POLE-TOP FIRES RISK ASSESSMENT: A SOUTH AFRICAN PERSPECTIVE

Pole-top fires on 22 kV overhead woodpole electrici ty distribution lines are addressed. The mechanism cov ered is where, under certain conditions, the surface of one or more phase insulators collects pollution, which conducts leakage current when lightly wetted. This leakage current c into and onto the wood of the structure and can, in certain cases, cause the wood to track, char and ignite. Experiences from tests and the field are used to pe rform a risk assessment of different mitigation options usi ng criteria such as pollution (leakage current) performance, li ghtning performance and bird safety. A proposal for differe nt structure configurations for use in different areas is made. The rationale behind the proposal is described, pra ctical considerations and limitations are discussed and fu rther research is recommended.