Abstract: Three electricians were running an energized 480-volt circuit from a 12.5-kilovolt transformer to a panelboard. One of the electricians had made one connection and was tightening the bolts for the phase conductors. When he was removing his socket wrench from the last bolt, he heard a noise that sounded as if someone had started a generator. He also noticed a small arc from the last bolt to the end of the socket wrench. An electrical fault occurred, and the ensuing electric arc burned the electrician. He sustained third-degree burns to his face and head and was hospitalized for his injuries. A second electrician, who was to his left, sustained second-degree burns on his right forearm and hand. He was also hospitalized. The third electrician, who was on the right side, suffered first-degree burns to his left forearm and a laceration to his right hand when he hit a table saw behind him.