Abstract: On June 8, 2009, Employee #1, an electrician, was wiring an electrical room to test for continuity at a construction site. Employee #1 and two coworkers, Coworker #1 and Coworker #2, were testing the continuity at the main panel outside. Coworker #1 went inside the building and had the tester inside the electrical room. Employee #1 and Coworker #2 went outside and opened up the main panel. Coworker #2 had a walkie-talkie and was standing behind Employee #1, relaying instructions from Coworker #1. Employee #1 thought that the power was down, and he did not check it prior to working on the panel. Employee #1 connected a length of wire from a grounded location on the frame to a connector that was hot, and there was an immediate flash arc. Employee #1 sustained second degree burns to his right arm, hand, and fingers, with a small area of third degree burns on his wrist. Employee #1 was transported to UCSD Burn Center, where he was hospitalized for eight days. The worksite where the accident occurred was a construction site where an existing building was undergoing remodeling into a medical facility.