Damp, salt cause 7,000 residences to lose power

About 7,000 Twin Cities households were darkened Sunday when half a dozen power transformers were short-circuited by a combination of damp weather and salt spray from roads, Xcel Energy said.

Last update: March 2, 2008 - 11:33 PM

About 7,000 Twin Cities households were darkened Sunday when half a dozen power transformers were short-circuited by a combination of damp weather and salt spray from roads, Xcel Energy said.

The tops of some power poles caught fire from the transformers, but no other damage was reported.

Three transformer-related power failures in St. Paul affected about 2,800, 1,400 and 600 customers Sunday. About 1,000 customers in Oakdale lost electricity in the afternoon, and more than 1,140 homes in northeast Minneapolis were without power shortly after noon on Sunday, said Tom Hoen, an Xcel spokesman.

Xcel Energy said the problem frequently occurs in the spring, when damp air carries aloft the salt spray from the roads. Because salt is an exceedingly good electrical conductor, it causes a short circuit by creating an electrical arc inside the pole transformers, Hoen said.

Fuses inside the transformers then trip, causing a loud pop. Tripping a transformer's fuse shuts down a section of the power grid, leaving large neighboring areas without electricity, Hoen said. The arc from inside the transformer sometimes sets the tops of power poles on fire, he said.

"It's always shocking to residents if they hear the pop when the transformer fuse goes off or if they see the top of a pole burning," Hoen said. "We always tell people to stay away from lines and call us. But people need not be overly concerned."

Xcel said the power failures were lasting an hour on average. Residential customers who heard or saw a pole transformer short out, or who lost electricity, were urged to call Xcel's emergency service number, 1-800-895-1999.

STEVE ALEXANDER

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