Running Microwave Empty

Running Microwave Empty

In Good To Know March 10th, 20210 Comments

This post may contain affiliate links for products I mention. If you click a link and buy something we may receive some compensation. This does not change the price you would pay. Learn more

A microwave provides us with a great and easy way to cook or warm up leftover food. Nevertheless, there are certain ways you need to use a microwave to maintain its functionality and be safe at the same time. Setting up the appliance is one thing, so is using it the right way.

There must be thousands of questions we all ask ourselves daily regarding what would happen to microwave in certain situations. Today, we are learning what happens when you microwave nothing.

One thing we know about microwaves is that they make use of radio waves at high frequencies to heat or cook your meal faster compared to conventional techniques. It is safe to say that this method of cooking or heating food is quite impressive. However, there is a limitation that comes with this unique heating method. For instance, what would happen if you accidentally ran a microwave empty? Well, read on to find out exactly what would happen.

Running a Microwave with Nothing

Magic Chef MCM1611W 1100W Oven, 1.6 cu. ft, White Microwave

The first thing you should know about microwaves is that they use a magnetron tube to make electromagnetic waves. These waves are the same ones we refer to as microwaves. How do these microwaves work? Well, these microwaves will hit your food and cause the water molecules present in your food to start vibrating. When these particles vibrate, they will cause some friction, which will then become heat and will in turn heat the food.

So, will running a microwave empty damage it? The truth is that if you run a microwave without anything, or if you heat something that does not contain some water molecules, then the electromagnetic waves will simply bounce around and back to the magnetron. As a result, the magnetron will start absorbing the same amount of microwaves it is producing. That might result in damage.

When you heat a microwave without anything in it, it will be fine in the first few seconds. The door, cavity, and tray will start absorbing energy and if you turn it off at that point, it will be okay. However, as it continues running, the door, tray, and cavity will begin to get hotter, even though it is still not at a critical point. But after it starts getting extremely hot, there will be excessive energy. That energy will start being reflected back to the magnetron and it will begin heating up at the same time. At that point, there might be a chance that a thermal fuse will be triggered, although that will depend on the appliance’s construction and size. In most appliances, you can reset that thermal fuse although it is not the same for all.

Also read: Can you Microwave Tupperware?

Poorly constructed appliances have a thermal runaway. Some parts of the appliance or location will superheat. That means it will get extremely hot to a point of liquefying porcelain. At some point, something will give out and there are chances that some plastic feature will burst into flames.
We recommend that you avoid running the microwave empty at all costs.

The Time it Takes

How long can you run a microwave empty before any damage can occur? Well, if you run a microwave without anything in it for a short period, such as few seconds, it will be okay. You might notice that certain appliances will run when you close the door, especially if the appliance had some time left on the timer the last time you used it.

Before the appliance becomes completely damaged, you will notice that it will give out a certain burning smell.

In regards to the time it would take for an appliance to be damaged when running empty, it depends. The time it might take might vary between a couple of seconds, to up to five minutes. It all depends on the appliance you are using.

So, how do you tell if your appliance is spoilt or damaged? There is a simple way. You can simply test the appliance by putting a microwaveable bowl with a bit of water inside the microwave and running it. A single minute will be adequate to prove if it still works. When you check the water after a minute, it should be hot. In case it is not, then the microwave is damaged and should be checked and repaired or replaced.

Additional Things to Avoid Microwaving

You can get the same damaging effects, even when the microwave is not empty. If you microwave some dry foods, you can expect the food to react in the same manner. Foods that do not have some water content should not be reheated with a microwave. Additionally, you should avoid any metal in the microwave because it will reflect the radio waves. In turn, it will create a different charge that will create other microwaves. The new waves will interfere with the first waves.

Safety Feature

We have established that it is not a good idea to microwave dry food or run a microwave empty. So, in case it happens accidentally? Will, it shut off automatically when it is overheated? A microwave will overheat unless it features some safety precautions and aspects that will make it shut off automatically.

A microwave with an automatic shut-off will turn off the heating elements once the temperature of the source of microwaves raises to a high level. That automatic shut-off feature is meant to prevent the machine from being damaged. It will prevent overheating, which would result in different types of failure.


We have figured out that you can run a microwave empty, but only for a few seconds, or a few minutes depending on the appliance model. However, you should know that it is highly discouraged. The appliance will be damaged because the same radio waves will damage the magnetron that produces them. Avoid running it without at least some water in it.

For further reading:

Feel free to share your observations with me in the comments section!

Also, if you find the information in this post to be useful, be sure to share this post with your friends on Facebook, Twitter, and Pinterest!

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.