On Jan. 19, almost two weeks after the Eaton fire broke out near Altadena, Calif., technicians for Southern California Edison began testing electrical equipment near the origin of the blaze. They soon noticed small white flashes appearing on high-voltage transmission lines when power was being restored — signs that the system was functioning abnormally.
The incident is one of several irregularities that Edison has been reviewing as it examines its electrical system in the wake of the deadly fire, Pedro J. Pizarro, president of Edison International, Southern California Edison’s parent company, said in an interview Wednesday.
He cautioned that the findings were part of the utility’s ongoing investigation and did not provide any conclusive evidence about whether faulty electrical equipment had ignited the blaze.
But the flashes, which could be similar to ones captured on video near electrical equipment just moments before the fire broke out on Jan. 7, add to a growing pool of evidence linking the utility to the possible origin of the fire, which killed 17 people and destroyed more than 9,400 homes and businesses.
It may take months for an official cause to be determined, but if Edison is found to be at fault, it could have sweeping consequences for how victims will be compensated — as well as how the utility, the state’s second largest, continues to operate.
“While we do not yet know what caused the Eaton wildfire, SCE is exploring every possibility in its investigation, including the possibility that SCE’s equipment was involved,” Mr. Pizarro said.
Edison is submitting the details of its latest findings in a report to state regulators on Thursday, the company said.
Utility equipment has been the source of some of California’s most deadly and devastating wildfires. After a series of blazes in the northern part of the state, including the Camp fire, which killed 85 people and destroyed the town of Paradise in 2018, Pacific Gas & Electric, the state’s largest utility, filed for bankruptcy.
For much of the last decade, California has worked to reduce wildfires set off by electrical equipment by requiring the state’s investor-owned utilities to develop prevention plans that have included moving wires underground, installation of weather stations to track storms and even deliberately cutting power to customers during dangerous conditions.
As Edison began reviewing its data after the Eaton fire, it noticed that its system was under strain from 100-mile-an-hour winds that night, but it did not initially find any direct evidence suggesting its equipment was at fault.
The utility later expanded its internal investigation after The New York Times published a video recorded outside an Arco gas station in Altadena that captured flashes in the area of transmission towers in Eaton Canyon where the fire began on Jan. 7. The flashes occurred in short succession — one at 6:10 p.m. and then another three seconds later — before flames burst out below the towers.
“After we saw the video, we went back and said, ‘Hey, are there things we just don’t understand here and we should bring back into the fold?’” Mr. Pizarro said.
The timing of the two flashes coincided with data released by Whisker Labs, a Maryland technology company that operates sensors in homes to help predict and prevent residential fires, that identified two huge transmission faults that originated in the Altadena area. The electrical disruptions were so strong that sensors registered the faults as far away as Portland, Ore., and Salt Lake City.
Edison said it was now looking at several factors that it initially had not considered relevant to the fire in Eaton Canyon, including electrical faults at 6:11 p.m. Jan. 7 on the transmission line near a substation several miles from the origin point of the Eaton fire.
It seemed a mystery, Mr. Pizarro said, that electrical problems so far from the origin point of the fire would play a role in igniting it.
The utility is considering whether an inactive transmission line might have sparked if electrified equipment nearby caused the line to energize. He said the utility had found signs of damage from arcing — when electricity jumps from one place to another and lines can dangerously flash and spark — on some inactive equipment. But, he added, it is unclear whether that damage occurred before or after the fire.
“What else happened in the system?” Mr. Pizarro said. “What else can we put together to try and concatenate some sequence of events?”
That led the utility to the incident on Jan. 19, Mr. Pizarro said, when field workers tested four transmission lines in Eaton Canyon. Those lines had been cut off a week earlier to prevent more fires, but that was after the initial blaze had already destroyed much of Altadena.
As a preventive measure on the afternoon of Jan. 7, Edison cut power to some of its customers in the area.
But the cutoff included only three distribution circuits that connected Kinneloa Mesa, a community of about 1,000 residents on the east side of Eaton Canyon that was largely unharmed, to the grid.
Edison considers cutting power to its transmission lines when winds reach 68 to 90 m.p.h., depending on other weather conditions.
Even as winds reached roughly 100 m.p.h., none of the higher-voltage transmission lines near Altadena were cut off, nor were the low-voltage distribution lines on the west side of the canyon, where more than 42,000 people lived.
A finding that Edison’s equipment caused the Eaton fire could have significant implications for how victims are compensated for their losses. Verisk, an analytics company, has estimated financial losses from the Eaton fire at as much as $10 billion.
That amount of liability could strain Edison’s resources. The utility already faces dozens of lawsuits from victims of the Eaton fire.
“We understand the community wants answers, and we remain committed to a thorough and transparent investigation,” Mr. Pizarro said. He added that 19 of the company’s employees had also lost their homes in the fire.
As a result of the fire and the potential liability, Edison’s stock has lost more than a third of its value since Jan. 7, when the fires that devastated Altadena broke out. Edison’s stock closed Tuesday at $52.44.