Central campus was plunged into darkness for more than two hours Friday morning due to worn-out equipment in the central circuit breaker.

The outage, which was one of the longest in recent memory, began around 9:40 a.m. Power was restored to the residential colleges and other affected buildings by noon.

In the course of a routine service check on Friday, a commercial electrician noticed a chafed wire in the central circuit breaker, Yale officials said. The power then had to be shut down so a Darian electrician could verify the problem and repair it.

“They did what they were supposed to do,” Director of Facilities Lou Annino said. “They’re supposed to fail-safe so no one gets hurt.”

It was not immediately clear who was responsible for maintaining the faulty equipment. Annino said it was the responsibility of United Illuminating Co., a New Haven-based electricity provider, but a UI spokesman, Al Carbone, said the outage involved solely Yale personnel and equipment.

Carbone and Annino said Yale and UI coordinated their response and worked with electricians Oakleigh South to restore the system.

The University’s response to the brief blackout included the first use (besides tests) of the campus alert system. Maria Bouffard, the director of emergency management services, said the system was activated because a power outage is considered an emergency.

Cell phones across campus rang and buzzed at 10:50 a.m. and 11:30 a.m. with automated phone calls reporting the status of the outage. Updates were also sent by e-mail.

The residential colleges are typically the first to lose power when Yale’s grid overloads, but some classroom buildings were affected by the blackout, too. (About 300 classes meet on Friday between 9 a.m. and noon.)

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