(Adds detail, including no damage assessment yet)
LOS ANGELES Oct 23 (Reuters) - The Southwest Powerlink that feeds power from Arizona into San Diego County is expected to be back in service as soon as Wednesday, said its owner, Sempra International (SRE.N) unit San Diego Gas & Electric Co.
A more precise timing of the return of the key line and an assessment of damage can't be known until wildfires diminish, SDG&E said.
The 500-kilovolt transmission line is one of two major transmission corridors bringing power into San Diego and the rest of the SDG&E service territory in San Diego County and southern Orange County.
SDG&E pleaded with customers on Tuesday to make significant cuts to electricity use because the amount of power available to the utility is only 60 percent of the normal capacity, said SDG&E spokeswoman Stephanie Donovan.
The north-south major transmission corridor that brings power into San Diego was operating Tuesday but was under threat of damage by fires in Orange and San Diego counties, Donovan said. This corridor connects with the Southern California Edison system near the San Onofre Nuclear Generating Station (SONGS), which is in northern San Diego County.
With the Southwest Powerlink out of service since Sunday as a precaution against wildfires, some internal transmission lines shut and the north-south lines at diminished capacity, SDG&E has only 60 percent of its usual electricity supply.
About 30 miles of the Southwest Powerlink has been affected by the fires, Donovan said. It was shut on Sunday to protect firefighters and protect it from damage.
Once the fires diminish to the point that SDG&E workers can approach the lines, damage assessments will be conducted. Then, with the high amount of ash and fire retardant on the lines, they will have to be cleaned before power can flow, said Donovan said.
The Sunrise Powerlink brings power from the biggest nuclear power plant in the United States, the 3,850-megawatt Palo Verde plant west of Phoenix.