Abstract: At approximately 8:30 a.m. on August 25, 2006, Employee #1, a journeyman electrician, was installing a new breaker for a branch circuit he was running to power the air handling units on a roof. He removed the cover and dead front from the panel and began pulling wire to connect it to the breaker. The panel was energized, and somehow the three main feeder lines coming into the main breaker contacted one another, causing an arc flash and blast. Employee #1 suffered burns on his arm and face, for which he was hospitalized. Company records indicate that he had been trained in lockout/tagout and in electrical safe work practices. Personal protective equipment was also available for his use. At the time of the accident, Employee #1 had been working for the company for about two months, but he had also worked for them earlier for about for five years.