PSPS stands for Public Safety Power Shutoff, a protocol where electric utilities deliberately turn off power to specific areas to prevent wildfires. When strong winds, extreme heat, and dry conditions create dangerous fire weather, power lines can spark fires if they’re knocked down or contact vegetation. Rather than risk a catastrophic wildfire, utilities proactively cut electricity to the areas most at risk until conditions improve.
Why Utilities Shut Off Power
Most wildfires linked to power infrastructure start the same way: high winds knock over a power line or blow tree branches into electrical equipment, creating sparks that ignite dry vegetation. PSPS exists as a last resort to break that chain. By de-energizing power lines before the worst winds arrive, utilities eliminate the ignition source entirely.
The practice is most closely associated with California, where six investor-owned utilities have authority to initiate shutoffs: Pacific Gas and Electric (PG&E), Southern California Edison, San Diego Gas & Electric, Liberty Utilities, Bear Valley Electric Service, and PacifiCorp. The California Public Utilities Commission oversees these events. Other states with high wildfire risk have adopted similar protocols, but California’s program is by far the largest and most established.
What Triggers a Shutoff
Utilities don’t flip the switch based on a single weather reading. They use a combination of factors, including a Fire Potential Index (FPI) that scores conditions on a scale of 1 to 17. Scores of 12 to 14 are considered elevated, and anything above 15 is extreme. Southern California Edison, for example, generally activates shutoff protocols when the FPI hits 13 for most areas, though it drops to 12 in coastal regions or when regional fire preparedness levels are already high.
Wind speed is the other major trigger. Utilities typically set thresholds around 31 mph sustained winds with 46 mph gusts, which aligns with National Weather Service wind advisory levels. Power lines that have been upgraded with insulated coverings get a higher threshold of 40 mph sustained and 58 mph gusts, since they’re more resistant to sparking on contact. During large-scale weather events when many circuits are at risk simultaneously, utilities may lower these thresholds and shut off power at even milder wind speeds as a precaution.
Each electrical circuit has its own activation threshold based on the specific terrain, vegetation, and historical wind patterns in that area. A hilltop circuit running through dense chaparral will have a lower trigger point than one crossing open terrain at lower elevation.
What Happens During a PSPS Event
Utilities are required to notify affected customers before a shutoff begins. Notifications typically go out in waves, starting about 48 to 72 hours before the anticipated event, then again closer to the shutoff time. You’ll receive alerts by phone call, text, and email if your contact information is on file with your utility.
Once power is cut, it stays off for the duration of the dangerous weather, which can range from several hours to multiple days. After conditions improve, utility crews physically inspect every mile of de-energized power line before restoring electricity, checking for downed lines, damaged equipment, and vegetation contact. This inspection process means power often stays off for hours after the weather clears.
Resources for Affected Residents
During active shutoffs, utilities open Community Resource Centers in affected areas. These provide air-conditioned spaces with power strips for charging phones and laptops, Wi-Fi access, bottled water, restrooms, and up-to-date information about the event timeline and restoration estimates. Utility representatives are on-site to answer questions.
People who rely on electricity for medical equipment get extra protections through Medical Baseline programs. If you use a CPAP machine, respirator, dialysis machine, motorized wheelchair, or similar device, enrolling in your utility’s Medical Baseline program provides additional notifications before shutoffs, including extra phone calls and doorbell rings. PG&E, for example, offers backup power support to qualifying Medical Baseline customers to keep medical devices running during outages. Local services like 211.org can connect residents with food replacement, transportation, and other support during extended shutoffs.
How Utilities Are Reducing Future Shutoffs
PSPS events are disruptive and unpopular, and utilities are investing heavily in infrastructure upgrades designed to shrink the scope and frequency of future shutoffs. The main strategies fall into three categories, each with very different costs and effectiveness.
The most cost-effective approach is replacing bare overhead wires with insulated (covered) conductors and swapping wooden poles for fire-resistant metal ones. This costs roughly $480,000 per mile and reduces fire risk by about 60% compared to burying the lines, making it the best bang for the dollar. It also raises the wind speed threshold needed to trigger a shutoff, meaning fewer customers lose power during moderate events.
Burying power lines underground eliminates fire risk from those lines almost entirely, but it’s expensive. Underground conversion runs about $3 million per mile, roughly seven times more than installing covered conductors. San Diego Gas & Electric has a dedicated undergrounding program focused on its highest fire-threat areas, while other utilities use it selectively where the risk justifies the cost.
Simply replacing old wires and poles with conventional materials costs around $300,000 per mile but only reduces fire risk by about 15%, making it largely ineffective as a wildfire mitigation strategy. It serves mostly as a baseline comparison for evaluating the other options.
As these upgrades spread across high-risk areas, the number of customers affected by any single PSPS event is expected to decrease. But the protocol itself will likely remain in place as a last line of defense for sections of the grid that haven’t yet been hardened.