Power Outages FAQ

We have identified the circuits available for use in rotating outages according to California Public Utilities Commission rules. A circuit is a set of electrical lines that supply power to a combination of residential and/or commercial customers within a given geographical area. These circuits have been arranged into groups. The amount of power the California Independent System Operator designates for curtailment will determine the number of groups that are interrupted at any one time. The groups will be interrupted, as operating conditions permit, and each outage is expected to last about one hour. At the end of the hour, service will be restored to the affected groups and the next groups on the list will be interrupted to maintain the amount of load requested by the CAISO. Once a group has been used in a rotating outage, it is moved to the bottom of the list.

Most of our circuits are subject to these rotating outages. Only those circuits that serve “Essential Use Customers" who provide critical public health, safety, and security services (such as large hospitals and police stations) are exempted from these outages. All remaining circuits are arranged into groups that represent all customer types (i.e., residential, commercial and industrial) and are dispersed throughout our 50,000-square-mile service area.

Your Rotating Outage Group is located on your bill. Summary Bill customers will find this information in the "Details" portion of their bill. As soon as the California Independent System Operator notifies us of a pending outage, we post the information on our website.

Although they are often used interchangeably in the media, these terms have distinct meanings we use to refer to the curtailment of normal electrical service. "Group" applies to Stage 3 Emergencies (see glossary below) when clusters of customers are subject to rotating outages. Rotating outage groups are designated with a letter and 3 numbers, for example, A001. "Block" is used in relation to our interruptible rate options for large commercial and industrial customers. Customers on these rates receive lower energy and demand charges in return for being interrupted at our request. When a Stage 2 Emergency (see glossary below) is declared, blocks are interrupted to meet the load specified. Blocks are designated with letters only.

To protect your privacy and safety we treat your Rotating Outage Group as confidential information. This practice makes it harder to perform illegal acts such as burglaries when your area is affected by a rotating outage. For the same reason we do not provide Rotating Outage Groups to you for other customers. If you want to stay abreast of the rotating outage status of another customer, such as a relative or your child's school, ask them for their Rotating Outage Group, which they may share at their discretion.

A rotating outage lasts approximately one hour, depending on circumstances.

No. We track the order of the groups of circuits that have been interrupted and rotate among them to ensure that the same group will not always be first and that the impact to any group is minimized. Once a customer group has been restored, it is placed at the end of the list.

Yes. It's possible for neighbors to be on different circuits. Circuits do not necessarily align with streets, neighborhoods, or community boundaries.

The first thing you should do is find out whether your neighbors have electrical service. If neighbors are also without power, call our emergency services at 1-800-611-1911 and we will send a worker out to investigate. If the neighbors do have service, you might have an isolated electrical problem in your home or business.

No. The California Public Utilities Commission rules prohibit utilities from offering any discounts due to emergency situations, including rotating outages.

We cannot guarantee uninterrupted service to any customer; however, we do keep track of all customers who have applied for, and been certified as, "critical care" customers (those who cannot be without electric service for more than 2 hours) pursuant to our Medical Baseline program.

Yes. It is possible that a rotating outage could occur during the night. A Stage 3 Emergency (see glossary below) could occur at any time. We recognize the safety concerns posed by darkened streets and intersections and we encourage everyone to be particularly careful during this time.

Minimize driving in an outage area, if at all possible. Anyone who must drive through a controlled outage area should be particularly careful at intersections controlled by traffic lights, since the lights may not be functioning. These intersections should be treated as four-way stops.

Turn off all appliances, machinery and equipment in use when the power goes out. Leave one light on to indicate when the power has been restored. This will prevent injuries that could occur if machinery and equipment were to suddenly restart. It will also prevent circuits from overloading when power is restored.

Rotating Outage Glossary

The California Independent System Operator (CAISO), the non-profit agency that controls 75% of the state's transmission grid and secures power supplies for most of the state's consumers. The CAISO continually monitors the state's electric system. When a significant imbalance between the supply and demand for electricity occurs, CAISO may issue a Restricted Maintenance Alert, a Warning, or a Stage 1, 2, or 3 Emergency. The conditions for each level of notification are:

Restricted Maintenance: Declared when routine maintenance on transmission lines or power plants could threaten grid reliability.

Alert: Activated one day before. CAISO may require extra resources to avoid electrical emergency.

Warning: Activated an hour ahead of when there may be a shortfall. Requests for conservation issued. Voluntary load reduction programs may be triggered at this point.

Emergency Stage 1: Concern about sustaining required operating reserves between 6% and 7% (Continuously recalculated) stronger request for conservation

Emergency Stage 2: Operating reserves less than 5% Indicates reserves are forecast to be below established criteria and requires ISO intervention in the market

Emergency Stage 3: Spinning reserve portion of operation reserves forecast to fall below 3%. Issue notice of potential load interruptions to utilities

*Transmission Emergencies – Many emergencies are tied to electric supply and operation reserve levels within the balancing authority. However, some emergencies are declared as a result of transmission line overloads, losses, or limitations.

Source: CAISO Alert, Warning and Emergency Notices