In addition, several small power suppliers that provide a total of about 500 megawatts of electricity to Southern California Edison served notice they will suspend service. A law firm representing the Qualified Facilities said in a press release that the company's failure to honor its contractual obligations may cause ‘‘serious financial injury'' to the suppliers.
Also lurking was the possible bankruptcy filings of Pacific Gas and Electric Co. and Southern California Edison Co., who say they have no way to raise money to pay huge bills due early next month.
Filing for bankruptcy court protection could occur at any time. That would allow the utilities to protect their assets from creditors, but the bankruptcies would rank among the biggest business failures in U.S. history.
California's electricity system has been in turmoil for months. The state's largest utilities, operating under a rate freeze imposed by the state's 1996 deregulation law, have been unable to pass on to their customers the spiraling costs of wholesale power.
Since June, SoCal Edison and PG&E, which serve 25 million people between them, have lost some $11 billion.
Sunday's outages marked the third time in five days that California was forced to cut power, though it occurred for a different reason.
The Oregon electricity surge required the California system to shed power to up to 75,000 customers from east of Sacramento to Turlock to avoid damage and outages along the grid, said Stephanie McCorkle of the Independent System Operator, which manages the power grid.
McCorkle said the impact of the outages was intensified by the state's stressed grid.
‘‘It shows you how close to the ragged edge we are when one transmission problem would cause that sort of outage,'' McCorkle said.
Power needs generally drop by 2,000 megawatts during weekends, but that yielded no relief. The ISO declared Stage 3 alerts, which means reserves dipped below 1.5 percent, both Saturday and Sunday, the first ever on a weekend. Sunday's alert is scheduled to continue through Monday.
The alerts were prompted by tight supplies and power plants that were idled for maintenance or repairs. The alerts were accompanied by urgent requests for Californians to conserve energy.
Among those implementing conservation measures was San Francisco International Airport. Although it is exempt from rolling blackouts, the airport has turned down the lighting and cooling systems and brought its emergency generators online.
Some other businesses and homeowners also are going a step beyond conservation by supplying their own power.
Jerry Twentyman, owner and president of Electro-Motion Inc. in Menlo Park on the northern edge of Silicon Valley, said his home generator sales are three times normal at $4,000 and up for each unit, while rentals and service calls have doubled.
His largest customers are computer hardware, software and networking companies, but his 14 employees also provide backup generators to hotels, motels, factories, office buildings and homes.
‘‘It's been a disruptive boom,'' Twentyman said Sunday. ‘‘We're in for the long haul, so we're not trying to take advantage.''
On the Net:
California ISO: www.caiso.com
Edison Int'l: http://www.edison.com