LOS ANGELES (AP) - Sweltering late-summer heat and the loss of key transmission lines Thursday forced power officials in Southern California to impose rolling blackouts, leaving as many as half a million people without power for an hour at a time, officials said. The California Independent System Operator, which operates the state's electric grid, declared a transmission emergency at 3:57 p.m., said Gil Alexander, a spokesman for SoCal Edison.
It marked one of the most serious power emergencies since the 2002 power crisis.
"It's not related to operating reserves. It is a transmission emergency," said ISO spokeswoman Stephanie McCorkle.
The situation was exacerbated by the sudden loss of key transmission lines from the Pacific Northwest, Alexander said.
The ISO ordered Edison to reduce demand throughout its territory, prompting initial blackouts in areas of Fontana, La Puente, Cathedral City, Huntington Beach, Long Beach and Ontario, Alexander said.
The utility scattered the outages to lessen the impact in any one place. Blackouts were expected to last about an hour before being shifted to other areas.
Higher-than-expected temperatures in 11 counties served by Edison created increased demand of about 1,500 megawatts, and the emergency order from the ISO caused Edison to reduce demand by 800 megawatts throughout its territory. A megawatt is enough power to serve about 750 homes.
In downtown Los Angeles, temperatures spiked at 94 degrees Thursday.
SoCal Edison has about 13 million customers in more than 400 Southern California cities and communities.
Northern California was not affected by the shutdowns.
