Explore the Damage Caused by Running a Microwave With Nothing Inside

Posted on: 28 September 2018


Microwaves make a very useful addition to your kitchen, but you should understand that there are things you shouldn't do with them – for example, you should never run a microwave when there's nothing inside it. Doing so can cause superheating and ultimately lead to the need for repairs or even a complete replacement.

Here's everything you need to know.

What Happens When You Turn on an Empty Microwave?

While ovens create heat to cook your food, microwaves cook things much faster by using high-frequency radio waves. That's great for speeding up cooking times, but something needs to be in the microwave for everything to work properly.

You see, all microwaves use something called a magnetron tube to create electromagnetic radio waves. Those waves cause water molecules in your food to vibrate; those vibrations create friction that in turns heats up your food. This is why it's hard or impossible to cook anything with a very low water content in your microwave.

If you run the microwave without anything inside, all the electromagnetic radio waves the appliance produces are redirected into back the magnetron. When the magnetron is forced to absorb as many microwaves as it sends out, it can be damaged. Without the magnetron, your microwave will no longer be able to properly heat your food.

How Can You Tell if the Microwave Is Damaged?

Running your microwave with nothing inside isn't going to cause an instant breakdown. Just a few seconds should be fine but going anywhere above a minute will probably lead to damage unless your machine is very well made.

If the magnetron is suffering damage, you should notice a slight burning smell. If your microwave doesn't have a thermal fuse to trip (or if the thermal fuse has already by tripped) extreme overheating could occur until something gives. This could be as minor as a standard fuse blowing or as major as combustion of the insulation covering wiring or plastic components.

If you think the magnetron might have been damaged, you can test the microwave by filling a microwave-safe container with water and running it for a minute. If the water doesn't get hot, the microwave has sustained damaged.

What Should You Do if You Damage the Magnetron?

Microwave magnetrons can be replaced relatively easily and inexpensively. Unless you have a very cheap model, it's better to call your local appliance repairs service people to have them repair the machine rather than simply throwing it out and buying new.