Abstract: A journeyman electrician was removing a 220-ampere circuit breaker at a service panelboard so that he could replace a bolt that had broken off the bus board. The employee was working the 480-volt energized, as he said he had done "a dozen times." He had been working for about 10 minutes and had removed the circuit breaker when a grounded part spun down (perhaps because of another broken bolt) and contacted the energized bus, causing an electrical fault. The ensuing electric arc ignited the employee's shirt. He was hospitalized at a burn center for a few weeks for burns to his hands, arms, chest, and lower face.