Abstract: On August 18, 2008, Employee #1, an electrician, was working on a 480-volt, 600-ampere breaker panel box when an arc flash occurred. The panel had one energized feeder at the time of the accident. The panel box was connected to another panel. The panel was set up with three phases (277-volts each, and 480-volts between phases). A coworker, the foreman, was in the process of working with 10-gauge wire when the wire appeared to have bridged the gap between one or both of the buss bars and the rear of the panel. The resulting arc caused extensive damage to the panel and inflicted severe burns to the electrician's face and right hand and forearm. The panel had not been deenergized, and personal protective equipment was not worn.