Abstract: A power line worker for an electric utility was repairing a defective transformer. He was working between grounds and was wearing electrical protective equipment. He tested the system to ensure that it had been deenergized in accordance with his employer's tagging system. When he found the lines to be deenergized, he removed his electrical protective equipment and removed the test probe from the defective elbow terminator. He received a very strong dc electric shock and was knocked to the ground. He was hospitalized for his injury. The transformer had been energized by another crew working in the same location. They had been testing for defective cables, apparently using cable fault locating equipment. The cable that they were testing was mismarked when it was installed. It was connected to the transformer on which the injured employee had been working.