Note: The company name and other identities in the story were deleted.

Fatal Accident While Inspecting Power Supply System
Seven workers were injured while removing an electrical bus from service so that the house power supply equipment in the Turbine Building could be inspected during the periodical (annual) outage. The accident occurred when a short circuit resulted from grounding equipment that came into contact with the energized section of the primary side of the main circuit connection stab causing an arc. The arc gas produced burns on the workers. The energized primary side of the connection stab had no protective covering.
Of the seven injured workers, three were taken to hospital by ambulance where they received intensive care, but one of the workers subsequently died.

Causes
The work was being performed by contractors who were not aware that the work for the grounding equipment installation would take place in proximity to energized equipment. Prior to the job, maintenance personnel failed to inform the contractors that the work would be in proximity to energized components. Hazard assessment activities in the pre-job briefing amounted to little more than just going through the formal motions.
Either the contractors failed to carry out voltage detector testing and measurement of insulation resistance, or they performed the test improperly. As a result, they were unaware that the primary side of the connection stab was energized.

Lessons Learned
• Never treat pre-job briefs as a formality or become complacent in their use.
• Prior to performing work, be sure to perform a job site review to identify hazards and address industrial safety hazards in pre-job brief.