Inspection Detail

Inspection: 122209992 - Electrical Contractors Of Wisconsin, Inc.

Inspection Information - Office: Milwaukee Area Office

Investigation Summary

Two journeyman electricians and an apprentice were installing a 400-ampere bus-plug circuit breaker onto a 4000-ampere Square D busway. The busway was installed at a height of about 3.7 meters above a new area of a plant to serve a new engine block line that was being installed at the time. A disconnect was located about 18.3 meters away, but the employees did not deenergize the circuit for fear of deenergizing other equipment in use at the time. However, there was no record that the employees made any inquiry about deenergizing the circuit. Similar requests had reportedly been summarily turned down without an evaluation of the available options. Two of the three employees were on a scissor lift, and the other one was atop the busway itself. They were trying to adjust the vertical position of the plug, which was slightly high at one end. The problem developed because the electricians had removed the insulating dead front at the plug entrance opening. (They had earlier been installing larger plugs, for which the installation method was different and required removal of that insulator.) When the employees lifted the bus plug enclosure up and away from the busway, the clamps that secured the plug to the individual busbars faulted across two phases, causing an electric arc and an ensuing fire. The employee on the busway suffered burns. He also shattered his tibia when he jumped from the busway to escape the flames. The other two employees suffered less severe burns, though one of them needed repeated medical treatment. All three employees were hospitalized for their injuries.

Keywords: BURN, ELECTRIC ARC, FRACTURE, E GI IV, ELECTRICAL, ELECTRICIAN, BUSBAR, ELECTRICAL WORK, LOCKOUT, ELECTRICAL FAULT