Abstract: On October 10, 2012, Employee #1, an electrician, arrived at a high school sometime in the morning. He obtained permission to access the electrical room and then drove behind the school to where the room was located. Employee #1 was onsite to replace the short circuit ratio (SCR) controller system board and the photo board on a Kohler emergency backup generator. These boards were within 9 in. of the exposed live current parts. The generator was set up in Phase 3, power factor 0.8, kilowatts 33, kilovolt-ampere 41, amperes 50 and factory test and reconnect F. Its model number was 33RZ272 and serial number was 245558 and was setup in voltage of 277/480. The generator was operating in normal operating limits with no problems. Employee #1 removed the positive battery cable on the generator and turned the generator in the off position. He then removed the front housing on the generator to access the area for replacing the SCR board and the photo board. Employee #1 used a socket wrench that was 7.5 in. long with a 2.375 in. deep well six-point socket to remove a 2.125 in. course thread bolt in the generator. As he removed the bolt, the wrench contacted a live terminal from the rear switch on the generator, which electrocuted him with approximately 277 volts. The incident occurred between 1:30 p.m., the time he arrived onsite and 9:00 a.m. on the next day. The assistant principal was on the kitchen dock, located behind the school, around 5:00 p.m. when he noticed Employee 1's company van still outside the electrical room, but did not check on him at that time. The next morning, a coworker called the school and spoke with the assistant principal, telling him that he had not heard from Employee #1 since early the day before. The assistant principal told the coworker to hold on while he went to the area where Employee 1 was working. When he arrived on scene, he noticed Employee #1 slumped over on his knees with a reach still into the generator. At the point, the assistant principal called the school resource officer and school nurse to the area. The resource officer instructed the assistant principal to have power to the entire school shut down before removing Employee #1 due to the concern that he was still energized. Power was shut down and he was removed and power was restored to the school. From the investigation, blue wires were found inside a closed electric box located 18 inches away. The blue wires went outside and then underground to another building to power lights. These blue wires on the hot side of the emergency lights breaker box created a back feed to the generator, which would have caused the generator to be hot even if the switches were in the off position on the generator. Black and white tape was placed to insure no exposed wires were visible even in the off position.