2468
THE NEW ZEALAND GAZETTE.
[No. 90

13. At the distributing-station in the Town of Gore the current from the transmission-wires shall be passed through oil-cooled transformers, which shall transform from 4,500 volts to 2,200 volts, and to 250 volts. The transformers reducing to 250 volts shall have three terminals on the secondary winding, so that 125 volts can be got between the central terminal and either of the outers.

14. All transformers, including those that may be placed on poles in the distributing system, shall have easily “removable” fuses for the primary circuit, shall have secondary fuses, and the fuse-chambers shall be entirely separated from the transformer windings. Transformers that are to be affixed to poles shall be oil-filled, shall be fitted with watertight cast-iron cases, and shall be placed up the pole so as to be inaccessible except by the use of a ladder or other special appliance. Every transformer shall have its primary and secondary coils protected by approved lightning-guards, shall have its iron case effectively connected with earth as near to its site as possible, and, excepting those at the distributing-station transforming to 2,200 volts, shall be fitted with Cardew’s or other approved earthing-device, which shall be set to operate at a pressure of 450 volts. Tests shall be made of each transformer at least every six months to see that each coil is highly insulated from the other and from the iron case, and that the earthing-devices will operate at the voltage for which they are set. A record shall be kept by the Corporation of the result of all such tests.

15. No wire smaller than the equivalent of a No. 6 standard wire gauge shall be used for making the lightning-guard, earthing-device, and transformer-case earth connections. The earth-wires shall be of stranded copper, shall be highly insulated, and carefully protected by casing from all liability of damage or of being interfered with. They shall be run as straight as possible, and be properly connected to an efficient earth, which shall be provided, in the case of transformers, at the site of the transformer being protected. An examination and test shall be made every three months, and oftener if required, of all earths, to secure that the earth wire is intact, its insulation unimpaired, that it is in intimate contact with the earth-plate, and that the earth is effective.

16. The current transformed to 2,200 volts at the distributing-station for transmission to East Gore shall be conveyed aerially by means of cables insulated throughout their entire length with 2,500 megohms per mile grade of vulcanised rubber insulation, taped and braided. The cables shall be suspended by raw-hide hangers from suitable galvanised-steel bearer wires, which shall be supported on strong wooden poles, and shall be properly bound in to double-shed highly vitrified porcelain insulators carried on cross-arms of suitable material and cross-section. The cables shall be not less than 18 ft. above the ground at their lowest point. This circuit shall not be brought into use unless the insulation of every part thereof has withstood the continuous application during one hour of pressure exceeding the maximum pressure to which it is intended to be subject in use. The poles shall be placed at distances not exceeding 2 chains apart. At East Gore the cables may terminate at transformers placed upon poles which shall be specially strong. The pole transformers shall have three terminals, and shall transform so that the pressure shall be 220 volts between the outer terminals and 110 volts between either outer and the middle terminal.

17. Conductors covered with insulating material shall not be attached to insulators with uninsulated metal bindings.

18. Distribution to consumers shall be on the three-wire system. Hard-drawn copper wire, which may be bare, shall be used.

19. Primary and bare secondary wires are not to be run on the same poles.

20. The maximum pressure for lighting purposes (except arc lamps) shall not exceed 110 volts at any pair of terminals on a consumer’s premises. For power purposes motors may be connected across the outers of the distribution system.

21. The low-tension electric-lighting lines and wires shall be aerial throughout, and these and the 2,200-volt transmission line to East Gore shall be placed, where they run on roads or streets, on the opposite side of the roads or streets where any telegraph or telephone lines exist at the time of their erection, except by permission from the Electric Telegraph Commissioner.

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

23. The maximum working-current in any conductor shall not be sufficient to raise the temperature of the conductor or any part thereof to such an extent as to materially alter the physical condition or specific resistance of the insulating covering, if any, or in any case to raise such temperature to a greater extent than 30° Fahr. The cross-sectional area and conductivity at joints must be sufficient to avoid local heating, and the joints must be carefully made, using resin as a flux, and must be protected against corrosion. In all new installations, and installations already existing that may require to be materially altered or rewired in the future, the sectional area of all conductors on the consumer’s premises from the main switchboard or from any distribution-block must be maintained throughout the circuit, and joints should be made only when branching off a circuit, and should be at least 8 in. distant from a joint in any other conductor.

24. The sectional area of the conductor in any electric line for distribution purposes laid or erected in any street shall not be less than the area of a circular wire 80 mils in diameter, and where the conductor is formed of a strand of wires each separate wire shall be at least as large as No. 20 standard wire gauge.

25. All material used for insulating electric lines or apparatus shall be of the best quality, and thoroughly durable and efficient, having regard to the conditions of its use. Suitable provision shall be made for the protection of the insulating material against injury or removal. If the protection so provided be wholly or partly metallic it shall be efficiently connected with earth.

26. Any metallic body to be “efficiently connected with earth” shall be connected with the general mass of the earth in such manner as will insure at all times an immediate and safe discharge of electrical energy.

27. Every main shall be tested for insulation after having been placed in position and before it is used for the purposes of supply, the testing-pressure being at least 220 volts, and the Corporation shall duly record the results of the tests of each main or section of a main.

28. The insulation of every complete high- and low-tension distribution-circuit used for the supply of energy from the transformers situated in the distributing-station at Gore, including all machinery, apparatus, and devices forming part of or in connection with such 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 for the immediate indication and localisation of leakage. Every leakage shall be remedied without delay. Every such circuit shall be tested for insulation at least once in every week, and the Corporation shall duly record the results of the testings.

29. Tests for insulation of the secondary-supply circuits from the pole transformers in East Gore shall be made at least once every two months and recorded.

30. Every low-tension aerial line shall be attached to supports at intervals not exceeding 200 ft. where the direction of the line is straight, or 150 ft. where the direction is curved or where the line makes a horizontal angle at the point of support.

31. Every support for an aerial line shall be of a durable material, and properly stayed against forces due to wind-pressure, change of direction of the line, or unequal lengths of span. The factor of safety shall be for all aerial lines and suspending wires at least 6, and for all other parts of the structure at least 12, taking the maximum possible wind-pressure at 50 lb. per square foot. Every support, if of metal, shall be efficiently connected with earth.

32. All aerial lines shall be attached to porcelain insulators, and shall be so guarded that they cannot fall away from the support.

33. Any aerial line or wire for distribution purposes 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 building or erection other than a support for the line, except where brought into a building for the purpose of supply.

34. Service lines 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. Every portion of any service line which is outside a building but is within 7 ft. from the building shall be completely enclosed in stout indiarubber tubing.

35. Where an aerial line crosses a street the angle between the line and the direction of the street at the place of crossing shall not be less than 60°, and the spans shall be as short as possible.

36. Where an aerial line crosses or is in proximity to any metallic substance, precautions shall be taken against the possibility of the line coming into contact with the metallic substance, or of the metallic substance coming into contact with the line, by breakage or otherwise.

37. Where telegraph or telephone wires are crossed either over or under by the low-pressure or the 2,200-volts-pressure electric-light wires, the former shall be insulated throughout the whole length of the span intersected, and when the crossing is near a pole the spans on each side of the pole shall be insulated if deemed necessary, in all cases at the expense of the Corporation.

38. Efficient guard-wires shall be erected in a manner to meet with the approval of the Electric Telegraph Commissioner at all crossings and places where either transmission