51054-1917-Regulations-under-the-Electricity-Supply-Ordinance-1911 — Page 7

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THE HONGKONG GOVERNMENT GAZETTE, MARCH 16, 1917.

Height from ground.

Are lamps to be guarded.

Connection

with earth of

a three-wire system.

Connection of other

Arc Lighting.

35. Are lamps used in any street for public lighting shall be so fixed as not to be in any part at a less height than 10 feet from the ground.

36. All are lamps shall be so guarded as to prevent pieces of ignited carbon or broken glass falling from them, and shall not be used in situa- tions where there is any danger of the presence of explosive dust or gas.

Connection 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:-

(a) the connection 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 ;

(b) 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 circuits with conditions as he may prescribe.

earth.

Special regulations

as to extra high

pressure.

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 pur- poses of supply, the insulation of every part thereof hos 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 con- ductor 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 clectric line shall be efficiently connected with earth, and shall be so jointed and connected across all street boxes and other openings so as to make good electrical connection 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 sub- way 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.

(7) Where extra high pressure mains for three-phase supply consist of insulated conductors laid together, provision shall be made to ensure that neither the ground nor any neighbouring or electric line or con- ductor can become charged by leakage from any such main.

Where this provision is made by a copper strip under a lead sheath, that strip shall be not less than sixteen-thousandths of an inch in thick- ness, and where it is made by steel wires outside a lead sheath, each of those wires shall be not less than one-tenth of an inch in diameter.

Where the mains are enclosed in a lead sheath, that sheath shall be not less than one-tenth of an inch in thickness, and shall be permanently and efficiently connected with earth,