Abstract: On April 22, 2008, Employee #1 and a coworker arrived at the site of a building housing two one-story retail suites. They planned to finish the job of installing a new sub-panel and directing power to the new panel in one of the two retail suites. The panel that originally served both suites is a Zinsco panel, housing a 208 volts, 600 amps and three-phase system. The work that remained was to install a new circuit breaker in the old panel and finish connecting the new subpanel to the old panel. Employee #1, the lead on the job, removed the dead front guarding of the breakers, which exposed the live conductors. He was not wearing gloves but was wearing safety glasses. He attempted to slide the new circuit breaker (a refurbished 200 volt Zinsco) into the panel opening, but before it was fully in place there was an arc and a flash, which burned the left side of Employee #1's face and the back of his left arm and hand. The coworker, who was standing behind Employee #1, received superficial burns. The coworker called emergency medical services. Emergency medical personnel arrived and transported Employee #1 to the local medical center burn unit, where he was hospitalized and received treatment for second degree burns.