Microwaves are pretty standard in most kitchens nowadays. Not only are they efficient and compact, but they also require minimal maintenance throughout their lifetimes.
So are they robust enough to take any form of abuse? Can you run them while empty?
Well, here’s the answer.
You shouldn’t operate a microwave for extended periods while it’s empty, as it will damage its electrical components. Depending on how well they’re designed, microwaves can run while empty for approximately 5 to 10 minutes. After the grace period, your microwave will trip or catch fire.
Therefore, never run your microwave oven while it’s empty for your safety and the people around you. You will be endangering your lives and voiding your insurance by doing so.
Today’s article looks more into the working of a microwave oven, what happens when you run it empty, and what to do if you do so. Let’s get going.
How Do Microwave Ovens Work?
The working of microwave ovens is pretty simple and sophisticated all at the same time. And given that we all know that opening a microwave oven while it’s running is a safety hazard, few of us know how it works or its safety measures. If you don’t, you’re in the right place.
Microwave ovens use non-ionizing electromagnetic energy to cook food uniformly and without any external heat source.
But how does it generate electrons?
The microwave oven has a transformer that steps up the supply voltage to 4,000 volts and feeds it to the magnetron. Within the magnetron is a filament that heats up pretty quickly and starts releasing electrons.
These electrons get directed through a waveguide and bombard the water molecules in the food, causing them to oscillate and bump against each other. This causes sufficient friction that warms up your food. And due to its nature, foods with high water content cook more quickly than the drier ones.
Generally, electromagnetic energy or waves have a frequency of 2450 MHz or a wavelength of 12.24 cm. Therefore, you’ll notice that most microwaves are of a standard size.
Additionally, microwaves don’t cook food from the inside out, as you may have heard. Instead, they cook the outer layers first and allow the inner layers to cook through conduction.
What Happens When You Run a Microwave With Nothing Inside?
Running a microwave with nothing inside is dangerous, and you shouldn’t attempt doing so. But if you forget and run it empty for a few seconds, you don’t have to worry. On the other hand, running your microwave while it’s empty for some minutes will damage its magnetron, melt some parts, and even catch fire.
Microwaves ovens take some time before they heat up, depending on their design and quality.
As we’ve seen, microwaves generate oscillating electromagnetic waves absorbed by the food while heating.
However, if your microwave is empty, the electromagnetic waves will bounce around the cooking chamber and may find their way back to the magnetron. At this instance, it may overheat, and you’ll notice a burning smell before it shuts down.
However, if it doesn’t shut down, the excessive energy buildup within the cooking chamber will overheat the microwave oven’s electrical components causing it to burn.
How Long Can You Run a Microwave Empty Without Damaging It?
While it’s best not to run a microwave while it’s empty, there are times when you accidentally do so. The good news is that you won’t damage your microwave if you run it empty for a small amount of time (less than 5 minutes).
Some protective devices inside the microwave oven shield the magnetron from the waves bouncing back from the cooking chamber. Additionally, the cavity, the door, and the tray absorb the excess energy while cooking your food.
While empty, it takes approximately 5 minutes for the electromagnetic waves to overwhelm these protective components. Running the microwave for extended periods, let’s say past 10 to 15 minutes, causes sparking, melting, and its components may catch fire.
If it’s designed well, your microwave will trip before any damage can happen to it.
If it doesn’t trip, it’ll get into a thermal runaway whereby some random part in your oven will superheat until a crucial part fails. It can be a breaker tripping, melting of electrical insulations, or the fuse blowing.
Of the three faults, melting of electrical insulations is very dangerous as it exposes your oven to short circuits. At this point, your microwave oven will catch fire and burst into flames.
The best that you can hope for if you mistakenly start cooking while your microwave is empty is for it to trip. However, it doesn’t always do so.
If it doesn’t catch fire immediately, be assured that you’ll have taken off some months from your microwave’s service life by running it while empty.
How Can I Tell If My Microwave Was Damaged By Running It Empty?
A clear indication of a damaged microwave oven is if it fails to heat your food on time. And you can’t tell that it’s broken by just looking at it. You’ll have to troubleshoot it since its failure can result from one or more causes.
Here are some clear signs of a microwave that has been damaged by running it while it’s empty.
1. A broken Control Board
The control board is directly behind your microwave’s control panel. Open your microwave’s casing to access the control board and look out for signs of arcing or molten insulations.
Also, look out for signs of burning around the relays, as these will indicate a short circuit within your control board. You’ll have to replace your control board if you find any signs of burning.
2. Faulty High Voltage Circuit
A microwave’s high voltage circuit consists of a magnetron, a high voltage diode, a transformer, and a high voltage capacitor. If any of these components fail, you won’t have enough heat in your microwave to cook or warm your food.
Telling whether any of them is faulty requires using a multimeter and checking for continuity. But remember to approach the high voltage circuit with caution to prevent cases of short circuits, electrocutions, or even fires.
As a safety precaution, disconnect your oven from your power supply line before beginning your diagnosis.
3. A Molten Turntable
Running a microwave while empty results in high heat buildup. This energy can sometimes be sufficient to melt the porcelain turntable. If you find that your microwave oven is not working and the turntable is molten, the chances are that it’s broken.
You should note that a broken turntable isn’t an indication of a faulty microwave. Instead, it’s a sign that indicates that your oven may have more outstanding underlying issues.
Don’t replace your turntable if it’s molten; consult an electrical professional first.
Conclusion
As we’ve seen, running an empty microwave is very dangerous. However, you don’t need to worry if you’ve done so for 5 minutes or less. If you’ve been running it empty for long periods, you’ll need to shut it off from the power source.
Leave it to cool for some time and run a simple test by placing some food inside. Turn it on, set it to your usual timing and wait for the results. Did it work well? If so, then you’re lucky.
If not, I’d recommend you consult an electrician to troubleshoot and repair the unit.