Abstract: At 10:00 a.m. on December 11, 2018, Employee #1, a journeyman electrician employed by an electrical services company, was preparing to install wiring for new heaters at a commercial greenhouse. He was operating a cordless drill with a step drill bit to drill a hole in the back of a metal trough connected to the 600 amp, 120 volt/208 volt 3-phase electrical panel that was to supply power to the heaters. A short circuit occurred inside the electrical panel, which caused an arc flash and fireball. Employee #1 was burned. Emergency services transported the employee to the hospital, where he was admitted and treated for second and third degree burns to his hands and the right side of his stomach.