The San Francisco Bay Area on Tuesday suffered a power blackout that forced Web and electronic-commerce companies onto backup systems for six hours.
Pacific Gas and Electric said power was out to 375,000 residential and commercial customers from in and around San Francisco. The utility company estimated that roughly 938,000 people were affected by the outage, which was blamed on human error.
The utility said the outage, which occurred about 8:15 a.m. originated at PG&E's San Mateo substation, approximately 20 miles south of San Francisco. Full restoration of power was completed by 2:15 p.m., the utility said.
"The cause of the outage was simple human error, which then triggered a complex sequence of events," PG&E said in a statement posted on its Web site.
The power system detected a switching surge and was tripped off as a safety measure, PG&E said, and the system had to be restored gradually, circuit-by-circuit.
Best Internet Communications, located in the heart of the city's South of Market district, was affected by the outage but still able to serve pages.
"We have a diesel generator out there in the garage," said Dylan McClintock, a network service engineer for Best Internet. "It's loud and smelly."
McClintock said his company, which hosts Web servers for about 70 Internet companies, has about 72 hours of backup power.
Other areas of the Bay Area were reportedly unaffected.
"We are fine right here," said Tim Mather, manager of security for Verisign, a digital certificate company based in Mountain View. "I just walked in the back door and the generator is not on."
Excite and At Home, both located in Redwood City, were unaffected by the blackout. Yahoo, located in neighboring Santa Clara, said it did not lose power.
Pacific Bell Internet said the company had backup email systems in San Francisco, San Diego, Los Angeles, and elsewhere so others were prepared to pick up the slack if one of its mail systems went down.
San Francisco International Airport had a total power failure and was running on generators, according to radio station KGO. More than a dozen flights into SFO were diverted to other airports, and as many as 40 outgoing flights were delayed.
The Bay Area Rapid Transit System lost 17 of its 57 trains. BART had the power to get the trains into the stations, so no one was trapped in the transbay tunnel that links San Francisco with the East Bay.
Power was reportedly out at the Pacific Coast Stock Exchange as well. The traders were out the street playing football.
