What to do when the power comes back on

The short answer

When the power comes back on, shut down and disconnect any generator first, then check fridge and freezer temperatures before eating anything. Toss refrigerated perishables held above 40°F for 4 hours or more (FDA). Wait a few minutes, then plug electronics back in one at a time, reset clocks and thermostats, and check medicine and medical devices.

Power often flickers on and off during restoration, so do not rush. Work through the list below in order. If you are still in the dark, go back to what to do when the power goes out.

Power on after a power outage: the order of operations

1. 01Disconnect the generator. Turn it off and unplug cords before relying on grid power. See the generator section below.
2. 02Check the food. Read the fridge and freezer thermometers before opening anything else. Decide keep or toss using the table below.
3. 03Check medicine and medical devices. Refrigerated drugs and device settings come next.
4. 04Restart big loads one at a time. HVAC, well pump, water heater, then smaller appliances, a few minutes apart.
5. 05Plug electronics back in. Use surge protectors and add devices gradually.
6. 06Reset what the outage scrambled. Clocks, thermostats, timers, garage door openers and sump pump alarms.
7. 07Inspect for damage. Water in the basement, tripped breakers, wet outlets and spoiled-food smells.
8. 08Restock. Recharge power banks and lanterns, replace used batteries and refill water containers before the next one.

Power outage: what food to throw out

FDA says a closed refrigerator keeps food cold for about 4 hours, and a full freezer holds its temperature for about 48 hours (24 hours if half full). Once power returns, use a thermometer, not your nose. FDA: you cannot rely on appearance or odor to judge whether food is safe.

Perishables means meat, poultry, fish, eggs, soft cheeses, milk and leftovers. Hard cheeses, butter, condiments and whole fruit are more forgiving, but the item-by-item rules are long. Our keep food safe during a power outage page has the full table and the thermometers that make this a 30-second job.

Refrigerated medicine and medical devices

• Refrigerated drugs. Ready.gov and CDC: if the power was out for more than a day, throw away medication that should be refrigerated unless the label says otherwise, and contact your doctor or pharmacist for a new supply.
• Insulin. FDA says insulin vials or cartridges from the manufacturer may be left unrefrigerated between 59°F and 86°F for up to 28 days. Do not use insulin that has frozen, and FDA says pump insulin exposed to temperatures above 98.6°F should be discarded. Ask your clinician if yours was outside those limits.
• Device settings. FDA: when power is restored, check that the settings on your medical device have not changed. Some devices return to a default mode after an interruption.
• Batteries. Put backup batteries for CPAPs, concentrators and wheelchairs back on charge first, before the next outage catches them half empty.

Generators: shut down and disconnect

Let the engine cool before you refuel or store it; Ready.gov notes spilled fuel on hot parts can ignite. Store fuel outside living spaces. Keep CO alarms in place: the generator is off, but the next outage starts the cycle again. For a permanent connection, BackupPowerAI explains transfer switch and interlock basics.

Turn appliances on gradually

Ready.gov advises unplugging or switching off appliances and electronics during an outage to avoid damage from surges or spikes when power returns. The same logic applies on the way back: start large motors one at a time, a few minutes apart, so they are not all drawing starting current at once on circuits that may still be unstable.

A plug-in surge protector protects electronics from short spikes, not from a lightning strike or a whole-house fault. If your area sees frequent restoration surges, ask an electrician about a whole-home surge protective device at the panel.

Reset clocks, thermostats, wells and sump pumps

Thermostats and timers

Smart thermostats usually reconnect on their own; older programmable ones may lose their schedule. Check the mode (heat, cool, off) before walking away. Reset clocks on ovens, microwaves, irrigation controllers and any timer that controls lights or pumps.

Private wells

The National Environmental Health Association's private well guidance says to turn off power to the well pump before inspecting the area around the well, and to look for damaged wiring, well caps, vents and pressure tanks. If the pump will not start, turn off the electricity and call a licensed well contractor. NEHA also advises having a certified lab test the well water after a power outage, and using bottled or stored water until you know it is safe.

Sump pumps

Confirm the sump pump restarted: pour a bucket of water into the pit and watch it cycle. If you have a battery backup, check that it is recharging and silence or reset its alarm. Options are in best battery backup for a sump pump.

Garage doors and gates

If you released an opener by hand, re-engage the trolley before you try the remote. The steps are in how to open a garage door without power.

Check the house for water and damage

• Basement water. A long outage with rain can mean a flooded pit. If water reached outlets, appliances or the panel, CDC says do not turn the power back on until a qualified electrician has inspected the equipment.
• Wet electrical gear. FDA: do not plug in a power cord or device if the cord or device is wet.
• Tripped breakers. One dead room after the rest of the house returns often means a tripped breaker. If it trips again when reset, leave it off and call an electrician.
• Smells. A gas smell means leave the house and call the gas utility from outside. A burning smell near an outlet means switch off that circuit.

Tools that make the next one easier

A fridge thermometer and a freezer thermometer turn the keep-or-toss decision into a reading. These are existing research-based picks from manufacturer specs; we do not test products.

No. 1Food safety

Rubbermaid Commercial Refrigerator/Freezer Thermometer (FGR80DC)

Best for: Checking both the 40°F and 0°F thresholds

• Range −20°F to 80°F; reads °F and °C
• Easy-to-read dial; hangs or stands
• NSF listed
• 3-year limited warranty

Tradeoffs

• · Analog dial without safe-zone markings
• · No alarm or temperature log

Check price on AmazonSpecs: manufacturer page, checked Oct 27, 2026

No. 2Food safety

Taylor Fridge/Freezer Thermometer (5924)

Best for: Quick safe/unsafe check at a glance

• 3" color dial
• Safe temperature zone indicators
• Hangs or stands
• NSF certified

Tradeoffs

• · Manufacturer page does not list the temperature range
• · Analog; no alarm

Check price on AmazonSpecs: manufacturer page, checked Oct 27, 2026

No. 3CO alarm

First Alert CO710 Carbon Monoxide Alarm with 10-Year Battery

Best for: A no-install alarm you can set on a nightstand or carry room to room

• Sealed 10-year lithium battery (no battery changes)
• Listed to UL 2034
• Backlit display: CO level, peak level and temperature
• 85 dB alarm; tabletop design

Tradeoff

• · Tabletop only, and when the sealed battery ends the whole unit is replaced.

Check price on AmazonRead the full reviewSpecs: manufacturer page, checked Nov 1, 2026

Then close the gaps the outage exposed. Take the readiness score, restock from the blackout checklist, and if the outage ran long, read how long a house can go without power.