Disturbance at Chatsworth Substation reported minutes before Woolsey Fire start
Nov 2018Published 22 Sept 2026Responsible editor: Chief Editor
- Where
- Chatsworth Substation, south of Simi Valley, Ventura County
- Operator
- Southern California Edison
- What
- Circuit relayed at 2:22 p.m., outage two minutes before Woolsey Fire
- Cause
- Not reported
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Companies named in the reporting of this entry (being named is not a finding of fault): Southern California Edison
What happened
Southern California Edison told state regulators that a circuit at the Chatsworth Substation relayed at 2:22 p.m. on Thursday, switching the circuit off after a sensor detected a disturbance. The utility linked this to an outage two minutes before the Woolsey Fire is believed to have started, at about 2:24 p.m., in the area of Alfa Road, south of Simi Valley in Ventura County. The substation is just south of Simi Valley, near that reported ignition area.
Edison said crews had not been able to reach its facilities in the area where the fire began, and that it had no indication from fire agency personnel that its facilities were involved in the start of the fire. It was not known whether the disturbance contributed to the fire, whether the fire caused the disturbance, or whether the two were unrelated. The company filed the report with the California Public Utilities Commission out of caution because the event might draw public attention.
Contributing factors
The cause of the sensor trip was not reported. Edison said it did not know what triggered the circuit sensor. Any link between the disturbance and the Woolsey Fire had not been established.
Lessons learned
- A substation circuit relay near a reported fire start must be logged and shared with investigators at once, without treating timing alone as proof of cause.
- Access limits during an active fire can delay inspection of substations, so early reports must state what has and has not been checked.
- Operators must keep protection-event records, including relay time and circuit identity, so investigators can compare them with ignition timing.
More lessons on electrical protection and isolation, maintenance, inspection and ageing assets, from every incident on the register.
Not yet known
- Cause of the sensor trip
- Whether disturbance linked to fire
- Model and age of the circuit equipment
This entry is updated when these are reported. Get an alert for the next one like it.
Source
Published 2026-09-22. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.
