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.

When the entire circuit from Central Station to building is run in underground conduits, Sections a to m inclusive do not apply.

a. Outside wires should be run in underground ducts or strung on poles, and, as far as practicable, kept off of buildings, 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.

b. When outside wires are run on same pole with electric light or power wires, the distance between the two inside pins of each cross-arm must not be less than twenty-six inches.

c. Where wires are attached to the outside walls of buildings they must have an approved rubber insulating covering (see No. 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 No. 41); must be provided with drip loops immediately outside the building and at entrance; must be kept not less than two and one-half inches apart.

e. Wires must enter building through approved non-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 ten amperes capacity, shall be provided for each wire. These cut-outs must not be placed in the immediate vicinity of easily ignitible stuff, or where exposed to inflammable gases, or dust or to flyings of combustible material.

h. The wires inside building shall be of copper not less than No. 16 B. & S. gage, and must have insulation and be supported, the same as would be required for an installation of electric light or power wiring, 0-550 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 one half 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 combustile 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:—

1. Shall be of copper, and not smaller than No. 18 B. & S. gage.
2. Must have an approved rubber insulating covering (see No. 41).
3. 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.

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

For All Other Systems.

1. Must be mounted on non-combustible, non-absorptive insulating bases, so designed that when the protector is in place, all parts which may be alive will be thoroughly insulated from the wall to which the protector is attached.
2. Must have the following parts:—
   • A lightning arrester which will operate with a difference of potential between wires of not over 500 volts, and so arranged that the chance of accidental grounding is reduced to a minimum.
   • A fuse designed to open the circuit in case the wires become crossed with light or power circuits. The fuse must be able to open the circuit without arcing or serious 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.

3. 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 six 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 within any building must have fire-resisting covering, or else be encased in a non-combustible tube or shaft.

• They must not be in the same tube with electric light or power wires, and if in the same shaft must be kept at least two inches from such wires. Ducts or shafts for wires must be of fireproof construction and thoroughly "stopped" at each floor or wall.

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.

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:—

67. Soldering Fluid.

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