San Francisco Power Outage Caused By Failure Of Circuit Breaker: Here's What Happened

City-wide power outages can cause major damage not only to physical structures but to the city's finances as well, since many businesses are forced to stay closed. That is why the people in San Francisco were alarmed when not only the city, but also New York and Los Angeles simultaneously experienced a blackout on the morning of April 21.

Like the sudden blackout that affected the San Francisco Bay Area in 2015, however, Friday's power outage was caused by an incident in one of the city's substations.

Sudden Power Outage

It was around 9:30 a.m. on April 21 when 14 San Francisco neighborhoods suddenly lost power and according to reports, almost 90,000 customers of Pacific Gas & Electric were affected. The power outage knocked out traffic signals, stalled cable cars, and forced businesses to close down for the day.

Many workers who were outside their buildings during that time could not get back in using their keycards and emergency workers were dispatched to about 20 elevator rescues.

"When I got here we had to shut down all the servers, all the work stations were off-line... I'm sure we've lost millions of dollars already. There's no business down here right now," Bard Wood, a financial district information technology worker said.

Twenty one schools were also affected but remained open and three affected hospitals had to rely on their back-up generators, but had to reroute patients to other hospitals.

The Sub-Station Fire Incident

Some people thought that the blackout could have been an act of terrorism or a cyber-attack since New York and Los Angeles also experience power interruptions on the same day. A U.S. Department of Homeland Security spokesperson, however, clarified that there is no evidence that it was a cyber-attack.

Investigators say that the power outage was caused by a fire in one of the PG&E substations.

"We had equipment failure, the catastrophic failure of a circuit breaker... Something went wrong with the breaker to cause it to explode," PG&E spokesperson Barry Anderson revealed.

According to reports, a circuit breaker failed and ignited the insulation leading to the Larkin substation fire that took three hours to subdue.

San Francisco Back In Action

San Francisco Mayor Ed Lee and the emergency operations center were quick to respond and deliver services to affected people in the city.

By 5:00 p.m., PG&E confirmed that the company had restored power for all affected customers and the San Francisco government reported that there were no major injuries caused by the blackout.

The San Francisco Police Department also repeated that the simultaneous blackouts were only a coincidence.