26. SWITCHES:

a. Must be mounted on moisture-proof and non-combustible bases, such as slate or porcelain.

b. Must be double pole when the circuits which they control supply more than six 16 candle-power lamps, or their equivalent.

c. Must have a firm and secure contact; must make and break readily, and not stop when motion has once been imparted by the handle.

d. Must have carrying capacity sufficient to prevent heating. e. Must be placed in dry, accessible places, and be grouped as far as possible, being mounted-when practicable-upon slate or equally non-combustible back boards. Jackknife switches, whether provided with friction or spring stops, must be so placed that gravity will tend to open rather than close the switch.

27. FIXTURE Work:

a. In all cases where conductors are concealed within or attached to gas fixtures, the latter must be insulated from the gaspipe system of the building by means of approved insulating joints placed as close as possible to the ceiling.

Insulating joints with soft rubber in their construction will not be approved. It is recommended that the gas-outlet pipe be protected above the insulating joint by a non-combustible, non-absorptive insulating tube having a flange at the lower end, where it comes in contact with the insulating joint, and that, where outlet tubes are used, they be of sufficient length to extend below the joint, and that they be so secured that they will not be pushed back when the canopy is put in place. Where iron ceilings are used care must be taken to see that the canopy is thoroughly and permanently insulated from the ceiling.

Insulating joints to be approved must be entirely made of material that will resist the action of illuminating gases, and will not give way or soften under the heat of an ordinary gas flame. They shall be so arranged that a deposit of moisture will not destroy the insulating effect, and shall have an insulating resistance of 250,000 ohms between the gas-pipe attachments, and be sufficiently strong to resist the strain they will be liable to in attachment.

b. Supply conductors, and especially the splices to fixture wires, must be kept clear of the grounded part of gas pipes, and where shells are used, the latter must be constructed in a manner affording sufficient area to allow this requirement.

c. When fixtures are wired outside, the conductors must be so secured as not to be cut or abraded by the pressure of the fastenings or motion of the fixture.

d. All conductors for fixture work must have a waterproof insulation that is durable and not easily abraded, and must not in any case be smaller than No. 18 B. & S., No. 20 B. W. G., No. 2 E. S. G.

e. All burs or fins must be removed before the conductors are drawn into a fixture.

f. The tendency to condensation within the pipes should be guarded against by sealing the upper end of the fixture.

g. No combination fixture in which the conductors are concealed in a space less than one-fourth inch between the inside pipe and the outside casing will be approved.

h. Each fixture must be tested for "contacts" between conductors and fixtures, for "short circuits," and for ground connections before the fixture is connected to its supply conductors.

i. Ceiling blocks of fixtures should be made of insulating material; if not, the wires in passing through the plate must be surrounded with hard-rubber tubing.

28. ARC LIGHTS ON LOW POTENTIAL CIRCUITS:

a. Must be connected with main conductors only through a double-pole cut-out and a double-pole switch, which shall plainly indicate whether "on" or "off."

b. Must only be furnished with such resistances or regulators as are inclosed in non-combustible material, such resistances being treated as stoves. Incandescent lamps must not be used for resistance devices.

c. Must be supplied with globes and protected as in the case of arc lights on high-potential circuits.

29. ELECTRIC GAS LIGHTING:

Where electric gas lighting is to be used on the same fixture with the electric light

a. No part of the gas piping or fixture shall be in electrical connection with the gas-lighting circuit.

b. The wires used with the fixtures must have a non-inflammable insulation, or, where concealed between the pipe and shell of the fixture, the insulation must be such as required for fixture wiring for the electric light.

c. The whole installation must test free from "grounds."

d The two installations must test perfectly free from connection with each other.

30. SOCKETS:-

a. No portion of the lamp socket exposed to contact with outside objects must be allowed to come into electrical contact with either of the conductors.

b. In rooms where inflammable gases may exist, or where the atmosphere is damp, the incandescent lamp and socket should be inclosed in a vapor-tight globe.

31. FLEXIBLE Cord:

a. Must be made of two-stranded conductors, each having a carrying capacity equivalent to not less than a No. 16 B. & S. wire, and each covered by an approved insulation, and protected by a slow-burning, tough, braided outer covering.

Insulation for pendants under this rule must be moisture and flame-proof. Insulation for fixture work must be waterproof, durable and not easily

abraded.

Insulation for cords used for all other purposes, including portable lamps and motors, must be solid, at least 2 of an inch in thickness, and must show an insulation resistance between conductors and between either conductor and the ground of at least one megohm per mile, after one week's immersion in water at 70 degrees Fahrenheit, with a current of 550 volts, and after three minutes' electrification.

b. Must not sustain more than one light not exceeding 50 candle-power.

c. Must not be used except for pendants, wiring of fixtures and portable lamps or motors.

d. Must not be used in show windows.

e. Must be protected by insulating bushings where the cord enters the socket. The ends of the cord must be taped to prevent fraying of the covering.

f. Must be so suspended that the entire weight of the socket and lamp will be borne by knots 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.

g. Must be equipped with keyless sockets as far as practicable, and be controlled by wall switches.

32. DECORATIVE SERIES LAMPS:

Incandescent lamps run in series circuits shall not be used for decorative purposes inside of buildings, except by special permission in writing from the Underwriters having jurisdiction.

CLASS D, ALTERNATING SYSTEMS.

CONVERTERS OR TRANSFORMERS.

33. CONVERTERS:

a. Must not be placed inside of any building, except the Central Station, unless by special permission of the Underwriters having jurisdiction.

b. Must not be placed in any but metallic or other non-combustible cases.

c. Must not be attached to the outside walls of buildings, unless separated therefrom by substanțial insulating support

34. IN THOSE CASES WHERE IT MAY NOT BE POSSIBLE TO EXCLUDE THE CONVERTERS AND PRIMARY WIRES ENTIRELY FROM THE BUILDING, THE FOLLOWING PRECAUTIONS MUST BE STRICTLY

OBSERVED:

Converters must be located at a point as near as possible to that at which the primary wires enter the building, and must be aced in an inclosure constructed of, or lined with, fire-resisting

material; the inclosure to be used only for this purpose, and to be kept securely locked, and access to the same allowed only to responsible persons. They must be effectually insulated from the ground, and the inclosure in which they are placed must be practically air-tight, except that it shall be thoroughly ventilated to the out-door air, if possible, through a chimney or flue. There should be at least six inches air space on all sides of the converter. 35. PRIMARY CONDUCTORS:

a. Must each be heavily insulated with a coating of moistureproof material from the point of entrance to the transformer, and, in addition, must be so covered and protected that mechanical injury to them, or contact with them, shall be practically impossible.

b. Must each be furnished, if within a building, with a switch and a fusible cut-out where the wires enter the building, or where they leave the main line. These switches should be inclosed in secure and fireproof boxes, preferably outside the building.

c. Must be kept apart at least ten inches, and at the same distance from all other conducting bodies when inside a building.

36. SECONDARY CONDUCTORS:—

Must be installed according to the rules for "Low-Potential Systems."

CLASS E, ELECTRIC RAILWAYS.

37. All rules pertaining to arc-light wires and stations shall apply (so far as possible) to street railway power stations and their conductors in connection with them.

Must be equipped in each circuit as it leaves the station with an approved automatic "breaker,' or other device that will immediately cut off the current in case the trolley wires become grounded. This device must be mounted on a fireproof base, and in full view and reach of the attendant.

used.

Automatic circuit breakers should be submitted for approval before being

39. TROLLEY WIRES.

a. Must be no smaller than No o B. & S. copper or No. B. & S. silicon bronze, and must readily stand the strain put upon them when in use.

b. Must be well insulated from their supports, and in case of the side or double pole construction the supports shall also be insulated from the poles immediately outside of the trolley wire.

c. Must be capable of being disconnected at the power house, 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.

d. Must be safely protected against contact with all other conductors.

Must be always run out of reach of the passengers, and must be insulated with a waterproof insulation.

41.

LIGHTING AND POWER FROM RAILWAY WIRES :

Must not be permitted, under any pretense, in the same circuit with trolley wires with a ground return, nor shall the same dynamo be used for both purposes, except in street railway cars, electric car houses, and their power stations.

42. CAR HOUSES:

a. Must have the trolley wires properly supported on insulating hangers.

b. Must have the trolley hangers placed at such a distance apart that in case of a break in the trolley wire, contact cannot be made with the floor.

c. Must have cut-out switch located at a proper place outside of the building, so that all trolley circuits in the building can be cut out at one point, and line circuit breakers must be installed, so that when this cut-out 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 whenever the same is not in use, or the road not in operation.

d. Must have all lamps and stationary motors installed in such a way that one main switch can control the whole of each installation (lighting or power), independently of main feeder switch. No portable incandescent lamps or twin wire allowed, except that portable incandescent lamps may be used in the pits; connections to be made by two approved rubber-covered flexible wires, properly protected against mechanical injury; the circuit to be controlled by a switch placed outside of the pit.

e. Must have all wiring and apparatus installed in accordance with rules under Class B.

f. Must not have any system of feeder distribution centering in the building.

g. Must have the rails bonded at each joint with not less than No. 2 B. & S. annealed copper wire; also a supplementary wire to be run for each track.