5 Reasons Why Microwave Is Sparking Inside

If you recently used your microwave for cooking and noticed sparking inside, it’s imperative that you determine why this happening and fix it.

While the sparking inside the microwave is generally safe and caused by something simple, it’s a definite sign there is a problem and it needs attention.

It can be alarming when this happens, but the good news is that most causes of microwave sparking are easy to fix yourself.

Today we’ll take a look at the most common reasons and how to fix them.

Reasons a Microwave Will Spark and How to Fix Them

Now that you’ve seen or heard a spark in your microwave, you’re probably asking “How do I fix my microwave from sparking”?

First, you will have to determine why the spark occurred in the first place and then you can complete the necessary fix.

Below are the most common reasons why microwaves spark and how to fix them.

Metal inside the microwave

Even the smallest piece of metal inside your microwave will create sparks.

It may be that you forgot to remove a spoon or fork from a plate, or even that a small piece of aluminum foil made it’s way inside.

Regardless of how big the metal is, metal contamination will cause sparking every time!

How to Fix:

This is an extremely simple fix. You simply open the microwave and remove the piece of metal that’s causing the sparking.

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The Waveguide Cover is Dirty

If you see sparks and don’t find a piece of metal, the waveguide cover is the next part to check.

When you look inside your microwave about halfway up on one side you will find a small square covered by mesh.

This is called the “waveguide cover”.

It plays an essential role with microwave function as it directs the cooking waves toward the food and covers the magnetron.

So, not only does it help evenly distribute the heat to your food, but it also prevents food particles from reaching the magnetron which can be dangerous.

The cover can cause the microwave to spark if it gets too dirty because food that’s splattered will continue to get burned by the magnetron and eventually create sparks.

How to Fix:

If you notice that your waveguide cover is dirty simply wash it with a damp paper towel or rag.

However, if this frequently happens it can actually damage the waveguide cover.

If you see that yours is damaged by burns it’s best to buy a new one and simply change it out.

A Burned Diode

All microwaves contain high voltage diodes.

It’s important that you always use recommended power sources and switches when using a microwave.

If you fail to do so it can actually cause the diode to become faulty.

When the diode on your unit is bad, you’ll notice sparking and that your food is taking longer to cook than it used to.

How to Fix:

New diodes are available for purchase from most local appliance parts stores.

They are easy to replace if you simply follow the directions included in the package.

Just be sure to disconnect the power before working on a microwave, as leaving the power on can be extremely dangerous.

If you do not feel comfortable with this type of repair you can either schedule a service call or take your microwave to a local appliance shop and they’ll be happy to help.

A Worn Rack Support

Not all microwaves have rack support.

However, if you have a style that features a cooking rack then you will notice it has a few supports that hold it in place.

The supports are made from metal that’s covered with protective plastic sheathing.

When the plastic wears off the metal, the exposed metal will cause sparks in the microwave.

How to Fix:

This is an easy fix. You’ll simply purchase a new rack support for your microwave model and replace it.

Just be sure to replace it before using the unit again, or the sparking will constantly occur.

Faulty Stirrer

The stirrer ensures all food heats evenly inside the microwave.

If your microwave’s stirrer is not functioning properly and the energy is being concentrated in one area, it can lead to sparking and burning.

There are two common reasons the stirrer stops working: the stirrer belt is broken or the drive motor is broken.

How to Fix:

This is one of the more complicated fixes.

The first thing you’ll want to do is disconnect the power to your unit so you can determine which part is faulty.

Next, you’ll need to remove the outer cabinet.

The stirrer belt is generally found at the very top of the microwave.

You’ll need to examine the belt to see if there’s anything blocking movement.

If you’re sure the belt is installed properly, you’ll want to visually inspect the belt for signs of burning, cracking, fraying, or other damages.

If you locate any type of damage it’s necessary to replace the stirrer belt.

The drive motor is a bit easier to test.

Most microwaves these days have a turntable.

When the drive motor is bad the table will not turn and the microwave will not function properly.

If you are unsure about this repair it may be best to call an appliance repairman or take your unit to a local appliance repair shop.

Commonly Asked Questions

Now that we’ve discussed the reasons a microwave will spark and how to fix them, you may still have a few questions.

Let’s go over a few commonly asked questions.

Is a sparking microwave dangerous?

As we mentioned, a sparking microwave is a common occurrence at one time or another. Most people panic when this happens, but that’s unnecessary. The fact is in most cases it’s safe.

Can I use my microwave after it sparks?

The simple answer is yes. Most generally the sparking is caused by an issue that’s easy to fix. After the repair has been completed the microwave is safe to use

Can radiation leakage cause this sparking?

Radiation leakage does not cause sparking. Microwaves usually begin to leak radiation due to an old or faulty door seal. To prevent this it’s best to wipe the microwave with a damp towel after each use. This will prevent crusty food from building up inside the door gasket.

In conclusion, if you notice sparking in your microwave it’s best to remain calm and turn the unit off immediately.

Go through the issues we discussed above and you’ll more than likely find the problem in no time.

Most of the time it’s something simple and easy to fix.

Don’t forget to leave a comment and let us know what you think!

Reader Comments (9)

  1. In my country they don’t sell the waveguide and I don’t know what to do am not be able to use my microwave for the pass 5 month now

  2. I cleaned the inside with steel woolpad. Probably the cause of the sparking. Great information and troubleshooters.

  3. Covering all food in the microwave is a good proactive way to prevent damage to the microwave, even if just a liquid like coffee or water

  4. Thanks this is helpful. Do you think a power surge could have damaged the diodes? This is a new 2 year top of the line microwave. Not only sparked but lots metallic smoke. There is no metal nor food particulates. Recleaned and dried with paper towels. Tried again but smoke a sparked much worst. Without tray or turn table. Worried the smoke is toxic. I will not try to fix. I might just buy a new. But not the same brand.

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