"A line idle for decades has been accused of starting the LA area's deadly Eaton Fire," writes Bloomberg, describing California's abandoned power lines as "a fire risk hiding in plain sight."

[Abandoned power lines] fall out of use, either because they've been replaced or because the power plants they once connected to the grid shut down... Sometimes the utilities that own idled lines disconnect them from the power grid, cutting off the flow of electricity through the cables. Other times, they don't, keeping them energized. California regulations require the companies to remove power lines they don't anticipate using again, but there's no set deadline. The companies can keep idled lines in place if they foresee needing them in the future, so long as they're regularly inspected and maintained.

Even those that have been unplugged from the grid can potentially pose a danger. The line under scrutiny due to the Eaton Fire is owned by Edison International's Southern California utility and was retired in 1971. Under normal circumstances, it carries no electricity, according to the company. Lawyers suing Edison allege that a January 7 power surge on a nearby, active line created a magnetic field that briefly re-energized the dormant cable, setting off the sparks that ignited the blaze. Edison said in a state filing that it is investigating that theory. State investigators have yet to announce a cause for the fire.

A 2019 fire that burned 77,700 acres (31,444 hectares) was started by an old power line for a plant that closed in 2001, according to the article. PG&E, the state's largest utility, "hadn't removed it, and it stayed connected to the grid, energized."

[PG&E] agreed to remove 72 permanently abandoned transmission lines — representing about 260 miles (418 kilometers) of dormant cables. The work could cost as much as $268 million spread over 10 years, the company estimated at the time. PG&E had removed 64 of the idled lines by the end of 2024, according to a spokesman.

"At the right conditions, failing idle facilities can pose significant wildfire and safety risks," PG&E said in its plan to remove the equipment.

Thanks to long-time Slashdot reader larryjoe for sharing the news.

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