Line Design and Electrical Properties of Wood

This paper deals with the use of the insulating properties of wood in transmission line practice. The electrical properties impulse strength and arc quenching and the possible damaging effects of surge currents and power frequency leakage currents are considered. Prediction of the lightning performance of shielded and unshielded lines is discussed, and it is shown that the impulse strength and arc quenching properties of wood influence performance, the latter property being the dominant one for unshielded lines. A design criterion using this arc quenching property has been developed from experimental data on arc characteristics.