conduit work may be used, but 
 molding will not be permitted. 
 
 c. For open work, wires must have an ap- 
 proved rubber insulating covering. Must be 
 rigidly supported on non-combustible, non- 
 absorptive insulators, which separate the wires 
 at least one inch from the surface wired over, 
 
INSIDE WORK. 69 
 
 31 B, Outline Wiring-Continued, 
 
 and must be kept apart at least two and one- 
 half inches for voltages up to 300, and four 
 inches for higher voltages. 
 
 Rigid supporting requires, under ordinary 
 conditions where wiring over flat surfaces, 
 supports at least every four and one-half feet. 
 If the wires are liable to be disturbed, the 
 distances between supports should be short- 
 ened. 
 
 d. Where flexible tubing is required, the 
 ends must be sealed and painted with moisture 
 repellant, and kept at least one-half inch from 
 surface wired over. 
 
 e. Wires for use in rigid or flexible steel 
 conduit must comply with requirements for 
 unlined conduit work. Where armored cable 
 is used, the conductors must be protected 
 from moisture by lead sheath between armor 
 and insulation. 
 
 /. Must be protected by its own cut-out, 
 and controlled by its own switch. Cut-outs, 
 switches, time switches, flashers and similar 
 appliances, must be of approved design, and 
 must, if located inside the building, be in- 
 stalled as required by the code for such 
 devices. If outside the building they must 
 be enclosed in a steel or cast-iron box. 
 
 If a steel box is used, the minimum thick- 
 ness of the steel must be 0.128 of an inch 
 (Xo. 8 B. & S. gage). 
 
 Boxes must be so constructed that when 
 switch operates the blade shall clear the door 
 by at least one inch, and they must be moisture 
 proof. 
 
 h. Circuits must be so arranged that not 
 more than 1,820 watts will be finally dependent 
 upon a single cut-out; nor shall more than 
 C6 sockets or receptacles be connected to 
 single circuit- 
 
70 LOW CONSTANT-POTENTIAL. 
 
 31 B, Outline Wiring-Continued, 
 
 i. Sockets and receptacles must be of the 
 keyless porcelain type, and wires must be 
 soldered to lugs on same. 
 
 32, Car Wiring and Equipment of Cars, 
 
 a. Protection of Car Body, etc. 
 
 1. Under side of far bodies to be protected by 
 approved fire-resisting, insulating material, not 
 less than 1-8 inch in thickness, or by sheet iron 
 or steel, not less than .04 inch in thickness, as 
 specified in Section a, 2, 3 and 4. This protection 
 to be provided over all electrical apparatus, such 
 as motors with a capacity of over 75 II. P. each, 
 resistances, contactors, lightning arresters, air- 
 brake motors, etc., and also where wires are 
 run, except that protection may be omitted over 
 wires designed to carry 25 amperes or less if they 
 are encased in metal conduit. 
 
 2. At motors of over 75 H. P. each, fire-resist- 
 ing material or sheet iron or steel to extend not 
 less than 8 inches beyond all edges of openings in 
 motors, and not less than six inches beyond motor 
 leads on all sides. 
 
 3. Over resistances, contactors, and lightning 
 arresters, and other electrical apparatus, excepting 
 when amply protected by their casing, fire-resist- 
 ing material or sheet iron or steel to extend not less 
 than 8 inches beyond all edges of the devices. 
 
 4. Over conductors, not encased in conduit, 
 and conductors in conduit when designed to carry 
 over 25 amperes, unless the conduit is so supported 
 as to give not less than 1-2 inch clear air space be- 
 tween the conduit and the car, fire-resisting 
 material or sheet iron or steel to extend at least 
 6 inches beyond conductors on either side. 
 
 The fire-resisting insulating material or sheet 
 iron or steel may be omitted over cables made up 
 
INSIDE WORK. r ll 
 
 32, Car Wiring and Equipment of Cars Continued, 
 of flame-proof braided outer covering when sur- 
 rounded by 1-8 inch flameproof covering, as called 
 for by Section i, 4. 
 
 5. 11 all cases fireproof material or sheet iron 
 or steel to have joints well fitted, to be securely 
 fastened to the sills, floor timbers and cross braces, 
 and to have the whole surface treated with a 
 waterproof paint. 
 
 6. Cut-out and switch cabinets to be substan- 
 tially made of hard wood. The entire inside of 
 cabinet to be lined with not less than 1-8 inch 
 fire-resisting insulating material which shall be 
 securely fastened to the woodwork, and after the 
 fire-resisting material is in place the inside of the 
 cabinet shall be treated with a waterproof paint. 
 
 6. Wires, Cables, etc, 
 
 1. All conductors to be stranded, the allow- 
 able carrying capacity being determined by Table 
 " A " of No. 10, except that motor, trolley and re- 
 sistance leads shall not be less than No. 7 B. & S. 
 gage, heater circuits not less than No. 12 B. & S. 
 gage, and lighting and other auxiliary circuits not 
 less than No. 14 B. & S. gage. 
 
 The current used in determining the size of 
 motor, trolley and resistance leads shall be the per 
 cent of the full load current, based on one hour's 
 run of the motor,as given by the following table : 
 
 Size each Motor Trolley Eesistance 
 
 motor. Leads. Leads. Leads. 
 
 75 H. P. or less 50% 40% 15% 
 
 Over 75 H. P. 45% 85% 15% 
 
 Approved fixture wire will be permitted for 
 wiring approved clusters. 
 
 2. To have an insulation and braid approved 
 for wires carrying currents of the same potential. 
 
 3. When run in metal conduit, to be protected 
 by an additional braid. 
 
72 LOW CONSTANT-POTENTIAL. 
 
 32, Car Wiring and Equipment of Cars Continued, 
 
 Where conductors are laid in conduit, not 
 being drawn through, the additional braid will 
 not be required. 
 
 4. When not in conduit, in approved mould- 
 ing, or in cables surrounded by 1-8 inch flame- 
 proof covering, must be approved rubber covered 
 (except that tape may be substituted for braid) 
 and be protected by an additional flame-proof 
 braid, at least 1-32 inch in thickness, the outside 
 being saturated with a preservative flame-proof 
 compound. Except that when motors are so en- 
 closed that flame cannot extend outside of the 
 casing, the flame-proof covering will not be re- 
 quired on the motor leads. 
 
 5. Must be so spliced or joined as to be both 
 mechanically and electrically secure without 
 solder. The joints must then be soldered and 
 covered with an insulation equal to that on the 
 conductors. 
 
 Joints made with approved splicing devices 
 and those connecting the leads at motors, plows, 
 or third rail shoes need not be soldered. 
 
 6. All connections of cables to cut-outs, 
 switches and fittings, except those to controller 
 connection boards, when designed to carry over 
 25 amperes, must be provided with lugs or termi- 
 nals soldered to the cable, and securely fastened to 
 the device, bjr bolts, screws or by clamping ; or, 
 the end of the cable, after the insulation is re- 
 moved, shall be dipped in solder and be fastened 
 into the device by at least two set screws having 
 check nuts. 
 
 All connections for conductors to fittings, etc., 
 designed to carry less than 25 amperes, must be 
 provided with up-turned lugs that will grip the 
 conductor between the screw and the lug, the 
 screws being provided with flat washers; or by 
 block terminals having two set screws, and the 
 end of the conductors must be dipped in solder. 
 
INSIDE WORK, 73 
 
 32. Car Wiring and Equipment of Cars Continued. 
 Soldering, in addition to the connection of the 
 binding screws, is. strongly recommended, and will 
 be insisted on when above requirements are not 
 complied with. 
 
 This rule only to apply to circuits where the 
 maximum potential is over 25 volts and current 
 exceeds 5 amperes. 
 
 c. Cut-outs, Circuit Breakers and Switches. 
 
 1. All cut-outs and switches having exposed 
 live metal parts to be located in cabinets. Cut- 
 outs and switches, not in iron boxes or in cabinets, 
 shall be mounted on not less than 1-4 inch fire- 
 resisting insulating material, which shall project 
 at least 1-2 inch beyond all sides of the cut-out or 
 switch. 
 
 2. Cut-outs to be of the approved cartridge or 
 approved blow out type. 
 
 3. All switches controlling circuits of over 5 
 ampere capacity shall be of approved single pole, 
 quick break or approved magnetic blow-out type. 
 
 Switches controlling circuits of 5 ampere or 
 less capacity may be of the approved single pole, 
 double break, snap type. 
 
 4. Circuit breakers to be of approved type. 
 
 5. Circuits must not be fused above their safe 
 carrying capacity. 
 
 6. A cut-out must be placed as near as possi- 
 ble to the current collector, so that the opening of 
 the fuse in this cut-out will cut off all current 
 from the car. 
 
 When cars are operated by metallic return 
 circuits, with circuit breakers connected to both 
 sides of the circuit, no fuses in addition to the 
 circuit breakers will be required. 
 
74 LOW CONSTANT-POTENTIAL. 
 
 32, Car Wiring and Equipment of Cars Continued, 
 <l. Conduit, 
 
 When from the nature of the case, or on account of 
 the size of the conductors, the ordinary pipe and junc- 
 tion box construction is not permissible, a special form 
 of conduit system may be used, provided the general 
 requirements as given below are complied with. 
 
 1. Metal conduits, outlet and junction boxes to 
 be constructed in accordance with standard re- 
 quirements except that conduit for lighting cir- 
 cuits need not be over 5-16 inch internal diameter 
 and 1-2 inch external diameter, and for heating 
 and air motor circuits need not be over 3-8 inch 
 internal diameter and 9-16 inch external diameter, 
 and all conduits where exposed to dampness must 
 be water tight. 
 
 2. Must be continuous between and be firmly 
 secured into all outlet or junction boxes and fit- 
 tings, making a thorough mechanical and elec- 
 trical connection between same. 
 
 3. Metal conduits, where they enter all outlet 
 or junction boxes and fittings, must be provided 
 with approved bushings fitted so as to protect 
 cables from abrasion. 
 
 4. Except as noted in Section , 2, must have 
 the metal of the conduit permanently and effect- 
 ively grounded. 
 
 5. Junction and outlet boxes must be installed 
 in such a manner as to be accessible. 
 
 6. All conduits, outlets or junction boxes and 
 fittings to be firmly and substantially fastened to 
 the framework of the car. 
 
 e. Moulding, 
 
 1. To consist of a backing and a capping and 
 to be constructed of fire-resisting insulating mate- 
 rial, except that it may be made of hard wood 
 where the circuits which it is designed to support 
 are normally not exposed to moisture. 
 
 2. When constructed of fire-resisting insulat- 
 ing material, the backing shall be not less than 1-4 
 
INSIDE WORK. 
 
 32, Car Wiring and Equipment of Cars Continued, 
 
 inch in thickness and be of a width sufficient to 
 extend not less than 1 inch beyond conductors at 
 sides. 
 
 The 'capping, to be not less than 1-8 inch in 
 thickness shall cover and extend at least 3-4 inch 
 beyond conductors on either side. 
 
 The joints in the moulding shall be mitred to 
 fit close, the whole material being firmly secured 
 in place by screws or nails, and treated on the in- 
 side and outside with a waterproof paint. 
 
 When fire-resisting moulding is used over 
 surfaces already protected by 1-8 inch fire-resisting 
 insulating material no backing will be required. 
 
 3. Wooden mouldings must be so constructed 
 as to thoroughly encase the wire and provide a 
 thickness of not less than 3-8 inch at the sides and 
 back of the conductors, the capping being not less- 
 than 3-16 inch in thickness. Must have both out- 
 side and inside two coats of waterproof paint. 
 
 The backing and the capping shall be secured 
 in place by screws. 
 
 /. Lighting and Lighting Circuits, 
 
 1. Each outlet to be provided with an ap- 
 proved receptacle, or an approved cluster. No 
 lamp consuming more than 128 watts to be used. 
 
 2. Circuits to be run in approved metal con- 
 duit, or approved moulding. 
 
 3. When metal conduit is used, except for 
 sign lights, all outlets to be provided with ap- 
 proved outlet boxes. 
 
 4. At outlet boxes, except where approved 
 clusters are used, receptacles to be fastened to the 
 inside of the box, and the metal cover to have an 
 insulating bushing around opening for the lamp. 
 
 When approved clusters are used, the cluster 
 shall be thoroughly insulated from the metal con- 
 
76 LOW CONSTANT-POTENTIAL. 
 
 32, Car Wiring and Equipment of Cars Continued. 
 
 duit, being mounted on a block of hard wood or 
 
 fire-resisting insulating material. 
 
 5. Where conductors are run in moulding the 
 receptacles or cluster to be mounted on blocks of 
 hard wood or of fireproof insulating material. 
 
 {/ Heaters and Heating Circuits, 
 
 1. Heaters to be of approved type. 
 
 2. Panel heaters to be so constructed and 
 located that when heaters are in place all current 
 carrying parts will be at least 4 inches from all 
 woodwork. 
 
 Heaters for cross seats to be so located that 
 current carrying parts will be at least 6 inches 
 below under side of seat, unless under side of seat 
 is protected by not less than 1-4 inch fire-resisting 
 insulating material, or .04 inch sheet metal with 1 
 inch air space over same, when the distance may 
 be reduced to 3 inches. 
 
 Truss plank heaters to be mounted on not less 
 than one-quarter inch fire- resisting insulating ma- 
 terial, the legs or supports for the heaters pro- 
 viding an air space of not less than one-half inch 
 between the back of the heater and the insulating 
 material. 
 
 3. Circuits to be run in approved metal con- 
 duit, or in approved moulding, or if the location of 
 conductors is such as will permit an air space of 
 not less than 2 inches on all sides except from the 
 surface wired over, they may be supported on 
 porcelain knobs or cleats, provided the knobs or 
 cleats are mounted on not less than 1-4 inch fire- 
 resisting insulating material extending at least 3 
 inches beyond conductors at either side, the sup- 
 ports raising the conductors not less than 1-2 inch 
 from the surface wired over, and being not over 12 
 inches apart. 
 
 h. Air Pump Motor and Circuits, 
 
 1. Circuits to be run in approved metal con- 
 duit or JTI approved moulding, except that when 
 
INSIDE WORK. 77 
 
 32. Car Wiring and Equipment of Cars Continued, 
 
 run below the floor of the car they may be sup- 
 ported on porcelain knobs or cleats, provided the 
 supports raise the conductor at least 1-2 inch from 
 the surface wired over and are not over 12 inches 
 apart. 
 
 2. Automatic control to be enclosed in ap- 
 proved metal box. Air pump and motor, when 
 enclosed, to be in approved metal box or a wooden 
 box lined with metal of not less than 1-32 inch in 
 thickness. 
 
 When conductors are run in metal conduit the 
 boxes surrounding automatic control and air 
 pump and motor may serve as outlet boxes. 
 
 i. Main Motor Circuits and Devices. 
 
 1. Conductors connecting between trolley 
 stand and main cut-out or circuit breakers in 
 hood to be protected where wires enter car to 
 prevent ingress of moisture. 
 
 2. Conductors connecting between third rail 
 shoes on same truck, to be supported in an ap- 
 proved fire-resisting insulating moulding, or in 
 approved iron conduit supported by soft rubber or 
 other approved insulating cleats. 
 
 3. Conductors on the under side of the car, 
 except as noted in Section i, 4, to be supported 
 in accordance with one of the following methods : 
 
 a. To be run in approved metal conduit, 
 junction boxes being provided where branches 
 in conduit are made, and outlet boxes where 
 conductors leave conduit. 
 
 b. To be run in approved fire-resisting 
 insulating moulding. 
 
 c. To be supported by insulating cleats, 
 the supports being not over 12 inches apart. 
 
 4. Conductors with flameproof braided outer 
 Dovering, connecting between controllers at either 
 
78 LOW CONSTANT-POTENTIAL. 
 
 32. Car Wiring and Equipment of Cars Continued, 
 
 end of car, or controllers and contactors, may be 
 run as a cable, provided the cable where exposed 
 to the weather is encased in a canvas hose or can- 
 vas tape, thoroughly taped or sewed at ends and 
 where taps from the cable are made, and the hose 
 or tape enters the controllers. 
 
 Conductors with or withoutflameproof braided 
 outer covering connecting between controllers at 
 either end of the car, or controllers and contactors, 
 may be run as a cable, provided the cable through- 
 out its entire length is surrounded by 1-8 inch 
 flameproof covering, thoroughly taped or sewed at 
 ends, or where taps from cable are made, and the 
 flameproof covering enters the controllers. 
 
 Cables where run below floor of car may be 
 supported by approved insulating straps or cleats. 
 Where run above floor of car, to be in a metal con- 
 duit or wooden box painted on the inside with not 
 less than two coats of flameproof paint, and where 
 this box is so placed that it is exposed to water, 
 as by washing of the car floor, attention should be 
 given to making the box reasonably waterproof. 
 
 Canvas hose or tape, or flameproof material 
 surrounding cables after conductors are in same, 
 to have not less than two coats of waterproof in- 
 sulating material. 
 
 5. Motors to be so drilled that, on double 
 truck cars, connecting cables can leave motor on 
 side nearest to king bolt. 
 
 6. Resistances to be so located that there will 
 be at least 6 inch air space between resistances 
 proper and fire-resisting material of the car. To 
 be mounted on iron supports, being insulated by 
 non-combustible bushings or washers, or the iron 
 supports shall have at least 2 inches of insulating 
 surface between them and metal work of car, or 
 the resistances may be mounted on hard wood 
 bars, supported by iron stirrups, which shall have 
 not less than 2 inches of insulating surface be- 
 
INSIDE WORK. 
 
 32. Car Wiring and Equipment of Cars Continued, 
 
 tween foot of resistance and metal stirrup, the 
 entire surface of the bar being covered with at 
 least 1-8 inch fire-resisting insulating material. 
 
 The insulation of the conductor, for about 6 
 inches from terminal of the resistance, should be 
 replaced, if any insulation is necessary, by a por- 
 celain bushing or asbestos sleeve. 
 
 7. Controllers to be raised above platform of 
 car by a not less than 1 inch hard wood block, the 
 block being fitted and painted to prevent moisture 
 working in between it and the platform. 
 
 J- Lightning Arresters. 
 
 1. To be preferably located to protect all aux- 
 iliary circuits in addition to main motor circuits. 
 
 2. The ground conductor shall be not less 
 than No. 6 B. & S. gage, run with as few kinks 
 and bends as possible, and be securely grounded. 
 
 fc. General Rules, 
 
 1. When passing through floors, conductors 
 or cables must be protected by approved insulat-* 
 ing bushings, which shall fit the conductor or 
 cable as closely as possible. 
 
 2. Moulding should never be concealed except 
 where readily accessible. Conductors should never 
 be tacked into moulding. 
 
 3. Short bends in conductors should be 
 avoided where possible. 
 
 4. Sharp edges in conduit or in moulding 
 must be smoothed to prevent injury to con- 
 ductors. 
 
 33, Car Houses, 
 
 a. The trolley wires must be securely supported 
 on insulating hangers. 
 
 6. The trolley hangers must be placed at such 
 a distance apart that, in case of a break in the 
 
SO LOW CONSTANT-POTENTIAL. 
 
 33. Car Houses-Continued, 
 
 trolley wire, contact with the floor cannot be 
 made. 
 
 c. Must have an emergency cut-out switch 
 located at a proper place outside of the building, 
 so that all the trolley wires in the building may 
 be cut out at one point, and line insulators must 
 be installed, so that when this emergency switch 
 is open, the trolley wire will be dead at all points 
 within 100 feet of the building. The current must 
 be cut out of the building when not needed for 
 use in the building. 
 
 This maybe done by the emergency switch, or if pre- 
 ferred a second switch may be used that will cut out all 
 current from the building, but which need not cut out 
 the trolley wire outside as would be the case with the 
 emergency switch. 
 
 d. All lamps and stationary motors must be 
 installed in such a way that one main switch may 
 control the whole of each installation, lighting and 
 power, independently of the main cut-out switch 
 called for in Section c. 
 
 . e. Where current for lighting and stationary 
 motors is from a grounded trolley circuit, the 
 following special rules to apply : 
 
 1. Cut-outs must be placed between the non- 
 
 grounded side and lights or motors they 
 are to protect. No set or group of incan- 
 descent lamps requiring over 2,000 watts 
 must be dependent upon one cut-out. 
 
 2. Switches must be placed between non- 
 
 grounded side and lights and motors they 
 are to protect. 
 
 3. Must have all rails bonded at each joint 
 
 with a conductor having a carrying ca- 
 pacity at least equivalent to No. B. & 
 S. gage annealed copper wire, and all 
 rails must be connected to the outside 
 ground return circuit by a not less thaji 
 Xo. B. & S. gage copper wire or by 
 
INSIDE WORK. 8t 
 
 33. Car Houses Continued, 
 
 equivalent bonding through the track. 
 All lighting and stationary motor circuits 
 must be thoroughly and permanently con- 
 nected to the rails or to the wire leading 
 to the outside ground return circuit. 
 /. All pendant cords and portable conductors 
 will be. considered as subject to hard usage. 
 
 g. Must, except as provided in Section e, have 
 all wiring and apparatus installed in accordance 
 with the rules for constant potential systems. 
 
 h. Must not have any system of feeder distri- 
 bution centering in the building. 
 
 i. Cars must not be left with the trolley in 
 electrical connection with the trolley wire. 
 
 34, Lighting and Power from Railway Wires, 
 
 a. Must not be permitted, under any pretence, 
 in the same circuit with trolley wires with a 
 ground return, except in electric railway cars, 
 electric car houses, power houses, passenger and 
 freight stations connected with the operation of 
 electric railways. 
 
 34 A, Electric Cranes, 
 
 All wiring, apparatus, etc., not specifically 
 covered by special rules herein given, must 
 conform to the Standard Rules and Re- 
 quirements of the National Electrical Code, 
 except that the switch required by Rule 
 8c for each motor may be omitted. 
 
 a. Wiring, 
 
 1. All wires except bare collector wires, those 
 between resistances and contact plates of rheostats 
 and those subjected to severe external heat, must 
 
82 LOW CONSTANT-POTENTIAL. 
 
 34 A, Electric Cranes Continued, 
 
 be approved, rubber-covered and not smaller in 
 size than ]So. 12 B. & S. Insulation on wires be- 
 tween resistances and contact plates of rheostats 
 must conform to Section d, while wires subjected 
 to severe external heat must have approved slow- 
 burning insulation. 
 
 2. All wires excepting collector wires and 
 those run in metal conduit or approved flexible 
 cable must be supported by knobs or cleats which 
 separate them at least one inch from the surface 
 wired over, but in dry places where space is limited 
 the distance between wires as required by Rule 
 24-ft cannot be obtained, each wire must be sepa- 
 rately encased in approved flexible tubing securely 
 fastened in place. 
 
 Collector wires must be supported by approved 
 insulators so mounted that even with the extreme 
 movement permitted the wires will be separated 
 at all times at least 1 1-2 inches from the surface 
 wired over. Collector wires must be held at the 
 ends by approved strain insulators. 
 
 3. Main collector wires carried along the run- 
 ways must be rigidly and securely attached to 
 their insulating supports at least every 20 feet, 
 and separated at least six inches when run in a 
 horizontal plane ; if not run in a horizontal plane, 
 they must be separated at least 8 inches. If spans 
 longer than 20 feet are necessary the distance be- 
 tween wires must be increased proportionately but 
 in no case shall the span exceed 40 feet. 
 
 4. Where bridge collector wires are over 80 
 feet long, insulating supports on which the wires 
 may loosely lie must be provided at least every 50 
 feet. 
 
 Bridge collector wires must be kept at least 
 2 1-2 inches apart, but a greater spacing should be 
 used whenever it may be obtained. 
 
INSIDE WORK. 83 
 
 34 Ai Electric Cranes Continued, 
 
 5. Collector wires must not be smaller in size 
 than specified in the following table for the vari- 
 ous spans. 
 
 Distance between Size wire 
 
 rigid supports. required. 
 
 Feet. B. & S. 
 
 to 30 6 
 
 31 to 60 4 
 
 Over 60 2 
 
 & Collectors, 
 
 Must be so designed that sparking between 
 them and collector wires will be reduced to a 
 minimum. 
 
 c. Switches and Cut-outs, 
 
 1. The main collector wires must be protected 
 by a cut-out and the circuit controlled by a switch. 
 Cut-out and switch to be so located as to be easy of 
 access from the floor. 
 
 2. Cranes operated from cabs must have a cut- 
 out and switch connected into the leads from the 
 main collector wires and so located in the cab as to 
 be readily accessible to the operator. 
 
 3. Where there is more than one motor on a 
 single crane, each motor lead must be protected 
 by a cut-out located in the cab if there is one. 
 
 d. Controllers, 
 
 Must be installed according to No. 4, except 
 that if the crane is located out doors the insula- 
 tion on wires between resistances and contact 
 plates of rheostats must be rubber where the 
 wires are exposed to moisture and insulation is 
 necessary and also where they are grouped. If 
 the crane operates over readily combustible ma- 
 terial, the resistances must be placed in an enclos- 
 ure made of non-combustible material, thoroughly 
 
84 LOW CONSTANT-POTENTIAL,. 
 
 34 A, Electric Cranes Continued. 
 
 ventilated and so constructed that it will not per- 
 mit any flame or molten metal to escape in the 
 event of burning out the resistances. If the re- 
 sistances are located in the cab, this result may be 
 obtained by constructing the cab of non-combusti- 
 ble material and providing sides which enclose 
 the cab from its floor to a height at least 6 inches 
 above the top of the resistances. 
 
 e. Grounding of Iron Work. 
 
 The motor frames, the entire frame of the 
 crane and the tracks must be permanently and 
 effectively grounded. 
 
INSIDE WORK. 85 
 
 HIGH-POTENTIAL SYSTEMS, 
 550 TO 3,500 VOLTS. 
 
 Any circuit attached to any machine or combina- 
 tion of machines which develops a difference 
 of potential between any two wires, of over 
 550 volts and less than 3,500 volts, shall be 
 considered at a high-potential circuit, and as 
 coming under that class, unless an approved 
 transforming device is used, which cuts the 
 difference of potential down to 550 volts or 
 less. For 550 volt motor equipments a margin 
 often per cent above the 550 volt limit will be 
 allowed at the generator or transformer with- 
 out coming under high-potential systems. 
 
 35. Wires, 
 
 (See also Nos. 14, 15 and 16.) 
 
 a. Must have an approved rubber-insulating 
 covering. 
 
 b. Must be always in plain sight and never en- 
 cased, except as provided for in No. 8 6, or where 
 required by the Inspection Department having 
 jurisdiction. 
 
 c. Must (except as provided for in No. 8 b), be 
 rigidly supported 011 glass or porcelain insulators, 
 which raise the wire at least one inch from, the 
 surface wired over, and must be kept about eight 
 inches apart. 
 
 Rigid supporting requires under ordinary con- 
 ditions, where wiring along flat surfaces, supports 
 at least about every four and one-half feet. If the 
 wires are unusually liable to be disturbed, the 
 distance between supports must be shortened. 
 
 In buildings of mill construction, mains of not 
 less than No. 8 B. & S. gage, where not liable to 
 be disturbed, may be separated about ten inches 
 and run from timber to timber, not breaking 
 around, and may be supported at each timber 
 only. 
 
HIGH-POTENTIAL SYSTEMS. 
 
 35, Wires-Continued, 
 
 d. Must be protected on side walls from me- 
 chanical injury by a substantial boxing, retaining 
 an air space of one inch around the conductors, 
 closed at the top (the wires passing through 
 bushed holes) and extending not less than seven 
 feet from the floor. When crossing floor timbers, 
 in cellars, or in rooms where they might be ex- 
 posed to injury, wires must be attached by their 
 insulating supports to the under side of a wooden 
 strip not less than one half an inch in thickness. 
 
 36, Transformers, (When permitted inside build- 
 
 ings under No. 13.) 
 
 (See also Nos. 13 'and 13 A.) 
 Transformers must not be placed inside of build- 
 ings without special permission from the Inspection 
 Department having jurisdiction. 
 
 a. Must be located as near as possible to the 
 point at which the primary wires enter the 
 building. 
 
 b. Must be placed in an enclosure constructed of 
 fire-resisting material ; the enclosure to be used 
 only lor this purpose, and to be kept securely 
 locked, and access to the same allowed only to re- 
 sponsible parties. 
 
 c. Must be thoroughly insulated from the 
 ground, or permanently and effectually grounded, 
 and the enclosure in which they are placed must 
 be practically air-tight, except that it must be 
 thoroughly ventilated to the outdoor air, if pos- 
 sible through a chimney or flue. There should be 
 at least six inches air space on all sides of the 
 transformer. 
 
 37, Series Lamps, 
 
 a. No multiple series or series multiple system 
 of lighting will be approved. 
 
 b. Must not, under any circumstances, be at- 
 tached to gas fixtures. 
 
INSIDE WORK. 87 
 
 EXTRA-HIGH-POTENTIAL SYSTEMS. 
 OVER 3,500 VOLTS. 
 
 Ang circuit attached to any machine or combina- 
 tion of machines which develops a difference 
 of potential, between any two wires, of over 
 3,500 volts, shall be considered as an extra- 
 high-potential circuit, and as coming under 
 that class, unless an approved transforming 
 device is used, which cuts the difference of 
 potential down to 3,500 volts or less. 
 
 38, Primary Wires, 
 
 a. Must not be brought into or over buildings, 
 except power stations and sub-stations. 
 
 39, Secondary Wires. 
 
 a. Must be installed under rules for high-poten- 
 tial systems when their immediate primary wires 
 iarry a current at a potential of over 3,500 volts, 
 inless the primary wires are installed in accord- 
 ince with the requirements as given in No. 12 A 
 ^r are entirely underground, within city, town 
 ind village limits. 
 
 CLASS D 
 
 Containing rules No. 40 to 63 inclusive relating to 
 Construction of Fittings and Materials is omitted 
 from this pamphlet. 
 
88 CLASS E. 
 
 CLASS E. 
 MISCELLANEOUS. 
 
 64, Signaling Systems, 
 
 Governing wiring for telephone, telegraph, dis- 
 trict messenger and call-bell circuits, fire and bur- 
 glar alarms, and all similar systems which are 
 hazardous only because of their liability to become 
 crossed with electric light, heat or power circuits. 
 
 a. Outside wires should be run in underground 
 ducts or strung on poles, and kept off of the roofs 
 of buildings, except by special permission of the 
 Inspection Department having jurisdiction, and 
 must not be placed on the same cross-arm with 
 electric light or power wires. They should not 
 occupy the same duct, manhole or handhole of 
 conduit systems with electric light or power wires. 
 
 Single manholes, or handholes separated into 
 sections by means of partitions of brick or tile will 
 be considered as conforming with the above rule. 
 
 The liability of accidental crossing of overhead sig- 
 naling circuits with electric light and power circuits 
 may be guarded against to a considerable extent by 
 endeavoring to keep the two classes of circuits on dif- 
 ferent sides of the same street. 
 
 When the entire circuit from Central Station to 
 
 building i* run in underground, conduits, 
 
 Sections b to m inclusive do not apply. 
 
 b. When outside wires are run on same pole 
 with electric light or power wires, the distance 
 between the two inside pins of each cross-arm 
 must not be less than twenty-four inches. 
 
 Signaling wires being smaller and more liable to 
 break and fall, should generally be placed on the lower 
 cross-arms. 
 
MISCELLANEOUS. 89 
 
 64, Signaling Systems Continued, 
 
 When the wires are carried in approved cables, 
 the next three sections (c, d and e) do not apply. 
 
 c. Where wires are attached to the outside walls 
 of buildings, they must have an approved rubber 
 insulating covering, and on frame buildings or 
 frame portions of other buildings shall be sup- 
 ported on glass or porcelain insulators, or knobs. 
 
 d. The wires from last outside support to the 
 cut-outs or protectors mustbe of copper, and must 
 have an approved rubber insulation must be pro- 
 vided with drip loops immediately outside the 
 building and at entrance ; must be kept not less 
 than two and one-half inches apart. 
 
 e. Wires must enter building through approved 
 non-combnstible, non-absorptive, insulating bush- 
 ings sloping upward from the outside. 
 
 Installations where the Current Carrying Parts 
 of the Apparatus Installed are Capable of 
 Carrying Indefinitely a Current of Ten 
 Amperes. 
 
 f. An all-metallic circuit shall be provided, ex- 
 cept in telegraph systems. 
 
 g. At the entrance of wires to building, ap- 
 proved single pole cut-outs, designed for 251-600 
 volts potential and containing fuses rated at not 
 over ten amperes capacity, shall be provided for 
 each wire. These cut-outs must not be placed in 
 the immediate vicinity of easily ignitible stuff, or 
 where exposed to inflammable gases, or dust or 
 to flyings of combustible material. 
 
 h. The wires inside building shall be of copper 
 not less than !No. 16 B. & S. gage, and must have 
 insulation and be supported, the same as would 
 be required for an installation of electric light or 
 power wiring, 0-600 volts potential. 
 
 i. The instruments shall be mounted on bases 
 constructed of non-combustible, non-absorptive, 
 
90 CLASS E. 
 
 64, Signaling Systems Continued, 
 
 insulating material. Holes for the supporting 
 screws must be so located, or countersunk, that 
 there will be at least one-half inch space, meas- 
 ured over the surface, between the head of the 
 screw and the nearest live metal part. 
 
 Installations where the Current Carrying Parts of 
 the Apparatus Installed are Not Capable 
 j of Carrying Indefinitely a Current of Ten 
 Amperes. 
 
 j. Must be provided with an approved protective 
 device located as near as possible to the entrance 
 of wires to- building. The protector must not be 
 placed in the immediate vicinity of easily ignitible 
 stuff, or where exposed to inflammable gases or 
 dust or flyings of combustible materials. 
 
 k. Wires from entrance to building to protector 
 must be supported on porcelain insulators, so that 
 they will come in contact with nothing except 
 their designed supports. 
 
 I. The ground wire of the protective device 
 shall be run in accordance with the following 
 requirements : 
 
 1. Shall be of copper and not smaller than 
 
 No. 18 B. & S. gage. 
 
 2. Must have an insulating covering approved 
 
 for voltages from to 600, except that 
 the preservative compound may be 
 omitted. 
 
 3. Must run in as straight a fine as possible to 
 
 a good permanent ground. This may be 
 obtained by connecting to a water or gas 
 pipe connected to the street mains or to a 
 ground rod or pipe driven in permanently 
 damp earth. When connections are made 
 to pipes, preference shall be given to 
 water pipes. If attachment is made to 
 
MISCELLANEOUS. 91 
 
 64, Signaling Systems Continued, 
 
 gas pipe, the connection in all cases must 
 be made between the meter and the street 
 mains. In every case the connection shall 
 be made as near as possible to the earth. 
 
 When the ground wire is attached to a water 
 pipe or a gas pipe, it may be connected 
 by means of an approved ground clamp 
 fastened to a thoroughly clean portion of 
 said pipe, or the pipe shall be thoroughly 
 cleaned and tinned with rosin flux solder, 
 and the ground wire shall then be wrapped 
 tightly around the pipe and thoroughly 
 soldered to it. 
 
 When the ground wire is attached to a ground 
 rod driven into the earth, the ground wire 
 shall be soldered to the rod in a similar 
 manner. 
 
 Steam or hot-water pipes must not be used 
 
 for a protector ground. 
 
 in. The protector to be approved must comply 
 witli the following requirements : 
 
 For Instrument Circuits of Telegraph Systems, 
 
 1. An approved single pole cut-out, in each 
 wire, designed for 2,000 volts potential, 
 and containing fuses rated at not over 
 one ampere capacity. When main line 
 cut-outs are installed as called for in sec- 
 tion gr, the instrument cut-outs may be 
 placed between the switchboard and the 
 instrument as near the switchboard as 
 possible. 
 
 For All Other Systems, 
 
 1. Must be mounted on non-combustible, non- 
 absorptive, insulating bases, so designed 
 that when the protector is in place, all 
 parts which may be alive will be thor- 
 oughly insulated from the wall to which 
 the protector is attached. 
 
92 CLASS K. 
 
 64, Signaling Systems Continued, 
 
 2. Must have the following parts : 
 
 A lightning arrester which will operate with a 
 difference of potential between wires of 
 not over 500 volts, and so arranged that 
 the chance of accidental grounding is 
 reduced to a minimum. 
 
 A fuse designed to open the circuit in case the 
 wires become crossed with light or power 
 circuits. The fuse must be able to open 
 the circuit without arcing or serious flash- 
 ing when crossed with any ordinary com- 
 mercial light or power circuit. 
 
 A heat coil, if the sensitiveness of the instru- 
 ment demands it, which will operate before 
 a sneak current can damage the instru- 
 ment the protector is guarding. 
 
 Heat coils are necessary in all circuits nor- 
 mally closed through magnet windings, 
 which cannot indefinitely carry a current 
 of at least five amperes. 
 
 The heat coil is designed, to warm up and melt out 
 with a current large enough to endanger the 
 instruments if continued for a long time, but 
 so small that it would not blow the fuses or- 
 dinarily found necessary for such instru- 
 ments. The smaller currents are oftn called 
 " sneak " currents. 
 
 3. The fuses must be so placed as to protect 
 the arrester and heat coils, and the pro- 
 tector terminals must be plainly marked 
 "line," " instrument," "ground." 
 
 An easily read abbreviation of the above 
 words will be allowed. 
 
MISCELLANEOUS. 
 
 64, Signaling Systems Continued, 
 
 The "Following Rules Apply to All System* 
 whether the Wires from the Central Office 
 to the Building are Overhead or Under- 
 ground. 
 
 7i. Wires beyond the protector, or wires inside 
 buildings where no protector is used, must be 
 neatly arranged and securely fastened in place in 
 some convenient, workmanlike manner. 
 
 They must not come nearer than three inches 
 to any electric light or power wire in the building, 
 unless separated therefrom by some continuous 
 and firmly fixed non-conductor creating a perma- 
 nent separation ; this non-conductor to be in 
 addition to the regular insulation on the wire. 
 
 The wires would ordinarily be insulated, but the kind 
 of insulation is not specified, as the protector is relied 
 upon to stop all dangerous currents. Porcelain tubing 
 or approved flexible tubing may be used for encasing 
 wires where required as above. 
 
 o. Wires where bunched together in a vertical 
 run within any building must have a fire-resisting 
 covering sufficient to prevent the wires from 
 carrying fire from floor to floor unless they are 
 run either in non-combustible tubing or in a fire- 
 proof shaft, which shaft must be provided with 
 fire stops at each floor. 
 
 Signaling wires and electric light or power 
 wires may be run in the same shaft, provided 
 that one of these classes of wires is run in non- 
 combustible tubing, or provided that when run 
 otherwise these two classes of wires shall be 
 separated from each other by at least two inches. 
 
 In no case shall signaling wires be run in the 
 same tube with electric light or power wires. 
 
 65, Electric Gas Lighting, 
 
 a. Electric gas lighting, unless it is the fric- 
 tional system, must not be used on the same fix- 
 ture with the electric light. 
 
94 CLASS E. 
 
 65 A, Moving Picture Machines, 
 
 a. Arc lamp used as a part of moving picture 
 machines must be constructed similar to arc 
 lamps of theatres, and wiring of same must not 
 be of less capacity than No. B. & S. gage. (See 
 No. 31Ad. [1].) 
 
 b. Rheostats must conform to rheostat require- 
 ments for theatre arcs. (See No. 31 A d. [1].) 
 
 c. Top reel must be encased in a steel box with 
 hole at the bottom only large enough for film to 
 pass through, and cover so arranged that this 
 hole can be instantly closed. No solder to be 
 used in the construction of this box. 
 
 d. A steel box must be used, for receiving the 
 film after being shown, with a hole in the top only 
 large enough for the film to pass through freely, 
 with a cover so arranged that this hole can be 
 instantly closed. An opening may be placed at 
 the side of the box to take the film out, with a 
 door hung at the top, so arranged that it cannot 
 be entirely opened, and provided with spring 
 catch to lock it closed. No solder to be used in 
 the construction of this box. 
 
 e. The handle or crank used in operating the 
 machine must be secured to the spindle or shaft, 
 so that there will be no liability of its coming off 
 and allowing the film to stop in front of lamp. - 
 
 /. A shutter must be placed in front of the 
 condenser, arranged so as to be readily closed. 
 
 g. Extra films must be kept in metal box with 
 tight fitting cover. 
 
 h. Machines must be operated by hand (motor 
 driven will not be permitted) . 
 
 i. Picture machine must be placed in an en- 
 closure or house made of suitable fireproof ma- 
 terial, be thoroughly ventilated and large enough 
 for operator to walk freely on either side of or 
 back of machine. All openings into this booth 
 must be arranged so as to be entirely closed by 
 
MISCELLANEOUS. 
 
 95 
 
 65 A, Moving Picture Machines Continued, 
 
 doors or shutters constructed of the same or 
 equally good fire-resisting material as the booth 
 itself. Doors or covers must be arranged so as to 
 be held normally closed by spring hinges or 
 equivalent devices. 
 
 66, Insulation Resistance, 
 
 The wiring in any building must test free from 
 grounds ; i. e., the complete installation must have 
 an insulation between conductors and between all 
 conductors and the ground (not including attach- 
 ments, sockets, receptacles, etc.) not less than 
 that given in the following table: 
 
 Up 
 
 ( 
 
 to 5 
 10 
 25 
 
 50 
 100 
 200 
 400 
 800 
 1 1,600 
 
 amf 
 
 ( 
 ( 
 
 >eres 4,000,000 oh 
 ... 2,000,000 
 800,000 
 400,000 
 200,000 
 100,000 
 50,000 
 25 000 
 
 ins. 
 
 12,500 
 
 The test must be made with all cut-outs and 
 safety devices in place. If the lamp sockets, 
 receptacles, electroliers, etc., are also connected, 
 only one half of the resistances specified in the 
 table will be required. 
 
 67. Soldering Fluid, 
 
 <i. The following formula for soldering fluid is 
 suggested : 
 
 Saturated solution of zinc chloride 5 parts 
 
 Alcohol 4 parts 
 
 Glycerine 1 part 
 
INDEX. 
 
 Classen A, It, C and 
 
 NUMBER AND 
 
 SECTION. 
 
 Acid fumes 10 (c) & 24 (i) to 24 (fc) 
 
 Arc lamps, location requirements 19 (c) & 29 (c) 
 
 Arc lamps on constant-current systems 19 
 
 Arc lamps on constant-potential systems 29 
 
 Armored Cable, Installation of 24 (s) & 24 A 
 
 Armored Cable, Metallic sheaths to be grounded 12 (i) & 
 
 24 A (c) 
 Attendance j 
 
 Halanciug coils on three-wire systems. (See Reactive 
 
 Coils.) 
 
 Base-frames for generators and motors 1 (c) & 8 (a) 
 
 Batteries, .storage and primary 10 
 
 Bell wires . 64 
 
 Binding screws not to bear strain 28 (g) 
 
 Blocks at fixture and switch outlets 22 (e) 
 
 Bonds required on rails in car houses 33 (g) 
 
 Boxing for wires. (See Protection for Wires.) 
 
 Burglar alarms 64 
 
 Burrs and tins in fixtures 26 (6) 
 
 Bus-bars 2 (6) & 3 (e) 
 
 Bushings at entrances to buildings 12 (g) & 64 (e) 
 
 Bushings for lamp sockets 28 (/) 
 
 Bushings inside of buildings 14 (d) 
 
 Cabinets, cut-out and switch, Use, 17 (6) to 17 (d), 21 (c; & 
 
 Cabinets for rheostats and auto-starters, where required, 
 
 8 (d) 
 Cable, Armored. (See Armored Cable.) 
 
 Car houses 33 
 
 ar wiring and equipment 32 
 
 -are and attendance 6 
 
 Carrying capacity of wires, Table of ....16 
 
 iling rosettes, Use of 21 (d) 
 
 intral stations 1 to 7 
 
 Circuit-breakers, how high maybe set 21 (e) 
 
 Circuit-breakers, Installation o'f 17 & 21 
 
 Circuit breakers, where required 8 (d) & 9 
 
 Compensator coils for arc lamps 30 
 
INDEX. 
 
 NUMBER ANI> 
 SECTION. 
 
 Compensator coils for three-wire systems. (See Re- 
 active Coils.) 
 
 Concealed "knob and tube" work 24 (q) to 24 (it) 
 
 Conductors. (See Wires.) 
 
 Conduit wiring ..24 (n) to 24 (p) 
 
 Conduits, metal, Installation of 25 
 
 Constant-current systems 18 to 20 
 
 Constant-potential systems, general rules 21 to 23 
 
 Converters. (See Transformers.) 
 
 Cranes, Electric 34 A 
 
 Crossing of constant-potential pole-lines, over 5,000 volts 
 
 12 A (d) 
 
 Cut-outs, Installation of 17 &21 
 
 Cut-outs must protect all wires of the circuit 17 (a) 
 
 Cut-outs, Number of lights allowed to one. ..21 (d) & 31 (a) 
 
 Cut-outs, where required 1 (d), 2 (d), 8 (c), 21 (a), 21 (6; 
 
 & 29 (a) 
 
 Damp places 14 (/), 17 (c),24 (i) to 24 (&) & 27 (6) 
 
 Decorative lighting systems ...." 31 
 
 Distance between conductors, inside work.. .18 (d),24 (h), 
 
 24(j),24(r) &35(e) 
 Distance between conductors, outside work........ ...12 (ofl 
 
 ranees to buildings :....12 (g) & 64 i 
 
 Dynamo Rooms 
 
 12 A (c) & 12 A (d) (2) 
 
 Drip loops at entrances to buildings 12 (g) & 64 (d) 
 
 1 to 7 
 
 Economy coils for arc lamps 
 
 Electric gas lighting 65 
 
 Electric heaters 
 
 Electrolytic corrosion of underground metal work.. .12 (n) 
 
 Electro-magnetic devices for switches not approved 
 
 20 (c) 
 
 Emergency switches note to 22 (a) 
 
 Enclosed arc lamps 19 (c) & 29 (c) 
 
 Equalizers, Installation of * 
 
 Extra-high constant-potential systems 38 & 39 
 
 Fan motors hung from ceilings 8 (g) 
 
 Feeders, Railway 33 (/) 
 
 Fished wires 24 (c) & 24 (*) 
 
 Fittings, List of approved. (See inside of front cover.) 
 
 Fixture canopies 24 (w) & 26 (a) 
 
 Fixtures 26 
 
 Fixture Wiring 24 (v) to 24 (y) 
 
 Flexible cord, Use of 28 
 
 Flexible tubing, where permitted 14 (d), 24 (s) & 24 () 
 
 Foreign currents, Protection against 64 
 
 Formula for soldering fluid 67 
 
 Fuses, Installation of 1 (d), 17&21 
 
 
INDEX. 09 
 
 NUMBER AND 
 SECTION, 
 
 Gas lighting, Electric 65 
 
 General plan of arrangement of rules page 4 
 
 General suggestions for electric work page 5 
 
 Generators 1 
 
 Ground connections for lightning arresters 5 (c) 
 
 Ground connections for low-potential circuits 
 
 13 A, (c) to (g) 
 
 Ground detectors, where required 1 (a) 
 
 Ground plates, Construction of 13 A (g} 
 
 Ground return wires, trolley systems 12 (n) 
 
 Grounded trolley circuits, Light and power from 34 
 
 Grounding dynamo and motor frames ..l(c) &8 )a) 
 
 Grounding interior conduits 25 (/) 
 
 Grounding low-potential circuits 13 A 
 
 Grounding sheaths of cables 12 (i) 
 
 Grounds, testing for 7 
 
 Guard irons or wires, Use of 12 (d), 12 (wi), 12 A, (d) 
 
 Guard strips, inside work, where required, 18 (e) &24 (e) 
 
 Heaters, Electric 23 
 
 High constant potential systems 35 to 37 
 
 Incandescent lamps as resistances 4 (6) & 29 (6) 
 
 Incandescent lamps in series : 20, 21 (d), 31 & 37 
 
 Incandescent lamps, where inflammable gases exist 
 
 27 (a) 
 Induction coils. (See Reactive coils. 1 ) 
 
 Inside work 14 to 39 
 
 Insulated platforms, at high-potential machines, 1 (c) & 
 
 8 (a) 
 
 Insulating joints, when required 26 (a) 
 
 Insulation of future canopies, when required 26 (a) 
 
 Insulation of trolley wires 12 (k) 
 
 Insulation resistance of completed systems 66 
 
 Insulator spacing, inside work 24 (ft), 24 (j), 24 (r) & 35 (c) 
 
 Joint pole crossing, high pressure line 12 A (d), 2 
 
 Joints, in conductors 12 (/) & 14 (c) 
 
 Junction boxes, conduit, Installation of..24 A (/) & 25 (g) 
 
 Knob and Tube work 24 (q) to 24 (u] 
 
 Knots in flexible cord, required in sockets and rosettes 
 
 28(5-) 
 
 Lumps. (See Arc Lamps and Incandescent Lamps.) 
 
 Lighting and power from railway wires... 34 
 
 Lightning arresters, Installation of 5 
 
 Low constant-potential systems 24 to 34 
 
 Lugs for terminal connections, when required 14 (c) 
 
100 INDEX. 
 
 NUMBER AND 
 SECTION. 
 
 Mercury vapor lamps 29 A 
 
 Motor enclosures 8 (/) 
 
 Motor equipments, 550 volt, voltage allowed at genera- 
 tor or transformer note before 24 
 
 Motors 8 
 
 Moulding, metal, Installation of 25 A 
 
 Moulding, on brick walls 24 (I) 
 
 Moulding, Wires in 24 (fc) to 24 (m) 
 
 Moving picture machines, Construction of 65 A 
 
 Multiple-series systems, when permitted 8 (e), 20 (c) & 
 
 29 (a) 
 
 Oily waste 6 (6) 
 
 Open wiring 24 (g) to -24 (k) 
 
 Outlet boxes or plates, Conduit, when required. ..24 A (b) 
 
 & 25 (d) 
 
 Outline Wiring 31 B 
 
 Outside work .12, 12 A, 13, 13 A & 64 
 
 Pendants for use in hazardous places 28 (d) 
 
 Pipe-hangers for incandescent lamps 27 (a) 
 
 Pole-lines, Constant-potential, over 5,000 volts 12 A 
 
 Pole-lines, High-pressure, near buildings 12 A (e) 
 
 Portable lamps, Installation of 28 (d) 
 
 Power, transformer and switch stations Ito7 
 
 Protection for gas outlet pipes 26 (a) 
 
 Protection for motor equipments 8 (d) 
 
 Protection for outlet wires 24 () & 26 (a) 
 
 Protection for wires on side walls or columns 18 (e). 
 
 24 (e) & 35 (d) 
 
 Protective devices on signal circuits, Construction of 
 
 64 (m) 
 Protective devices on signal circuits, Installation of 
 
 64 (g) to 64 (J) 
 
 Railway power plants 9 
 
 Railway wires. (See Trolley Wires.) 
 
 Receptacles. (See Sockets.) 
 
 Resistance boxes. (See Rheostats.) 
 
 Resistances used with constant-potential arc lamps, 29(6) 
 
 Rheostats, Installation ot 4, 8 (c) & 8 (d) 
 
 Roof wiring 12 
 
 Rosettes, Use of 2l(rf) 
 
 Running-boards, Construction of 18(e) 
 
 Running-boards, where required 18 (e),24 (e) & 35 (d) 
 
 Screen of wires, at cross-over in high-pressure pole line* 
 
 over 5,000 volts 12 A(rf) (3) 
 
 Series arc lamps Is* 
 
 Series incandescent lamps 20 & 37 
 
 ' 
 
INDEX. 101 
 
 NUMBER AND 
 SECTION. 
 
 Series-multiple systems, when permitted 8 (e) &20 (c) 
 
 Service -wires, Underground 15(a), 15(c), 15(d) 
 
 Signaling systems 64 
 
 Sockets, Installation of 27 
 
 Soldering fluid, Formula for 67 
 
 Soldering stranded wires 14 (c) & 19 (d) 
 
 Spark arresters, when required 19 (c) & 29 (c) 
 
 Static electricity, due $o belt friction 1 (c) & 8 (a) 
 
 Stations and dynamo rooms I to 7 
 
 Stiff pendants for incandescent lamps 27 (a) 
 
 Storage battery rooms 10 
 
 Strips for protecting inside wires. (See Guard Strips.) 
 
 Switchboards 3 
 
 Switches, Electro-magnetic, not approved 20 (c) 
 
 Switches, Emergency note to 22 (a) 
 
 Switches, Flush, Installation of 22 (d) 
 
 Switches for constant-current systems 18 (6) 
 
 Switches in damp places 17 (c) 
 
 Switches, Indicating, when required 8 (c), 23 (6) 
 
 Switches, Installation of 17 &22 
 
 Switches must disconnect all wires of circuit 17 (a) 
 
 Switches, Service 18 (6),22(a) 
 
 Switches, Single-pole, when permitted 8(c) &22(c. 
 
 Switches, Snap, when preferred 22 (6) 
 
 Switches, Time 17 (d} 
 
 Systems, Constant-current ... ..18 to 20 
 
 Systems, Constant-potential, general rules 21to23 
 
 Systems, Extra-high constant-potential 38&S9 
 
 Systems, High constant-potential 35 to3' 
 
 Systems, Low constant-potential. 24 to 34 
 
 Systems, Multiple- series 8 (e) & 20 (c) 
 
 Systems, Series-multiple 8 (e) and 20 (c) 
 
 Systems, Signaling 64 
 
 Telegraph, telephone and signaling circuits 64 
 
 Testing for grounds 7 
 
 Testing for insulation resistance of completed systems, 
 
 Theatre wiring 31 A 
 
 Three-pole cross-over for high-pressure line 12 A (d-1) 
 
 Tie wires 12 (a) &14 (6j 
 
 Transformers, grounding of secondaries 13 A(6i 
 
 Transformers, Installation of, inside 11 and 36 
 
 Transformers, Installation of, outside 13 
 
 Transformer stations Ito7 
 
 Transmission lines, constant-potential, over 5,000 volts 
 
 12 A 
 
 Trolley circuits, Grounded, Light and power from 34 
 
 Trolley wires 120') to 12 (m) 
 
 Tubes, Insulating. (See Bushings.) 
 Tubing, Flexible. (See Flexible Tubing.) 
 
102 INDEX. 
 
 NUMBER AHD 
 SECTION. 
 
 "Voltmeter, Switchboard, circuit for ........................... 2 (d) 
 
 Waste, oily ...................................................................... 6(6) 
 
 Waterproof construction ............................. 24 (f) to 24 (k) 
 
 Waterproof pendants ................................................. 27 (6) 
 
 Wire, Netting required on arc lamps ........... 19 (c) & 29 (c) 
 
 Wires, Carrying capacity table ....................................... 16 
 
 Wires, Car Work ............................................................ 32 
 
 Wires, Concealed "knob and tube "work. ..24 (q) to 24 (u) 
 Wires, Conduit work ................................ 24 (n) to 24 (p) 
 
 Wires, Constant-current systems .................................. 18 
 
 Wires in stations and dynamo rooms .......................... 2 (e) 
 
 Wires, Spacing, inside work ......... 18 (d),24 (A), 24 (j), 24 (r) 
 
 & 35 (c) 
 Wires, Spacing, outside work .................. 12 (6), 12 A (c) & 
 
 12 A (d-2) 
 Wires, Extra-high constant-potential systems ...... .38 & 39 
 
 Wires, Fished ............... ................................... 24 (c)&24 (s) 
 
 Wires, Fixture work ....................................... 24(u) to 24 (y) 
 
 Wires, Ground- re turn, trolley systems ..................... 12 (n) 
 
 Wires, High constant-potential systems ........................ 35 
 
 Wires, Inside work, general rules .................................. 14 
 
 Wires, Inside work, protection in crossing wires and 
 pipes .................................................................... 14 (e) 
 
 Wires, Low constant-potential systems .......................... 24 
 
 Wires, Moulding -work .................................... 24 (I) &24(w) 
 
 Wires, of high-pressure pole lines near buildings, 12 A (e) 
 Wires on roofs .................................................................... 12 
 
 Wires, Open work, damp places ..... 14 (/) &24 (i) to 24 (K) 
 
 Wires, Openwork, dry places ....................... 24 (g) &24 (h) 
 
 Wires, Outside ............................................. 12 and 12 A 
 
 Wires, Service ......................................... 12 (a), 12 (g), 64 (d) 
 
 Wires, Signal ................................................................... 64 
 
 Wires, Stranded ............................................ 14 (c) & 19 (d) 
 
 Wires, Tie ....................................... 12 (a) and 14 (6) 
 
 Wires, Trolley, installation of ..................... 12 (j) to 12 (TO) 
 
 Wires, Trolley, Light and power from ........................... 34 
 
 Wires, Twin when permitted 
 
 Wires, Twin when pe 
 
 Wires, Underground .............................................. 12 (i) & 15 
 
 Wires, when considered exposed to moisture ......... 24 (./) 
 
 vyiring, General suggestions for .............................. P a ge 5 
 

Information regarding tests mac 
 these rules can be obtained by ad 
 Underwriters' Laboratories, Chicago, 
 
\ 
 
 
 Q.O "775 M- 
 
 THE UNIVERSITY OF CALIFORNIA LIBRARY