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OSHA Does Not Investigate Arc Flash Explosion at Hydroelectric Plant

By Sally Murdoch

Hydroelectric power and electric panels can make conditions ripe for arc flash blasts

Dam Power + Electricity Can Contribute Arc Flash Incidents

In April of 2016, an arc flash explosion hospitalized three men working at a vintage power plant in Ware, Massachusetts. The workers were conducting high voltage wiring work in a plant perched on the side of the Ware River, currently being commissioned into a modern hydroelectric plant. The building, almost 200 years old and a central part of the mill town’s history. OSHA was set to investigate the arc flash incident, however by mid-August deemed the accident to be the result of incidental error as opposed to a violation of regulations, or systematic disregard for safety, and will not be launching an investigation.

According to a news report in The Republican, the worker most seriously injured in the blast had pulled a lever on a 600-volt box to disconnect power while the other two workers were behind him. The three employees were alone in the plant when the panel arced, possibly caused by a mechanical issue with the fuse disconnect switch. The man who pulled the lever received 2nd-degree burns over 30% of his body, according to Fire Chief Thomas Coulombe, and was immediately transferred to a burn center in Boston by helicopter. A second employee was taken by ambulance to the University of Massachusetts Medical Center.

With investigations underway by the Massachusetts state fire marshal's office, the team concluded in Mid-August 2016 that the incident was “not suspicious and was likely the result of some type of human or mechanical accident,” the office and subsequent news reports stated. The third worker had been hospitalized but returned to the scene in April to assist investigators.

The arc flash explosion caused an incidental brush fire outside the plant when it overloaded an outside transformer. This arc flash incident is one of a number arc flash explosions at dams, including the Priest Rapids Dam in the Pacific NW in late 2015.

Hydroelectric Power Safety

The rehabilitated hydroelectric facility is privately owned by Ware River Power which had purchased the former Pioneer Hydroelectric Company Project out of bankruptcy a decade ago. The company, and its five dams in the area, harnesses hydro power, estimating that 4-7% of New England's power could be obtained from existing (decommissioned) hydro facilities. The company’s five dams have the power-generating capacity of more than 2 megawatts, or enough electricity for 2,000 houses, according to the newspaper reports.

According to The Republican, OSHA initially was contacted and was expected to conduct an investigation, however did not do so because of the low number of employees at Ware River Power (companies with fewer than 10 employees are exempt from OSHA inspections). Police reports obtained by the newspaper say investigators "determined that the incident was not suspicious and was likely the result of some type of human or mechanical accident."

Like many Northeastern towns, the area has a long history of industrialization and boom and bust cycles. The Ware River Precinct came into existence in 1742. According to the Massachusetts Department of Conservation and Recreation and a historic document dedicated to revitalizing the mill community, “the Ware River is a beautiful landscape element passing through Ware Village, and it contributes clean energy, hydro-electricity to the Massachusetts grid… Ware’s mill companies built a canal system that directed the Ware River into the water wheels and turbines of the mills along its banks, and they constructed dams to regulate water flow to assure year-round power source.”

The Otis Company mills, which ceased operation in 1937, have only been used for light industrial work since their cotton production heyday in the 19th century with hundreds of employees, and some buildings have remained vacant. The building where the arc flash happened, Pioneer Hydroelectric, was purchased in 2015 as part of a package of two structures for $100,000.

Graphic Products has Resources to Help Avoid Arc Flash Incidents

Arc flash accidents can be avoidable with arc flash labeling, PPE, and arc flash education. Access your free practical solution guide to arc flash hazards on Graphic Products’ site.

For more information, please go to:

Electrical Safety & Arc Flash Training