Abstract: On September 15, 2005, Employees #1 and #2, of Daniel Electric, were installing circuit breakers on the main electrical panel at a 99 Cents Only store, a chain with which the employer, a licensed electrical contractor, had a long-time business relationship. Employee #1 was holding a screwdriver with one hand and a breaker with the other hand, while Employee #2 held a flashlight and watched from a few feet away. Employee #1 lost his grip on the breaker and it fell across two energized busbars, creating an arc flash that knocked both employees to the ground. The nominal phase-to-phase voltage on the panel was 277 volts, and the phase-to-ground voltage was 480 volts. Employees #1 and #2 were transported USC Medical Center, where Employee #1 was hospitalized and Employee #2 was treated and released. Neither of them had been equipped with approved personal protective equipment, such as face shields, insulated gloves, or insulated tools. The employer was cited for a violation, serious, for not providing and ensuring the use of approved insulated gloves, insulated tools, and eye protection, and for not providing instructions on work techniques and hazards involved in working on energized equipment.