Failed Manual Transfer Switch in Generator Causes Fire at a Farm

Location: Chilliwack, BC
Regulated industry sector: Electrical – Low voltage electrical system (30V to 750V)

Incident overview

During a power outage at a rural farm, a tractor driven PTO generator was used to power a 200 Amp electrical panel through a 40-year-old transfer switch. When the power was restored, the transfer switch was moved back to the "utility power” position so that the panel would be powered by the utility again. The switch started smoking and sparking, causing a small fire after an hour of its change to the “utility power” position. The fire damaged the transfer switch, the electrical panel and the wall where it was mounted. Evidence suggests that the fire was caused by poor connection in the manual transfer switch due to misalignment. The heat generated by the high resistance of the poor connection melted insulation inside the conductors and caused an electrical short circuit on the metal enclosure of the switch.