ELECTRIC POWER POLES.

Hauraki Plains Gazette, Volume XXXVI, Issue 4916, 16 December 1925, Page 4

ELECTRIC POWER POLES.

DURABILITY OF N.Z. TIMBERS.

THAMES VALLEY EXPERIMENTS.

Some time ago the Thames Valley Electric Power Board interested itself in the matter of preserving transmission poles and decided upon an undertaking in order to experiment with a number of treatments th ascertain which would be the most satisfactory for preservative purposes, and whether New Zealand-grown timbers compared favourably with the imported article- Mr F. M. Strange,, a member of the board, offered thei use of a portion of his land at Mangaiti lor the conduct of these experiments. In all, 103 samples of poles obtained fr&m the State Forest Service at Rotorua were placed in the ground five feet deep and nine feet apart, the wood beneath .the ground being treated in 13 different ways. Six species of timber were used.

A visit was made to Mr Strange’s farm by members of the board after the conclusion of the ordinary meeting las,t week. The poles we ; re seen to be placed in sandy soil, which is more destructive to wood than any other claps, of land, the explanation being that sandy soil allows more air to get at the buried wood than any other class, and it is. said .that it is the air that causes, rot in wood underneath tlie surface o<f the ground. The various treatments were explained by Mr N. G. McLeod (the power board engineer), who, said that some specimens were placed in the ground without receiving any treatment whatever, the remainder being treated as follows : One coat of hotpreservative brushed on hot; two coats of hot presei'vativei No,. 1 brushed on hot; two coats of hot preservative, No. 2 brushed on hot; two coats of hot preservative,, No. 2 brushed on hot; one coat of hot Creosote brushed on ; two coats of hot creosote brushed on ; dipped once in hot creasote ; butt charred and no other treatment; butb charred and dipped in hot creosote ; brushed with hot tar; butt charred and dipped in hot tar.

The species of timber were all eucalypts (Australian), but were New Zealand grown, and are as follows : Eu. Amygdalina, eu. MueUeriana, eu. Obliqua, eu. Ovata, eiL Risdoni, eu. Genoides. The whole of the specimens are numbered so that a complete check can be kept of them. Being planted only last April, the experiment has no value up to the present, and’ it is considered that it will be five years before any indication can be given as to. the comparison of the durability of the various poles. The first examination will be made after the specimens have been in the ground for five years, and as: time goes on the experiment will prove of more value. It is the intention of the board to leave the poles there indefinitely.

“While on the farm the powe; boil’d momlers and’ the press, represent□tives were shown a plantation of trees of the eucalyptus variety which Mr Strange had planted seven or eight years ago. One of these trees blew down recently, and was, found lo be 40ft in length. Mr. Strange bad also planted other trees of the same variety about three years ago.