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How Often To Run a Generator To Keep the Refrigerator Cold?

Unscheduled power outages are no fun, but we have to deal with them occasionally. Thankfully, we can use generators to generate our own electricity for essential home appliances like the refrigerator. But how long should you run the generator to keep the refrigerator cold so that the food doesn’t spoil?

Running the generator for a minimum of 1 hour should keep the refrigerator cool for up to 4 hours. Putting some ice packs, frozen water bottles, or any container with ice cubes in the fridge can also help keep it cold longer. Only open the fridge door when you absolutely have to.

The rest of this article will cover how often you should run a generator to keep the fridge cold and how long your fridge stays cold after losing power. I’ll also share a few food safety guidelines that you should know for the next time you get a power outage.

How Long a Refrigerator Stays Cold Without Power

Man with fridge open in dark kitchen

A refrigerator can keep cold for up to 4 hours on average without power. Smaller refrigerators may start to get too warm after about 2 to 3 hours, while a large refrigerator filled with large, cool water bottles can keep cold for over 5 hours. The freezer can stay cold for up to 48 hours without power.

Basically, the more stuff you have packed into the refrigerator, the longer it can stay cold. This is because it takes longer for heat transfer to occur when there’s more mass.

If power outages are frequent in your area, it’d be a good idea to stuff your fridge full of items so that you can ensure the fridge stays cold for as long as possible.

Plastic bottles filled completely with water are a good example. Ice packs and cold therapy gel packs also work great.

If you lost power recently, don’t open the fridge. Keep the door closed because it’ll stay cold for about 4 hours without power. Additionally, your freezer will probably be fine for a day or two, depending on how much food and ice you managed to cram into it.

If you’re worried about food safety, I strongly suggest that you get a thermometer. Stick it onto the inside part of your fridge door. That’s the least cool spot. If you notice that the fridge temperature is substantially over 40° F (4° C), throw all opened foods away. You should also get rid of unopened perishable foods like milk, butter, and eggs, too – keeping them is not worth the risk.

How Often to Run a Refrigerator During a Power Outage

You should run a refrigerator for at least one hour during a power outage. Your food will stay safe for 3 to 4 hours afterward. However, you should run the fridge continuously whenever possible. It’ll keep your food safe and lower the total power consumption.

Running your generator intermittently to keep the fridge cold enough is likely safe. But why risk it?

If the fridge stays on, you won’t have to throw away any food. What you pay in propane or gas can save on food waste exponentially.

Moreover, keeping the generator going means you’ll save energy in the long run. This is because the fridge will stay at its running wattage. 

The rated/running watts tell you how much power the fridge needs to stay on. Nearly all generators in existence can handle it. It’s only about 100-250 W for home fridges.

On the other hand, a fridge consumes about 800-1200 W to cool down. This is what we call starting watts, and your generator must support the required peak wattage to work in the first place.

So, you should run the fridge on your generator continuously until the power comes back. However, if that’s not an option, run the generator for 1 hour after every 3 hours of no power.

Related How to Run a Generator in the Rain (And Not Ruin It).

Can a Generator Damage a Refrigerator?

A generator can damage a refrigerator, but this only happens if you force it to supply more power than it’s rated for. If the refrigerator’s power consumption is well below the generator’s maximum output, the generator will not be able to damage your refrigerator.

If you stay within the maximum wattage that your generator provides, it can’t damage your refrigerator. 

Generators provide stable electric power as long as you feed them enough energy in the form of gas or propane.

When hooking up your generator to the fridge, pay attention to the running and peak power rating. If your fridge’s peak (surge) power rating is higher than what the label on the generator says, don’t use it.

Pushing your generator too far can cause it to overheat. The best-case scenario is that the generator’s safety switch goes off and turns the generator off. 

The generator can blow up or even catch on fire in more severe cases. Not to mention that it’ll probably take the fridge with it too.

However, this doesn’t mean that you should avoid using the generator when the power is out altogether. That said, make sure only to turn on home appliances that need to be or those that have low energy consumption.

Hooking up an electric kettle, washing machine, stovetop, and dishwasher all at the same time will overwork even the most powerful home generators. Additionally, connecting a small outdoor generator to your fridge isn’t a good idea either. You need at least a 1500 W generator if you have a 1000 W fridge. 

The extra headroom helps with both safety and power efficiency. Less power will be lost to heat if you don’t run the generator at 90-100% constantly.

The Temperature Food Spoils in the Refrigerator

Food starts to spoil in the refrigerator when the temperature exceeds 40°F (4°C). Food bacteria thrive at temperatures between 95°F (35°C)-104°F (40°C), but food can spoil well below that range. If the temperature in your fridge has gone above 40°F (4°C), throw all the food away.

The USDA and other government agencies often refer to the “Danger Zone” for food storage. This is the 40°F (4°C)-140°F (60°C) range, where common food bacteria reproduce quickly.

40°F (4°C) is the highest temperature your fridge should be at. If possible, turn it up even lower. As long as the water in your fridge isn’t reaching freezing temps, you’ll be fine.

It’s worth noting that some foods will spoil much faster than others in the Danger Zone. Here are a few foods that spoil the quickest in an unpowered fridge:

  • Meats (especially raw, unprocessed cuts)
  • Eggs
  • Milk
  • Butter
  • Berries
  • Cooked beans
  • Cooked grains
  • Fish
  • Leftovers

If you have any of these things in the fridge that hasn’t been on for longer than 4 hours, you should ideally throw them away. Remember, food doesn’t have to smell or look bad to be unsafe for consumption.

How Long Can You Keep a Generator Running?

A man pulls the starter cord to start the generator

If you’re using a generator with a steady natural gas supply, you can keep it running for around 500 hours. If the generator runs on gasoline or diesel, it shouldn’t run for longer than 4 to 10 hours at a time. The exact number depends on your specific model, so check your manual.

The safety of keeping your generator on depends on several factors. For example, if it’s an old generator, it’s probably less safe than newer models.

However, your main limitations are how much gas the generator gets and how much it heats up. If you must refuel your generator manually, you’ll have to shut it off when the tank runs out of juice for refueling. Never refuel a generator while it’s still on because that’s a major fire hazard.

If there’s a constant stream of natural gas through a pipeline, you still need to shut it off after 500 hours for maintenance. The exact number varies by model.

Final Thoughts

If it’s possible, keep your generator running the whole time to keep your refrigerator cold until the power comes back. This will keep your food from spoiling, and your fridge won’t have to work as hard.

If it’s a longer blackout, you can turn the generator on for 1 hour after 3-4 hours have passed to recool the fridge. However, keep in mind that you’ll waste more energy with this method.

For more, check out What Size Generator Do You Need To Run a Furnace?