I love my microwave for the same reasons everyone else does – the speed & convenience.
The problem with convenience devices though is they can be a bit of a trap for personal mishaps.
You take your eye off the ball, you don’t really engage with using them, and before you know it you’ve done something you shouldn’t!
Has your microwave died after running empty? In this article I’ll explain what’s happened, what your options are now, and how you should proceed in the short-term.
What’s Happening Inside Your Microwave
Whenever you heat food or liquids inside your microwave, the appliance’s magnetron generates a huge amount of electromagnetic radio waves.
These waves agitate the water molecules in your food, which in turn transfer energy to their surroundings in the form of heat.
This is a very simple explanation of how a microwave works, but it paints a pretty good overview of what’s going on inside.
What happens if you run your microwave empty though, and why does this so often result in a dead appliance?
The problem is actually pretty simple!
Once generated, all of that energy has to go somewhere. In the case of your microwave, that means straight back into the electrical components of the appliance – including the magnetron.
In effect, you’re cooking your magnetron, rather than your dinner. This damages the magnetron, it won’t be able to produce heat any longer, and so you won’t be able to use the appliance for heating food anymore.
At this point, you have two options:
- Repair your microwave magnetron
- Replace your microwave altogether
Which of these options you choose depends on the age of your appliance, and the cost of organizing a repair locally.
Microwaves have a life expectancy of around 7 to 10 years if they’re looked after properly. Even an undamaged magnetron will fail after a certain amount of time – it’s just the nature of how they work.
If you’re well below that timeframe, you might consider getting a professional to replace the magnetron inside your microwave.
If you’ve already had – say – 5 or so years of use out of your appliance though, it’s probably going to be more cost-effective to simply buy a replacement.
You’ll not only reset the clock on the appliance’s lifespan, you’ll likely get access to some new features and technology.
Like every other kitchen appliance, microwave technology is always evolving, and so it might be worth taking an “every cloud has a silver lining” approach to the problem!
How Long Can You Run A Microwave Empty?
It’s never a good idea to run a microwave empty for any period of time, but you do get some wiggle-room.
Additionally, some of the more modern microwaves feature a small amount of protection if you accidentally run the appliance empty for a short period of time.
As a general rule, if you’ve noticed your error immediately and shut the empty microwave down after a few seconds, you’ll probably be fine.
Do it for any longer than that though and you’ll damage the magnetron to some degree or another.
The key thing to watch out for here is a burning smell. This may be a sign that the microwave is no longer safe to use, so disconnect it immediately.
When it comes to things you can safely ignore in a microwave, a burning smell is not one of them! This is definitely a sign that you should either repair your microwave before using it again, or get a replacement.
(If your food’s been burned in the microwave, that’s only a short-term problem.)
How To Test If Your Microwave Has Died
Assuming your microwave is still safe to work with, there is a test you can perform to see how much damage you’ve done by running the microwave empty.
- Fill a microwave-safe cup two-thirds full with water.
- Cook it in the microwave for one minutes.
- See if the water has heated at all.
If it’s heating up, you can at least get some use out of your microwave. It may well not perform as well as it used to though, so keep an eye on performance the next time you’re reheating something.
If the water is barely tepid, then this is a sign that you’ve done some pretty significant damage to the microwave. Again, time for a repair or a replacement.
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Microwave Care Tips
While we’re on the subject of looking after our microwaves, here are a few tips that are worth keeping in mind:
- We’re all guilty of throwing away owner manuals – how hard can a microwave be to use anyway? Still, beyond not running the microwave empty, there are likely some important usage tips in there that are specific to your microwave make and model.
- Don’t cram your microwave into any old space! The vents need plenty of clearance space to keep that air flowing, which in turn will stop the microwave from overheating.
- Check the power cord periodically. If it’s showing signs of wear and tear, get a replacement. You can likely do this online yourself, or contact the manufacturer if the appliance is still in warranty.
- Unless you’re a qualified electrician, leave the repair jobs to a professional. You can easily make a bad problem worse, or reduce the safety of the appliance.
Frequently Asked Questions
Before I wrap things up I just wanted to answer some of the most common, related questions that readers have around this topic.
Can You Ruin A Microwave By Running It Empty?
Yes, you can truly ruin a microwave by running it empty. All that energy created by the magnetron has to go somewhere – and it goes right back into the magnetron.
You may get away with a short burst of cooking while the microwave’s empty, but there are no guarantees.
In general though, running a microwave empty is very likely to cause some damage to the appliance.
How Long Can You Run A Microwave Empty?
If you’re doing so deliberately, the answer is you shouldn’t run a microwave empty for any period of time at all!
If it’s a matter of a few seconds, you might not do any lasting damage. As always, watch out for any kind of burning smell.
If you notice that, stop using the appliance immediately and arrange for a repair or a replacement.
Can You Microwave Empty Plates, Bowls & Mugs?
For the same reasons I’ve covered elsewhere in this guide, it’s not a good idea to microwave things like empty plates, bowls and mugs.
They’ll absorb some of the energy, but microwaves are not designed for this kind of task.
Warm your dinner plates up in the oven on a low heat instead – it’s worth the extra time it takes, compared to the cost of having to buy a new microwave!
Can Running A Microwave Empty Cause A Fire?
Technically, you could start a fire in your microwave by running it empty.
It’ll take a long time for things to get this bad though, so don’t fret if you’ve done this accidentally and are worrying about future mishaps.
If you have a modern microwave with any kind of built-in protection, you’re likely to notice a burning smell before things get any more serious than that.
Again, burning smells from an appliance are always a sign you should shut it down immediately, and either replace it or get a qualified professional to inspect / repair it.
Will An Empty Microwave Explode?
An empty microwave will not explode, except under the most extreme circumstances.
As explained in the last answer, you do have a very small chance of causing a fire if you leave the microwave running empty for a very long period of time.
Even before that happens, it’s much more likely that the microwave will fail completely.
If there’s one good thing about a dead microwave, it’s that it can’t create any more damage!
Why Does An Empty Microwave Spark?
If your empty microwave is starting to spark, it’s definitely time to replace it. Sparks like this typically happen when you put metal in a microwave.
If there’s nothing in there, I’d be concerned that a metal element is loose in the appliance.
Things like forks are magnets for microwave sparks – it’s those pointy bits that tend to create the energy arcs.
I can only advise that you get this sort of thing checked out by a qualified professional sooner, rather than later!
It’s likely that you’ve found yourself reading this article because you’ve run your microwave empty and things aren’t looking good. Don’t beat yourself up – everyone makes mistakes!
Just to summarize, keep the following in mind:
- Don’t use the microwave again until a professional has checked it over for safety. Search online for a qualified repair service, but consider buying a replacement instead if the microwave’s more than a few years old.
- If there’s a burning smell, don’t use the microwave again until it’s been checked over.
- Avoid using your microwave to heat objects (ie plates), rather than food. They’re just not designed for this purpose.
Mark’s a lifelong food fanatic and spent ten years working as an entertainment journalist. He now combines his love of food, drink and writing as the founder and editor of Viva Flavor. Read more