Abstract: On September 21, 2005, Employee #1, of Pacific Data Electric, an electrical contractor, was helping install a new 440-volt electrical power service for a machine in a spectacle grinding facility in Los Angeles, CA. His supervisor, who was not on site, had assigned him several tasks. He was replacing a slide in a module in an electrical cabinet that contained two 220-volt buses when a nut fell, causing him to jump and cross-phase the buses with a screwdriver. An arc blast occured and Employee #1 suffered second-degree burns on his hands and forearms and first-degree burns on his face. He was hospitalized for two days. Employee #1 was not wearing protective gloves.