LOS ANGELES — The number of faults on the power grid near three of the major Los Angeles County fires skyrocketed in the hours before the blazes began, according to a company that monitors electrical activity.

Bob Marshall, the CEO of Whisker Labs, said in an interview with The Times that the areas near the Eaton Fire, Palisades Fire and Hurst Fire all saw massive increases in faults in the hours leading up to the fires. Faults on the power grid are caused by tree limbs hitting electrical wires or wires hitting each other, among other causes. Each fault causes a spark.

The fires together have destroyed or damaged more than 9,000 structures. Power equipment has caused destructive wind-driven California wildfires in the past, but L.A. city and county fire officials say their investigators have not determined what sparked any of the fires.

"What I cannot say is one of these faults sparked the fire. I don't know that," Marshall said in an interview. "But it just takes one to start the fire."

Data shared with The Times, but not yet released publicly, showed the increase in faults.

In the area of the Palisades fire, in the hour before the fire started, there were 25 faults on the grid. In the hour that the fire started, there were 18 faults, according to Whisker Labs' data.

The Eaton Fire had even more faults. In that area, there were 50 faults in the hour that the fire started.

At the Hurst Fire, there were 51 faults the hour the fire was reported. That came after four hours of continuous high fault levels. There were 120 faults in the four previous hours.

That means despite the sparks flying in the area, over the previous four hours, energy was left on.

"What we know is the lines were not de-energized prior to the ignition of fire," Marshall said. "The problem is the utilities don't have the sensors to know this is occurring. This sensor network is sophisticated and sensitive. We have more information than they do. Our objective, we've been trying to get utilities to pay attention to the data because it's valuable to know when the grid is stressed."

In all three of those areas, faults in the days leading up to the fires were negligible, with only a few occurring.

Whisker Labs monitors electrical data using its Ting sensors, which monitor about 14,000 homes in the Los Angeles area. The monitors help Angelenos stop electrical fires in their homes, but taken together provide information on the entire power grid.

"So when something bad happens on grid — a power outage or surge — we see that because it's measured by many sensors," Marshall said.

Robert Garcia, the Angeles National Forest fire chief for the U.S. Forest Service, said at a news conference that the cause of the Eaton fire remains under investigation but there are a number of factors to consider.

"There's a number of different activities in [Eaton Canyon]," Garcia said. "There was public in there when it was occurring. And there's power lines run through there. So we have teams looking at all [possible starts]."

L.A. fire officials say the cause of the Palisades fire is also still under review.

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