Abstract: At approximately 9:00 p.m. on July 23, 2007, Employee #1 was an electrician with Sweetener Products Co., a company that warehoused and distributed sugar and sugar syrups to industry. He was working alone on an electrical panel in the electrical penthouse of the maintenance building. An additional branch circuit was being run from the 480V, 3000A main panel of the maintenance building which required the installation of a 400A circuit breaker. While the panel was still energized, Employee #1 removed the front access cover and sat down near the corner of the panel in order to bolt the circuit breaker onto the bus bar brackets. The mounting holes of the breaker were not aligned with the threaded bus bar bracket holes. Employee #1 used a steel ball peen hammer with a wooden handle to tap the lowest bus bar bracket upwards in an attempt to align the mounting holes. He caused an arc flash that burned his face, arms and lower left leg. He was hospitalized for treatment of his burns.