What is a Flex Alert?

A Flex Alert is a call for consumers to voluntarily conserve electricity when there is an anticipated shortage of energy supply, especially if the California Independent Operator (ISO) needs to use reserves to maintain grid integrity. When Californians reduce electricity use during a Flex Alert, it can prevent more dire emergency measures, including rotating power outages.

Who issues a Flex Alert?

A Flex Alert is issued by the California ISO, a nonprofit, public benefit corporation, which manages the flow of electricity along the high-voltage electric grid for 80 percent of California. The state’s three investor-owned utilities, Pacific Gas & Electric, San Diego Gas & Electric, and Southern California Edison, are responsible for delivering electricity from the high-voltage grid to its customers. Learn more about the California ISO.

What can trigger a Flex Alert?

A Flex Alert is typically issued in the summer when extremely hot weather drives up electricity use, making the available power supply scarce. Flex Alerts are typically issued from 4 p.m. to 9 p.m. when solar generation is rolling off the system, but temperatures remain high and consumers are using air conditioners, lights, and appliances.

Other contributing factors include:

  • Unplanned power plant outages
  • Fires that threaten or affect transmission lines
  • Humid, hot weather and heat storms

When is a Flex Alert issued?

Flex Alerts are typically issued a day before it is needed, so consumers can prepare. However, grid emergencies can happen suddenly, prompting the ISO to issue a Flex Alert will little or no advance notice. When possible Flex Alerts are targeted to regions of the state where the system is stressed.

What should consumers do when a Flex Alert is issued?

During a Flex Alert, consumers can reduce stress on the power grid by shifting energy use to the morning and early afternoon hours.

On the morning of a Flex Alert, consumers should:

  • Pre-cool their homes by lowering air conditioning thermostats to 72 degrees
  • Close blinds and drapes to keep the sun from heating up the home
  • Turn off unnecessary lights
  • Use dishwashers, washing machines and other major appliances
  • Set pool pumps to run early in the morning
  • Charge mobile devices and laptops
  • Pre-cook meals

During a Flex Alert, when conservation is needed, consumers should:

  • Set air conditioner thermostats to 78 degrees or higher, if health permits
  • Avoid using dishwashers, washers, dryers, and ovens
  • Turn off unnecessary lights
  • Unplug or turn off electrical devices not in use
  • Keep blinds and drapes closed to prevent the sun from heating up the home
  • Use fans when possible