Edison International, owner of the Southern California Edison utility, said about 5,000 customers lost power after an earthquake hit Southern California just before noon July 29.
Residents in Ventura and Santa Barbara felt the 5.4 quake, but no injuries or serious damage was reported.
Some Edison customers east of Los Angeles in Chino, Chino Hills, Diamond Bar and Pomona were affected, said Paul Klein, a spokesman for Rosemead-based Edison.
The quake struck at 11:42 a.m., the U.S. Geological Survey said, in the Chino Hills area, about 40 miles east of downtown Los Angeles.