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the main lines, and secondary currents of low electromotive force are developed in local "converters" or "transformers," it is important that the entire primary circuit aud the transformers should be excluded from any insured building, and be confined to the aerial line (the transformers being attached to the poles or the exterior of the buildings) or to underground conduits, if such are used, or placed in fireproof vaults or exterior buildings.
33. In those cases, however, where it may not be possible tc exclude the transformers and entire primary from the buildings, the following precautions must be strictly observed:
34. The transformer must be constructed with or inclosed in a fireproof or incombustible case, and located at a point as near as possible to that at which the primary wires enter the building. Between these points the conductors must be heavily insulated with a coating of approved waterproof material, and in addition must be so covered in and protected that mechanical injury to them, or contact with them, shall be practically impossible.
35. These primary conductors, if within a building, must also be furnished witli a doublepole switch, or separate switches on the ingoing and return wires, and also with automatic double-pole cut-out where they enter the building or where they leave the main line, on the pole or in the conduit. The switches above referred to should, if possible. be inclosed in secure and fireproof boxes outside the building.
36. In the case of isolated plants using the secondary system, the transformers must be placed as near to the dynamos as possible, and all primary wires be protected in the same manner as is indicated in paragraph 34.
37. Where there is a possible exposure to water, the first or second coating must be impervious to the fluid.
38. For incandescent lamp fixtures and electroliers, exceptions may be made to the foregoing rule in which the wires can be placed nearer than the prescribed distance to each other, or to other conductors, provided the fixture is fully insulated at the base from house and ground piping, and further provided that a double pole safety catch is placed at the base of each fixture, or at the nearest branch connection as may be required by the Inspector of the Board.
39. In all cases where combination (gas and electric) fixtures are used, extra precaution must be taken to secure complete and continuous insulation from the gas piping.
Insulation in General.
40. It is to be understood as a general or universal rule that all machines, lamps, wires, and other parts of electric systems are to be so constructed, mounted and secured as to insure complete and continuous insulation; with such exceptions unly as are hereinbefore stated, and that in no case shall ground circuits be employed, or any part of the system be allowed to come in contact with the earth through gas or water pipes, or the like.
Automatic S hunt.
41. Wherever a current of such high electromotive force is employed that if concentrated on one lamp or motor of the series it would produce an arc capable of destroying or fusing parts of such lamp, an automatic switch must be introduced in each lamp or motor by which it will be thrown out of circuit before the arc approaches any such dangerous extent.
42. Means by which those in charge of the dynamo-electric machines will be warned of any excessive flow of current, or means whereby the same will be automatically checked, must in all cases be provided.
Fusible or Other Automatic Cut-Outs for Low Potential Circuits.
43. Wherever a connection is made between a larger and smaller conductor at the entrance to or within a building, some approved automatic device must be introduced into the circuit of the smaller conductor at or close to its junction, by which it shall be interrupted whenever the current passing is in excess of its safe carrying capacity.
44. The safe carrying capacity of a wire is the current which it will convey without becoming painfully warm when grasped for a minute in the closed hand.
Cut-Out Boxes or Switches.
45. All cut-out boxes or switches which shift, transmit, or break a current must be mounted on incombustible bases, and so arranged as to close one circuit before they open another and. operate in such a manner that no arc can be formed between the contact surfaces when thrown "on" or "off." It must be so far positive in its action that it cannot stop between its extreme positions. It must indicate on inspection whether current is "on" or "off." This rule applies to isolated plants as well as to those connected with central stations.
46. The Rules and Regulations under the head of Capacity of Wires, Insulation, Auto matic Cut-Outs and Switches shall be observed, where electric motors are used, and in addition the motor frames must be properly insulated, and so mounted as to be free from grounds, and each motor shall be provided with an approved switch to prevent an excessive flow of current.
47. When the current for lights or power is taken from storage batteries, the same general regulations are to be observed.
Meaning of Technical Terms, Etc., Etc.
48. High Potential Circuits Or Wires.— This term includes all wires arranged with the view of carrying currents of more than 250 volts difference of potential between any two parts of the system, even if such current is used to run incandescent lamps.
49. Low Potential Circuits Or Wires are such as do not carry currents of more than 250 volts.
50. Companies furnishing electricity from central stations must enter into an agreement with the New York Board of Fire Underwriters, binding themselves to test their lines for ground connections at least once every day (and preferably three times per day), and to report the result of such tests to the Board weekly.
51. The Rules and Regulations of the Board of Electrical Control and all existing regulations of the local authorities in reference to the stringing of wires must be strictly observed.