Abstract: A power line worker and his supervisor had pumped water from an underground electrical vault. The power line worker entered the vault and attached a rope to the switch handle of a 15-kilovolt, 400-ampere T-GRAM oil switch, which controlled a transformer in the same vault. He had attached the rope so that he could operate the handle from outside the vault. The switch handle had three positions: on, off, and test; and the employee was going to use the rope to pull the handle from the on position to the off position. Unfortunately, when he pulled the rope, the handle went past the off position to the test position. A metal block used to prevent this from happening was not in place. The supervisor and the power line worker assumed that the handle was in the off position even though a brief inspection would have revealed it was not. (The switch was visible to both from outside the vault.) When the power line worker reentered the vault to remove the rope, he contacted an unguarded, energized bushing on the oil switch and received an electric shock. He was hospitalized with serious injuries.