As private and public sector utilities scrambled to adjust power flows around transmission corridors threatened by a series of brush fires in Southern California last week, the California Independent System Operator (CAISO) reported a peak demand record for the third straight day on Wednesday, hitting 44,360 MW.

Mirroring what utilities were reporting from the current electricity power system constraints in Arizona where customer response has been a key, Southern California Edison Co. reported late Wednesday that it initiated some of its voluntary load response programs to reduce demand on its grid by 327 MW which, along with conservation by other customers, alleviated an emergency situation. Transmission lines lost Tuesday to fires in the far northwest end of Los Angeles County were back in service by Wednesday afternoon, but the fires continued to be watched closely, an Edison spokesperson said.

Edison and its neighboring public sector utility, the Los Angeles Department of Water and Power (LADWP), urged customers generally to cutback their usage, particularly in the noon-to-7 p.m. peak demand time.

“The reliability of our system has been incredible,” said LADWP’s communications director, Randy Howard, despite the fires’ proximity to three of the city-run utility’s 500-kV transmission lines. Howard said LADWP reduced its loading on the threatened lines by about 50% as a precaution if the fires move in their direction. On Wednesday the lines operated at reduced capacity, and the utility did what Howard called “a swap” with ScottishPower’s PacifiCorp operations in Utah, bringing in added power from the northwest and letting PacifiCorp take some of LADWP’s supplies from Utah-based Intermountain.

The ongoing daily problems in Arizona caused by a major transmission substation fire northwest of Phoenix earlier this month don’t affect LADWP, although they cut short the state’s (CAISO’s) overall back-up power safety net in the event a lot of unplanned outages hit generating plants in California (see related story).

From the fires over the weekend, Howard said that LADWP still has one transmission line in its northern most region “on the ground.” That is a 115-kV line out of a pumped storage hydro facility tied to the California Aqueduct. “It is going to take us about another week to get in and get the repairs completed,” he said.

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