UNITED STATES
DEPARTMENT OF LABOR

Abstract: A two-employee crew was assigned to check a General Electric 46-kilovolt, 1200-ampere oil circuit breaker (Type FKA-48-3-29000-6y, Tank Serial No. 0251A9526-201, manufactured in 1974). The reported problem was that the mechanical red indicator was only showing half way across the window when the circuit breaker was in the closed position. The circuit breaker was located in a naval substation. The top of the oil-circuit-breaker tank had six bushings. The bushings on the right were positioned 1, 3, and 5 o'clock and were connected to circuit #4639L. The three other bushings (on the left) were at 7, 9, and 11 o'clock and were connected to circuit #4639C. When the two employees arrived at the substation, the lead worker on the crew located the oil circuit breaker (circuit breaker #4639) and observed that the overhead disconnect switch for circuit #4639L (on the right side) was open, locked, and tagged. A troubleman had opened, locked, and tagged this switch in the morning just before the arrival of the two employees. The lead worker then called the load dispatcher for permission to open the left-side overhead switch (circuit #4639C). The dispatcher granted the request to open the switch and ordered the lead worker to leave the right-side switch open because another crew was working on that line outside of the substation. The lead worker walked into the substation control house and observed that the control switch for circuit breaker #4639 was in the locked-out position. The troubleman had placed this switch to lockout mode, opened the DC control knife switch in the control cabinet #4639, and tagged them before the crew had arrived. The lead worker moved circuit-breaker control switch #4639 from the locked-out position to the neutral position so that he and his assistant could conduct tests on the oil circuit breaker. He walked next to the circuit breaker tank and took some measurements of the travel of the linkage rod for the mechanical indicator in the circuit breaker's integral control cabinet. He opened the covers for the bell crank, checked the mechanical indicators, and made a continuity test across the phases. He decided that was all he and his assistant could do. The two employees closed the overhead disconnect switch for circuit #4639C. The lead worker went back into the control house and moved the circuit-breaker control switch back to its original locked-out position. The two employees packed up their tools and got ready to leave this substation. While they were in their truck and about to leave, the lead worker called his supervisor to brief him on their findings. The supervisor asked if he had a timing rod and instructed him to take a penetration reading of the internal oil circuit breaker's contact rod and receptacle assembly if a measuring tool could be found. The lead worker informed his assistant of their instructions and asked him to find the timing rod in the truck. Meanwhile, the lead worker went back to the control house and moved the breaker switch from its locked-out position to the neutral position. The two employees met at the oil circuit breaker's control cabinet. They were trying to see where the cutoff switch for the circuit breaker's spring charging motor was so that the lead worker could manually close the circuit breaker to get a measurement. The assistant was within about 600 millimeters of the lead worker at this time. The spring charging motor was not working, so the lead worker began troubleshooting this problem when electric arcing occurred. The lead worker, who had been looking into the control cabinet, heard something fall. His assistant was lying about 2 meters away with his cotton shirt on fire. The lead worker extinguished the burning clothing, called the load dispatcher for emergency assistance, and administered cardio-pulmonary resuscitation to his injured coworker. Emergency medical services transported the injured employee to a hospital within minutes after the accident. His injuries inc