Effect of Water Storage on Electrical Resistance of Wood

Poles, intended for use as supports in power transmission line circuits, are often first transported or stored in fresh- or salt-water. This study was carried out to determine the electrical conductivity of such poles and thereby increase the safety factor for linemen working on the poles. Test specimens of western redcedar and red pine were conditioned in salt water and fresh-water for 6 months. Comparative resistance measurements were obtained, to good accuracy, on red pine at moisture content values of from 15 to 200 percent. Salt-water cedar was approximately 50 times more conductive over most of the moisture-content range. Fresh-water soaking increased the resistance of wood by at least a factor of 2. A time dependence of this resistance increase was clearly noted. The net long-term increase in resistance appeared to be a function of the amounts and types of water-soluble extractives present in the wood.

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