Fires – an everyday occurrence

In the United States, it’s estimated that a mineral-oil transformer fire occurs on average every day. These damaging events can harm people, equipment, property, and the environment—wildlife, plants, streams, soil. For the utility, a single incident can mean tens of thousands of dollars in clean-up and remediation costs—and that’s just what can be calculated—not to mention the cost and ill-will created by resulting power outages. In terms of potential liability and reputation damage, the costs are inestimable.

Below are several recent incidents of transformer fires and their ramifications across the globe.

  • In 2001, transformer fires in Los Angeles led to an average of one fire department dispatch per day. (Source: LAFD Weekly Bulletin March 27, 2002.) In one such fire in 2007 in downtown Los Angeles, three men were seriously injured when a flash explosion occurred at a transformer they were installing at a construction site. Firefighters were transferred to a local hospital with severe burns.
  • In 2007, an explosion in a Greek Public Power company high voltage unit caused northern Greece’s network power supply system to fail, resulting in outages that spread to the neighboring countries of Macedonia and Thrace.
  • In 2007, damage to a reactor at a nuclear power plant near Hamburg, Germany was sustained when an oil-cooled transformer exploded approximately 50 meters from the reactor. Although there were no reported injuries, the shutdown of the reactor was responsible for numerous incidents that needed to be investigated by authorities.
  • 14,000 gallons of oil burned for two days after a transformer malfunction caused an explosion in Lakeland, Fl. Close to 2,600 residents and workers in the area were required to evacuate, while dozens of firefighters used liquid foam to keep the fire from spreading during the 2007 incident.
  • A major California utility paid $9 million in settlements to customers and city and state governments for a 2003 transformer fire that resulted in a four-hour power outage impacting more than 100,000 people.
  • In 2005, the primary chamber of an underground transformer at this same utility caused an explosion inside the vault that resulted in an above-ground explosion, severely injuring at least one bystander.
  • In 1997, a transformer explosion in Tennessee resulted in injury to two bystanders, one fatality, and a company settlement of $2 million.

Out of sight, out of mind?

Once you know what to look for, you will become aware that electric utility transformers are all around you. Large and small transformers can be pad-mounted (installed on a concrete pad) or pole-mounted. Larger-size transformers are typically pad-mounted near commercial establishments such as shopping centers. You might have a small green transformer pad-mounted in your own backyard. Pole-mounted transformers are everywhere—just look up wherever there are overhead electric distribution lines. And structures called substations, which look like warehouses or other enclosures sometimes surrounded by fences, can house a number of large transformers.

Below are some examples of different types of transformers that can catch fire.

Large pad-mounted:

Pole-mounted:

Substation: