TORRANCE ( — A “wiring error” associated with an ongoing equipment upgrade project in the South Bay led to a wide-scale power outage that knocked out service for about 100,000 customers and triggered flaring at the Torrance Refining Co., Southern California Edison officials said Wednesday.

The outage, reported at 5:41 a.m. Tuesday, affected Edison customers in parts of Gardena, Hawthorne, Hermosa Beach, Manhattan Beach, Redondo Beach and Torrance.

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Electricity was restored to 63,000 of those customers by 6:12 a.m., and all remaining customers had their power back by 7 a.m., according to SCE.

The outage led to a flare-off at the Torrance Refining Co., which was shut down and partially evacuated, according to the Torrance police and fire departments.

Refinery officials said additional flaring could be done in the coming days as crews work to bring the refinery fully back on line.

According to Edison, its crews are in the midst of a “multi-year project to improve reliability in the South Bay.”

“Progress on this reliability project necessitated temporarily modifying components in a Torrance substation,” according to the utility. “A wiring error associated with that modification resulted in an outage Tuesday morning when there was increased power use following the long holiday weekend.”

Utility officials said work on the project was immediately halted in response to the outage, “and we have since restored the wiring configuration to its normal state.”

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“An extensive and thorough review is under way and SCE will not resume the reliability project until that review is complete,” according to Edison. “SCE sincerely apologizes to its affected customers for this unexpected event.”

The refinery flaring resulted in a temporary “shelter-in-place” warning for some residents near the facility, and the Torrance Unified School District canceled classes for the day.

Refinery officials said restarting the facility will take several days, and crews “plan to do so safely with minimal noise and flaring.”

“Following the last outage, we initiated discussions with SCE about improving their grid to the refinery and will obviously look to accelerate those discussions and action by SCE to provide more reliable electricity to the refinery and the community,” according to the refinery, which is now owned by PBF Energy.

The refinery shutdown triggered fears of possible gas price spikes in the area.

Refinery officials said that despite the outage, “we are able to meet all of our commercial obligations in fuel markets.”

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