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e. Must be carefully insulated from the circuit in all their exposed parts.
/. Must be provided with a wire netting around the globe, and an approved spark arrester above to prevent escape of sparks, melted copper, or carbon, where readily inflammable material is in the vicinity of the lamps. It is recommended that plain carbons, not copper plated, be used for lamps in such places. (See Definitions).
g. Hanger boards must be so constructed that all wires and current-carrying devices thereon shall be exposed to view, and thoroughly insulated by being mounted on a waterproof, non-combustible substance. All switches attached to the same must be so constructed that they shall be automatic in their action, not stopping between points when started, and preventing an arc between points under all circumstances.
h. "Where hanger boards are not used, lamps to be hung from insulated supports other than their conductors.
14. Incandescent Lamps In Series CirCuits Having A Maximum Potential Op 300 Volts Or Over:— . a. Must be governed by the same rules as for arc lights, and each series lamp provided with an approved handspring switch and automatic cut-out.
b. Must have each lamp suspended from a hanger board by means of a rigid tube.
c. No electromagnetic device for switches and no system of multiple series or series multiple lighting will be approved.
d. Under no circumstances can series lamps be attached to gas fixtures.
Class C. Low Potential Systems. 300 Volts Or Less, Outside Conductors. 15. Outside Overhead Conductors:—
a. Must be erected in accordance with the rules for (high potential) conductors.
b. Must be separated not less than 12 inches, and be provided with an approved fusible cut-out, that will cut off the entire current as near as possible to the entrance to the building and inside the walls. (See Definitions). 16. Underground Conductors:—
a. Must be protected against moisture and mechanical injury, and be removed at least two feet from combustible material when brought into a building, but not connected with the interior conductors.
b. Must have a switch and a cut-out for each wire between the underground conductors and the interior wiring when the two parts of the wiring are connected.
These 'switches and fuses must be placed as near as possible to the end of the underground conduit, and connected therewith by specially insulated conductors, kept apart not less than two and a half inches. (See Definitions).
c. Must not be so arranged as to shunt the current through a building around any catch-box.
17. At the entrance of every building there shall be an approved switch placed in the service conductors by which the current may be entirely cut off. (See Definitions).
a. Must have an approved insulating covering, and must not be of sizes smaller than No. 14 B. & S., No. 16 B. W. G., or No. 4 E. S. G., except that in conduit installed under Rule 22, No. 16 B. & S., No. 18 B. W. G., or No. 4 E. S. G., may be used. (See Definitions).
b. Must be protected when passing through floors; or through walls, partitions, timbers, etc., in places liable to be exposed to dampness by waterproof, noncombustible, insulating tubes, such as glass or porcelain.
Must be protected when passing through walls, partitions, timbers, etc., in places not liable to be exposed to dampness by approved insulating bushings specially made for the purpose.
c. Must be kept free from contact with gas, water, or other metallic piping, or any other conductors or conducting material which they may cross (except high potential conductors) by some continuous and firmly fixed non-conductor creating a separation of at least one inch. Deviations from this rule may sometimes be allowed by special permission.
d. Must be so placed in crossing high potential conductors that there shall be a space of at least one foot at all points between the high and low tension conductors.
e. 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 all pipes upon which condensed moisture is likely to gather, or which by leaking might cause trouble on a circuit.