Abstract: A crew of maintenance electricians for an electric utility was troubleshooting a malfunctioning circulating pump. A problem relating to voltage drop in the control circuit was suspected, so a portion of the circuit was bypassed. Subsequent attempts to start the motor resulted in a burned relay and damage to the closing coil in the motor contactor. A power plant operator (employee #4) was disengaging the motor contactor from a 4160-volt bus when an electrical fault occurred. The ensuing electric arc burned the plant operator, along with three other employees who were standing in front of the contactor's cubicle. Two of the three employees standing in front of the cubicle died of their injuries. The other two employees were hospitalized with severe burns.