Live working on high-voltage lines

The review covers the two principal classes of technique for working on live, high-voltage power lines, respectively, `hot stick¿¿ and `bare hand¿¿. Developments to meet conditions in the UK are emphasised. The basic principles, to avoid flashover and to prevent the passage of undesirable currents in the workmen´s bodies, are illustrated by descriptions of actual operations. The history of live working, which is largely North American in conception, covers its progressive application from relatively low-voltage distribution systems to UHV transmission. The levels of atmospheric pollution and humidity in places like the UK pose special problems of leakage and flashover which have necessitated research. Some of the results are described. The questions of exposure to electric fields and the need for protective measures such as conducting suits are considered. The long-established rule of thumb about currents in humans, that perception, local paralysis and possible fatality occur at about 1, 10 and 100 mA, is contrasted with the recent furore about the alleged consequences of imperceptible induction. Future developments towards live working at the highest voltages and in adverse climatic conditions are foreseen.