Abstract: Two employees were assigned to a gas station to relocate all liquid sensors to the bottom of the fuel sumps. At approximately 9:15 a.m. on April 11, 2000, Employee #1 entered a 5-ft-6-in.-deep by 2-ft-9-in-diameter concrete fuel sump to reinstall a sensor's bracket under a metal electric conduit about 1 in. from the bottom. An old black sensor wire was lying on top of the electric conduit. No tests for flammable vapors were conducted before the entry, and no mechanical ventilation was provided by the employer. A strong smell of gasoline was coming out of the fuel sump. Permit-required confined space procedures were not followed. According to Employee #1, he was using a 19-volt Dewalt drill to screw the bracket into the vinyl insulation. Apparently, Employee #1 broke the wire's insulation when he grabbed onto the conduit to raise himself up. This caused the bare wire to spark while making contact with the metal conduit. The burning wire pealed the soft skin on Employee #1's right palm as electrical sparks were igniting the vapors. Employee #1 saw a red flash fire then heard a pop sound. Employee #1 stayed under the flame for few seconds until his coworker pulled him out of the round underground fuel sump. Employee #1 sustained very severe burn injuries to his face, neck, arms and hands as result of a contact with fire flash/explosion from gas vapors. Employee #1 was hospitalized for more than nine days.