San Francisco officials late Thursday revealed why Candlestick Park went dark a second time during Monday night's 49ers game, as PG&E and the city vowed several fixes designed to prevent a blackout during next month's NFL playoffs.

San Francisco Mayor Ed Lee and PG&E CEO Anthony Earley sent separate letters to 49ers CEO Jed York assuring they are on track to fix the problems that caused two blackouts at the stadium during the nationally televised game.

Investigators have known the first outage shortly before kickoff was caused when the main power line that feeds the stadium broke. Now, Lee said an investigation by state utilities officials and city fire inspectors showed the second outage at the beginning of the second quarter was caused by a malfunctioning switch on the stadium's backup power system.

Lee said officials expect to start replacing the switch Friday and should have the work completed by the middle of next week. He said officials will test the new equipment before putting it into use.

Earley, meanwhile, said the utility has discovered the 12,000-volt power line that caused the first outage fell apart because of a failed "splice," the sleeve that holds two ends of overhead wire. Crews already have fixed the line and replaced six other similar splices on nearby power lines as a precaution, he said.

He said the downed line actually caused a brief or flickering outage to 783 homes and businesses, but within a few seconds only Candlestick was left in the dark as the backup lights were "cycling on." Lee said the city is installing upgrades to ensure the backup lights come on quicker in the future.


Advertisement

The outages marred a 20-3 victory by the 49ers over the Pittsburgh Steelers in what was supposed to be a coming-out party for the revamped franchise. After finishing the season on the road, the team is guaranteed at least one home game in the playoffs next month.

Earley said crews are conducting inspections with infrared technology on both the main and backup power sources for the stadium, a strategy designed to detect potential problems before a blackout occurs, and will fix any issues Friday.

PG&E is also running tests on the failed sleeve in its San Ramon lab to figure out why it broke, and along with the city will run tests to ensure the backup system works. The utility is installing equipment to get real-time data on the electrical system serving the stadium.

"We are completely confident that these measures will keep PG&E's equipment at the stadium operating safely and reliably as the 49ers advance to the playoffs," Earley said.

Contact Mike Rosenberg at 408-920-5705.