Abstract: An employee was replacing a switching device on a 480-volt Siemens JXD 63L400 circuit breaker. He had not deenergized the supply conductors for the circuit breaker as recommended by the manufacturer. He removed two bolts that were holding the switching device in place. The bolts were also holding up a guard that protects against contact with energized parts when the cabinet is open. The guard fell across the three phase contacts, causing an electrical fault. The ensuing electric arc burned the employee, and he sustained second-degree burns to both hands and both forearms. He was hospitalized for his injuries.