Electricity Link Into San Diego Goes Out

Wildfires in San Diego County knocked out a major Southern California electricity transmission line Monday. Authorities warned of possible rolling blackouts, but that threat passed by early evening with the help of heavy power conservation.

The Southwest Power Link, a 500-kilovolt line that brings electricity from Arizona to the San Diego area, tripped out of service about 10 a.m. Monday, eliminating more than 900 megawatts of power imports into Southern California, according to the state’s grid operator. That’s enough electricity to supply more than 675,000 homes.

Several smaller transmission lines blinked on and off all day, complicating efforts to keep electricity flowing to customers of Southern California Edison Co. and San Diego Gas & Electric Co., said Stephanie McCorkle, spokeswoman for the California Independent System Operator, which runs the electricity transmission grid for about 75% of the state.

In addition, two 775-megawatt power plants in Ventura County went offline Sunday, although one of those plants came back Monday, she said.

Authorities said rotating blackouts were avoided Monday largely because of reduced usage, mostly through voluntary conservation but also because fires and evacuations reduced demand from homes and businesses in the affected areas.

Electricity usage peaked shortly before 4 p.m. at 33,666 megawatts statewide, excluding some municipal utilities that are not part of the grid, McCorkle said. She said that was a “fairly mild peak given the temperatures we saw.”

McCorkle also credited close communication between the grid operator and the California Department of Forestry and Fire Prevention, which alerted the energy agency of the movement of various fires. That allowed Cal-ISO to quickly reroute power and activate various power plants to make up for the loss of transmission wires, she said.

SDG&E; customers “helped a lot” by using 15% to 20% less power on Monday, estimated Debra L. Reed, president of Sempra Energy Utilities, which oversees SDG&E; and Southern California Gas Co.

Edison estimated that about 40,000 customers were without power late Monday because of the fires. An additional 4,500 customers in two communities, Forest Falls in San Bernardino County and Idyllwild in Riverside County, had their electricity turned off as a fire-prevention measure.

SDG&E; said more than 50,000 customers had no electricity Monday because of the fires.