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Fire Cause: 'Castastrophic Failure' of Cable

NStar says no investigation could have predicted the fire.

By Cate Lecuyer  
March 16, 2012

The "catastrophic failure" of an underground electrical cable connected to a transformer at NStar's Scotia Street substation sparked the four-alarm fire Tuesday night, NStar officials said Thursday afternoon.

Soot buildup in the backout transformer then caused the major blackout that cut off power to 21,000 customers across the Back Bay and surrounding area. The power was restored Thursday afternoon.

NStar CEO Thomas May said in his 35 years at the job, he's never seen anything like it. The electric company has "the best engineers in America who are routinely inspecting this every month," and has invested $9 million over the past five years into the substation, he said.

Mayor Thomas Menino expressed his frustration at a press conference Thursday afternoon, saying he would assemble a panel of energy experts to investigate the transformer.

"There's no way you can inspect it, there's no way you can predict it," May said. "Sometimes you just don't know why it failed."

Power Back Up

May said NStar has been working day and night, and power has been restored to all 21,000 customers, except for the Pru. The company teamed up with other ulitlity companies to station about 60 generators across the neighborhood as a temporary fix to power homes, hotels and businesses.

Workers had to dig up the street to access the underground cables, and they also re-routed cables from another power station to jump-start the Scotia Street transformers, which were not damaged.

"We've never before jumped one network to another network," May said. It involved more than "1,000 switching operators each to put the jumpers into effect."

May said they hope the Scotia Street transformer will go into its regular operation in the next few days, and everything should be back to normal by the end of the week or early next week.

The system, he stressed is very reliable, and there hasn't been a power outage in the Back Bay in 25 years.

"I understand his frustration," May said in response to the Mayor's statement. "We're frustrated too."