How to Keep Food Safe During a Power Cut

When the power goes off, keep the fridge and freezer doors closed and note the time. A closed fridge should keep food cold for up to four hours. Food in a full freezer may remain frozen for up to 48 hours, while a half-full freezer may manage about 24 hours. These freezer timings are estimates, not guarantees.

According to the Food Standards Agency’s power-cut guidance, an outage lasting less than four hours is unlikely to affect the safety of correctly stored chilled or frozen food. Longer outages require decisions based on temperature, time, the type of food and whether the appliance remained closed.

How long will food stay safe during a power cut?

Storage area	Estimated safe period	Important condition
Fridge	Up to 4 hours	Door kept closed as much as possible
Full freezer	Up to 48 hours	Door kept closed and freezer was working normally before the cut
Half-full freezer	About 24 hours	Door kept closed and freezer was working normally before the cut
Chilled food at 8°C or above	Use within 4 hours of reaching this temperature	Discard affected high-risk food after that period

The actual time can be shorter. Appliance design, room temperature, how full the freezer is, the starting temperature and how often the door is opened all make a difference. A freezer in a hot kitchen will warm faster than one in a cool utility room.

A fridge should normally operate between 0°C and 5°C. During a power cut, chilled food can remain stored while the temperature is below 8°C. If it reaches 8°C or above, food that normally requires refrigeration should be eaten within four hours or discarded.

What to do as soon as the electricity goes off

1. Write down the time. Do not rely on remembering when the outage began, especially if it continues overnight.
2. Close the fridge and freezer. Do not repeatedly open them to inspect the food or let children browse for snacks.
3. Check the outage. Look for an estimated restoration time from the electricity network operator. In England, Scotland and Wales, power cuts can be reported through 105.
4. Turn off cooking appliances. Make sure electric hobs, ovens, air fryers and other heating appliances will not restart unexpectedly when power returns.
5. Find your fridge thermometer. A thermometer gives better evidence than touching food or guessing from the length of the outage.
6. Plan one deliberate opening. If food must be removed, decide what is needed first so the door is open for the shortest possible time.

If the outage is expected to last only an hour or two, leaving everything closed is generally more useful than transferring food into cool boxes. Opening a cold freezer unnecessarily releases the cold air you are trying to preserve.

Which food should you eat first?

For a prolonged outage, use food in an order that protects the items most likely to become unsafe while preserving shelf-stable supplies for later.

1. Food that requires refrigeration: chilled meat, poultry, fish, dairy products, prepared salads, sandwiches, cooked meals and leftovers.
2. Defrosted frozen food that does not require cooking: provided it has remained at a safe chilled temperature.
3. Room-temperature perishable food: bread, fresh fruit and similar short-life items.
4. Tinned, bottled and dried food: preserve these longer-lasting supplies until the more perishable food has been used safely.

Do not attempt to save more refrigerated food than the household can safely eat. Cooking a large quantity is not helpful if there is no reliable way to cool and store the leftovers afterwards.

A planned supply of food that can be eaten without refrigeration or cooking makes this decision easier. See our guide to emergency food storage for UK homes for suitable cupboard foods and stock-rotation advice.

How to decide whether refrigerated food is safe

Use temperature and elapsed time wherever possible. The foods requiring the most caution include:

• Raw or cooked meat, poultry and fish.
• Cooked meals and leftovers.
• Milk, cream and many soft dairy products.
• Pre-packed sandwiches, prepared salads and deli meats.
• Products marked with a use-by date or instructions to keep refrigerated.
• Opened jars, sauces and other products that require refrigeration after opening.

A use-by date relates to safety. A best-before date primarily relates to quality. Food can become unsafe before its use-by date if it has not been kept at the required temperature, so an in-date label does not override the power-cut temperature rules.

Do not rely on smell to declare high-risk food safe. Harmful bacteria may be present without producing an obvious smell, taste or visible change. The GOV.UK guide to use-by and best-before dates reserves sensory checks for foods carrying a best-before date, where the issue is normally quality rather than safety.

How to protect frozen food

Keep the freezer closed. A full freezer retains its temperature longer because the frozen contents act as thermal mass. A half-empty freezer contains more air that can warm rapidly when the door is opened.

Before an outage, empty space can be filled with securely closed containers of frozen water or freezer packs. Leave enough expansion space in any container holding water. Grouping frozen items and keeping an inventory on the door can also reduce the time spent searching.

When power returns, deal with thawed food carefully:

• Food that is still hard frozen can remain in the freezer once it has returned to its normal operating temperature.
• Fully defrosted food should be treated as chilled food and retained only if you know it stayed at a safe temperature.
• Food safely defrosted under chilled conditions should normally be used within 24 hours, subject to its label instructions.
• Defrosted raw food may be frozen again after it has been cooked safely, but unsafe food cannot be rescued by cooking or refreezing.
• Discard high-risk food if you cannot establish how warm it became or how long it was warm.

Ice cream that has substantially thawed should not be refrozen. Even where a food remains safe, thawing and refreezing can significantly reduce its quality.

Can you move food into a cool box or outside?

A well-insulated cool box may help if you have enough frozen packs or ice to keep its contents below 8°C. Use a thermometer and minimise opening. Moving food into a box without enough cooling simply transfers it from one warming container to another.

Cold outdoor conditions can also be used, but only when the temperature will remain below 8°C. Place the food in a sealed box in clean, dry conditions, out of direct sunlight and protected from animals. Do not assume that a garage, shed, balcony or winter night is cold enough. Check the actual temperature and consider how it will change during the day.

Do not place unpackaged food directly outside, in snow or on a wet surface. This introduces contamination risks and gives poor control over temperature.

How to cook food safely during a power cut

An electric oven, induction hob, microwave and most modern cooking appliances will not work. A gas cooker may continue to operate, although its electric ignition, controls or safety systems may require power. Follow the appliance manufacturer’s instructions and do not improvise if it cannot be lit in the approved way.

A camping stove, barbecue or bottled-gas stove may provide an alternative, but most are designed for outdoor use. Never bring a barbecue into a home, tent, conservatory, garage or other enclosed space. It can produce fatal carbon monoxide even after the flames appear to have gone out.

Alternative cooking equipment can take longer than a normal cooker. Food must still be steaming hot and cooked all the way through. The Food Standards Agency’s cooking guidance recommends following packet instructions and using a clean food thermometer where appropriate.

• Keep raw meat, cooked food and ready-to-eat food separate.
• Use different utensils or clean them thoroughly between raw and cooked food.
• Wash hands before preparing food.
• Do not prepare more cooked food than can be eaten immediately if refrigeration is unavailable.
• Do not taste questionable food to test whether it is safe.

A power cut may also affect the water supply. If that happens, use safe stored water for drinking, infant feeding, food preparation and essential cleaning. Alcohol-based hand sanitiser can help with hand hygiene, while suitable antibacterial wipes can reduce the water needed for surfaces and utensils.

Take extra care with babies and vulnerable people

Young children, pregnant women, older people and people with an underlying health condition can be more seriously affected by food poisoning. Be especially cautious with chilled ready-to-eat food, smoked fish, deli meat, leftovers and anything with uncertain storage history.

Powdered infant formula requires safe water and correct preparation. The NHS formula guidance says freshly boiled water should still be at least 70°C when mixed with the powder. Powdered formula is not sterile, and ordinary bottled water is not sterile either.

If water cannot be boiled safely, ready-to-use liquid infant formula is an important emergency option. Follow the label closely and discard any formula left in the bottle after a feed. An opened container may require refrigeration, so smaller ready-to-use containers can be more practical during an extended outage.

Do not apply household food timings to refrigerated medicines. Ask the pharmacist, prescribing team or medicine manufacturer what temperature range applies and what to do after an interruption. Households relying on refrigerated medicine or powered medical equipment should make a specific outage plan with their clinical team.

Can a portable power station keep a fridge running?

A suitable portable power station can run some fridges and freezers, but compatibility and runtime must be checked before an emergency. Refrigeration appliances draw a higher burst of power when the compressor starts, so the battery station’s continuous output rating is not the only figure that matters.

• Check the appliance’s rated power and compressor starting demand.
• Make sure the power station can supply the required starting surge.
• Allow for inverter losses and the power station’s usable battery capacity.
• Measure the appliance’s real energy consumption before an outage if possible.
• Follow the battery manufacturer’s ventilation, cable and operating-temperature instructions.
• Plug the appliance into the power station as directed. Never attempt to feed electricity into household wiring through a wall socket.

Our backup battery runtime calculator can estimate how long a battery may support a measured load. If you are selecting equipment, compare appropriate models in the portable power stations for home backup buying guide.

Do not assume the fridge must be powered continuously from the first minute. During a short outage, leaving a cold appliance closed may preserve both food and battery capacity. During a longer outage, backup power can be valuable, particularly for a freezer containing costly food or for a household with additional health needs.

What to do when the power returns

1. Confirm that the electricity is stable. Leave the fridge and freezer closed while the appliances begin cooling again.
2. Check the recorded outage time. Do not calculate it from the moment you noticed the power had returned.
3. Read the thermometer. Assess chilled food against the 8°C limit and the four-hour period.
4. Inspect frozen food. Separate still-frozen items from food that has defrosted.
5. Discard unsafe high-risk food. Do not let cost or an acceptable smell override uncertain time and temperature.
6. Clean leaks safely. Raw meat juices and thawed food can contaminate shelves, drawers and other packaging.
7. Let appliances recover. Check that the fridge returns to 5°C or below and the freezer to around minus 18°C.

If a fridge or freezer does not cool normally after power returns, move safe food to another working appliance or properly chilled cool box. A temporary display reading may not show the temperature of every food item, so take a cautious approach when the storage history is uncertain.

Prepare your food supply before the next outage

• Keep a clearly visible fridge thermometer and check it regularly.
• Keep the fridge between 0°C and 5°C and the freezer around minus 18°C.
• Freeze water containers or cold packs to provide additional thermal mass.
• Keep a simple freezer inventory so the door does not need to remain open while you search.
• Store ready-to-eat food that does