1909

"NATIONAL ELECTRICAL CODE."

INSTALLATION RULES (Except Marine Work)

OF THE

National Board of Fire Underwriters

FOR

ELECTRIC WIRING

AND

APPARATUS

As Recommended by the

UNDERWRITERS' NATIONAL ELECTRIC ASSOCIATION

EDITION OF 1909

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 composing the National Conference on Standard Electrical 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 Association. Associated Factory Mutual Fire Ins. Co's. Association of Edison Illuminating Companies. International Association of Municipal Electricians. National Board of Fire Underwriters. National Electric Light Association. National Electrical Contractors' 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 the contractor "on the job," and is for general distribution. Another volume is issued in a small edition containing 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 the contractor all the information as to approved devices which he may need.

GENERAL PLAN

GOVERNING THE ARRANGEMENT OF RULES

CLASS A.—STATIONS AND DYNAMO ROOMS. Includes Central Stations; Dynamo, Motor, and Storage-Battery Rooms; Transformer Sub-stations, 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 volts. Rules 35 to 37. Extra-High-Potential Systems, over 3,500 volts. Rules 38 and 39.

CLASS D.—FITTINGS, MATERIALS, AND DETAILS OF CONSTRUCTION, all systems and voltages. Rules 40 to 63.

NOTE.—Class D is omitted from this 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 must 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 complicated 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 channeling and pocketing of buildings for electric light or power wires, and also for telephone, district messenger 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.

b. 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.

d. Constant potential generators, except alternating 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 generators 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, capacity in volts and amperes, and the normal speed in revolutions per minute.

f. 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 generators 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 bushings 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 :—

a. Must be in plain sight or readily accessible. Wires from generator to switchboard may, however, be placed in a run-way in the brick or cement pier on which the generator stands. When protection against moisture is necessary, lead covered cable or iron conduit must be used. b. 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 together, 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 should 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 volume 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.

3. Switchboards.

a. Must be so placed as to reduce to a minimum the danger of communicating fire to adjacent combustible material. Switchboards must not be built up to the ceiling, a space of three feet being left, if 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-carrying parts of the apparatus on the switchboard must be separated therefrom by non-combustible, 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 better 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, if not thereon, at a distance of at least one foot from combustible material, or separated therefrom by a non-combustible, non-absorptive, insulating material, such as slate or marble.

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 porcelain 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 receptacle 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 connection between resistances and the contact plate of a rheostat, the insulation must be slow burning (see Rule 43). 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 difference 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 at least ½ inch separation from surface wired over, or, where it is necessary to protect the wires from mechanical injury or moisture, be run in approved lined conduit or equivalent.

5. Lightning Arresters.

(For construction requirements, see Rule 63.)

a. Must be attached to each wire of every overhead 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.

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 metal cans and removed daily.

7. Testing of Insulation Resistance.

a. All circuits except such as are permanently grounded in accordance with Rule 13 A must be provided with reliable ground detectors. Detectors 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.

b. Where continuously indicating detectors are not feasible, the circuits should be tested at least once per day, and preferably oftener.

c. Data obtained from all tests must be preserved for examination by the Inspection Department having jurisdiction.

8. Motors.

a. Must, when operating at a potential in excess 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 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.

b. 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 approved unlined metal conduit firmly secured in 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 Rule 25 and Rule 49 a, j and k), except that at outlets approved outlet bushings shall be used.

The motor leads or branch circuits must be designed to carry a current at least 25 per cent. greater than that for which the motor is rated, in order to provide for the inevitable occasional overloading of the motor, and the increased current required in starting, without overfusing the wires; but where the wires under this rule would be overfused, in order to provide for the starting current, 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 substantially bonded to the metal casings of all fittings and apparatus connected to the inside high-tension circuit. It would be much preferable to make the conduit system continuous throughout by connecting the conduit to fittings and motors by means of screw joints, and this construction is strongly recommended wherever practicable.

High-potential motors should preferably be so located that the amount of inside wiring will be reduced to a minimum.

Inspection department having jurisdiction may permit the wire for high-potential motors to be installed according to the general rules for high-potential systems when the outside wires directly enter a motor room (see Section f). Under these conditions there would generally be but a few feet of wire inside the building, and none outside the motor room.

c. Each motor and resistance box must be protected by a cut-out and controlled by a switch (see Rule 17 a), said switch plainly indicating whether "on" or "off." With motors of one-fourth horse power or less, on circuits where the voltage does not exceed 300, Rule 21 d must be complied with, and single pole switches may be used as allowed in Rule 22 c. The switch and rheostat must be located within sight of the motor, except in cases where special permission to locate them elsewhere is given, in writing, by the Inspection Department having jurisdiction.

The use of circuit-breakers with motors is recommended, and may be required by the Inspection Department having jurisdiction.

Where the circuit-breaking device on the motor starting rheostat disconnects all wires of the circuit, the switch called for in this section may be omitted.

Overload release devices on motor-starting rheostats will not be considered to take the place of the cut-out required by this section if they are inoperative during the starting of the motor.

The switch is necessary for entirely disconnecting the motor when not in use, and the cut-out to protect the motor from excessive currents due to accidents or careless handling when starting. An automatic circuit-breaker disconnecting all wires of the circuit may, however, serve as both switch and cut-out.

In general, motors should preferably have no exposed live parts.

d. Rheostats must be so installed as to comply with all the requirements of Rule 4. Auto starters must comply with requirements of Rule 4 c.

e. Must not be run in series-multiple or multiple-series, except on constant potential systems, and then only by special permission of the Inspection Department having jurisdiction.

f. 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.

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.

i. Terminal blocks when used on motors must be made of approved non-combustible, non-absorptive, insulating material such as slate, marble or porcelain. j. Variable speed motors, unless of special and appropriate design, if controlled by means of field regulation, must be so arranged and connected that they cannot be started under weakened field.

9. Railway Power Plants.

a. Each feed wire before it leaves the station must be equipped with an approved automatic circuit-breaker (see Rule 52) or other device, which will immediately cut off the current in case of an accidental ground. This device must be mounted on a fireproof 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 Rules 24 i to 24 k)

d. All secondary batteries must be mounted on non-combustible, non-absorptive insulators, such as glass or thoroughly vitrified and glazed porcelain.

e. The use of any metal liable to corrosion must be avoided in cell connections of secondary batteries.

11. Transformers.

(For construction rules, see Rule 62.)

(See also Rules 13, 13 A and 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 harm.

b. In central or sub-stations casings of all transformers must be permanently and effectively grounded.

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 weatherproof or rubber insulating covering (see Rules 44 and 41). That portion 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 (see Rule 41), but from the above-mentioned support to the line, may have an approved weatherproof insulating covering (see Rule 44), if kept free from awnings, swinging signs, shutters, etc.

b. Must be so placed that moisture cannot form a cross connection between them, 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 waterproof paint.

c. Must be at least 7 feet above the highest point of flat roofs, and at least 1 foot above the ridge of pitched roofs over which they pass or to which they are attached.

d. Must be protected by dead insulated guard irons or wires from possibility of contact with other conducting wires or substances to which current may leak. Special precautions of this kind must be taken where sharp angles occur, or where any wires might possibly come in contact with electric light or power wires.

e. Must be provided with petticoat insulators of glass or porcelain. Porcelain knobs or cleats and rubber hooks will not be approved.

f. Must be so spliced or joined as to be both mechanically and electrically secure without solder. The joints must then be soldered, to insure preservation, and covered with an insulation equal to that on the conductors.

g. Must, where they enter buildings, have drip loops outside, and the holes through which the conductors pass must be bushed with non-combustible, non-absorptive insulating tubes slanting upward toward the inside.

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 26 inches.

i. The metallic sheaths to cables must be permanently and effectively connected to "earth."

Trolley Wires.

j. Must not be smaller than No. 0 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 current may be shut off from the particular section and not interfere with the work of the firemen. This rule also applies to feeders.

m. Must be safely protected against accidental contact where crossed by other conductors.

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 potential between the grounded dynamo terminal and any point on the return circuit will not exceed 25 volts.

12 A. Constant-Potential Pole Lines, Over 5,000 Volts.

(Overhead lines of this class unless properly arranged may increase the fire loss from the following causes :—

Accidental crosses between such lines and low-potential lines may allow the high-voltage current to enter 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 fire in the building. The object of these rules is so to direct this class of construction that no increase in fire 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 cover 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, where there is a liability to contact, the route should be changed by mutual agreement between the parties in interest wherever possible.

b. 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 signalling 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 Section b 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 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 3 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:—

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.
A joint pole may be erected at the crossing point, the high-pressure wires being supported on this pole at least 3 feet above the other wires. Mechanical guards or supports must then be provided, 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.

Such liability of contact may be prevented by the use of suspension wires, similar to those employed for suspending aerial telephone cables, which will prevent the high-pressure wires from falling, in case they break. The suspension wires should be supported 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 contact likely to occur under the conditions existing.

Whenever neither of the above methods is feasible, a screen of wires should be interposed 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.

e. When it is necessary to carry such lines near buildings, they must be at such height and distance 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 accordance with the following table:—

Distance of wire from building (Feet)	Elevation of wire above cornice of building (Feet)
25	0
20	2
15	4
10	6
5	8
2½	9

13. Transformers.

(For construction requirements, see Rule 62.) (See also Rules 11, 13 A and 36.)

a. Must not be placed inside of any building, excepting central stations and sub-stations, unless by special permission of the Inspection Department having jurisdiction.

b. Must not be attached to the outside walls of buildings, unless separated therefrom by substantial supports.

13 A. Grounding Low-Potential Circuits.

The grounding of low-potential circuits under the following 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.

Direct-Current 3-Wire Systems.

a. Neutral wire may be grounded, and when grounded the following rules must be complied with:—

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.
In underground systems the neutral wire must also be grounded at each distributing box through the box.
In overhead systems the neutral wire must be grounded every 500 feet, as provided in Sections c to g.

Alternating-Current Secondary Systems.

b. Transformer secondaries of distributing systems should preferably be grounded, and when grounded, the following rules must be complied with :—

The grounding must be made at the neutral point or wire, whenever a neutral point or wire is accessible.
When no neutral point or wire is accessible, one side of the secondary circuit may be grounded, provided the maximum difference of potential between the grounded point and any other point in the circuit does not exceed 250 volts.
The ground connection must be at the transformer or on the individual service as provided in sections c to g, and when transformers feed systems with a neutral wire, the neutral wire must also be grounded at least every 250 feet for overhead systems, and every 500 feet for underground systems.

Ground Connections.

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 0 to 600 volts. (See Rule 41.)

d. The ground wire in direct-current 3-wire systems 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 alternating-current systems must never be less than No. 4. B. & S. gage.

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, avoiding kinks, coils and sharp bends, and must be protected when exposed to mechanical injury.

f. The ground connection for central stations, transformer sub-stations and banks of transformers must be made through metal plates buried in coke below permanent moisture level, and connection should also be made to all available underground piping systems, including the lead sheath of underground cables.

g. For individual transformers and building services, the ground connection may be made as in Section f, or may be made to water piping systems 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 protected 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 sweated into a lug attached to an approved clamp, and the clamp firmly bolted to the water pipe after all rust and scale have been removed; or be soldered into a brass plug and the plug forcibly screwed into a pipe-fitting, or, where the pines 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 probably answer for the ordinary sub-station or bank of transformers. For a large central station, a plate with considerably 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 protected 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 RULES.

14. Wires.

(For special cases, see Rules 18, 24, 35, 38 and 39.)

a. Must not be of smaller size than No. 14 B. & S. gage, except as allowed under Rules 24 v and 45 b.

b. Tie wires must have an insulation equal to that of the conductors they confine.

c. Must be so spliced or joined as to be both mechanically and electrically secure without solder. The joints must then be soldered to insure preservation, and covered with an insulation equal to that on the conductors. Stranded wires 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.

d. Must be separated from contact with walls, floors, timbers or partitions through which they may pass by non-combustible, non-absorptive insulating tubes, such as glass or porcelain, except as provided in Rule 24 u.

e. Must be kept free from contact with gas, water or other metallic piping, or any other conductors 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.

f. 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.

15. Underground Conductors.

a. Must be protected against moisture and mechanical 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 current 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 98% conductivity, according to the standard adopted by the American Institute of Electrical Engineers, must be followed in placing interior conductors.

	Table A.	Table B.
	Rubber Insulation.	Other Insulations.
	See Rule 41.	See Rules 42 to 44.
B. & S. G.	Amperes.	Amperes.	Circular Mils.
18	3	5	1,624
16	6	8	2,583
14	12	16	4,107
12	17	23	6,530
10	24	32	10,380
8	33	46	16,510
6	46	65	26,250
5	54	77	33,100
4	65	92	41,740
3	76	110	52,630
2	90	131	66,370
1	107	156	83,690
0	127	185	105,500
00	150	220	133,100
000	177	262	167,800
0000	210	312	211,600
Circular Mils.
200,000	200	300
300,000	270	400
400,000	330	500
500,000	390	590
600,000	450	680
700,000	500	760
800,000	550	840
900,000	600	920
1,000,000	650	1,000
1,100,000	690	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

17. Switches, Cut-Outs, Circuit-Breakers, etc.

(For construction requirements, see Rules 51, 52 and 53.)

a. On constant potential circuits, all service switches and all switches controlling circuits supplying current to motors or heating devices, and all cut-outs, unless otherwise provided (for exceptions as to switches see Rules 8 c and 21 a; for exceptions as to cut-outs see Rules 21 a and b), must be so arranged that the cut-outs will protect and the opening of the switch or circuit-breaker 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 cut-out and disconnected by the operation of the switch or circuit-breaker.

b. 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.

c. Must, when exposed to dampness, either be enclosed in a moisture-proof box or mounted on porcelain knobs.

d. Time switches, sign flashers and similar appliances must be of approved design and enclosed in a steel box, a cabinet lined with fire-resisting material.

CONSTANT-CURRENT SYSTEMS.

PRINCIPALLY SERIES ARC LIGHTING.

18. Wires.

(See also Rules 14, 15 and 16.)

a. Must have an approved rubber insulating covering (see Rule 41).

b. Must be arranged to enter and leave the building through an approved double-contact service switch (see Rule 51 b), 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.

d. Must be supported on glass or porcelain insulators which separate the wire at least 1 inch from the surface wired over and must be kept rigidly at least 8 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, retaining an air space of 1 inch around the conductors, closed at the top (the wires passing through bushed holes), and extending not less than 7 feet from the floor. When crossing floor timbers in cellars, 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 ½ inch in thickness. Instead of the running-boards, guard strips on each side of and close to the wires will be accepted. These strips to be not less than ⅞ inch in thickness and at least as high as the insulators.

19. Series Arc Lamps.

(For construction requirements, see Rule 57.)

a. Must be carefully isolated from inflammable material.

b. 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 1¼ inches) around the globe, and an approved spark arrester (see Rule 58), when readily inflammable material is in the vicinity of the lamps, to prevent escape of sparks of carbon or melted copper. It is recommended that plain carbons, not copper-plated, be used for lamps in such places.

d. Where hanger-boards (see Rule 56) are not used, lamps must be hung from insulating supports other than their conductors.

e. 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.

20. Incandescent Lamps in Series Circuits.

a. Must have the conductors installed as required in Rule 18, and each lamp must be provided with an automatic cut-out.

b. 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.

CONSTANT-POTENTIAL SYSTEMS.

GENERAL RULES—ALL VOLTAGES.

21. Automatic Cut-Outs — Fuses and circuit-breakers.

(For construction requirements, see Rules 52 and 53.) (See also Rule 17.)

a. Must be placed on all service wires, either overhead or underground, as near as possible to the point where they enter the building and inside the walls, and arranged to cut off the entire current from the building.

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 Rule 16)].

c. Must be in plain sight, or enclosed in an approved cabinet (see Rule 54), and readily accessible. They must not be placed in the canopies or shells of fixtures.

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 case of large chandeliers. (For exceptions, see Rules 31 A, b 3 [b] and 4 [b], for border lights.) 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 outside wires is over 250 volts, and both wires of such branch or tap circuits must be protected by proper fuses.

e. The rated capacity of fuses must not exceed the allowable carrying capacity of the wire as given in Rule 16. Circuit-breakers must not be set more than 30% above the allowable carrying capacity of the wire, unless a fusible cut-out is also installed in the circuit.

22. Switches.

(For construction requirements, see Rule 51) (See also Rule 17.)

a. Must be placed on all service wires, either overhead or underground, in a readily accessible place, as near as possible to the point where the wires enter the building, and arranged to cut off the entire current.

b. Must always be placed in dry, accessible places, and be grouped as far as possible. (See Rule 17 c.) Single-throw knife switches must be so placed that gravity will tend to open rather than close them. Double-throw knife switches may be mounted so that the throw will be either vertical or horizontal as preferred.

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 described in 21 d.

d. Where flush switches or receptacles are used, whether with conduit systems or not, they must be enclosed in boxes constructed of iron or steel. No push-buttons for bells, gas-lighting circuits, or the like shall be placed in the same wall plate with switches controlling electric light or power wiring.

e. Where possible, at all switch or fixture outlets, a ⅞-inch block must be fastened between studs or floor timbers flush with the back of lathing to hold tubes, and to support switches or fixtures. When this cannot be done, wooden base blocks, not less than ¾-inch in thickness, securely screwed to lathing, must be provided for switches, and also for fixtures which are not attached to gas pipes or conduit.

f. Sub-bases of non-combustible, non-absorptive insulating material, which will separate the wires at least ½ inch from the surface wired over, must be installed under all snap switches used in exposed knob and cleat work. Sub-bases must also be used in moulding work, but they may be made of hardwood.

23. Electric Heaters.

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.

b. Must never be concealed but must at all times be in plain sight.

c. Flexible conductors for smoothing irons and sad irons, and for all devices requiring over 250 watts, must comply with Rule 45, section g.

d. For portable heating devices the flexible conductors must be connected to an approved plug device, so arranged that the plug will pull out 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 inflammable 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.

f. Stationary electric heating apparatus, such as radiators, ranges, plate warmers, etc., must be placed in a safe location, isolated from inflammable materials, and be treated as sources of heat.

g. Must each be provided with name-plate, giving the maker's name and the normal capacity in volts and amperes.

LOW-POTENTIAL SYSTEMS.

550 VOLTS OR LESS.

Any circuit attached to any machine, or combination of machines, which develops a difference of potential, between any two wires, of over 10 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 10 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 Rule 12 A, or are underground.

Before pressure is raised above 300 volts on any previously existing system of wiring, the whole must be strictly brought up to all of the requirements of the rules at date.

24. Wires.

GENERAL RULES.

(See also Rules 14, 15, and 16.)

a. Must be so arranged that under no circumstances will there be a difference of potential of over 300 volts between any bare metal parts in any distributing switch or cut-out cabinet, or equivalent center of distribution.

b. Must not be laid in plaster, cement, or similar finish, and must never be fastened with staples.

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 necessary.

e. Must be protected on side walls from mechanical injury. When crossing floor timbers in cellars, 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 ½ inch in thickness, and not less than 3 inches in width. Instead of the running-boards, guard strips on each side of and close to the wires will be accepted. These strips to be not less than ⅞ inch in thickness, and at least as high as the insulators.

Suitable protection on side walls should extend not less than five feet from the floor. This may be secured by a substantial boxing, retaining an air space of one inch around the conductors, closed at the top (the wires passing through bushed holes) or by approved metal conduit, or pipe of equivalent strength.

When metal conduit or pipe is used, the insulation 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 Rule 25 (sections c and f excepted), and the wire used complies with Rule 47. The two or more wires of a circuit each with its flexible tubing (when required), if carrying alternating current must, or if direct current, may be placed within the same pipe.

In damp places the wooden boxing may be preferable because of the precautions which would be necessary 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.

f. When run in unfinished attics, will be considered as concealed, and when run in close proximity to water tanks or pipes, will be considered as exposed to moisture.

SPECIAL RULES.

For Open Work.

In dry places:—

g. Must have an approved rubber, slow-burning weatherproof, or slow-burning insulation (see Rules 41, 42 and 43.)

h. Must be rigidly supported on non-combustible, non-absorptive insulators, which will separate the wires from each other and from the surface wired over in accordance with the following table:—

Voltage.	Distance from Surface.	Distance between Wires.
0 to 300	½ inch	2½ inch
301 to 550	1 "	4 "

In damp places or buildings especially subject to moisture or to acid or other fumes liable to injure the wires or their insulation:—

i. Must have an approved insulating covering.

j. Must be rigidly supported on non-combustible, non-absorptive insulators, which separate the wire at least 1 inch from the surface wired over, and must be kept apart at least 2½ inches for voltages up to 300, and 4 inches for higher voltages.

For Moulding Work (Wooden and Metal).

(For construction requirements, see Rule 50.) (See also Rule 25 A.) k. Must have an approved rubber insulating covering. (For wooden moulding, see Rule 41, for metal moulding see Rule 47.)

l. 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.

m. Must for alternating current systems if in metal moulding have the two or more wires of a circuit installed in the same moulding.

For Conduit Work.

n. Must have an approved rubber insulating covering (see Rule 47).

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 accordance with the following table:— No. 14 to 0 every 100 feet. No. 00 to 4-0 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. A turn of 90° in the conduit system will constitute a satisfactory support, as per above table. The following methods of supporting cables are recommended :—

Junction boxes may be inserted in the conduit system at the required intervals, in 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.
Cables may be supported in approved junction boxes on two or more insulating supports so placed that the conductors will be deflected at an angle of not less than 90°, and carried a distance of not less than twice the diameter of the cable from its vertical position. Cables so suspended may be additionally secured to these insulators by tie wires. Other methods, if used, must be approved by the Inspection Departments having jurisdiction.

p. Must, for alternating systems, have the two or more wires of a circuit drawn into the same conduit.

For Concealed "Knob and Tube" Work.

q. Must have an approved rubber insulating covering. (See Rule 41.)

r. Must be rigidly supported on non-combustible, non-absorptive insulators which separate the wire at least one inch from the surface wired over. Should preferably be run singly on separate timbers, or studdings, 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 insulating tubes, such as glass or porcelain.

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 (see Section t), 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 outlet, or from outlet to outlet.

t. Mixed concealed "knob and tube" work, as provided for in Section s, must comply with the requirements of Section n to p, and Rule 25, when conduit is used, and with the requirements of Rule 24 A, when armored cable is used.

u. Must at all outlets, except where conduit is used, be protected by approved flexible insulating tubing, extending in continuous lengths from the last porcelain support to at least 1 inch beyond the outlet. In the case of combination fixtures, the tubes must extend at least flush with outer end of gas cap.

For Fixture Work

v. Must have an approved rubber insulating covering (see Rule 46), and be not less in size than No. 18 B. & S. gage.

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 fulfilment of this requirement.

x. Must, when fixtures are wired outside, be so secured as not to be cut or abraded by the pressure of the fastenings or motion of the fixture.

y. Under no circumstances must there be a difference of potential of more than 300 volts between wires contained in or attached to the same fixture.

24 A. Armored Cables.

(For construction requirements, see Rule 48.)

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 secured in position.

b. Must be equipped at every outlet with an approved outlet box or plate, as required in conduit work. (See Rule 49 A.)

c. Must have the metal armor of the cable permanently and effectively grounded.

d. When installed in so-called fireproof buildings in course of construction or afterwards if concealed, or where it is exposed to the weather, or in damp places such as breweries, stables, etc., the cable must have a lead covering at least 1-32 inch in thickness placed between the outer braid of the conductors and the steel armor.

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.

f. 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.

25. Interior Conduits.

(See also Rules 24 n to p, and 49.)

a. No conduit tube having an internal diameter of less than ⅝ inch shall be used. Measurements to be taken inside of metal conduits.

b. Must be continuous from outlet to outlet or 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.

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. (See Rule 49 A.)

e. Metal conduits where they enter junction boxes and at all other outlets, etc., must be provided with approved bushings 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.

f. Must have the metal of the conduit permanently and effectually grounded.

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 must not be less than 3½ inches. Must have not more than the equivalent of four quarter bends from outlet to outlet, the bends at the outlets not being counted.

25A. Metal Mouldings.

(See also Rules 24 k to m, and 50.)

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 insulation 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 from the ceiling below to a point five feet above the floor, which will serve as an additional mechanical protection and exclude the presence of moisture often prevalent in such locations.

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 permanently and effectively grounded, and must be so installed that adjacent lengths of moulding will be mechanically and electrically secured at all points.

e. Must be installed so that for alternating systems the two or more wires of a circuit will be in the same metal moulding.

26. Fixtures.

(See also Rules 22 e, 24 v to y.)

a. Must, when supported from the gas piping or any grounded metal work of a building, be insulated from such piping or metal work by means of approved insulating joints (see Rule 59) placed as close as possible to the ceiling or walls.

b. Must have all burs or fins removed before the conductors are drawn into the fixture.

c. Must be tested for "contacts" between conductors and fixture, for "short circuits" and for ground connections before it is connected to its supply conductors.

d. All fixture arms made of tubing smaller than ½ 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 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.

27. Sockets.

(For construction requirements, see Rule 55.)

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 (see Rule 41) soldered directly to the circuit.

b. In damp or wet places "waterproof" sockets must be used. Unless made up on fixtures they must be hung be separate stranded rubber-covered wires, not smaller than No. 14 B. & S. gage, which should preferably be twisted together when the pendant is over three feet long. These wires must be soldered direct to the circuit wires but supported independently of them.

c. Key sockets will not be approved if installed over especially inflammable stuff, or where exposed to flyings of combustible material.

28. Flexible Cord.

a. Must have an approved insulation and covering. (See Rule 45.)

b. Must not be used where the difference of potential between the two wires is over 300 volts.

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.

The practice of making the pendants unnecessarily long and then looping them up with cord adjusters is strongly advised against. It offers a temptation to carry about lamps which are intended to hang freely in the air, and the cord adjusters wear off the insulation very rapidly.

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 are on the market, and should be used. (See Rule 45 f.)

The standard socket is threaded for ⅛ inch pipe, and if it is properly bushed, the reinforced flexible cord will not go into it, but this style of cord may be used with sockets threaded for ⅜-inch pipe, and provided with substantial insulating bushings. The cable to be supported independently of the overhead circuit by a single cleat, and the two conductors then separated and soldered to the overhead wires.

e. Must not be used in show windows except when provided with an approved metal armor.

f. 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 device 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.

For construction requirements, see also Rule 57

a. Must have a cut-out (see Rule 17 a) for each lamp or each series of lamps.

b. 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 Rules 19 and 58).

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.

30. Economy Coils.

a. Economy and compensator coils for arc lamps must be mounted on non-combustible, non-absorptive insulating supports, such as glass or porcelain, allowing an air space of at least 1 inch between frame and support, and must in general be treated as sources of heat.

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 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 1320 watts shall be dependent on one cut-out.

b. Incandescent lamps connected in series must not be used for decorative purposes inside of buildings except by special permission in writing from the Inspection Department having jurisdiction.

31 A. Theatre Wiring. {INCOMPLETE}

INCOMPLETE SECTION, SOURCE DID NOT INCLUDE THIS PART

32. Car Wiring and Equipment of Cars. {INCOMPLETE}

INCOMPLETE SECTION, SOURCE DID NOT INCLUDE THIS PART

a. Protection of Car Body, etc.

Under side of car 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 H. 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.
At motors of over 75 H. P. each, fire-resisting material or sheet iron or steel extend to not less than 8 inches beyond all edges of openings in motors, and not less than 6 inches beyond motor leads on all sides.
Over resistances, contactors, and lightning arresters, and other electrical apparatus, excepting when amply protected by their casing, fire-resisting material or sheet iron or steel to extend not less than 8 inches beyond all edges of the devices.
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 between the conduit and the car, fire-resisting material or sheet iron or steel to extend at least 6 inches beyond conductors on either side.

In 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.
Cut-out and switch cabinets to be substantially 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.

b. Wires, Cables, etc.

All conductors to be stranded, the allowable carrying capacity being determined by Table "A" of Rule 16, except that motor, trolley and resistance 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 a 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.	Motor Leads.	Trolley Leads.	Resistance Leads.
75 H. P. or less	50%	40%	15%
Over 75 H. P.	45%	35%	15%

To have an insulation and braid as called for by Rule 41 for wires carrying currents of the same potential.
When run in metal conduit, to be protected by an additional braid as called for by Rule 47.

When not in conduit, in approved moulding, or in cables surrounded by 1-8 inch flameproof covering, must comply with the requirements of Rule 41—except that tape may be substituted for braid—and be protected by an additional flameproof braid, at least 1-32 inch in thickness, the outside being saturated with a preservative flameproof compound.

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.

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 terminals soldered to the cable, and securely fastened to the device, by bolts, screws, or by clamping; or, the end of the cable, after the insulation is removed, 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 turned-up 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. 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.

c. Cut-outs, Circuit Breakers and Switches.

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.
Cut-outs to be of the approved cartridge or approved blow-out type.
All switches controlling circuits of over5 ampere capacity shall be of approved single pole, quick break, or approved magnetic blow-out type. INSIDE WORK. Switches controlling circuits of 5 ampere or less capacity may be of the approved single pole, double break, snap type.
Circuit breakers to be of approved type.
Circuits must not be fused above their safe carrying capacity.
A cut-out must be placed as near as possible to the current collector, so that the opening of the fuse in this cut-out will cut off all current from the car.

d. Conduit.

Metal conduits, outlet and junction boxes to be constructed in accordance with Rule 49, except that conduit for lighting circuits 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.
Must be continuous between and be firmly secured into all outlet or junction boxes and fittings, making a thorough mechanical and electrical connection between same.
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.
Except as noted in Section i, 2, must have the metal of the conduit permanently and effectively grounded.
Junction and outlet boxes must be installed in such a manner as to be accessible.
All conduits, outlets, or junction boxes and fittings to be firmly and substantially fastened to the framework of the car.

e. Moulding.

To consist of a backing and a capping and to be constructed of fire-resisting insulating material, except where circuits which they are designed to support are nominally not exposed to moisture, they may be constructed of hard wood.
When constructed of fire-resisting insulating material, the backing shall be not less than 1-4 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-inside and outside with a waterproof paint.

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 outside and inside two coats of waterproof paint. The backing and the capping shall be secured in place by screws.

f. Lighting and Lighting Circuits.

Each outlet to be provided with an approved porcelain receptacle, or an approved cluster. No lamp of over 32 candle power to be used.
Circuits to be run in approved metal conduit, or approved moulding.
When metal conduit is used, except for sign lights, all outlets to be provided with approved outlet boxes.
At outlet boxes, except where approved clusters are used, porcelain 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 conduit, being mounted on blocks of hard wood or fire-resisting insulating material.
Where conductors are run in moulding the porcelain receptacles or cluster to be mounted on blocks of hard wood or of fireproof insulating material.

g. Heaters and Heating Circuits.

Heaters to be of approved type.
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.
Circuits to be run in approved metal conduit, 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 supports 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

Circuits to be run in approved metal conduit or in approved moulding, except that when run below the floor of the car they may be supported 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.
Automatic control to be enclosed in an approved 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.

Conductors connecting between trolley stand and main cut-out or circuit breakers in hood, to be protected where wires enter prevent ingress of moisture.
Conductors connecting between third rail shoes on the same truck, to be supported in an approved fire-resisting insulating moulding, or in approved iron conduit supported by soft rubber or other approved insulating cleats.
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.

Conductors with flameproof braided outer covering, connecting between controllers at either 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 canvas 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 without flameproof 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 throughout 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 conduit 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 insulating material.
Motors to be so drilled that, on double truck cars, connecting cables can leave motor on side nearest to king bolt.
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 between 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 porcelain bushing or asbestos sleeve.
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

To be preferably located to protect all auxiliary circuits in addition to main motor circuits.
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.

k. General Rules.

When passing through floors, conductors or cables must be protected by approved insulating bushings, which shall fit the conductor or cable as closely as possible.
Moulding should never be concealed except where readily accessible. Conductors should never be tacked into moulding.
Short bends in conductors should be avoided where possible.
Sharp edges in conduit or in moulding must be smoothed to prevent injury to conductors.

33. Car Houses.

a. The trolley wires must be securely supported on insulating hangers.

b. The trolley hangers must be placed at such a distance apart that, in case of a break in the 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 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.

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 incandescent 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 capacity at least equivalent to No. 00 B. & S. gage annealed copper wire, and all rails must be connected to the outside ground return circuit by a not less than No. 00 B. & S. gage copper wire or by equivalent bonding through the track. All lighting and stationary motor circuits must be thoroughly and permanently connected to the rails or to the wires leading to the outside ground return circuit.

f. All pendant cords and portable conductors will be considered as subject to hard usage (see Rule 45 f).

g. Must, except as provided in section e, have all wiring and apparatus installed in accordance with rules for constant potential systems.

h. Must not have any system of feeder distribution 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 pretense, in the same circuit with trolley wires with a ground return, except in electric railway cars, electric car houses and their power stations, nor shall the same dynamo be used for both purposes.

HIGH-POTENTIAL SYSTEMS.

550 To 3500 Volts.

Any circuit attached to any machine or combination of machines which develops a difference of potential, between any two wires, of over 550 volts and less than 3500 volts, shall be considered as 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.

35. Wires.

(See also Rules 14, 15 and 16.)

a. Must have an approved rubber-insulating covering (see Rule 41).

b. Must be always in plain sight and never encased, except as provided for in Rule 8 b, or where required by the Inspection Department having jurisdiction.

c. Must (except as provided for in Rule 8 b), be rigidly supported on glass or porcelain insulators, which raise the wire at least 1 inch from the surface wired over, and must be kept about 8 inches apart.

d. Must be protected on side walls from mechanical injury by a substantial boxing, retaining an air space of 1 inch around the conductors, closed at the top (the wires passing through bushed holes) and extending not less than 7 feet from the floor. When crossing floor timbers, in cellars, 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 ½ inch in thickness.

36. Transformers. (When permitted inside of buildings under Rule 13.)

(For construction requirements, see Rule 62.) (See also Rules 13 and 13 A.)

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 for this purpose, and to be kept securely locked, and access to the same allowed only to responsible 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 out-door air, if possible through a chimney or flue. There should be at least 6 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 attached to gas fixtures.

EXTRA-HIGH-POTENTIAL SYSTEMS.

OVER 3500 VOLTS.

Any circuit attached to any machine or combination of machines which develops a difference of potential, between any two wires, of over 3500 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 3500 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-potential systems when their immediate primary wires carry a current at a potential of over 3500 volts, unles the primary wires are installed in accordance with the requirements as given in Rule 12 A or are entirely underground, within city, town and village limits.

Class D

containing rules No. 40 to 63 inclusive relating to Construction of Fittings and Materials is omitted from this pamphlet.

Class E.

MISCELLANEOUS.

64. Signaling Systems.

Governing wiring for telephone, telegraph, district messenger and call-bell circuits, fire and burglar 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.

When the entire circuit from Central Station to building is 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 26 inches.

c. Where wires are attached to the outside walls of buildings they must have an approved rubber insulating covering (see Rule 41), and on frame buildings or frame portions of other buildings shall be supported on glass petticoat insulators, or porcelain knobs.

d. The wires from last outside support to the cut-outs or protectors must be of copper, and must have an approved rubber insulation (see Rule 41); must be provided with drip loops immediately outside the building and at entrance; must be kept not less than 2½ inches apart, except when brought in through approved metal-covered cables.

e. Wires must enter building through approved non-combustible, non-absorptive, insulating bushings 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, except in telegraph systems.

g. At the entrance of wires to buildings, approved single pole cut-outs, designed for 251-600 volts potential and containing fuses rated at not over 10 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, insulation material. Holes for the supporting screws must be so located, or countersunk, that there will be at least ½ of an inch space measured 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 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 material.

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.

l. The ground wire of the protective device shall be run in accordance with the following requirements:—

Shall be of copper, and not smaller than No. 18 B. & S. gage.
Must have an approved rubber insulating covering as described in Rule 41, for voltages from 0 to 600, except that the preservative compound specified in Rule 41 h may be omitted.
Must run in as straight a line as possible to a good permanent ground. This may be obtained by connecting to a water or gas pipe connected to the street mains and in service, 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 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 water or gas pipes, these pipes shall be thoroughly cleaned and tinned with rosin flux solder, if such a method is practicable; the ground wire shall then be wrapped tightly around the pipe and thoroughly soldered to it.
- When the above method is impracticable, then if there are fittings where a brass plug can be inserted, the ground wire shall be thoroughly soldered to it; if there are no such fittings, then the pipe shall be thoroughly cleaned and an approved ground clamp fastened to an exposed portion of the pipe and the ground wire well soldered to the ground clamp.
- 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.

m. The protector to be approved must comply with the following requirements:—

For Instrument Circuits of Telegraph Systems.

An approved single pole cut-out, in each wire, designed for 2,000 volts potential, and containing fuses rated at not over 1 ampere capacity. When main line cut-outs are installed as called for in section g, the instrument cut-outs may be placed between the switchboard and the instrument as near the switchboard as possible.

For All Other Systems.

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 thoroughly insulated from the wall to which the protector is attached.
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 flashing when crossed with any ordinary commercial light or power circuit.
- A heat coil, if the sensitiveness of the instrument demands it, which will operate before a sneak current can damage the instrument the protector is guarding.

The fuses must be so placed as to protect the arrester and heat coils, and the protector terminals must be plainly marked "line," "instrument," "ground."

The following Rules apply to all Systems whether the wires from the Central Office to the Building are Overhead or Underground.

n. 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 6 inches to any electric light or power wire in the building unless encased in approved tubing so secured as to prevent its slipping out of place.

o. Wires where bunched together in a vertical run within any building must have fire-resisting covering sufficient to prevent the wires from carrying fire from floor to floor unless they are either in non-combustible tubing or in a fireproof shaft, which shaft shall 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 2 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 must not be used on the same fixture with the electric light.

65 A. Moving Picture Machines. {UNCON}

a. Top reel must be encased in an iron 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.

b. A box must be used for receiving the film after being shown, made of galvanized iron 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 a spring catch to lock it closed. No solder to be used in the construction of this box.

c. 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 the lamp.

d. A shutter must be placed in front of the condenser, arranged so as to be normally closed, and held open by pressure of the foot.

e. A metal pan must be placed under the arc lamp to catch all sparks.

f. Extra films must be kept in metal box with tight-fitting covers.

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 attachments, sockets, receptacles, etc.) not less than that given in the following table:—

Up to 5 amperes	4,000,000 ohms.
Up to 10 amperes	2,000,000 ohms.
Up to 25 amperes	800,000 ohms.
Up to 50 amperes	400,000 ohms.
Up to 100 amperes	200,000 ohms.
Up to 200 amperes	100,000 ohms.
Up to 400 amperes	50,000 ohms.
Up to 800 amperes	25,000 ohms.
Up to 1,600 amperes	12,500 ohms.
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.

a. The following formula for soldering fluid is suggested:—

Saturated solution of zinc chloride	5 parts
Alcohol	4 parts
Glycerine	1 part

INDEX. {UNCONFIRMABLE}

	NUMBER AND SECTION
Acid fumes	10 (c) & 24 (i) to 24 (k)
Arc lamps, Construction of	57
Arc lamps, location requirements	19 (c) & 29 (c)
Arc lamps on constant-current systems	19
Arc lamps on constant-potential systems	29
Armored Cable, Construction of	24 A (d) & 48
Armored Cable, Installation of	24 (s) & 24 A
Armored Cable, Metallic sheaths to be grounded	12 (i) & 24 A (c)
Attendance	6
Balancing 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 fins in fixtures	26 (b)
Bus-bars	2 (b) & 3 (e)
Bushings at entrances to buildings	12 (g) & 64 (e)
Bushings for lamp sockets	28 (f) & 55 (q)
Bushings for wires, Construction of	50 A
Bushings inside of buildings	14 (d)
Cabinets, cut-out and switch, Construction	17 (d), 24 (a) & 54
Cabinets, cut-out and switch, Use	17 (b) to 17 (d), 21 (c) & 22 (b)
Cabinets for rheostats and auto-starters, where required	8 (d)
Cable, Armored	(See Armored Cable.)
Car houses	33
Car wiring and equipment	32
Care and attendance	6
Carrying capacity of wires, Table of	16
Ceiling rosettes, Construction of	54 A
Ceiling rosettes, Use of	21 (d)
Central stations	1 to 7
Circuit-breakers, Construction of	52 (a), 52 (d) & 52 (e)
Circuit-breakers, how high may be set	21 (e)
Circuit-breakers, Installation of	17 & 21
Circuit-breakers, where required	8 (d) & 9
Cleats, Construction of	50 B
Compensator coils for arc lamps	30
Compensator coils for three-wire systems	(See Reactive Coils.)
Concealed "knob and tube" work	24 (q) to 24 (u)
Concentric wire	47 (c)
Condensers	61 (b)
Conductors	(See Wires.)
Conduit wire, Construction of	47
Conduit wiring	24 (n) to 24 (p)
Conduits, metal, Construction of	49
Conduits, metal, Installation of	23
Constant-current systems	18 to 20
Constant-potential systems, general rules	21 to 23
Converters.	(See Transformers.)
Crossing of constant-potential pole-lines, over 5,000 volts	12 A (d)
Cut-outs, Construction of, open link fuse	52 (f) to 52 (l)
Cut-outs, Construction of, enclosed fuse	52 (m) to 52 (s)
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 (b) & 29 (a)
Damp places	14 (f), 17 (c), 24 (i) to 24 (k) & 27 (b)
Decorative series incandescent lamps	31
Distance between conductors, inside work	18 (d), 24 (h), 24 (j), 24 (r) & 35 (c)
Distance between conductors, outside work	12 (b), 12 A (c) & 12 A (d) (2)
Drip loops at entrances to buildings	12 (g) & 64 (d)
Dynamo rooms	1 to 7
Economy coils for arc lamps	30
Electric gas lighting	65
Electric heaters	23
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	4
Extra-high constant-potential systems	38 & 39
Fan motors hung from ceilings	8 (g)
Feeders, Railway	33 (f)
Fished wires	24 (c) & 24 (s)
Fittings, List of approved	(See inside of front cover.)
Fittings, materials and details of construction	40 to 63
Fixture canopies	24 (w) and 26 (a)
Fixtures	26
Fixture wire	46
Fixture wiring	24 (v) to 24 (y)
Flexible cord, Construction of, general rule	45 (a)
Flexible cord for heating apparatus, Construction of	45 (g)
Flexible cord for pendant lamps, Construction of	45 (b) to 45 (e)
Flexible cord for portable use, Construction of	45 (f)
Flexible cord, Use of	28
Flexible tubing, Construction of	50 C
Flexible tubing, where permitted	14 (d), 24 (s) & 24 (u)
Foreign currents, Protection against	64
Formula for soldering fluid	67
Fuses, Construction of, enclosed	53 (d) to 53 (k)
Fuses, Construction of, open link type	53 (a) to 53 (c)
Fuses, Installation of	1 (d), 17 & 21
Gas lighting, Electric	65
General plan of arrangement of rules	page 3
General suggestions for electric work	page 4
Generators	1
Ground connections for lightning arresters	5 (c) & 64 (l)
Ground connections for low-potential circuits	13 A, (c) to (g)
Ground detectors, where required	7 (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	1 (c) & 8 (a)
Grounding interior conduits	25 (f)
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 (m), 12 A, (d)
Guard strings, inside work, where required	18 (e), & 24 (e)
Hanger-boards, Construction of	56
Heaters, Electric	23
High constant-potential systems	35 to 37
Incandescent lamps as resistances	4 (b) & 29 (b)
Incandescent lamps in series	20, 21 (d), 31 & 37
Incandescent lamps, where inflammable gases exist	27 (a)
Induction coils	(See Reactive Coils.)
Inside work	14 to 39
Insulated platforms, at high-potential machines	1 (c) & 8 (a)
Insulating joints, Construction of	59
Insulating joints, when required	26 (a)
Insulation of fixture canopies, when required	26 (a)
Insulation of trolley wires	12 (k)
Insulation resistance of completed systems	66
Insulator spacing, inside work	24 (h), 24 (j), 24 (r) & 35 (c)
Joint pole crossing, high-pressure line	12 A (d), (2)
Joints, in conductors	12 (f) & 14 (c)
Junction boxes, Conduit, installation of	24 A (f) & 25 (g)
Knob and tube work	24 (q) to 24 (u)
Knots in flexible cord, required in sockets and rosettes	28 (g)
Lamps	(See Arc Lamps and Incandescent Lamps.)
Lighting and power from railway wires	34
Lightning arresters, Construction of	63
Lightning arresters, Installation of	5
Low constant-potential systems	24 to 34
Lugs for terminal connections, when required	14 (c), 51 (h), 52 (i), 52 (p) & 60 (c)
Marine work	68 to 83
Motor enclosures	8 (f)
Motor equipments, 550 volt, voltage allowed at generator or transformer	note before 24
Motors	8
Moulding, Construction of	50
Moulding, on brick walls	24 (m)
Moulding, Wires in	24 (l) & 24 (m)
Moving picture machines, Construction of	65 A
Multiple-series systems, when permitted	8 (e), 20 (c) & 29 (a)
Oily waste	6 (b)
Open wiring	24 (g) to 24 (k)
Outlet and switch boxes, Construction of	49 A
Outlet boxes or plates, Conduit, when required	24 A (b) & 25 (d)
Outside work	12, 12 A, 13, 13 A & 64
Panel boards, Construction of	53 A
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 heaters, conductors for	45 (g)
Portable lamps, Installation of	28 (d)
Portable lamps, motors, etc., conductors for	45 (f)
Power, transformer and switch stations	1 to 7
Protection for gas outlet pipes	26 (a)
Protection for motor equipments	8 (d)
Protection for outlet wires	24 (u) & 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.)
Reactive coils	61 (a)
Resistance boxes	(See Rheostats.)
Resistances used with constant-potential arc lamps	29 (b)
Rheostats, Construction of	60
Rheostats, Installation of	4, 8 (c) & 8 (d)
Roof wiring	12
Rosettes, Construction of	54 A
Rosettes, Use of	21 (d)
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 (d) (3)
Series arc lamps	19
Series incandescent lamps	20, 31, & 37
Series-multiple systems, when permitted	8 (e) & 20 (c)
Service wires, Underground	15 (a), 15 (c), 15 (d)
Signaling systems	64
Sockets, Construction of	55
Sockets, Installation of	27
Soldering fluid, Formula for	67
Soldering stranded wires	14 (c) & 19 (d)
Spark arresters, Construction of	58
Spark arresters, when required	19 (c) & 29 (c)
Static electricity, due to belt friction	1 (c) & 8 (a)
Stations and dynamo rooms	1 to 7
Stiff pendants for incandescent lamps	27 (a)
Storage battery rooms	10
Strips for protecting inside wires	(See Guard Strips)
Switchboards	3
Switch boxes, Conduit, Construction of	49 A
Switches, Construction of knife	51 (c) to 51 (k)
Switches, Construction of, snap	51 (l) to 51 (t)
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 (b) & 51 (b)
Switches in damp places	17 (c)
Switches, Indicating, when required	8 (c), 23 (b), 51 (a) & 51 (b)
Switches, Installation of	17 & 22
Switches must disconnect all wires of circuit	17 (a)
Switches, Service	18 (b), 22 (a) & 51 (a)
Switches, Single-pole, when permitted	8 (c) & 22 (c)
Switches, Snap, when preferred	22 (b)
Switches, Time	17 (d)
Systems, Constant-current	18 to 20
Systems, Constant-potential, general rules	21 to 23
Systems, Extra-high constant potential	38 & 39
Systems, High constant-potential	35 to 37
Systems, Low constant-potential	24 to 34
Systems, Multiple-series	8 (e) & 20 (c)
Systems, Series-multiple	8 (e) & 20 (c)
Systems, Signaling	64
Tablet boards, Construction of	53 A
Telegraph, telephone and signaling circuits	64
Testing for grounds	7
Testing for insulation resistance of completed systems	66
Three-pole cross-over for high-pressure line	12 A (d-1)
Tie wires	12 (a) & 14 (b)
Tinning of wires, when required	41 (a) & 46 (b)
Transformers, Construction of	62
Transformers, grounding of secondaries	13 A
Transformers, Installation of, inside	11 & 36
Transformers, Installation of, outside	12
Transformer stations	1 to 7
Transmission lines, constant-potential, over 5,000 volts	12 A
Trolley circuits, Grounded, Light and power from	34
Trolley wires	12 (j) to 12 (m)
Tubes, Insulating	(See Bushings.)
Tubing, Flexible	(See Flexible Tubing.)
Voltmeter, Switchboard, circuit for	2 (d)
Waste, oily	6 (b)
Waterproof construction	24 (i) to 24 (k)
Waterproof pendants	27 (b)
Wire, Concentric	47 (c)
Wire, Conduit	47
Wire, Construction of, general rules	46
Wire, Fixture	46
Wire, Netting required on arc lamps	19(c) & 29 (c)
Wire, Rubber-covered	41
Wire, Slow-burning	43
Wire, Slow-burning, weatherproof	42
Wire, Weatherproof	44
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)

Errata

Insufficiencies in this restoration

Rules 31 A and 32 are not able to verified in accuracy yet. The source the text is pulled from left those sections out as they were not applicable to their purpose.

NEC 1909

TO CONTRACTORS

GENERAL PLAN

GOVERNING THE ARRANGEMENT OF RULES

GENERAL SUGGESTIONS.

Class A.

STATIONS AND DYNAMO ROOMS.

1. Generators.

2. Conductors.

3. Switchboards.

4. Resistance Boxes and Equalizers.

5. Lightning Arresters.

6. Care and Attendance.

7. Testing of Insulation Resistance.

8. Motors.

9. Railway Power Plants.

10. Storage or Primary Batteries.

11. Transformers.

Class B.

OUTSIDE WORK.

ALL SYSTEMS AND VOLTAGES.

12. Wires.

Trolley Wires.

Ground Return Wires.

12 A. Constant-Potential Pole Lines, Over 5,000 Volts.

13. Transformers.

13 A. Grounding Low-Potential Circuits.

Direct-Current 3-Wire Systems.

Alternating-Current Secondary Systems.

Ground Connections.

Class C.

INSIDE WORK.

ALL SYSTEMS AND VOLTAGES

GENERAL RULES.

14. Wires.

15. Underground Conductors.

16. Table of Carrying Capacity of Wires.

17. Switches, Cut-Outs, Circuit-Breakers, etc.

CONSTANT-CURRENT SYSTEMS.

PRINCIPALLY SERIES ARC LIGHTING.

18. Wires.

19. Series Arc Lamps.

20. Incandescent Lamps in Series Circuits.

CONSTANT-POTENTIAL SYSTEMS.

GENERAL RULES—ALL VOLTAGES.

21. Automatic Cut-Outs — Fuses and circuit-breakers.

22. Switches.

23. Electric Heaters.

LOW-POTENTIAL SYSTEMS.

24. Wires.

GENERAL RULES.

SPECIAL RULES.

For Open Work.

For Moulding Work (Wooden and Metal).

For Conduit Work.

For Concealed "Knob and Tube" Work.

For Fixture Work

24 A. Armored Cables.

25. Interior Conduits.

25A. Metal Mouldings.

26. Fixtures.

27. Sockets.

28. Flexible Cord.

29. Arc Lamps on Constant-Potential Circuits.

30. Economy Coils.

31. Decorative Lighting Systems.

31 A. Theatre Wiring. {INCOMPLETE}

INCOMPLETE SECTION, SOURCE DID NOT INCLUDE THIS PART

32. Car Wiring and Equipment of Cars. {INCOMPLETE}

INCOMPLETE SECTION, SOURCE DID NOT INCLUDE THIS PART

a. Protection of Car Body, etc.

b. Wires, Cables, etc.

c. Cut-outs, Circuit Breakers and Switches.

d. Conduit.

e. Moulding.

f. Lighting and Lighting Circuits.

g. Heaters and Heating Circuits.

h. Air Pump Motor and Circuits

i. Main Motor Circuits and Devices.

j. Lightning Arresters