A bad electrical cable cut power to 20 University of Oregon buildings for about seven hours on Wednesday, according to campus emergency management officials.

Electrical crews from Campus Operations and other campus staff worked through the afternoon and evening to identify the troubled line, which was in an underground electrical vault. Crews eventually were able to reroute power to affected buildings through a different, stable feeder line.

The outage happened around 2:20 p.m. Wednesday. Power started to be restored around 9 p.m. All classes and UO offices were operating normally Thursday morning.

A faulty cable is uncommon, said Tony Hardenbrook, director of utilities and energy in Campus Operations. Failures typically originate at a transformer or some other junction on the electrical feeder line. To identify and repair the trouble spot, crews must work slowly, testing each section and making sure not to create power overloads that could cause fires, damage equipment or injure workers.

The buildings that lost power were Allen, Chapman, Chiles, Computing Center, Deady, Fenton, Friendly, Gerlinger Annex, Gilbert, Hendricks, Johnson, Collier House, Knight Library, Lawrence West, Lillis, Museum of Art, Music, Peterson, Susan Campbell and Villard.

In an unrelated incident, Knight Library was evacuated at about 2:45 p.m. Wednesday when a general fire alarm was triggered by a burst steam pipe in a lower level mechanical room. The Eugene-Springfield Fire Department, UO Campus Operations and UO Safety and Risk Services responded, and steam was shut off.

Because of the power outage, Knight Library closed for the rest of the evening, but reopened at normal time Thursday.

UO departments experiencing computer network problems should call 541-346-NETS for help.