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Investigation Into Cause of Bobcat Fire Now Includes Edison Power Line

Southern California Edison’s Dalton Substation in Irwindale, CA. (Google maps)
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Southern California Edison has informed its regulator, the state Public Utilities Commission, that one of its power circuits had a momentary interruption (“a relay operation”) minutes after the Bobcat Fire was discovered by cameras positioned on nearby mountain peaks.

Edison has been spending hundreds of millions of dollars to update and upgrade power lines and transmission equipment in rural and fire-prone areas after it was attributed as the cause of other large fires, including the 2018 Thomas Fire that burned more than 1,000 homes and caused billions of dollars in damage.

It could take months to determine the cause of the Bobcat Fire.

The power interruption was at 12:16 p.m. on Sept. 6, when Southern California Edison equipment across its vast service territory was in the grip of a heat wave.

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It happened on the 12,000-volt Jarvis Circuit (see the map), which carries power from Edison’s Dalton Substation in Irwindale into the mountains for use by nearly 900 customers at locations along the west and east forks of the San Gabriel River.

As part of its investigation, the PUC asked Edison to hand over a section of overhead power line that was located near Cogswell Dam at the farthest northwestern reach of the circuit.

An east-facing fire alert camera at Mount Wilson recorded the initial smoke from the fire at 12:10 p.m. The fire burned from a point near Cogswell Dam and Bobcat Creek (which feeds into the reservoir) west toward Highway 2 and Mount Wilson.

It’s not clear if the heat wave played any part in the power interruption. Equipment failed on the Jarvis Circuit in 2019, according to Edison’s 2020 reliability report, but it's unclear how that affected the circuit this year.

On the date Edison made the report to the state, Sept. 15, the fire had already grown to more than 41,000 acres, and it's unclear why the company took one week to provide the report. It's also unclear why Edison updated the Jarvis Circuit map on Sept. 7, the day after the fire started.

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An Edison spokesman said he could not comment on the inquiry beyond what the company said in its report to the PUC. It's not unusual for Edison to report on equipment problems that occur around the time that fires start. Here are several other incidents that Edison reported to the PUC.

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