About a third of campus buildings were without power beginning at about 3 p.m. on Wednesday.

Power was restored by Land, Buildings & Real Estate (LBRE) staff members to all buildings except the Bass Biology Building by about 10 p.m. Updates have been posted on emergency.stanford.edu.

The exact cause of the fault – meaning the interruption in power – is still undetermined. However,  LBRE  isolated the fault to  a cable failure at a transformer at the new Bass Biology, which is not yet occupied. LBRE believes the fault was due to equipment failure.

Sixty-seven buildings were affected by the power outage, ranging from athletics facilities on the east side of campus to parts of the School of Medicine on the west side. In between, a plethora of buildings had no power or were running on back-up generators, including the Arrillaga Alumni Center, the Graduate School of Business campus, the Sapp Center for Science Teaching and Learning and the Clark Center.

Evening classes were canceled in affected buildings.

As the outage persisted throughout the afternoon and evening on Wednesday, Environmental Health & Safety officials recommended out of an abundance of caution that lab researchers in affected buildings cease work with hazardous materials, citing concerns about ventilation systems. Warnings were also issued that network and voice services could be lost as battery backups ran out.

Additional illumination was installed in areas where lighting was affected, including the intersection of Campus Drive and Roth Way. Department of Public Safety personnel were also dispatched to streets where bollards were not working.

At around 5:30 p.m., LBRE workers began slowly and methodically testing individual circuits throughout campus, searching for the cause of the power outage. By around 7:30 p.m., all but eight major buildings had power restored. Those buildings included Psychiatry Academic and Clinical, the Anderson Collection, Roth Way garage, Mudd Chemistry, Stauffer I and II, Gilbert Biology, portions of the Paul Allen Building and Chemistry Conference Center.

LBRE continued working throughout the evening to identify the fault on a line called “Feeder #5,” which is about 2 miles long.

For more information and further updates, visit emergency.stanford.edu.