Lockout/Tagout Accident Investigation

Lockout/tagout was one of the first requirements OSHA mandated, starting in 1990. The electrical lockout/tagout regulation became effective in 1990, as well as part of Subpart S. Lockout/tagout training is conducted ad nauseam in every facility in the United States. All of us in the field have had repeated training on lockout/tagout. Lockout/tagout is often the topic of tailgate meetings and safety briefings. It is probably human nature to hear something so often and from so many sources that we go on autopilot at times. Instead of going through the procedures deliberately, even the best of us may not hit it as hard as we should. The following true case study illustrates this point.
The project involved maintenance work that was being performed by several contractors at a company’s location in the Midwest (the host). The work involved medium-voltage switchgear in a building and an outside substation. The switchgear was of a standard metal-clad, drawout, vacuum interrupter design and was in excellent condition. The switchgear also was marked with the single-line on the front of the gear.
The worker involved in the incident was assigned to clean the switchgear and vacuum bottles in a section of equipment that had been properly locked out, tagged out, tested, and grounded. The work on this section of switchgear had been ongoing for a couple of days. One of the other contractors asked the worker to clean and test a circuit breaker cell that was not on the original list of equipment to be maintained. The host company that owned the equipment approved the addition of this circuit breaker cell to the list. The circuit breaker cell was to a bus tie breaker that had been deenergized the evening before but had been returned to service.