Abstract: A journeyman electrician responded to a no power trouble call by the shop operator of a drill press-mill. The electrician measured no voltage at the machine, which was connected by permanent wiring. He went to the panelboard for the circuit and noticed that the circuit breaker for this circuit was in the closed position. He reset the breaker by opening and closing it. He heard the usual click when he opened it; however, when he closed it, the circuit breaker failed and blew up in his face. The employee sustained burns to his face, apparently from the ensuing electric arc. Investigation revealed that the circuit breaker was faulty, probably due to deterioration from heating. Under load conditions, the breaker contacts would open.