The literature concerning the use of the Shigometer® for detecting decay in standing trees and wood poles is reviewed and the differences of opinion over the effect of timber moisture content on electrical resistance are highlighted. A simple experiment designed to test this effect is described and the implications of the results for testing poles in service are discussed. There was a large difference between the electrical resistance of timbers below 38% and above 45% moisture content. In sound poles, moisture gradients may be present which can cause an abrupt drop in electrical resistance readings which would be interpreted as indicating decay when using the recormnended criteria.

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