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20. Mouldings with open grooves laid against the walls or ceilings will not be approved. A wood moulding having a backing of at least one-fourth inch thickness to intervene between the wire and the wall or ceiling of the building, the backing to be protected by at least two coats of water-proof paint, and the moulding of such shape as to protect the wire from moisture, will be approved.
21. When wires are run in new buildings, and are to be concealed from view by walls and ceilings, care must be taken to separate them ten inches or more, whenever it is possible to do so, by running them singly on separate timbers, studding, etc. Cleats are not desirable for concealed work. All concealed wires should be supported on insulators, such as porcelain knobs, or other equally good, non-combustible, insulating substance. Wires should, where it is possible, be kept from contact with any part of the building by means of such insulators, rather than to depend upon the insulation covering. Where complete separation from the building by air space and insulators is not possible, an approved insulation covering, that shall be water-proof and non-combustible, will be required. Wires run in non-combustible and water-proof tubes, made of a suitable insulating material, will be approved.
Care must be taken to keep the wires away from metal pipes and other conductors. Outlet wires should be left in such a way as not to be injured by plasterers. They should not, as a rule, be brought through the same opening with gas-pipes, but must be carefully insulated from them.
22. Approval will not be given to any work where the wires have been " fished" any great distance.
23. Moulding must not be used in wet places.
24. In dye-houses, paper and pulp mills, and other buildings specially liable to moisture, all wires (except when used for pendants) must be separated at least six inches. The wire must be thoroughly and carefully put up and must be supported by glass or porcelain insulators, or by rubber hooks.
25. In crossing any metal pipes, or any other conductor, wires must be separated from the same by an air space of at least one-half inch, where possible, and so arranged that they cannot come in contact with each other by accident. Wires should go over water-pipes where possible.
26. Where wires pass through partitions, floors, etc., glass insulators, or an outer covering of hard rubber, should be used to protect them.
27. Wires must never be left exposed to mechanical injury, or to disturbance of any kind.
28. Metallic staples must never be used; when staples are used, they must be of an approved insulating material.
29. None but an approved tubing will be accepted as a durable water-proof insulation.
30. Wires of the same polarity, but belonging to different circuits, or leading to and from a double-pole switch, must not run in one groove, through the same tube, nor in the same slot in a cleat.
31. Cleats should be made of well seasoned hard wood (filled to prevent the absorption of moisture), porcelain or other approved material, and so made as to separate the wire at least one-fourth inch from the building. When secured by cleats not over four feet apart and tightly stretched in the same horizontal plane, wires having a difference of potential of 120 volts or less, should be separated at least one and one-half inches; when they are confined in moulding, a half-inch space is sufficient. This rule applies only to small mains, taps, etc.; mains carrying currents of large volume should be separated a greater distance.
32. The dividing strip between grooves in moulding must never be reduced below one-half inch in thickness by cutting out to admit joints in wires.
33. Where exposed to acid fumes, vapors of ammonia, etc., wires should be provided with an insulation that will not be injured thereby, and should be put up in the manner described in Rule 24.
34. All splices in wires must be soldered; a solderingbolt should be used for this purpose, if possible. Care must be taken not to render the wire brittle by over-heating. Resin should not be used as a flux. Nothing but an acid solution should be used, and any excess should be washed off before the splice is covered.
35. The insulation of any joint must be equal to that of the other parts of the same wire.
SAFETY-CUT-OUTS AND SWITCHES.
36. Every system of conductors must be protected by safety cut-outs that will interrupt the passage through the conductors of a current stronger than they can safely carry. The carrying capacity (in amperes) of a fusible metal must be less than that of the smallest conductor it is designed to protect. Conductors include wire, cord, binding-serews, contact point of switches, sockets, cutouts, etc.
Any fuse must melt immediately with any excess of the amperes which it is marked to carry.
37. A cot-out must be placed where the underground or overhead service joins the inside wires, and at every point where a change is made in the size of the wire (unless the cut-out in the larger wire is intended to protect the smaller).
38. Cut-outs, switches, and other devices which occasion a break in the circuit, must be so arranged that leakage of electricity from them is impossible, and should be mounted on non-combustible material; must not be put in places liable to become damp; must be protected from rubbish, etc., and should be easy of access.
39. Where it is necessary to use cut-outs and switches in damp places, great care must be taken to protect them from moisture, and to use only such as are provided with bases that will not absorb moisture.
40. When necessary, cut-out devices must be covered with some fire-proof and water-repelling material.
41. All cut-outs must be double-pole.
42. The plug or other device for enclosing or supporting the fusible strip or wire should be incombustible and moisture-proof, and so constructed that an arc cannot be maintained across its terminals by the fusing of its metals.
43. No lead or composition strips carrying more than ten amperes before melting, shall be used, unless provided with contact surfaces of some harder metal having perfect electrical connection with the fusible part of the strip.
44. All switches must have a firm and secured contact that will make and break readily, and that will not stick between "full on " and "off," nor get out of repair easily in other ways. The points of contact must not be allowed
, to scrape or rub the entire surface of an insulating material between the contact strips — an air space must intervene. The carrying capacity of the different parts must be sufficient to prevent heating.
45. Where points varying widely in potential are brought near each other by means of cut-outs, or switches, hard rubber, lava, or other approved material must be used in the construction of the cut-outs and switches.
46. Switches should be double-pole, and they must be when the circuits which they operate are connected to fixtures attached to gas-pipes.
47. On any combination fixture, no group of lamps requiring a current of seven amperes or over shall be ultimately dependent on one cut-out.
48. In all cases where wires are concealed within, or attached to fixtures the latter must be insulated from the gas-pipe by some device approved by this Exchange. An exception to this rule will sometimes be made in the case of a wall gas-bracket wired for one or two lights.
49. When holes are drilled in fixtures, all burs or fins must be removed from the edge of the holes before the conductors are drawn through.
50. When wired outside, the conductors used must be so secured as not to be cut or abraded by the pressure of the fastenings or motion of the fixture.
51. All wire used for fixture work must have an insulation that is durable, and not easily abraded; and must not in any case be smaller than No. 18 "B. & S." or No. 20 "B. W. G."
52. Each fixture must be tested for possible "contact" between wire and fixture, and for "short-circuit," before current is turned on.
53. The tendency to condensation within the pipes or fixtures should be guarded against by sealing the upper end.
54. No combination fixture with less than 1-4 inch clear space between the inside pipe and the outside casing will be approved.
PENDANTS AND SOCKETS.
55. No portion of the lamp-socket exposed to contact with outside objects will be allowed to come into electrical connection with either of the conducting wires.
56. Cord pendants must be protected by hard rubber bushing, or something equally good, where they enter the socket.
57. The use of paraffined insulation for pendants will not be approved.
58. Key sockets must not be used with wire pendants, unless the wire be composed of strands, i. e., flexible.
59. When exposed to the weather, or used in wet rooms, care must be taken to keep moisture from the inside of sockets.
60. The weight of every socket and lamp suspended by a cord must be borne by a ceiling block, rosette, or cleat, and by a knot under the bushing in the socket, in order to take all strain from the joints and binding-screws.
61. Flexible cord must not be used except for pendants, wiring of fixtures, portable lamps, and "mill work."
62. The two conductors of flexible cord must not have an insulation composed of an inflammable water-proof compound between them, but should be separated by a fibre insulation, or the like. If a water-proof insulation is necessary, it must be placed outside the two conductors, and must in all cases be covered with a non-inflammable outside coating, to prevent cord from carrying fire.