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Description of Driving Event:

An electrical mishap occurred on January 30, 1997, at the Water Deluge Pumping Substation 202 at the Cryogenic Transfer Area at the Stennis Space Center (SSC). Electrical Technicians were working under a Troubleshooting Incident Report (TIR) and standard operating procedures as required. The troubleshooting was necessary to determine why the "Run" indicating lights for Deluge Pumps No. 2 and No. 3 (of four) were reversed from actual pump operation.

While attempting to also check Pump No. 4, the mishap occurred when the technician jumpered terminals at a field wiring terminal block in the rear of the north switchgear section, believing they were the "Pump No. 4 Run" contact. An electric arc caused second degree burns on the hands and third degree burns to the left index finger of the technician. The arc occurred because the two terminals were a 480 VAC tap from the switchgear incoming bus. When the terminals were shorted with the jumper, fault current flowed, and the electric arc formed as the circuit was interrupted.