By Laura Haefeli

SACRAMENTO (CBS13) — For the first time since 2001, the California Independent System Operator (ISO) declared a statewide Stage 3 emergency Friday evening due to high electricity use in excessive heat.

The agency said the heat was driving up electricity use and putting a strain on the power grid, so they initiated rotating power outages to maintain grid stability. It was the first time since 2001 that the area was hit by rolling blackouts

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ISO canceled the alert around 9 p.m., ending the rotating power outages that affected more than 240,000 Northern California customers. PG&E said power should be restored to the impacted customers by 11 p.m.

Power outages around 8:30 p.m. Friday. (source: Cal OES)

Following the Stage 3 order around 7 p.m., tens of thousands of customers in El Dorado County were experiencing blackouts. Much of the Bay Area, from San Jose to Vallejo, also lost power.

You can find statewide power outage data here

“This is happening because it’s hot,” ISO spokesperson Anne Gonzales said. “The excessive heat is causing people to use their air conditioning and when they use the air conditioning, the electricity demand goes up.“

All of the businesses in El Dorado Town Center lost power.

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“It got hot fast,” David Arbogast in El Dorado Hills said.

He’s one of the hundreds of thousands of people who lost power without warning. Officials say the demand for power quickly exceeded California’s own supply and what was available from neighboring states Friday.

“The nature of this heat wave is it’s causing record-breaking heat in the entire western United States, so it’s hampering our ability to get imports, especially from the Southwest,” Gonzales said.

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ISO is asking people to do their part and conserve energy until the heat wave is over.

SMUD and Roseville Power are not connected to ISO, so their customers were not impacted by the power outages. A SMUD spokesperson told CBS13 their grid did not experience any problems Friday.

The ISO has three stages of emergency alerts.  The first stage is declared when contingency reserve shortfalls exist or are forecasted to occur. Stage 2, which was declared Friday afternoon, happens when “The ISO has taken all mitigating actions and is no longer able to provide its expected energy requirements.”

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Stage 3, which was declared Friday evening is when the ISO is “unable to meet minimum contingency reserve requirements, and load interruption is imminent or in progress.” During this stage, the ISO said there will be rotating power outages.