ELECTRICITY WIRES.

Auckland Star, Volume LXVI, Issue 170, 20 July 1935, Page 12

ELECTRICITY WIRES.

OVERHEAD OR UNDERGROUND?

merits discussed:

The merits of overhead as opposed to underground electrical reticulation were dealt with at length by Mr. E. Hitchcock, general manager of tlie municipal electricity department, in an address to the Christchurch branch of die Town Planning Institute. Mr. Hitchcock held that after a frank and fair consideration of all the possibilities most people would be convinced that the case for the overhead distribution was very strong, and the making of a case for the adoption of underground circuits was exceedingly difficult.

Mr. Hitchcock said that the argument put forward for underground cable was almost entirely one. of sentiment, doubtless a worthy sentiment if sentiment could be divorced without penalty from practical questions of cost. Four points had to be examined—transmission, reticulation, distribution, and street lighting. Where high tension distribution was required in city areas, and where high tension overhead lines would be unsafe and impracticable, the use of underground cables offered a satisfactory, practicable, and reasonably economical metliod.

The term "reticulation" was usually applied electrically to the low tension street mains from which electrical supply was given to individual houses, shops, factories, and public buildings. This portion of a city's electrical supply was usually carried overhead."Because it is necessary to control it independently of the general street mains, and to work on it during the daytime, the_ street lighting supply is normally given from independent street lighting circuits," said Mr. Hitchcock. "In Christcliurcli a 3000-volt series system has been adopted. Where it has to be tapped frequently for supply to street lamps it is carried overhead. Where it carries supply direct from point to point, as between a sub-station and the circ.iit to be supplied, or for supply to lamp standards, it is carried underground."

Underground Cable. Where extra high tension cable was carried overhead continuous insulation was not practicable. Bare wire was used, with insulation at the pole supports. Danger was thus created" and liability to interruption, and intersections with other lines involved undue risks. With low buildings where a satisfactory safe elevation could not be obtained for entrance mains, or where architectural reasons demanded particular attention to the front of the building, there was a strong case for low tension underground cable. The same might be argued about street lighting in some scenic or decorative localities. It- was argued that the placing of cables underground would bring a great improvement in appearance.

Mr. HitchcocSv gave a cost comparison of the installation of two similar Isq. in four-conductor circuits. Overhead, £146; underground. £203; the latter exceeding the former by 80 per cent. Cost (shillings) per ampere per 100 yards, 0.4 as opposed to 8.9, a difference of 39 per cent. The comparison had to je considered with certain reservations. llr. Hitchcock said it was claimed that o\erhead wires arid poles were unsightly, and that their removal would improve the appearance of the streets. What was unsightlincss ? Did not the appearance of this particular equipment even if it were unsightly—the point could be debated—constitute a worth-while pric* for the invaluable facilities and amenities provided by electricity?