JULY 12.] THE NEW ZEALAND GAZETTE. 2365

account be interconnected with each other or with any earth-connection used for earthing circuits or equipment.
(3) Where, in the case of pole substations, the distance of 6 ft. specified in the last preceding subclause cannot be obtained, the distance shall be the maximum obtainable on the substation structure.
(4) Earthing-leads for lightning-arresters shall not pass through iron or steel pipes, and shall be taken as direct as possible between the lightning-arrester and the earth-connection. Bends shall be avoided where possible, but where bends are unavoidable they shall have as large a radius as possible.
47. On alternating-current star-connected systems, with the neutral earthed, pipe crossings for medium, low, or extra-low pressure electric lines may be earthed by running a bare neutral wire in the pipe.
48. Where the neutral of a medium or any lower pressure three-phase four-wire system is used for earthing stay-wires, earthing-bars, and other line hardware, it shall not be of a less area than that specified in Regulation 44 hereof unless such neutral is earthed at points as nearly equidistant as possible and at intervals of not more than 15 chains each.
49. Joints between earth-wires shall be soldered or made with suitable clamps or metal sleeves.
50. Earthing-leads, if laid underground, shall, unless otherwise mechanically protected, be laid slack to prevent their being readily broken, and shall have all joints carefully painted or otherwise protected against corrosion.
51. Earth-pipes, earth-plates, and other earth-connections, shall be located, where practicable, below permanent moisture-level, or, failing this, at least 6 ft. below ground-level. Areas where ground-water level is close to the surface shall be used when available.

EARTH TESTS.

52. All earth-wires and earth-connections shall, before the electric lines are livened up, be tested for electrical resistance, and if such resistance exceeds 10 ohms the licensee shall not, save with the consent in writing of the Minister, use the electric line, electrical apparatus, or other device so earthed until the resistance has been reduced to 10 ohms or less.
53. (1) All earthing-leads and earth-connections except those specified in Regulation 190 shall be tested at least once every twelve months.
    (2) All earth-wires and earth-connections under Regulations 46, 59, and 156 (b) hereof shall be tested at regular intervals of not more than six months.
    (3) The tests required by this regulation shall be made by the licensee during the dry months as far as possible, to ensure that all earthing-leads are intact and that the earth-connections are effective.
    (4) Where the neutral of a low-pressure star-connected system or the intermediate conductor of a low-pressure three-wire single-phase system is connected to earth on the consumer’s premises the aforesaid tests may be omitted on such connection.
54. Records of all tests made shall be kept by the licensee, and shall be available for inspection by the Inspecting Engineer and other officers of the Public Works Department and officers of the Post and Telegraph and Government Railways Departments when required.
55. Not later than the 30th day of June in every year, in respect of the period of twelve months ending on the 31st day of March then last past, there shall be forwarded—
    (a) To the Chief Electrical Engineer of the Public Works Department, a certified copy of the record of all earth tests made ;
    (b) To the District Telegraph Engineer or his deputy, a certified copy of the record of all tests made on guards erected over telegraph-wires and on all earthed metal at telegraph crossings ;
    (c) To the Signal and Electrical Engineer of the Government Railways Department, a certified copy of the record of all tests made on guards and earthed metal at railway crossings.
56. Each earth-connection shall be given a designation number for identification purposes, and such number shall be used in all records. Should the number be changed for any reason, then both the old and new designation numbers shall be entered in the first certified copies of records forwarded, pursuant to the last preceding regulation, after such change.
57. Additional tests of any earthing-leads or earth-connections shall be made if and when required by the Minister.

SWITCHBOARDS.

58. (1) All power-house and substation switchboards, including the frames to which they are attached, shall be made of fireproof material ; and the maximum permissible current and temperature in any conductor mounted thereon or leading thereto shall not exceed the values permitted under the British Engineering Standards Association’s Specification No. 159.
    (2) No conductor at a pressure above 650 volts shall be exposed on the front of any switchboard ; and the back of any switchboard on which bare live metal at a pressure of 250 volts and over to earth is mounted shall be made inaccessible (except to authorized persons) by means of screens or otherwise.
    (3) Every door leading to the back of a switchboard shall be provided with a spring or other approved device which shall ensure that the door remains wide open when not properly shut and locked.
    (4) No fuse (other than the primary fuse of a potential transformer) circuit-breaker or switch (other than an isolating switch) shall be fixed on the back of any switchboard or in the screened-in space at the back thereof if it is necessary to operate such fuse circuit-breaker or switch from behind the switchboard. No equipment shall be mounted at the back of any switchboard if it is of such a construction as will endanger any other equipment when such first-mentioned equipment is in normal operation.
59. (1) All power-house and substation switchboards controlling high or extra-high pressure circuits shall be provided with two efficient and independent earth-connections, connected in parallel, to which all metal frames, all metal instrument-cases (unless otherwise protected), and other metal parts thereof shall be connected.
    (2) Means shall be provided for testing the resistance through the earth between these two earth connections, as specified in Regulations 52 and 53 hereof.
60. (1) A rubber mat of not less than ¼ in. thickness shall be provided for the protection of operators in front of every power-house and substation switchboard,—
    (a) Which controls lines or apparatus working at a pressure above 250 volts to earth.
    (b) Which, being mounted on a floor of conducting material, controls lines or apparatus working at a pressure above 100 volts to earth, except in the case of medium or any lower pressure, where all live metal on such switchboard is totally enclosed and all other metal thereon, or connected therewith, is efficiently and permanently connected to earth.
    (2) A rubber mat as aforesaid shall be provided in the screened-in space at the rear of every powerhouse and substation switchboard (not being of the totally enclosed iron-clad cubicle type) when such switchboard controls lines or apparatus working above medium pressure, or where such switchboard is mounted on a floor of conducting material, and controls lines or apparatus working at a pressure above 250 volts to earth.
61. All switchboard circuits shall be so arranged that the course of any main conductor may be readily identified. The standard colourings and conductor location shall comply with the British Engineering Standards Association’s Specification No. 158.
62. All panels shall have marked thereon, near each switch, the name of the feeder controlled by such switch.
63. (1) Except in the cases mentioned in the next succeeding subclause, isolating-links shall be fitted in the leads of each panel of all high or extra-high pressure switchboards so that the panel can be made dead when necessary.
    (2) The last preceding subclause shall not apply—
    (a) Where the oil circuit-breaker can be withdrawn from all sources of supply (e.g., truck-type cubicles) :
    (b) Where the switchboard consists of one panel and it can be made dead by opening a switch outside and adjacent to the substation :
    (c) Where there is a single panel supplied from one generator.
64. (1) Every power-house or substation switchboard shall be erected in such a position as to provide, in front and behind the switchboard, the clear unobstructed spaces hereinafter mentioned, namely—
    (a) Medium and low-pressure switchboards—an overhead clearance (except in screened spaces dealt with in paragraph (c) of this regulation) of not less than 7 ft. from the floor to any bare conductor under which it is necessary to pass, and a passage-way in front of the switchboard with at least 3 ft. horizontal clearance from the face of the switchboard or any bare live metal affixed thereto.
    (b) High and extra-high pressure switchboards (not exceeding 11,000 volts between phases), other than operating desks or panels working solely at medium, low, or extra-low pressure—an overhead clearance (except in screened spaces dealt with in paragraph (c) of this regulation) of not less than 8 ft. from the floor to any bare conductor under which it is necessary