On May 26, 2003, a crew of electricians and utilities personnel for Patrick Cudahy, Inc., had completed an annual cleaning of electrical utilization substations #1 and #2 within the company food processing facilities.
To facilitate cleaning of the substations, the plant was switched from outside utility supplied power to supplied power from emergency generators. After the substations were cleaned, the process to switch from the generator power back to the outside supplied utility power was started. When powering down of the generators to facilitate the switch back to the utility supplied power, the auto switching mechanism would not disengage. It was determined that the switching problem was isolated to the outside switchgear that housed a three phase in-feed power supply of 13.2 KV and a 120 volt, 4 amp switchgear motor.
During the trouble shooting process to engage the switchgear to switch over to utility power, a ground fault or phase to phase fault occurred causing an arc flash and blast to occur engulfing the Electrical Supervisor, Lead Electrician and Instrumentation Mechanic in fire. The employees received body encompassing second and third degree burns. All three employees were hospitalized for treatment of their burns.