Abstract: On August 11, 2008, the head of maintenance for a hotel was attempting to remove and replace an air conditioning/heating unit in room 105. Before beginning, the mechanic turned off the circuit breaker marked for room 105 where he was working. However, the breaker was mislabeled, and was actually for Room 103. Consequently, the wiring in Room 105 was still energized. The mechanic did not ensure nor did the employer have procedures in place to ensure that the electrical wiring was not energized. The worker had successfully removed the old air conditioning unit and was in the process of installing the new unit, when he came into contact with the 240-volt power source and was electrocuted.