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SAN DIEGO (CNS) – The heat wave roasting California prompted the manager of the state’s power grid to direct San Diego Gas & Electric to initiate rotating outages in San Diego and Orange counties, which lasted less than 90 minutes and affected 58,700 customers.

SDG&E announced at 7 p.m. that the California Independent System Operator had directed it to begin rotating, one-hour service interruptions in San Diego and Orange counties.

The utility company announced on Twitter at 8:20 p.m. that its rotating outages had ended for the night, and all 58,700 customers impacted should have had their power restored.

Cal-ISO, which oversees California’s electrical grid, declared a Stage 3 Emergency for all of California at 8 p.m., initiating rotating outages throughout the state.

“A Stage 3 Emergency is declared when demand outpaces available supply,” Cal-ISO said in a statement. The order was declared after “extreme heat drove up electricity demand across California, causing the ISO to dip into its operating reserves for supply to cover demand.”

“Although a Stage Emergency is a significant inconvenience to those affected by rotating power interruptions, it is preferable to manage an emergency with controlled measures rather than let it cause widespread and more prolonged disruption,” Cal-ISO said.

A Flex Alert was issued earlier in the day, urging residents statewide to conserve electricity between 3 p.m. and 10 p.m. to avoid overloading the power system. But shortly after 5 p.m., demand on the system was so severe that Cal-ISO declared a Stage 2 Emergency.

Residents were being urged to cut back their electricity usage. Cal- ISO offered a series of tips, including:

  • Turning off unnecessary lights;
  • Using major appliances before 3 p.m. and after 10 p.m.;
  • Setting air conditioner thermostats to 78 degrees or higher;
  • Using fans; and
  • Keeping drapes drawn.