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shunt the circuit around the carbon filament should it break; (c) it must be suspended from a hanger board by means of a rigid tube, and (d) must not be used in damp or wet places.
14. Any method of distributing current to incandescent lamps on high potential circuits other than as above provided for must receive the approval of this Exchange before being put into use.
15. In arc lamps indoors, (a) the light must be surrounded by a globe with a closed base; (6) the depth of the globe must be such that the point of contact between the carbons when the lamp is newly trimmed shall not be less than three inches below the upper edge of the globe; and (c) the globe must be inclosed by a wire netting where there is any material under the lamp that could be damaged or ignited by hot cinders, or (d) when the lamp is an “all-night” lamp. (e) Where exposed to flyings, or where any inflammable material is suspended near the lamp, spark arresters must be used.
16. Hanger boards for arc or series incandescent lamps must not be used in damp or wet places.
17. Each arc lamp must be provided (a) with a proper hand switch, (b) with an automatic switch that will shunt the current around the carbons should they fail to feed properly, and (c) with "stops" to prevent the carbons from falling out in case their clamps fail to hold them.
18. The entire installation must test free from grounds.
Low Potential (350 Volts or Less) Incandes
19. For inside work, no wire smaller than No. 14 “B. & S.,” or No. 16, “B. W. G.,” will be
20. Samples of wire to be used, or in actual use, must be submitted to this Exchange, for tests of conductivity or of insulation, at any time when required.
21. (a) Wires must never be left exposed to mechanical injury, or to disturbance of any kind. (b) Wires must not be fastened by metallic staples. (c) When wires pass through walls, floors, partitions, timbers, etc., glass tubing or so-called “floor insulators,” or other moisture-proof, non-inflammable insulating tubing must be used. (d) At all outlets to and from cut-outs, switches, fixtures, etc., wires must be separated from gas pipes or parts of the building by porcelain, glass, or other non-inflammalle insulating tubing (e), and should be left in such a way as not to be disturbed by the plasterers. (f) Wires of whatever insulation must not in any case be taped or otherwise fastened to gas piping. (9) If no gas pipes are installed at the outlets an approved substantial support must be provided for the fixtures.
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22. In crossing any metal pipes, or any other conductor, (a) wires must be separated from the same by an air space of at least onehalf inch, where possible, and (b) be so arranged that they cannot come in contact with each other by accident. (c) They should go over water pipes where possible.
23. Twin wire must not be used except (a) as allowed in "conduit” wiring, (b) or for “pendants,” fixture wiring, and “portables.” (c) An exception may be made to this rule, by the inspector, where it is necessary to run a short distance, if the wire (d) has a nonmflammable covering, (e) is not concealed, and (f) carries but a small current.
24. The safe carrying capacity of wires when exposed to the air may be taken from the following table:
Current in Ampères. 262
B. & S. Gange.
30) 245 215 190 160 135 115 100 90 80 67 60 40 30 22 15
When wires are inclosed in molding or otherwise treated so as to prevent cooling by radiation, the carrying capacity is reduced about forty per cent. under such circumstances, or when the wires are installed where
the temperature is unusually high, as in boiler rooms, dry rooms, and the like, wires should be fused accordingly.
25. (a) In rooms where inflammable gases may develop, or (b) where the amosphere is very damp, the incandescent lamps should be inclosed in vapor-tight globes. (c) Switches are not permitted in places filled with inflammable gases (breweries, distilleries, etc.), as the spark at make or break might cause an explosion. (d) Fusible safety plugs, if necessary in such places, must be inclosed in airtight, non-combustible cases.
26. Soft rubber tubing will not be approved in cases where these rules require an additional covering to the insulation of the wire.
27. The entire installation must test free from grounds.
Cleat-Work. 28. (a) Cleats made of well filled, dry, hard wood may be used to support wires not concealed, in perfectly dry places only. (b) They must be so constructed as to separate wires of opposite polarity at least two and one-half inches. (c) Wires must be drawn taut, and cleats placed near enough together to prevent the possibility of contact between the wires.
29. Except on wooden surfaces so filled as to prevent the absortion of moisture, (a) the wire must have a waterproof insulation, or (6) the cleats must have a backing that will
separate the wire at least one-fourth inch from the building.
Molding. 30. Moldings must not be used (a) in concealed work, nor (b) in places where there is any probable exposure to moisture.
31. (a) Molding must consist of two parts; viz., a back piece, which shall separate the wire at least one fourth inch from the part of the building to which it is fastened, and a cover, one of which parts shall contain the grooves, (b) these grooves to have between them a septum or tongue of wood so as to separate the wires at least one-half inch. (c) The molding must be coated inside and out with shellac or waterproof paints, cr treated in some other manner so as to prevent any possible absorption of moisture. (d) Moldings with open grooves laid against walls or ceilings will only be approved when such walls or ceilings are of wood and so filled as to prevent the absorption of moisture.
Concealed Work. 32. In unfinished lofts, between floors and ceilings, in partitions, and other concealed places, wires must (a) be kept free of contact with the building, (b) be supported on glass, porcelain, or other non-combustible insulators, (c) have at least one inch clear air space surrounding them, (d) be at least ten inches apart when possible, and (e) should be run