Abstract: On April 3, 2003, Employee #1, who worked for an HVAC contractor, was installing an air conditioning (A/C) unit just outside of the Stabilizer Switch House at a refinery. He was in a 10 in. wide space between the A/C condensing unit and a chainlink fence. The air conditioning unit had three main components: the thermostat, the air blower, and the condensing unit. The first two units were located inside the building, and the condensing unit was outside of the building, about 10 ft from the east wall. At the time of the accident, Employee #1 was installing the PVC drain pipe and two copper refrigerant lines that ran from the blower to the condenser. On the same day, the wires from the MCC to the primary disconnect were terminated and energized, per the request of the communications office. Over the lunch hour, the electrical contractor completed energizing the new electrical installation up to the lighting panel, and then left the site. At approximately 12:30 p.m., Employee #1 arrived back from lunch and continued installing the rest of the PVC pipe drain, the sight glass, and liquid line filter dryer on the 3/8 in. refrigerant line. At about 2:00 p.m., his body was found lying on the ground, with the back of his head propped up against the last 6 in. of the chain link fence. When he was found, there were sparks and smoke coming from the back of his head. Employee #1 had been electrocuted. Refinery personnel who came to the rescue immediately turned off power from the MCC. The causal factors of this accident included: (a) a crossed wire between the MCC and the primary disconnect, so that phase C on the load side of the MCC (hot) was connected to the grounding terminal on the transformer disconnect; (b) the absence of the proper color coding of the grounding wire, which was the main reason for the crossed wires; and (c) the absence of bonding between the primary disconnect and the MCC, which would have allowed the system to conduct safely any faulty current imposed on it.