Power Restored to Most After Big California, Arizona Blackout

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Power companies in Southern California restored electricity to most customers by early Friday after a massive blackout on Thursday left nearly 5 million people in parts of California, Arizona and Mexico in the dark.

Although the Sept. 8 outage, apparently caused by human error, was just a tenth the size of the 2003 blackout that left about 50 million people without power in the eastern United States and Canada, it will surely rank as one of the biggest blackouts in recent history – certainly one of the biggest caused by human error.

Sempra Energy’s San Diego Gas & Electric power company said it restored power to its 1.4 million customers at 3:25 a.m. Western time on Friday.

That was almost 12 hours after a major electric transmission system outage in western Arizona and the loss of a key connection with the 2,150-megawatt San Onofre nuclear power plant in California resulted in the most widespread power outage in the company’s history, SDG&E said.

Blackouts also affected 3.5 million people in Baja California, according to local officials.

San Onofre, which is operated by Edison International’s Southern California Edison, shut on Thursday and remained out of service early Friday, according to the U.S. Nuclear Regulatory Commission.

“Restoring power in the aftermath of the loss of the entire local grid serving San Diego and southern Orange counties was a monumental task,” David Geier, SDG&E vice president of electric operations, said in a release.

“The restoration process, however, has left our local power grid very fragile and we are asking our customers to conserve electricity throughout the day Friday,” Geier said.

SDG&E and the California ISO, which operates the power grid for much of the state, said they would focus on maintaining and ensuring the integrity of the local power system for the next few days before determining the sequence of events that led to the outage and establishing practices and procedures to ensure that outages such as the Sept. 8 event are not repeated.

“There appears to be two failures here — one is human failure and the other is a system failure. Both of those will be addressed,” said Damon Gross, a spokesman for Pinnacle West Capital’s Arizona utility Arizona Public Service.

(Reporting by Scott DiSavino; Editing by Alden Bentley)