Power Outages and Commercial Refrigeration: What to Do

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When the power goes out, every cooler, freezer, prep table and ice machine in the building stops at once. You cannot fix the outage, but you control two things that decide how much food survives it: how often the doors open, and how carefully you track time and temperature. And when the power comes back, how you restart the equipment decides whether you get a second, more expensive problem.

This page is part of our Commercial Refrigeration Help Center. If a single unit has failed and the rest of the building has power, use the cooler or freezer down checklist instead.

The first 15 minutes

1. Note the time. CDPH's first instruction during an outage is to "Document temperature of the food and the time the power outage began." Write it down now, on paper.
2. Take readings. Record each unit's thermometer and probe a few items in each. A battery clock and a paper log keep working when the POS and the tablets do not.
3. Close everything. "Keep all refrigerator/freezer doors closed as much as possible." Tape a sign on the walk-in door if you need to.
4. Cover open cases. For open display cases, CDPH suggests covering them or consolidating product to lessen heat gain. Night covers or blinds help if you have them.
5. Find out how long it may last. Santa Clara County's food-facility flyer lists PG&E's number for outage information, 1-800-743-5002 (Santa Clara County DEH). Knowing whether it is a short fault or a long event changes your plan.
6. Stop cooking for the cooler. Do not put freshly cooked food into units that have no power to cool it.

How long will the food stay cold?

The honest answer is that it depends on the box, how full it is, and how often it is opened, so measure rather than guess. The official figures give a starting point:

The FDA and USDA figures are written for household refrigerators and freezers. A walk-in that is packed full and kept closed may do better; a reach-in on a hot line that staff keep opening will do worse. Your log is what counts.

Deciding what to keep

For restaurants and stores, the decision comes from California's 41°F cold-holding rule and CDPH's outage table, not from the consumer figures above. Under CDPH guidance, refrigerated food that reaches 50°F or above must be discarded, and food held above 41°F for 4 hours or more must be discarded. Food at 42°F to 49°F that has been warm for less than 3 hours must be cooled back to 41°F quickly. If you cannot verify how long product was warm, CDPH says to discard it: "When in doubt, throw it out!"

San Mateo County's guidance adds practical steps: "Write down time when food rises above 41°F," "If food cannot be re-chilled to 41°F within four hours, discard it," and "Check hot foods every hour and cold foods every two hours" (San Mateo County EHS). The full table, refreezing rules by county and the county phone numbers are on our food safety when refrigeration fails page.

County guidance also covers closing. Santa Clara County's flyer says food facilities must be closed when adequate refrigeration cannot be provided, and San Mateo County says to close if food temperatures are unsafe and to call Environmental Health before reopening. Santa Clara County DEH: 408-918-3400. San Mateo County EHS: 650-372-6200.

Keeping product cold without power

• Consolidate. Santa Clara County suggests you "quickly consolidate frozen foods into one freezer." A full box holds cold longer than two half-empty ones. Do the same with high-risk refrigerated items.
• Prioritize. Raw meat, poultry, seafood, dairy and cooked food matter most. Beverages and whole produce can wait.
• Dry ice or ice. Useful for a long outage, but plan it. Handle dry ice with gloves, keep it out of spaces where staff work, and remember CDPH's carbon dioxide caution for enclosed rooms.
• Off-site cold storage. For a long outage, moving product to another location or a rented refrigerated trailer may save more than waiting. Keep logging temperatures during the move.

Generators: useful, but a job for professionals

A standby or portable generator can carry refrigeration through an outage, but sizing is not a guess. Compressors draw several times their running current for a moment at startup, so a generator that runs one condensing unit comfortably can stall when three start together. A licensed electrician should size the generator and install a transfer switch; a refrigeration technician can tell you each unit's electrical load and which circuits matter most. Place portable units outdoors, well away from doors, windows and air intakes, and keep the fuel plan in writing.

Planning ahead for storms and planned shutoffs

Wind storms, wildfire-season Public Safety Power Shutoffs and planned utility work give you some warning. Use it. CDPH recommends having "Calibrated food thermometers, a battery operated clock and a temperature log" ready before an outage. Add:

• A one-page outage plan by the walk-in door: who is in charge, the log sheet, the county phone number, and our number.
• A priority list of what to move first and where it goes.
• Labeled breakers and disconnects for every refrigeration circuit, so staff can find them in the dark.
• A supplier for ice or dry ice, and a plan for off-site cold storage.
• Run inventory low before a scheduled shutoff, and bring freezers to setpoint and full before it starts.

When the power comes back: restart in order

The moment after an outage is hard on equipment. Every compressor in the building tries to start at once, often against high pressures in a warm box, and voltage can sag while the grid recovers.

1. Wait for stable power. If lights flicker or power drops and returns, turn refrigeration off at the disconnects until it settles.
2. Stagger the restarts. Bring units back one at a time, a few minutes apart, starting with the freezers and the walk-in holding the most product. This keeps startup current down and gives each compressor a fair start.
3. Check the controls. Controllers may reboot to default settings. Confirm setpoints and alarms. Mechanical defrost timers lose time during an outage, so reset them to the correct time of day or defrosts may land in the middle of service.
4. Listen and look. A compressor that hums but will not start, a breaker that trips, or a unit that runs but does not cool needs a technician. Do not keep resetting it. Our page on compressor problems explains why.
5. Restart ice machines last, and check that they fill and harvest normally. Any ice made before or during the outage that sat in a warm bin is food, so treat it as such.
6. Confirm pull-down before restocking. Each unit should reach 41°F or below (freezers back to setpoint) before you load product back in. Keep logging for the next day.

After the outage

Keep your log, discard list and any county instructions together. If a compressor or condensing unit failed on restart, a technician will check the electrical side first: contactors, capacitors, overloads and wiring, then refrigerant pressures. Sometimes the right answer is a replacement; our condensing unit replacement page covers that work. For stores with many cases and a rack system, outages are a good reason to review the maintenance plan; see why grocery stores need preventive maintenance.

Book a post-outage refrigeration check

Frequently asked questions

Written and reviewed by Jim McKinny, owner of Cool Aid Air Conditioning & Refrigeration — California C-20 and C-38 licensed, EPA Universal certified, second generation of a family business serving the Bay Area since 1966. Every job we complete is backed by our 1-year parts & labor warranty.