What to Do When the Power Goes Out: A Step-by-Step Checklist

When the power goes out, check whether anyone depends on an electrical medical device, note the time, and keep the fridge and freezer closed. Then find out whether the fault is inside your home or affects the wider area. You do not need to decide what battery to buy while the lights are out.

This checklist follows the decisions that change as an outage continues. Food-safety times below follow US FoodSafety.gov guidance; local advice may differ.

Quick Answer

When	Do this	Why
First minutes	Check medical needs and hazards; note the outage time; use a torch or battery lantern.	Safety and the food clock come before battery planning.
Once safe	Check your breaker if safe to do so, then the utility outage map or report line.	A tripped circuit and a neighbourhood outage need different responses.
While waiting	Keep fridge and freezer doors closed. Put your phone in low-power mode.	Preserves cold air and communication.
If the outage continues	Prioritise essential devices and watch the food-safety time limits below.	Running everything at once can exhaust backup before it is needed most.
When power returns	Check food temperatures and any medical-device settings before returning to normal use.	Restored electricity does not make spoiled food safe or confirm a device kept its settings.

The First Ten Minutes

Deal with immediate hazards first. If someone relies on a life-sustaining powered medical device and its backup has failed, seek emergency help immediately. Follow the person’s existing care plan. The FDA’s outage advice for home medical devices says to check the device instructions or contact its supplier about approved backup power. A calculator result is not a substitute for that plan.

Note when the outage began. Use a torch or battery lantern, especially where oxygen is in use. If electrical equipment or cords are wet or damaged, do not reconnect them. Check your breaker panel only if you can do so safely; otherwise contact the utility or a qualified electrician.

Keep the fridge and freezer shut. Check whether neighbours have power, then use the utility’s outage map or report line for a restoration estimate. Preserve your phone battery for updates and calls.

Decide What Gets Backup Power

The right order depends on your household. A medical device, a sump pump during flooding, and a router for emergency communication can each be the first priority in different homes. Make a short list of what must run, how many watts it draws and how long it needs to last.

Load	Decision to make	Useful guide
Medical equipment	Use the device-specific emergency plan and approved power source; arrange help if it cannot be kept running.	CPAP or oxygen concentrator
Router, modem and fibre terminal	Back up every powered box needed for the connection. The provider's network may also be down.	Router and modem runtime
Sump pump	Check startup watts and whether water is arriving continuously; a short duty-cycle estimate can fail in heavy inflow.	Sump-pump backup
Fridge or freezer	Leave the door closed first. If backup becomes necessary, check both compressor startup and running energy.	Fridge or freezer backup

Turn off loads you do not need. A UPS can bridge a brief interruption for a computer or network device; a portable power station can provide more energy for a longer outage. The UPS and power-station comparison explains the choice. Use a generator only outdoors, more than 20 feet from windows, doors and vents, following CDC carbon-monoxide guidance. Never run one in a home or garage, even with the door open. See power station vs generator for how the two compare.

Keep Food Cold, Then Check It

FoodSafety.gov says an unopened fridge keeps food cold for about four hours. A closed, full freezer holds temperature for about 48 hours; a half-full freezer for about 24 hours. These are planning windows, not a reason to open the door repeatedly and check. An appliance thermometer gives better evidence when power returns.

If the fridge has been without power for four hours or more, FoodSafety.gov advises discarding refrigerated perishables, including meat, poultry, fish, eggs and leftovers. For frozen food, check each item: food that still contains ice crystals or is at 40°F (4°C) or below can be cooked or refrozen. Do not taste food to decide if it is safe.

If you have a cooler and enough ice to keep it at 40°F (4°C) or below, moving refrigerated food there before the four-hour limit may help. For a long outage, plan the transfer rather than repeatedly opening the fridge. Follow the FoodSafety.gov item-by-item charts when assessing food after power returns.

When the Power Returns

Check the fridge and freezer thermometers and make food decisions before putting everything back. Inspect any equipment that became wet or damaged. Keep sensitive electronics unplugged until the supply is stable, then reconnect them through a surge protector; a power strip is not a surge protector. If someone uses an electrical medical device, confirm it has resumed the correct settings; the FDA warns that settings can reset after power loss.

Record what ran out of backup power and when. That real result is more useful for future planning than a battery’s headline watt-hours. Recharge the UPS or power station and revise the list of devices you actually needed.

Prepare the Next Outage

The calculator sizes portable-power-station capacity from your devices and target duration. It does not verify that a medical device accepts a particular power source or that a traditional UPS will meet a runtime target. For a UPS, compare your measured load with the exact manufacturer’s runtime curve.

Setup	Planning window	Open calculator
Router + modem	8 hours	Calculate
CPAP	8 hours	Estimate energy only
Small fridge + router + phone	8 hours	Calculate

What People Miss

The outage clock matters for food. Write down the start time. Without it, a fridge that feels cool can be mistaken for proof that perishables are safe.

Every network box needs power. A powered fibre terminal in another room can stop internet access even while the router stays on.

A generator brings a separate hazard. Carbon monoxide is invisible and odourless. Its placement matters as much as its watt rating.

Restoration is another check. Food temperature, medical-device settings and depleted backup batteries all need attention.

Bottom Line

Start with people and hazards, record when power failed, and leave cold-storage doors shut. Use backup for the loads that matter to your household, then make food decisions using the outage time and thermometer readings. Once power returns, check equipment and replenish the backup. To size backup before the next outage, try your devices in the calculator.