July 12.] THE NEW ZEALAND GAZETTE. 2401.

(4) All nuts or parts carrying over 25 amperes, and fixed at the back of switchboards, shall be effectively locked so that they cannot become loose.

(5) All bus-bars and connections on switchboards shall be in accordance with British Standard Specification No. 159.

(6) Where a scheme of colouring is employed to distinguish switchboard bus-bars and connections to individual poles or phases, such scheme of colouring shall be in accordance with British Standard Specification No. 158.

(7) The arrangement of bus-bars carrying alternating currents shall be in accordance with British Standard Specification No. 158.

38. Conductors must be symmetrically placed and spaced apart, and so arranged that the course of every conductor may be easily traced.

39. All circuits, instruments, and important apparatus shall be clearly and indelibly labelled for identification.

40. Switches shall be so arranged that their blades or moving parts are disconnected from the supply in the “off” position. They shall be so mounted that the top of the handle is at a height not exceeding 7 ft. 6 in. above floor-level.

41. In every case in which the switches and fuses are fitted on the same pole or phase these switches shall preferably be so arranged that the fuses are disconnected from the supply when their respective switches are in the “off” position.

42. In all cases panel switchboards shall be mounted on iron brackets or standards extending vertically the full length of the board, and of such dimensions as to adequately support the board. The minimum size of brackets shall be ¾ in. by ⅜ in. Brackets shall be fitted at points not greater than 24 in. apart, measured horizontally, unless the board is, in the opinion of the Authorized Inspector, of such strength and thickness as to ensure rigidity when the devices mounted thereon are operated.

43. Where meters, service-fuses, or other apparatus belonging to the supply authority are to be mounted on a switchboard, loops shall be left in the leads of sufficient length to allow the ends of the conductors to be properly connected by the supply authority.

DISTRIBUTION AND SECTION BOARDS.

44. The general design and construction of distribution and section boards shall conform to the requirements of Regulations 29 to 43 and 66 hereof so far as they are applicable. The fuses fitted in such boards shall conform to the requirements of Regulations 68 to 70 hereof.

45. (1) Every distribution or section board shall be controlled by a switch mounted thereon, and shall be contained within a case.

(2) Containing cases shall, except as provided in the next succeeding regulation, be secured by screws in such a manner as to be easily removable for the purpose of inspection.

46. The cases of distribution and section boards, if not removable, shall be of sufficiently ample dimensions to allow of easy access for the attachment of cables and for conduits and fixing nuts.

47. If glass fronts be provided they shall be clear of all live parts by not less than 1 in., and such fronts may be regarded as insulating-shields.

48. All cases in positions exposed to the weather, to drip, or to an abnormally moist atmosphere shall be weatherproof, and shall be provided with cable glands or bushings, or be adapted to receive screwed conduit, according to the way in which the cables entering the cases are run.

49. (1) In earthed concentric wiring systems distribution-boards shall, in addition to complying with the foregoing requirements, be contained in cases in which provision is made for the following :—

(a) If of metal, the attachment to the case of all external conductors of the concentric cables entering it.

(b) If of wood, a sheet of incorrodible metal, of the same area and shape as the base of the case, interposed between it and the wall or other support to which it is attached.

(2) The sheet of metal required by paragraph (b) of the last preceding subclause shall be not less than ¹⁄₁₆ in. in thickness, and be electrically and mechanically connected to all the external conductors of the concentric cables entering the case, by means of a metal bar, or rod, or bare wire conductor, of which the resistance shall be not greater than that of the inner conductor of the cable feeding the board.

50. The design, construction, and arrangement of the cut-outs and the metal case (if any) shall be such that an arc cannot be set up to the case or between poles or phases when the fuse is melted by a short-circuit current.

51. (1) All self-contained subcircuit fuse-cases made of wood other than jarrah or teak shall be lined with non-ignitable insulating-material, which shall be clear of all live parts by not less than 1 in.

(2) When any such case is not provided with a back forming an integral part thereof, a non-ignitable insulating-shield shall be fixed between the contents of the case and any ignitable structure to which it may be fixed.

52. Where cut-outs are grouped on a board they shall be fixed vertically, and a shield of non-ignitable insulating-material shall be inserted between cut-outs of opposite polarity or phase when placed one above the other, if the fuses are of a type which on blowing expel the gas parallel to the axis of the fuse.

MAIN SWITCH-GEAR.

53. (1) Every main switchboard shall be fitted, as a minimum, with such of the switch-gear mentioned in Part I of the Second Schedule hereto as is appropriate to the particular system of wiring.

(2) Where the supply is from an external source the service-fuse installed by the supply authority may take the place of the fuse mentioned throughout the said Schedule in connection with the control of main supply, provided that the supply authority’s service-fuse is used solely for the one consumer.

(3) Where more than one generator is installed, the generators not being arranged to run in parallel, or where the supply is derived from a duplicate service from an external source, double-throw switches shall be provided in suitable positions to prevent the generators or services being connected together.

(4) In the case of submains or circuits of 50 amperes connected load or less the switches specified in the said Part of the Second Schedule hereto may be omitted.

(5) In the case of a non-earthed system where double-pole circuit-breakers are specified in the said Schedule only one overload trip shall be necessary.

(6) Where a separate fuse and switch or separate fuses and linked switches are specified in the said Part I of the Second Schedule hereto a fuse-switch or linked fuse-switches, as the case may be, may be used.

DISTRIBUTION SWITCH-GEAR.

CONTROL OF SUPPLY.

54. Every installation shall be adequately protected by suitable controlling-apparatus (as required by the last preceding regulation) easily accessible to the consumer and situated as near as possible to—

(a) The point or points of entry of the service-main in the case of a public supply : or

(b) The generator in the case of a private plant.

55. (1) In the case of an overhead supply, service-fuses shall be fixed either outside the building or in a permanently accessible position free from combustible material within a building and as near the point of entry as possible. They shall not be placed between ceiling and roof.

(2.) When the supply is from an underground source the service-fuses shall be as near the point of entry as possible and in a permanently accessible position free from combustible materials.

56. (1) All supply from an underground source shall be controlled by a master-switch placed in a conveniently accessible position as near an entrance or exit-door as circumstances permit.

(2) Where the main switch is in the above position it may be used as the master-switch.

(3) Where the master-switch is protected by a case, the case shall have a hinged clear glass or wooden front. If the front is of wood it shall have the words “Master Switch” painted thereon in block letters not less than 1 in. in height.

57. In all cases when more than one consumer is connected to a service the various consumers’ switchboards shall be distinctly labelled for purposes of identification.

58. (1) The service-fuses of any building to which Part IX hereof applies shall not be used for the supply of current to any other electrical installation whatever.

(2) Where failure of light might cause panic, or be otherwise dangerous, the lighting shall be controlled by independent service-fuses, and no apparatus other than permanent lighting shall be connected to this service.

59. In the case of a private plant where the building containing the generator is isolated from the building in which the electricity is consumed, a main switch shall be installed at the point at which the main cables enter the latter building. Where more than one building is supplied from a common main, main fuses shall also be installed at each building.

60. In installations in which the normal-working current in any circuit or circuits exceeds 100 amperes there shall be provided a circuit-breaker with overload trips. This device shall be set to operate with any prescribed value of current