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it shall be automatic in its action, not stopping between points when started, and prevent an arc between the points under all circumstances; it must indicate on inspection whether the current be “on” or “off,” and be mounted in a noncombustible case, and kept free from moisture, and easy of access to police or firemen. So-called “snap switches” shall not be used on high potential circuits. c. Must be always in plain sight, and never encased, except when required by the Inspector. d. Must be covered in all cases with an approved non-combustible material that will adhere to the wire, not fray by friction, and bear a temperature of 150° F. without softening. (See Definitions). e. Must be supported on glass or porcelain insulators, and kept rigidly at least eight inches from each other, except within the structure of lamps or on hanger boards, cut-out boxes, or the like, where less distance is necessary. f. Must be separated from contact
with walls, floors, timbers, or partitions through which they may pass by noncombustible insulating tube. g. Must be so spliced or joined as to be both mechanically and electrically secure without solder. They must then be soldered, to insure preservation, and covered with an insulation equal to that On the conductors. LAMPS AND OTHER DEVICES. 13. ARC LAMPS–In every case:– a. Must be carefully isolated from inflammable material. b. Must be provided at all times with a glass globe surrounding the arc, securely fastened upon a closed base. No broken or cracked globes to be used. c. Must be provided with an approved hand switch, also an automatic switch, that will shunt the current around the carbons should they fail to feed properly. (See Definitions). d. Must be provided with reliable stops to prevent carbons from falling out in case the clamps become loose.
e. Must be carefully insulated from the circuit in all their exposed parts. f. 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 OF 300 Volts of 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.