Electrical contact accident with a welding machine

In 1991, a Bonneville Power Administration (BPA) worker suffered severe injury during an electrical contact accident involving a welding machine. This incident occurred during a complete station outage at a BPA substation. Injuries to the employee consisted of muscle, tissue, and bone damage to one of the worker´s shoulders. Tests simulating the accident were performed at BPA´s High Voltage Laboratory and at the substation where the accident originally took place in order to determine why the electrical shock occurred and how this type of accident can be prevented in the future. It was concluded from testing and analysis that the injuries occurred to the worker because he came in bare handed contact with a grounded steel structure and a riser that was being welded. In such a situation, the 60 Hz voltage output from the welding machine had the capability of generating enough current to tetanize the muscles in the worker´s arms and chest, probably leading to the muscle, tissue, and bone damage to his shoulder