ORINDA, Calif. — Leonard Hernandez was not going to let his clients down just because his power company let him down.

His shop dark, he took it all outside: spray bottle, clippers, two brushes, a pair of scissors and Neal Dawson, a retired computer scientist, whose barber smock flapped in the gentle wind as Hernandez gave him a trim.

With electricity cut intentionally overnight to Hair 2000 — and to thousands of other small businesses across the Bay Area — the grooming took place alfresco. So did the acidic arguments over the blackout imposed by Pacific Gas & Electric, the state’s largest utility and among its least-liked companies.

“This is a whole new deal from PG&E,” Dawson said. “And it’s amazing to see the power this company has — scary, really, because there is no recourse.”

The utility company’s planned blackout ebbed and flowed Thursday, with some neighborhoods getting electricity back and others waking up to no power at all. And much like the utility itself, business owners and others carried out countless acts of improvisation, adapting on the fly to an expensive inconvenience that could become commonplace as the California climate shifts toward the extremes.

After expanding the blackout overnight to some areas, including this town east of Oakland, PG&E began the slow process of inspecting lines in other areas in preparation to flip the switch back on. The company has said it will take days to bring the power back up to all of the more than half a million customers affected.

The shut-off, which began before dawn Wednesday and has played out in frustrating fits and starts for residents, is a relatively new, if drastic, measure to lessen the threat of wildfires during high-risk weather. Utilities are allowed to cut the power without government approval, though such decisions are reviewed by the state Public Utilities Commission.

But those conditions have not materialized as predicted, leaving many across the region to interpret the blackout as a political act by a company seeking to loosen the state’s strict liability law that holds utilities accountable for any fire their equipment starts. A cool, dry wind blew through the hills of this town Thursday, but at nowhere near the strength forecast just a few days ago.

PG&E filed for bankruptcy protection earlier this year, with about $20 billion in claims against it for its role in recent wildfires. One fire last year burned through the hill town of Paradise north of here, killing 85 people and leaving about 14,000 homes in ashes.

The shut-off, by far the largest ever in California, has drawn sharp criticism from state and local leaders for the economic loss and daily disruptions it has caused. During a Thursday news conference,  Gov. Gavin Newsom (D) said the blackout has less to with California’s changing climate than with PG&E’s “greed and mismanagement.”

“What has happened in the last 48 hours is unacceptable,” Newsom said. “And it’s happened because of  neglect.”

PG&E said the shut-offs are for safety, and it urged patience.

“We understand that this power shut-off is difficult for our customers and communities. Please check on your neighbors, friends and family and know that we will work safely, and quickly as possible, to restore power across the region,” Sumeet Singh, a PG&E vice president, said in a statement on the company’s website.

Southern California Edison followed PG&E’s lead, cutting power to 13,000 customers in parts of four Central and Southern California counties on Thursday.

The company said spiking Santa Ana winds, as the high fire-risk breezes are known in the south, prompted the decision. Winds can bring down power lines, which in turn can spark fires. The winds then drive the flames quickly across the tinder-dry landscape, heavy with natural fuel after an unusually wet spring.

The state’s utility companies have lobbied unsuccessfully for significant changes to the liability law. But Newsom signed legislation earlier this year that establishes a $21 billion emergency fund to help pay for future fire-damage costs. The measure also will loosen some of the liability rules when utility company equipment causes a fire, but only after those utilities carry out billions of dollars in fire-prevention safety work.

Along Orinda Way, the blackout’s effects played out on a small stage of mini-malls featuring mostly locally owned enterprises. Small-business owners blasted the big-business utility, many saying they might not make rent.

Almost every store is closed.

Police tape is strung across the gas pumps at the Mobil and Shell stations. The Safeway is the only source of food in town, with the insectlike buzz of its generator ringing through the parking lot. Inside, shoppers rolled through half-lit aisles. One wore a miner-style headlamp; another shouted simply, “This is like an adventure!”

The shelves inside the store’s aisles of refrigerators are empty.

“It’s going to be Cheetos and Fritos for lunch today,” said Hernandez, the hair stylist.

Among the most frustrating elements of the blackout has been the utility’s inaccurate warnings and, in some cases, lack of warnings at all.

Stated times for blackouts have been missed consistently, prompting some businesses to close when it has not been necessary and surprising others by happening without notice.

Dipping Nails opened for business Thursday morning just across from Hair 2000.

The shop had closed the previous day — canceling dozens of appointments — after receiving word from PG&E that the power would be off. It was not. But it was cut overnight, and when Vy Nguyen arrived to open up, she was stunned when the lights would not turn on.

“If they want to shut off the power — fine,” said Nguyen, the shop manager. “But they have to tell us the right times so we can plan for it.”

Nguyen said she is losing about $1,000 a day because of the shutdowns and threat of them.

“I just don’t know why they are doing it,” she said. “We’re losing a lot, but, of course, we still have to pay the rent.”

Cyndi Hilton faced the prospect of missing her rent when, days before the power went out in her consignment and design store in the same mini-mall as Hair 2000, her customers responded to the threat of a shutdown by avoiding the shop.

She worked behind the dark counter at the back of Hilton House, reading sales sheets and examining a set of earrings with a consulting jeweler by flashlight. Her iPhone played mood music.

“It’s been very, very slow since this whole thing started,” Hilton said. “I hadn’t sold a thing in days, and the rent is due.”

She tried to jump-start her 20-year-old business a few days ago by sending an email to 1,100 customers, saying she is open and that times are tough. Many came in the following morning in a show of support, but with the lights out now, the store is empty.

“PG&E has gotten way too big, and it should be broken up,” Hilton said. “They hold way too much power over us.”

David Blount-Porter, the jeweler, said he believed that was the point of the blackout, to show some of the company’s 16 million customers and state lawmakers just how much leverage the utility has.

“It’s like they are saying, ‘You guys are going to sue us?’ ” he said. “ ‘Okay, well then, here you go; how do you like this?’ ”

Hernandez, at Hair 2000, said the blackout has “forced us to live like we’re back in the old days, but the problem is that we didn’t live in the old days, so we don’t know what we’re doing.”

Dawson, the retired computer scientist getting a haircut, has power at his Walnut Creek home even though PG&E warned it would be cut the previous day. All of his neighbors pulled their cars out of their garages, preparing for electric door openers not to work.

“This just feels like PG&E exercising its muscles,” Dawson said.