A wildfire in Southern California that grew to be among the largest ever recorded in Los Angeles County may have been caused by tree branches coming into contact with power equipment, a utility said Monday.
Southern California Edison (SCE) said in a letter to the California Public Utilities Commission (CPUC) that investigators from the U.S. Forest Service (USFS) have taken a 23-foot-long line of conductor belonging to the utility, an “H-Frame structure” with two power poles and three tree branches.
The letter on Monday came after the utility filed another notice with the agency saying there was an "incident" on their grid around the time of the Bobcat Fire that started on Sept. 6.
The blaze was reported near the Cogswell Dam in Angeles National Forest at 12:21 p.m. SCE reported in its letter that it experienced a "relay operation" on the company's Jarvis 12 kV circuit out of a nearby substation.
In the letter, the utility noted that cameras in the area showed smoke was already developing around 12:10 p.m. before the grid incident.
"Although USFS has not shared the details of its investigation with SCE, it appears that USFS is investigating whether vegetation was involved in the ignition of the fire," the utility said.
While SCE is investigating the cause of the relay on its system, it's also evaluating whether vegetation in the area could have been a factor, including "whether vegetation may have encroached within the minimum clearance distance or contacted the section of the overhead conductor retained by USFS."
"SCE is also investigating the impact an active fire might have had on our circuit, and is investigating other potential causes of the ignition such as customer-owned electrical facilities and human activity in the area," the utility said in its letter Monday.
The Bobcat Fire was 92% contained as of Monday, after burning some 115,796 acres, according to InciWeb. The blaze has destroyed 171 structures, including 87 residences, and damaged 47 structures, including 28 residences.
The Nature Center at the Devil's Punchbowl Natural Area was destroyed, according to Los Angeles County parks officials.
The probe of the power equipment with the Bobcat Fire comes as officials in the northern part of the state are investigating another utility for a blaze that killed four.
In a filing with the California Public Utilities Commission, Pacific Gas and Electric (PG&E) said Friday investigators with the California Department of Forestry and Fire Protection (Cal Fire) have taken some of its equipment as part of the ongoing investigation into the Zogg Fire.
PG&E recently emerged from bankruptcy stemming from financial fallout from several devastating wildfires caused by its utility equipment that killed more than 100 people and destroyed more than 27,000 homes and other buildings in 2017 and 2018.
Wildfires in California have incinerated more than 4 million acres in 2020, a new record. Virtually all the damage has occurred since mid-August when five of the six largest fires in state history erupted. Lightning strikes caused some of the most devastating blazes, with many burning in largely unpopulated land.
Over 12,600 firefighters continue to battle 14 major and six large blazes in the state.
The Associated Press contributed to its report.