Nov. 9.] THE NEW ZEALAND GAZETTE. 3345

insulation of the supply and return wires shall be at least 300-megohms grade of vulcanized rubber, and higher-grade rubber shall be provided where required. On telegraph-poles these wires shall be placed well out on the arms away from the pole. The placing of these circuits on telegraph-poles shall be restricted as far as possible. They may intersect other wires in the same way as the three-phase circuits on compliance with the conditions of insulation and of guard-wires where necessary. The tramway-rail may be used as a return.

40. Constant-current circuits, either alternating or direct, in excess of medium pressure, for lighting incandescent street-lamps in series, shall have the supply-wire of each phase insulated with not less than 600-megohms grade of vulcanized rubber. The return or neutral of these circuits may be of bare wire where both ends of the neutral are earthed. These circuits shall not be run along on the telegraph-poles except as provided for in clause 25, but they may be attached thereto. When direct current is used, provision shall be made for the insertion of an ammeter in the earth lead nearest to the source of supply of the current. The current passing through the ammeter from the earth shall at no time exceed one-quarter of an ampere. Readings shall be taken at least every two weeks, and a record of them shall be kept. Lamps forming part of these constant-current circuits may be affixed to telegraph-poles. The methods of attachment to those poles, the means on the poles of safely supplying the lamps, and the position of the lamps, shall be subject to the approval of the Minister of Telegraphs.

41. Efficient guard-wires shall be erected in a manner to meet with the approval of the Minister of Telegraphs at all crossings and places where electric-lighting wires intersect any wires on telegraph-poles as may be required by the Minister to be protected. If required by the Board of Control, other wires shall be protected by efficient guard-wires in a manner to meet with its approval. The Corporation shall bear the expense of such guard-wires in all cases where an aerial electric-lighting wire intersects any wires previously existing.

42. Where the erection of the electric-light lines or wires necessitates the alteration of existing telegraph lines or wires, the expense of such alteration shall be borne by the Corporation.

43. Every support for an aerial wire shall be of a durable material, and shall be properly secured against forces due to wind-pressure, change of direction of the line, or unequal lengths of span. Every support, if of metal, shall be efficiently earthed. The factor of safety for all parts of the aerial-line structure shall not fall below at least 6, taking the maximum possible wind-pressure at 20 lb. per square foot. If iron towers are used as supports, the factor of safety of the tower need not exceed 4.

44. The interval between any two wooden poles used singly as supports for an overhead line other than a transmission-line shall not exceed 200 ft. where the direction of the line is straight, or 150 ft. where the direction is curved, or where the wires make a horizontal angle at the point of support.

45. All aerial wires shall be attached to porcelain insulators carried on cross-arms of suitable material and cross-section, and they shall be so attached to the insulators or guarded that they cannot fall away from the support. Conductors covered with insulating material shall be so attached that their insulation will not be impaired where they are secured to the insulator.

46. Any aerial wire shall not in any part thereof be at a less height from the ground than 18 ft., or within 5 ft. measured horizontally or 7 ft. measured vertically from any part of any building or erection other than a support for the wire, except where led to transformers or brought into a building for the purpose of supply.

47. Service-wires from aerial lines shall be led as directly as possible to insulators firmly attached to some portion of the consumer’s premises which is not accessible to any person without the use of a ladder or other special appliance. In those places where the medium- and low-pressure wires are weatherproof—insulated or bare—every portion of such wires (except the neutral wire) which is within 7 ft. of any part of any building shall be efficiently protected by rubber insulating-material.

48. Where any aerial wire crosses a street the angle between the wire and the direction of the street at the place of crossing shall not be less than 60 degrees, and the spans shall be as short as possible.

49. Every aerial wire, including its supports and all the structural parts and electrical appliances and devices belonging to or connected with the line, shall be duly and efficiently supervised and maintained as regards both electrical and mechanical conditions.

50. An aerial line or wire shall be removed after it has ceased to be used for the supply of energy, unless it is intended within a reasonable time again to take it into use.

51. In running overhead lines through streets where telegraph-lines do not exist, the Corporation shall keep its lines on one side of the street, and the Telegraph Department in running its lines shall do the same, and in providing service-wires to the opposite side of the street to that on which its line of poles is placed the Corporation shall arrange to supply so as to interfere as little as possible with the route on that side of the street.

52. The sectional area of the conductor in any electric line laid or erected in any street shall not be less than that of a strand of seven wires, each of which is of No. 20 standard wire gauge, and the sectional area of every wire in a strand forming any such conductor shall not be less than that gauge.

53. Where any support or portion of any electric line is exposed in such a position as to be liable to injury from lightning, it shall be protected as far as may be practicable against such injury, but where any such protection can be shown to be detrimental to efficient service it may be dispensed with.

Electric Lines other than Overhead Lines.

54. Every low-pressure and medium-pressure main laid underground shall be tested for insulation before it is used for the purpose of supply, the testing-pressure being the maximum pressure to which it is intended to be subjected in use, and in any case at least 230 volts. The Corporation shall duly record the result of such tests.

55. The insulation of every complete circuit laid underground and used for the supply of energy, including all machinery, apparatus, and devices forming part of or in connection with that circuit, shall be so maintained that the leakage-current shall not under any conditions exceed one-thousandth part of the maximum supply-current, and suitable means shall be provided where practicable for the indication and localization of leakage. Every leakage shall be remedied without delay. Every such circuit shall be tested for insulation at least once a week, and the results of the tests shall be duly recorded. Provided that when any part of any electric circuit is normally connected with earth, the provisions of this regulation shall not apply to that circuit so long as the connection with earth exists.

56. A high-pressure underground circuit shall not be brought into use unless the insulation of every part thereof has withstood the continuous application during half an hour of a pressure twice the maximum pressure to which it is intended to be subjected in use. The result of such tests shall be recorded.

57. All conduits, pipes, casings, and street-boxes used as receptacles for electric lines shall be constructed of durable material, and shall be of ample strength to prevent damage from heavy traffic, and reasonable means shall be taken to prevent the accumulation of gas in such receptacles.

58. Where any electric line crosses or is in proximity to any metallic substance, special precautions shall be taken against the possibility of any electrical charging of the metallic substance from the line, or from any metallic conduit, pipe, or casing enclosing the line.

59. All metal conduits, pipes, or casings containing any high-pressure electric line shall be efficiently earthed, and shall be so jointed and connected across all street-boxes and other openings as to make good electrical contact throughout their whole length.

60. The covers of street-boxes shall be so secured that they cannot be opened except by means of a special appliance. Street-boxes shall be inspected from time to time for the presence of gas, and suitable action shall be taken to check its influx and accumulation. Where mains at different pressures pass through the same street-box they shall be readily distinguished from one another.

61. All apparatus and conductors for all pressures shall be sufficient in size and power for the work they are called upon to do, and so constructed, installed, protected, worked, and maintained as to prevent danger so far as is reasonably practicable.

For Medium and High Pressure.

62. All conductors shall be covered with insulating-material, and further efficiently protected where necessary to prevent danger.

63. Every switch, switch-fuse, and circuit-breaker shall be (a) so constructed, placed, or protected as to prevent danger; (b) so constructed and adjusted as accurately to make and to maintain good contact; (c) so constructed or arranged that it cannot accidentally fall or move into contact when out of contact.

64. Every switch intended to be used for breaking a circuit, and every circuit-breaker, shall be so constructed