The utility said yesterday afternoon that about 30,000 customers remained without power, and it had no estimate on when electrical and natural gas service would be restored.

Numerous problems were to blame for the outages, spokeswoman Christy Heiser said, including power poles destroyed by the fires, blown transformers and burned distribution lines. The fires are preventing much of the needed repair work.

The utility also has lost the use of a major transmission line into the region, the Southwest Power Link, which has been shut down since midday Sunday. The line, which carries about 1,750 megawatts, runs roughly parallel to Interstate 8 and brings electricity to the region from Mexico and Arizona.

Regional demand for power was moderate yesterday, peaking at about 3,500 megawatts, which allowed the utility to meet regional needs despite the loss of the transmission line. SDG&E had record demand of about 4,600 megawatts during a heat wave this year.

To meet yesterday's demand, the utility deployed all local electricity-generation resources and tapped power from the north. When the north-south transmission lines were shut down because of the fires, the utility had to cut power briefly to about 70,000 customers. The north-south link was repaired within about 30 minutes.

In order to restore power to all customers, SDG&E is sending out all available crews and has asked for assistance from other Western utility companies, Heiser said.

The utility is still asking customers to conserve electricity by avoiding the use of major appliances until evening hours and shutting down air conditioners, unless the health of a resident is dependent on the filtration of pollutants that some cooling systems provide.

Critics of SDG&E's plan to build the Sunrise Powerlink said yesterday's fires underscored their long-held concern about the fire hazard the proposed transmission line would bring to the backcountry.

Fire officials have said an electric-system failure appears to have started the Witch Creek fire, though a final determination will require further investigation.

“The Sunrise Powerlink would just be another ignition source,” said David Hogan of the Center for Biological Diversity, which opposes the Sunrise project.

Hogan and other critics also said the section of Sunrise from Ramona to the west would likely have been shut down by the fires, keeping the line from delivering power to large population centers.

SDG&E has said the line would ensure electricity reliability in the region, particularly if the Southwest Power Link had to be shut down.

But yesterday's events showed that fires can simultaneously shut down both power lines, said Michael Shames, executive director of the Utility Consumers' Action Network.

Heiser of SDG&E said eastern sections of the Sunrise Powerlink – planned to originate in Imperial County and run across North County – would not have been affected by the fires. State grid officials also said yesterday that larger power lines such as the proposed Sunrise project are less likely to cause fires than smaller local-distribution lines.