How to fix a microwave that’s sparking or arcing

Ever had that moment when you’re zapping your favorite meal in the microwave, and bam! Do sparks start flying inside? It can make you jump and question your machine’s safety.

Let’s dig into this issue so you can resolve sparking and arcing issues.

If you need any replacement parts for your microwave, you can enter your model number at AppliancePartsPros.com to order them. Most orders arrive in just two business days, and we have thousands of free guides to show you how to install your new parts.

Disclaimer: The troubleshooting information provided in this article is based on general service manuals and may not apply to your specific appliance model. While we strive to offer helpful advice for DIY appliance repairs, variations in models and configurations can lead to differences in troubleshooting steps, error codes and part replacements. For the most accurate guidance, we strongly recommend consulting the technical sheet for your specific appliance model.

READ MORE: How to prevent appliance fire hazards

Why does my microwave arc or spark?

Sparking – also known as arcing – in a microwave oven is a phenomenon that often results from the presence of metallic objects such as forks, spoons, or aluminum foil inside the microwave. Chipping interior paint can also cause sparks while the microwave is running. These items can reflect the microwaves used for cooking food and cause electric sparks as the electromagnetic waves concentrate on the metal’s sharp edges or points.

Sparking or arcing can also be caused by a damaged or dirty waveguide cover or debris on the microwave’s interior walls that creates a pathway for electrical discharge. A microwave that is sparking or arcing may also cause an unpleasant burning smell.

Can I use my microwave after it sparks?

Only if you address the problem and make sure it no longer sparks. It’s important to troubleshoot & resolve the sparking before you continue to use your microwave to heat up food. When you see microwave sparks, turn off and unplug your microwave immediately and inspect the interior for any metal objects that got left behind or any damage, like chipped paint.

Does arcing damage a microwave?

Arcing or sparking can damage a microwave over time, especially if the problem isn’t fixed soon enough. Even a single arcing event has the potential to cause significant damage such as:

• Waveguide burnout
• Magnetron damage
• Cavity damage
• Electronics damage (control board, sensors, etc.)
• Fire

Microwave safety tips

Microwaves contain high-voltage parts and can store voltage even when they’re disconnected from a power source. Please be very careful while working on a microwave’s internal parts to avoid electrocution, which has the potential to cause serious injuries or death.

• Always unplug the microwave before troubleshooting or making repairs.
• Discharge the high-voltage capacitor before working on high-voltage parts to eliminate the risk of electric shock.
• Never attempt to run the microwave while its casing is open or when internal parts are exposed. Always completely reassemble the microwave before testing or using it.
• Never attempt to bypass any microwave safety features.
• With the microwave unplugged, remove the outer case to gain internal access.
• Wear insulating gloves and use insulated tools when testing any parts.
• Check all parts for damage before reassembling and powering up the microwave again.
• If the appliance has recently been used, give it plenty of time to cool down before working on it.
• Take your time while working to prevent accidents and personal injuries. Rushing is the enemy of precision.
• Work in a well-lit area so you can clearly see and access appliance parts.
• Keep your workspace free of clutter and other obstacles. Keep children and pets away from the work area.
• Check the user manual to see if there are specific installation or safety instructions related to your appliance or replacement part.
• Be gentle when handling or removing parts. Excessive force might damage the appliance or cause personal injury.
• Don’t test live voltage with a multimeter if you’re unfamiliar with how to prevent short-circuiting.

READ MORE: 9 safety tips for using a microwave

How to troubleshoot arcing or sparking in a microwave

Step 1 – Check for any metal in the microwave

1. Turn off the microwave and unplug it.
2. Open the door.
3. Look around the microwave’s interior to see if there are any metal pieces or utensils. Remove them if any are found.

Step 2 – Check the waveguide cover

Your microwave has a waveguide cover over the magnetron that protects it and keeps microwaves directed at the food for cooking.

If a microwave is sparking or arcing, it could be due to a dirty waveguide cover. Cleaning can help, but if the sparking persists, the cover may be damaged, in which case you’ll need to replace it.

How to check the waveguide cover:

1. Make sure the microwave is turned off and unplugged.
2. Open the microwave door.
3. Find the waveguide cover, which is typically located on the right side of the microwave oven, behind a removable panel or cover.
4. Remove the waveguide cover.
5. Visually inspect the cover for any signs of damage such as cracks, burn marks or warping.

If the waveguide cover looks good, make sure it’s correctly installed and seated, then move on to the next step.

If the waveguide cover is visibly damaged or won’t stay in place, it’s time to replace it with a new one. Take your model number to AppliancePartsPros.com to find the right part for your unit.

READ MORE: How to Clean a Microwave

Step 3 – Address chipped or exposed interior metal

Microwaves have a protective coating on the interior metal surfaces to prevent arcing between the metal and the high-voltage components. But if the coating is chipped or the metal in the microwave is exposed, it can create a path to ground for the high-voltage components, which can lead to sparking or arcing. Arcing can also occur between the exposed metal and the microwaves generated by the magnetron.

If the interior of your microwave oven shows signs of chipped or exposed metal, you’ll need to fix it as soon as possible to prevent more damage. Here’s what you can do:

1. Make sure the microwave is off and unplugged from the power supply.
2. Carefully inspect the oven cavity and see if there are any sections with chipped or exposed metal in the microwave. Pay close attention to areas near the rack support or turntable. If the chipped or exposed area is near the rack support, it may be more practical to replace the entire rack support with a new one.
3. Use fine-grit sandpaper to gently sand the damaged area and remove any loose or jagged metal edges.
4. Use a microwave-safe interior paint that’s specifically designed for microwaves. Apply a thin, even coat over the exposed metal. Make sure to follow the manufacturer’s instructions.

READ MORE: Do’s & Don’ts for Microwavable Materials

Step 4 – Replace the rack support (if needed)

The rack support is a metal component that holds the turntable or cooking rack in place. If this part is damaged, chipped, or has exposed metal, it can cause sparking or arcing. The exposed metal acts as a path to ground for the high-voltage components, and arcing can occur between the exposed metal and the microwaves generated by the magnetron.

If the rack support itself is damaged or has exposed metal, you should replace it with a new one. Here’s how:

1. Consult your microwave’s manual to see if there are instructions on how to remove the rack support from the oven cavity.
2. Purchase the correct OEM replacement rack support for your specific microwave model. Take your model number to AppliancePartsPros.com to locate the correct part for your unit.
3. Carefully follow the manufacturer’s instructions to install the new rack support securely in the oven cavity.

READ MORE: 4 Simple Ways to Reduce Kitchen Waste

Maintenance tips to prevent microwave arcing

Preventive maintenance is key to avoid sparking and arcing issues in your microwave. Here are some tips to keep your microwave in top condition:

• Wipe down the interior of the microwave regularly with a damp cloth or mild cleaning solution to prevent food particles from building up on the waveguide cover and potential damage to the protective coating.
• Never use metal utensils, containers, or foil in the microwave, as they can cause arcing and potentially damage the oven.
• Periodically inspect the oven cavity, waveguide cover, and rack support for any signs of damage or wear and address any issues as soon as possible.
• Consult your microwave’s manual for recommended maintenance and usage guidelines, as well as any specific instructions for addressing sparking or arcing issues.

READ MORE: My part is no longer available! What do I do now?

More information

Thank you for reading! We hope this guide helped you get your microwave working again.

If you have any other appliance repair needs or projects, don’t hesitate to explore our other troubleshooting guides and videos.

If you need replacement parts or some extra help with ordering them, grab your model number and head over to AppliancePartsPros.com, where you can chat with a pro, read our DIY blog and more. We can also help you troubleshoot common microwave problems here.

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