(CNN) California's largest utility started intentionally shutting off power to customers Wednesday to prevent its equipment from setting off fires.

The shut-offs began at 7 a.m. (10 a.m. ET) for about 50,000 customers in 10 northern California counties, said Katie Allen, a spokeswoman for Pacific Gas & Electric. Another 100,000 are on standby to lose their electricity Wednesday, she said.

PG&E said it expects high winds and dry conditions Wednesday as a storm bears down on the state, leading to increased risk of fire. The utility said earlier the shut-off would affect 18 counties.

"PG&E will safely restore power in stages as quickly as possible, with the goal of restoring the most customers by end of day Thursday, based on the current weather conditions," the company said.

"Forecasts indicate the period of peak winds should end mid-morning on Thursday. Once the high winds subside, PG&E will inspect the de-energized lines to ensure they were not damaged during the wind event, and then restore power."

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