What Is a PSPS — and Why It Is Not a Normal Outage#
A Public Safety Power Shutoff (PSPS) is a deliberate de-energization of power lines ordered by utilities — primarily PG&E — when extreme fire weather conditions create an unacceptable ignition risk. Unlike a storm-caused outage that ends when crews restore a damaged line, PSPS events are held until weather conditions improve and crews can safely inspect every mile of transmission line before re-energizing.
The CPUC's PSPS framework requires utilities to notify affected customers 24 to 48 hours in advance and to provide medical baseline customers with 72 hours of notice. PG&E's shutoff criteria include Red Flag Warnings issued by the National Weather Service, forecast wind speeds exceeding 25–45 mph depending on terrain, relative humidity below 20%, and critically dry fuel moisture in vegetation.
For businesses, the critical distinction is duration. PSPS events routinely last 48 to 96 hours. Planning for a 4-hour inconvenience and getting hit with a 72-hour shutdown is a common and expensive mistake.
How PSPS Affects Different Business Types#
Restaurants and Food Service#
Food spoilage is the most immediate risk. A walk-in refrigerator without power will hold safe temperatures for approximately 4 hours; a freezer for up to 48 hours if unopened. An extended PSPS easily exceeds those windows.
Quantifying the exposure:
- Food inventory loss: $3,000–$8,000 for a typical sit-down restaurant per 72-hour event
- Lost revenue: $5,000–$25,000 per weekend closure, depending on size and season
- Reputational impact: guest reviews referencing a powerless kitchen follow a property for months
For restaurants in Sonoma, Napa, Lake, or Nevada counties — areas within PG&E's highest-frequency PSPS zones — 2–4 events per fire season is a reasonable planning assumption based on 2018–2025 historical patterns.
Hotels and Hospitality Properties#
A boutique hotel with 20 rooms at $300/night loses $6,000 per day — before accounting for cancelled future bookings from guests who remember the experience. Beyond revenue, guest safety obligations include maintaining emergency lighting, fire alarms, and in many cases, elevator service.
Larger properties also face liability questions: a guest who cannot safely exit a dark stairwell during a medical emergency creates exposure that exceeds the cost of a properly sized backup power system many times over.
Professional Services and Medical Offices#
Medical offices, dental practices, and pharmacies face regulatory requirements that make power loss a compliance issue, not merely an inconvenience. Refrigerated medications (insulin, vaccines, biologics) must be maintained within temperature ranges specified by each manufacturer. California Board of Pharmacy regulations require documented temperature excursion investigations for any deviation — and may require disposal of affected stock.
For a dental practice with 6 operatories, a single cancelled business day represents $6,000–$12,000 in lost production at typical production rates.
Sizing a Generator for Your Business#
The right generator size depends on which loads you need to protect. A tiered approach — covering only what is critical versus restoring full operations — has a significant impact on both capital cost and installation complexity.
| Coverage Level | Typical Loads | Approximate Size |
|---|---|---|
| Critical only | Refrigeration, emergency lighting, POS systems, communications | 20–45 kW |
| Essential operations | Above + HVAC, kitchen equipment, office systems | 60–100 kW |
| Full facility | All circuits | 125–500 kW+ |
For most small businesses, the critical-loads tier protects perishable inventory, allows limited operations, and maintains guest or customer safety — at a fraction of the cost of full-facility backup. Use the generator sizing calculator to estimate your specific load requirements, or consult with our team for a load study.
The generator sizing process should start with an electrical load inventory: list every piece of equipment, its nameplate amperage, and whether it is a continuous or starting load. HVAC compressors and commercial kitchen equipment carry high starting currents — typically 2–4 times running current — that must be accounted for in generator and transfer switch sizing.
Automatic Transfer Switches and Control Strategy#
A generator without an automatic transfer switch (ATS) requires someone on-site to start the generator and manually connect loads when the utility drops out. For PSPS events — which typically begin between 9 PM and 4 AM — this is an unreliable strategy.
An ATS senses utility voltage loss within 1–3 seconds and automatically starts the generator and transfers load in 10–30 seconds without human intervention. When utility power returns, the ATS retransfers loads and shuts down the generator after a cool-down period.
For small business installations, a transfer switch rated for 100–400A is typical, matched to the building's main electrical service. Generator dealers should specify the ATS to match the generator's output and the service entrance configuration — mismatched transfer equipment is one of the most common causes of installation cost overruns.
If you are protecting refrigeration circuits only, a manual transfer panel with a portable generator connection can serve as a low-cost interim solution while a permanent system is planned — but it requires someone to operate it and carries personnel safety risks if not done correctly.
Fuel Planning: Natural Gas vs. Diesel for PSPS#
Fuel choice has material consequences for PSPS resilience.
Natural gas draws from the utility distribution system, which remains pressurized during power outages. You will not exhaust fuel during a 72-hour PSPS regardless of load — as long as the gas distribution infrastructure is intact (it almost always is during PSPS events, which are electrical shutoffs, not gas system events). Natural gas is the preferred fuel for facilities in urban and suburban areas with gas service.
Diesel stores fuel on-site, independent of any utility. A 500-gallon aboveground tank running a 60 kW generator at 60% load provides approximately 60–80 hours of runtime. For multi-day events, fuel delivery logistics become a variable — demand spikes during widespread PSPS events can delay scheduled deliveries. Plan contracts with a priority delivery clause, and keep tanks at minimum 75% full entering September each year.
Propane is common in rural areas without natural gas service. Runtime is comparable to diesel for the same tank capacity, and propane does not degrade in storage the way diesel does. Size for at least 96 hours of runtime at expected load.
Pre-Season Readiness Checklist#
Complete the following each August, before fire season peaks in Northern California:
- Run a full load bank test to confirm the generator can carry 100% rated load
- Verify ATS transfer time and retransfer timing meet specification
- Check coolant concentration (summer heat stresses cooling systems; maintain 50/50 antifreeze/water)
- Inspect and test starter batteries under load — replace if more than 3 years old or if load test fails
- Check fuel level and fuel quality — diesel older than 12 months should be polished or replaced
- Review automatic exerciser schedule — NFPA 110 requires monthly runs of at least 30 minutes under load
- Confirm your facility is registered in PG&E's Medical Baseline or Critical Facility programs if applicable
- Verify contact information in PG&E's PSPS notification system
Taking the Next Step#
If your business has not yet invested in backup power, the most important first step is a load study. Understanding what you need to protect — and what you can do without — determines whether the right solution is a $15,000 standby installation or a $75,000 full-facility system.
Contact our team for a site assessment, or explore generator purchase options for businesses across the Bay Area and Northern California.