Pole fires due to insulator contamination

WOOD POLES and crossarms of overhead electric lines may become ignited and damaged when the surface of the insulators and wooden parts are contaminated by industrial dirt and exposed to fog or light drizzle. A few pole fires have occurred in the Chicago area under circumstances which gave a basis for further laboratory study. The circumstances surrounding these fires were peculiar in that on similar lines under apparently the same conditions no burning occurred. This prompted an investigation of the various factors contributing to pole burning in an attempt to evaluate the importance of the different variables and to develop means of prevention.