Abstract: At 1:40 p.m. on September 23, 2011, Employee #1 was working for Corix Utilities (US), Inc., an electrical contractor, at an industrial building located in Fullerton, CA. He was installing new Edison meters to replace the legacy meters on an existing electrical panel at an industrial complex. In an interview, he related the details of the incident. Employee #1 had successfully installed the first of three meters on a bank of meter switchgear that was vertically arrayed. The meters were in a three-phase 480-volt system. At 1:40 p.m., he had scanned the first meter, using an MBLink mobile handheld device to record that it was operable. Employee #1 next removed the second meter and seated its replacement. He was placing the lock ring around that meter, when he heard a humming sound. He immediately turned away, and an arc flash occurred. It was the result of a phase-to-phase fault. He was thrown back by the force of the blast. Because he had turned away upon initially hearing the humming sound just before the arc flash, he sustained burns to his ear and cheek. He watched as the electrical system continued to burn and arc. He used his fire extinguisher to mitigate the ensuing fire before the Fullerton fire department arrived on the scene. Employee #1 was wearing full personal protective equipment (PPE) for electrical work: rubber insulated gloves, leather gloves, long sleeve shirt, face shield, and safety glasses. The arc flash resulting from the fault caused Employee #1 to sustain second- and third-degree burn to the right side of his face and ear. He was treated at an emergency room and released the same day. Employee #1 was a journeyman electrician with IBEW local 47. He had over 10 years of experience working as an electrician. He had worked full-time for the company replacing Edison meters since July 2011. The company had written procedures for replacing the meters, and they provided documentation of training the employee on those written procedures. Further, Employee #1 confirmed that he was following those procedures when the accident occurred. During the course of the worker's employment, he had installed 35 to 40 new meters per workday without incident. On the date of the accident, the employee had successfully completed 38 installations, with only two remaining for the day. It is unknown exactly what caused the fault that resulted in the arc flash. The arc flash may, however, have been attributed to any of the following conditions: 1) the meter was defective, 2) a demand was placed on the load side during installation that caused a surge, 3) the meter was not properly seated into the meter socket, or 4) the employee made contact with the energized components with either a tool or the meter's lock ring. There were no violations of Title 8, California Code of Regulations found during the investigation.