A lot can be learned from the Fatality Assessment and Control Evaluation (FACE) reports published by the National Institute for Occupational Safety and Health (NIOSH), Division of Safety Research (DSR). These reports, which include investigations of selected electrical-related and confined space-related injuries and fatalities, outline the circumstances leading up to the incident. By analyzing the forensic evidence, NIOSH investigators offer recommendations for prevention of similar incidents, which is of great use to all electrical professionals. EC&M will present such cases on a regular basis in future issues of the Market Watch “Safety Zone” section — in hopes of promoting lessons learned from NIOSH's findings.
For our first case, we'll review how an employee of an electrical contracting firm was electrocuted while wiring an energized 7,200V — 240V/120V single-phase, step-down transformer at a townhouse development in North Carolina. After making the two “hot” terminal connections to the transformer spade lugs, the foreman then instructed the inexperienced worker to make the three neutral connections. The foreman then left the area to confer with the residential electrician. The employee (who was wearing insulated lineman's gloves) permanently secured two neutral connections and loosely assembled the third connection. (Terminal connectors were not covered with rubber insulating boots.)
According to the report, the trench leading to the transformers was open, muddy, and slippery. Evidence indicated the victim's left foot slipped into the trench, causing him to fall into the hot terminals. Because the victim had burn marks on the left side of his stomach and his right forearm, contact with a terminal and the transformer box is probable. The victim was pronounced dead on arrival at a county hospital.
NIOSH offers the following recommendations to avoid similar tragedies:
Provide adequate work space/areas. Construction of a 30-inch extension to the concrete transformer pad would provide an adequate work area and would be relatively inexpensive. Additionally, non-conducting, safety grates provide a structurally safe work area and electrically insulate personnel working on like transformers. In addition, an anti-slip surface will provide safe footing.
Use rubber terminal boots. Employees should always make use of terminal boots and/or rubber blankets. Rubber insulating boots are for personal protection from energized spade terminals and should be used at all times when direct cable attachment to the spade terminals is not in progress.
Hold supervisors accountable. A foreman witnessed the hazardous condition that resulted in a fatality and did not intervene. Require accountability for all levels of supervision regarding job-site safety. Performance evaluations and other incentives should address safety as well.
Carefully train new employees. The employee involved in this incident had only nine months of experience. All electrical-related training was on-the-job. On-the-job training should be carefully evaluated to assure that it is complete and reinforces the policies of management (i.e., safety concerns).
Reprinted with permission from the National Institute for Occupational Safety and Health (NIOSH), Division of Safety Research (DSR). All electrical-related FACE reports can be viewed in their entirety at http://www.cdc.gov/niosh/face/default.html.