July 12.] THE NEW ZEALAND GAZETTE. 2403

Low and Medium Pressure.

69. For low and medium pressure every cut-out shall comply with the following requirements in addition to the requirements of paragraphs (a) to (h) of the last preceding regulation:—
    (a) It shall be provided with a suitable incombustible and insulating carrier for the fuse of such shape as to protect a person handling it from shock and burns; and contacts shall be provided on the carrier to which the ends of the fuse can be readily attached.
    (b) The base shall be provided with fixed circuit contacts of such shape as to retain the carrier in position in the presence of vibration.
    (c) The bus-bars, fixed contacts, removable contacts, and fuses shall be so shielded as to protect a person against contact with live metal when the fuse-carrier is being inserted or removed.

70. Where iron-clad fuses are used they shall be so erected that the covers cannot accidentally open or come apart at the hinges, and so that each cover can be fully opened.

PART V.—DISTRIBUTION.

SUBDIVISION OF CIRCUITS.

71. (1) The maximum number of points that may be connected in parallel to a final subcircuit shall be as follows:— Where the total rating of the points supplied from the subcircuit does not exceed—6 amperes, 10 points; 8 amperes, 6 points; 10 amperes, 4 points; 20 amperes, 2 points.

Final subcircuits supplying one lamp or appliance are not limited as to current-carrying capacity.
(2) For the purpose of calculating the current of a lighting circuit no lamp shall be rated at less than 60 watts, lamps of larger wattage (if any) being allowed for in full.
(3) For the purpose of calculating the current of a heating circuit each plug shall be rated at not less than 5 amperes; consuming-devices of larger capacity, if any, being allowed for in full. The minimum size of cable shall be 3/·036 in.
(4) When the fusing-current of the fuse controlling the final subcircuit exceeds 7 amperes the smallest cable or flexible cord which is used for any purpose on such circuit shall be capable of carrying continuously a current not less than half of such fusing-current. For the purposes of this sub-clause the carrying-capacity of a flexible cable or cord shall be considered to be that specified in Table XVI in the Third Schedule hereto.

72. Every final subcircuit shall be connected to a switchboard and be controlled by—
    (a) Fuses or circuit-breakers as specified in Part I of the Second Schedule hereto, where the connected load does not exceed 50 amperes.
    (b) Circuit-breakers or switches and fuses as specified in Part I of the Second Schedule hereto, where the connected load exceeds 50 amperes.

CONDUCTORS OF CABLES.

MATERIAL OF CONDUCTORS.

73. All conductors for internal wiring other than the outer conductors of earthed concentric systems shall be of annealed copper, and shall conform to British Standard Specification No. 7.

74. When the insulating covering of the conductor may contain sulphur, each wire shall be adequately and uniformly coated with tin free from all impurities.

STANDARD SIZE OF CONDUCTORS.

75. (1) The sizes of solid and stranded conductors and resistances set out in Table I in the Third Schedule hereto shall be the standard sizes for the purposes of these regulations.
    (2) The sizes of conductors and resistances for flexible cables set out in Table III in the Third Schedule hereto shall be the standard sizes for the purposes of these regulations.
    (3) The sizes of conductors and resistances for flexible cords set out in Table VII in the Third Schedule hereto shall be the standard sizes for the purposes of these regulations.

MINIMUM SIZE OF CONDUCTORS.

76. No cable having a conductor of nominal sectional area less than 0·0015 square inch (1/·044 in.), and no flexible cord having a conductor of nominal sectional area less than 0·001 square inch (23/·0076 in.), shall be used except for wiring fittings, for which a conductor having a nominal sectional area not less than 0·001 square inch (1/·036 in.) may be employed: Provided that where the design of a fitting renders it impossible to use a conductor of this size, a flexible cord having a conductor of nominal sectional area not less than 0·0006 square inch (14/·0076 in.) may be used.

77. (1) Service mains shall be stranded, and shall have a carrying-capacity not less than the maximum demand of the installation, but in no case shall they be smaller than 7/·029 in.
    (2) Where the maximum demand is not readily ascertainable it shall be assessed as follows:—
    Lighting . . . . Two-thirds of connected load.
    Heating (including cooking) . . . Three-quarters of connected load.
    Power—
    One motor . . Total connected load.
    Two motors . . Three-quarters of connected load
    Exceeding two and not exceeding five . Two-thirds of connected load.
    Exceeding five . . One-half of connected load.
    (3) Where electrical energy is used for more than one purpose the maximum demand shall be assessed by adding together the figures obtained from the above calculations.

78. (1) The earthing-lead shall be stranded cable or flat strip, the latter not less than ¾ in. wide by No. 18 gauge. No conductor of a less cross-sectional area than 0·0045 square inch (7/·029 in.) shall be used as an earthing-lead, provided that where the cross-sectional area of portable leads is less than 0·0045 square inch the earthing-conductor in the portable lead may be equal in cross-sectional area to the live conductor.
    (2) The minimum size of such conductor (0·0045 square inch) shall be deemed sufficient for installations not exceeding 50 amperes working current.
    (3) The effective area of the earthing-lead shall be increased by 0·0045 square inch for each 50 amperes or part thereof.

MAXIMUM SIZE OF SINGLE WIRE.

79. No single wire having a nominal sectional area exceeding 0·0015 square inch (1/·044 in.) shall be used as a conductor.

CURRENT-CARRYING CAPACITY OF CONDUCTORS.

80. The size of conductors shall be so selected that—
    (a) For lighting and heating, the fall in pressure from the terminals of the main switch of the main switchboard controlling the various circuits to any and every point on the installation does not exceed 1 volt plus 2 per cent. of the pressure at the said terminals when the conductors are carrying the maximum demand under the practical conditions of service.
    (b) In no case, whether for lighting, heating, or power, shall the current exceed that given in Tables IV and V in the Third Schedule hereto for each size of conductor when the maximum current referred to in the last preceding paragraph is being carried.

81. In the case of flexible cables and flexible cords the values shown in Table VI and column 9 of Table VIII in the Third Schedule hereto respectively shall be adopted.

INSULATION AND PROTECTIVE COVERING OF CONDUCTORS.

INSULATION OF CONDUCTORS.

82. Except as provided in Regulation 122 with respect to earthed concentric wiring, all conductors shall be insulated, either by being carried on insulators (as provided by Regulation 102) or by the use of insulated cables.

TYPES OF INSULATION AND PROTECTIVE COVERING.

83. Cables shall be single, twin, three-core, four-core, concentric, or triple concentric in accordance with the dimensions and other requirements of British Standard Specification No. 7, and only the types mentioned in the next succeeding regulation and such other types as may from time to time be approved by the Chief Electrical Engineer shall be employed.

84. The following types of insulation and protective covering are hereby declared to be approved types for the purposes of these regulations:—

Vulcanized Rubber-insulated Cables.

(a) Taped as in Regulation 87 and compounded.
(b) Taped as in Regulation 87 and braided.
(c) Sheathed with a closely fitting seamless covering of commercially pure lead having a smooth exterior surface and of uniform radial thickness in accordance with British Standard Specification No. 7.
(d) Lead-covered as in the last preceding paragraph, and bedded and armoured, with or without serving or braiding over the armour; the bedding, armouring, and serving or braiding (if any) to be in accordance with British Standard Specification No. 7.