ELECTRICITY SUPPLY.
No. 18 of 1911.
1945
Connexion of circuits with earth.
37. Where the pressure of a supply between the adjacent conductors of a three-wire system of mains exceeds 125 volts, the intermediate conductor shall be connected with earth in accordance with the following conditions :-
(1) the connexion with earth of the intermediate conductor shall be made at one point only on each distinct circuit, namely, at the generating station, sub-station, or transformer, and the insulation of the circuit shall be efficiently maintained at all other parts;
(2) the current from the intermediate conductor to earth shall be continuously recorded, and, if it at any time becomes excessive, steps shall be immediately taken to improve the insulation of the system.
38. The company shall not connect any other circuit with earth except with the approval of the Director of Public Works and subject to such conditions as he may prescribe.
Extra high pressure.
39.-(1) This regulation shall have effect in the case of a supply at extra high pressure, and shall be in addition to and not in substitution for the obligations imposed by the foregoing regulations.
(2) An extra high pressure main shall not be brought into use unless, after it has been placed in position and before it is used for the purposes of supply, the insulation of every part thereof has withstood the continuous application, during half-an-hour, of pressure exceeding the maximum pressure to which it is intended to be subject in use, that is to say, in the case of every electric line to be used for a pressure not exceeding 10,000 volts twice the said maximum pressure, and in the case of a line to be used for a pressure exceeding 10,000 volts, a pressure exceeding the said maximum pressure by 10,000 volts: and the company shall record the results of the tests of each main or section of a main.
(3) Every extra high pressure main shall be protected by a suitable fuse or automatic circuit-breaker, but in the case of a concentric main that fuse or circuit-breaker shall not be inserted in any external conductor thereof which is connected with earth.
(4) In every case where an extra high pressure supply is transformed or converted to a reduced pressure, some suitable automatic and quick-acting means shall be provided to protect the reduced pressure circuits from any accidental contact with or leakage from the extra high pressure system, either within or without the transforming or converting apparatus,
(5) All metal conduits, pipes, or casings containing any extra high pressure electric line shall be efficiently connected with earth, and shall be so jointed and connected across all street boxes and other openings as to make good electrical connexion throughout their whole length.
(6) Every portion of any extra high pressure electric line placed above the surface of the ground, otherwise than in a sub-station, or in any subway not in the sole occupation of the company, shall be completely enclosed either in a tube of highly insulated material embedded in brickwork, masonry, or cement-concrete, or in strong metal casing efficiently connected with earth.
ELECTRICITY SUPPLY.
No. 18 of 1911.
1945
Connexion of circuits with earth.
37. Where the pressure of a supply between the adjacent conductors [Schedule of a three-wire system of mains exceeds 125 volts, the intermediate contd.” conductor shall be connected with earth in accordance with the following Connexion conditious :-
with earth of a three-wire
(1) the connexion with earth of the intermediate conductor shall be system. made at one point only on each distinct circuit, namely, at the gencrating station, sub-station, or transformer, and the insulation of the circuit shall be efficiently maintained at all other parts ;
(2) the current from the intermediate conductor to earth shall be con- tinuously recorded, and, if it at any time becomes excessive, steps shall be immediately taken to improve the insulation of the system.
38. The company shall not connect any other circuit with earth except Comexion with the approval of the Director of Public Works and subject to such of other conditions as he may prescribe.
Extra high pressure.
circuits with earth.
39.-(1) This regulation shall have effect in the case of a supply at Special extra high pressure, and shall be in addition to and not in substitution for regulations the obligations imposed by the foregoing regulations.
as to extra
high
(2) An extra high pressure main shall not be brought into use unless, pressure. after it has been placed in position and before it is used for the purposes of supply, the insulation of every part thereof has withstood the continuous application, during half-an-hour, of pressure exceeding the maximum pressure to which it is intended to be subject in use, that is to say, in the case of every electric line to be used for a pressure not exceeding 10,000 volts twice the said maximum pressure, and in the case of a line to be used for a pressure exceeding 10,000 volts, a pressure exceeding the said maximum pressure by 10,000 volts: and the company shall record the results of the tests of ench main or section of a main.
(3) Every extra high pressure main shall be protected by a suitable fuse or automatic circuit-breaker, but in the case of a concentric main that fuse or circuit-breaker shall not be inserted in any external conductor thereof which is connected with earth.
(4) In every case where an extra high pressure supply is transformed or converted to a reduced pressure, some suitable antomatic and quick-acting means shall be provided to protect the reduced pressure circuits from any accidental contact with or leakage from the extra high pressure system. either within or without the transforming or convorting apparatus,
(5) All metal conduits, pipes, or casings containing any extra high pressure electric line shall be efficiently connected with earth, and shäll be so jointed and connected across all street boxes and other openings as to make good electrical connexion throughout their whole length.
(6) Every portion of any extra high pressure electric line placed above the surface of the ground, otherwise than in a sub-station, or in any subway not in the sole occupation of the company, shall be completely inclosed either in a tube of highly insulated material embedded in brickwork, masonry, or cement-concrete, or in strong metal casing efficiently connected with earth.
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