ELECTRICITY FOR FARMS.

New Zealand Herald, Volume LXIV, Issue 19764, 11 October 1927, Page 13

ELECTRICITY FOR FARMS.

♦ CONVEYANCE UNDERGROUND REPORT MADE BY ENGINEER. [BY TELEGRAPH. —OWN CORRESPONDENT.] TE AROHA, Monday. The extent to which underground cables may be utilised for the conveyance of electrical energy to farms is discussed in a special report prepared by Mr. N. G. McLeod, chief engineer to the Thames Valley Electric-Power Board. Mr. McLeod says underground cables were used for general power supply before overhead lines were considered, and were very reliable indeed. The cost of supply by underground cables is usually very "much greater than by overhead wires, although there are cases where the installation would be less costly. Opinions had been obtained from cable manufacturers in Britain, and from the Hydro-Electric Power Commission of Ontario. The latter use plain leadcovered conductors in the country, the lead covering being used for the neutral or earthed conductor. In Britain plain lead-covered conductors are not allowed underground, nor can the lead sheath be used as a conductor. The lead covering must be protected by armouring, or else the cable must be placed in a suitable trough and a separate conductor used for the neutral. Tho arguments against using unprotected lead covering are that the mechanical strength of the lead covering is low, and that heavily fertilised soil would cause trouble with the lead; also stones in the soil may come in contact with the lead and cause damage. Nevertheless, a case has occurred in which plain lead-covered and waterproofed cables have been in the ground for ten years, and are still giving satisfactory service. The cables were laid at a depth of 12in., and covered by a lin. thick creosoted board for low-tension cables, and by a 2in. thick board for high-tension cables. The New Zealand regulations also state that underground cables must be protected by armouring, or suitable enclosure, although, continues the report, it is possible that recognition might be given to unarmonred underground cables if suitable provision were made. The qnestion does not seem to have been dealt with in New Zealand yet, with a view to having the system allowed by regulation An estimate for ten chains of underground service, excluding for a single-phase 230-volt service, show that the cost ranges from £27 for lead-covered cable, to £43 for steel tape. Using armoured cable for a 400-volt service, the cost ranges from £36 to £52.