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High-voltage transmission lines and towers in the Los Angeles area, pictured during a heat wave in July 2018.  Frederic J. Brown/AFP-Getty Images
High-voltage transmission lines and towers in the Los Angeles area, pictured during a heat wave in July 2018.  (Frederic J. Brown/AFP-Getty Images)

Wildfire-Driven Power Blackouts: Coming This Year to a Community Near You?

Wildfire-Driven Power Blackouts: Coming This Year to a Community Near You?

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Updated Sept. 24, 2019


he California Public Utilities Commission has adopted an expanded set of rules aimed at clarifying when the state's big utilities can shut off power during times of high fire danger and what they need to do before they turn out your lights.

The commission voted unanimously in late May to approve the guidelines — detailed in a 118-page decision. The five-membrer panel also approved the utilities' first-ever wildfire mitigation plans.

The power shutoffs — a practice the regulatory world calls de-energization — have been used sparingly in the past as a tool to reduce the risk of electrical equipment touching off fires during exceedingly windy, dry, hot weather. The shutdowns are a technique pioneered by San Diego Gas and Electric Co. after its power lines ignited 2007's Witch Fire, which killed two people and destroyed 1,100 homes.

Here are questions and answers on how the public safety power shutoffs work and what the CPUC's new guidelines will mean for utility customers.


Who makes the decision to shut off power?

The decision rests solely in the hands of California's three investor-owned utilities: PG&E, Southern California Edison and San Diego Gas and Electric. To assist in making the decision, each utility now maintains a special command center -- PG&E's is called a wildfire safety operations center -- to assess weather data and reports from field personnel and begin the process of deciding when and where a power shutoff might be necessary. The emergency operations centers typically include engineering, safety and communications personnel.


What conditions could prompt a public safety power shutoff?

There is no one standard for the three utilities that have been directed to develop shutoff plans. But the factors the utilities use involve an assessment of upcoming weather — a National Weather Service red-flag fire warning for hot, dry, windy weather, for instance — and conditions on the ground — such as topography and the moisture content of grass, brush and trees in areas the CPUC has identified as being at high risk for wildfires.

Below is one example: SDG&E's list of factors considered in shutting down power during a period of dangerous fire weather last November. Among them: a red-flag warning coupled with a warning of winds gusting up to 70 mph.


How do public safety power shutoffs affect people with disabilities and other vulnerable populations?

Advocates for those with disabilities have pointed out for years -- in cases involving San Diego Gas and Electric, which began pre-emptive power shutoffs in 2013 -- that their clients face a potentially life-threatening situation if their electricity is turned off. In a declaration filed in PG&E's federal probation case earlier this year, Melissa Kasnitz, an attorney for Berkeley's Center for Accessible Technology, summarized the dangers:

"Some people will lose access to medical equipment necessary for health and safety, such as home dialysis machines, nebulizers, or respirators. Some will lose the ability to power equipment they rely on for mobility, such as power wheelchairs. Some will face health risks if they lose the ability to regulate the temperature or environment in their homes. Some will lose access to vital (and expensive) medication if they lose access to refrigeration."

While the CPUC's de-energization decision recognizes the issue, it focuses on identifying and educating vulnerable individuals and making sure they're notified in the event a power shutoff is imminent. The guidelines stop short of calling for steps to aid those who lose the use of medical equipment, saying that utilities should partner "with community-based organizations and other entities to develop plans in advance to ensure that needs can be met in the event of a power loss."


Are there other major objections to the public safety power shutoffs?

The principal concern, voiced by the CPUC itself and many parties who have commented on its new rules, centers on the potential impact to public safety when power is cut off. A blackout would likely disable traffic signals and could interrupt the supply of electricity to police and fire stations. A loss of power could disrupt public water systems needed to fight fires and play havoc with emergency responders' radio communications.

The CPUC's response has been to focus on identifying the full range of potential impacts and developing communication strategies so that all the agencies that might be affected by a power outage know well in advance and have developed contingency plans for the blackout period. Longer term, the commission is encouraging adoption of technology that will limit the extent of outages by allowing utilities to precisely target the areas where shutoffs may be needed.


How will I find out if my utility is considering turning off the power because of extreme fire weather?

Your utility has the primary responsibility for alerting emergency responders, other public safety-related agencies, local governments and customers that it is considering a public safety power shutoff. Under the CPUC's new guidelines, the utilities will be required to give emergency responders and other high-priority groups and agencies between 48 and 72 hours' notice that a shutdown is under consideration. The companies will need to give 24 to 48 hours' warning to everyone else, including customers. The guidelines also require follow-up messages within one to four hours of a shutdown, when it's occurring and again when the process of restoring power is underway.

Online resources for each of the major utilities shutoff programs:


Have past power shutoffs been effective in preventing wildfires?

It's hard to give a definitive answer, but the most persuasive evidence that de-energizing power lines may be effective in preventing catastrophic wildfires comes from San Diego Gas and Electric. According to data the company provided to the CPUC, its power facilities were involved in starting 175 fires from 2013 through 2018. Of those fires, just three were larger than 10 acres.


Lawyers who have sued PG&E on behalf of Northern California wildfire victims have pointed out that the San Francisco-based utility's equipment started 1,552 fires in a shorter time frame -- 2014 through 2017 -- with 68 of those blazes growing to larger than 10 acres. (PG&E has challenged the comparison, noting that its service area is 17 times larger than SDG&E's and that its distribution and transmission line mileage is five times larger than that maintained by the San Diego utility.)

Bottom line: The CPUC's decision declares that pre=emptive power shutdowns "can save lives" if coupled with tougher measures to keep trees and other vegetation away from electrical lines.

PG&E transmission lines like these in South San Francisco could be shut down during periods of extreme fire danger. (Justin Sullivan/Getty Images)


How many people could lose electricity in a public safety power shutoff?

In the past, power shutoffs have involved utilities' local distribution circuits and have affected relatively small areas. San Diego Gas and Electric has conducted the most shutoffs. Six of the nine shutdowns the company has conducted since 2017 have involved fewer than 1,000 customers. SDG&E's largest shutoff, last November, involved about 25,000.

When PG&E decided to pre-emptively shut down lines last Oct. 14, it targeted about 40 distribution circuits spread across Napa, Sonoma, Lake, El Dorado, Placer, Amador and Calaveras counties. The number of customers on each circuit varied from as few as 14 up to about 5,200, and about 60,000 customers in all lost power -- which stands as the single-largest public safety power shutoff in California to date.

However, the limited size of shutdowns could change this year, with PG&E announcing it will consider shutting down high-voltage transmission lines like the one in Butte County that touched off last November's Camp Fire. In filing its state-mandated wildfire mitigation plan earlier this year, PG&E said de-energizing transmission lines could mean a loss of power anywhere in it 70,000-square-mile service area -- even for cities like San Francisco and San Jose that face no immediate wildfire threat. Such a shutdown could also affect factories, airports and other facilities served directly by transmission lines.

The CPUC's decision says that in the event a transmission line shutoff is being considered, utilities must inform the California Independent System Operator, which manages the state's grid, as soon as possible. The power companies must also coordinate with regional and national agencies that provide grid reliability.


If there's a public safety power shutoff, how long will I be without electricity?

San Diego Gas and Electric, the utility that has the most experience with power shutoffs, says blackouts in its service area have lasted from one minute -- you read that right: 60 seconds -- to six full days. A review of its biggest shutdown to date, which took place last November, shows that most of the 25,000 or so affected customers lost power for 30 to 48 hours; one circuit, with about 1,400 customers, was out for four days.

In PG&E's power shutdown last October, most of the 60,000 affected customers appear to have had the lights back on within 24 to 30 hours. Some were in the dark for a little more than two days.

The main reason for delays in restoring power comes from continuing dangerous fire conditions and the need for crews to inspect lines for damage and complete repairs when necessary.


All the food in my fridge spoiled because of a public safety power shutoff. Will the utilities pay?

Here is another "that depends" answer. San Diego Gas and Electric has a claims procedure and received 300 reports of losses in its November 2018 shutdown. About 220 of the claims were for food spoiled because of loss of refrigeration.

PG&E reported receiving 146 claims after its October 2018 shutoff -- again, mostly for food losses. The company remarks in its report: "PG&E has stated publicly that because of the safety-related nature of (public safety power shutoff) events, customers will not be reimbursed for associated losses."


What changes are being considered in the way public safety power shutoffs are conducted?

The California Public Utilities Commission is due to review this year's shutoffs and hear comment from the utilities, emergency operations officials, first responders and business and residential customers – among other stakeholders – about how the pre-emptive blackouts could be refined.

The Legislature is likely to at least try to make its voice heard, too. State Sen. Scott Wiener, D-San Francisco, has introduced a bill for the next session that would impose new rules on how the shutoffs are handled.

Responding to concerns from both large and small businesses and public officials like San Jose Mayor Sam Liccardo about the disruptive effects of pre-emptive blackouts, Wiener's bill would require utilities to compensate customers and local governments for costs incurrred during the outages. The bill would also impose fines for every hour a public safety power shutoff is in place – a measure designed to ensure the utilities impose then only when necessary and not a step meant to avoid potential liability.

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