California’s utility companies, including PG&E, now must notify customers and follow other set procedures when switching off power lines to prevent fires.

State utility regulators unanimously approved Thursday new rules for power companies that de-energize lines in extreme weather conditions to safeguard against fire risk. Utilities must try to reach individual customers ahead of shutting down the grid.

Prior to Thursday’s decision, the rules applied only to San Diego Gas & Electric, as it was the only publicly traded utility to establish the practice to date. Now, the rules extend to the state’s other dominant utilities.

“De-energization can be very helpful during an emergency situation where having electricity flowing is potentially harmful, but it must be done with great thought and with consideration of customers,” Liane Randolph, of the California Public Utilities Commission, said in a statement.

“Our decision today helps ensure that utilities communicate early and consistently with communities that will be potentially affected by de-energization.”

After October’s devastating Northern California fires, PG&E adopted the practice of de-energizing its lines in high fire-risk conditions, including hot and windy weather that can spark blazes by toppling lines into nearby brush. In May, the company also opened a new wildfire safety operations center in San Francisco to monitor dangerous weather and avoid a repeat fire event.

PG&E faces dozens of lawsuits from hundreds of plaintiffs who lost family members or homes in the October fires. Cal Fire last month announced the company’s equipment started 12 of the region’s major fires. In eight of those fires, state investigators found evidence the company violated state codes.

PG&E has disputed some of Cal Fire’s findings regarding the deadly Atlas fire in Napa County, but executives at the San Francisco-based company last month warned investors of at least $2.5 billion in liabilities tied to the fires.

Overall, insured losses in the Northern California fires have been estimated at $10 billion.

A Cal Fire determination on the cause of the Tubbs fire, the most destructive blaze, is still pending. The fires killed 24 people in Sonoma County and destroyed about 5,300 homes.

Under the state’s new guidelines, a utility company must submit within 30 days a report to the Public Utilities Commission outlining its plans for customer outreach, notification and limiting impacts from preemptive blackouts.

Utilities also must notify the commission as soon as possible after deciding to turn off power and report back within 12 hours after restoring it.

PG&E spokeswoman Deanna Contreras said the company’s highest priority remains customer safety, and it welcomed the new regulations.

“We know how much our customers rely on electric service and would only consider temporarily turning off power in the interest of safety, and as a last resort during extreme weather conditions,” Contreras said.

“We want our customers to know that PG&E has a plan to deal with these types of events and we want them and their families to have plans, too.”

You can reach Staff Writer Kevin Fixler at 707-521-5336 or at kevin.fixler@pressdemocrat.com. On Twitter @kfixler.