FRP hot stick flashovers during EHV live line work

In 1997 a FRP hot stick flashed over during live line work at 550 kVac. A rigourous maintenance program was instituted and all FRP hot sticks used in live line work must now withstand an annual dielectric test at 105 kVdc per 305 mm with the surface wet consistent with IEEE Std 978. More frequent electrical tests are made using a hand held tester and limits have been set for the hydrophobicity of the surface. In spite of these measures a second flashover of a FRP hot stick occurred during live line work at 550 kVac in 2002. Both flashovers occurred during work from the tower on "V" suspension insulators, the first at a temperature near the freezing point and the second at a temperature well below freezing. In both cases the wind was blowing from the conductor to the worker. Our investigation is trying to establish an adequate explanation for these events as well as corrective measures. The work to date is summarized in this paper. Industry standards for limits of approach are based on the switching surge withstand of air gaps and should not be equated to the minimum safe leakage distance of FR.P hot sticks.