What would cause a microwave to catch fire on the inside?

Author: Astrid Schaden Sr.  |  Last update: Thursday, October 23, 2025

Therefore any material which has dried out can overheat and ignite in a microwave oven. Also, any metal objects inside a microwave can cause severe sparking which could lead to a fire.

Why does my microwave catch fire inside?

Turn off and unplug the microwave. Don't open the door. Lack of oxygen inside the microwave suffocates flames. If you have any doubts about the situation, call the fire department immediately.

What causes microwave to burn inside?

Metal reflects microwaves and creates a concentrated area where electrical currents form. The concentrated energy can lead to sparking, or arcing. The presence of metal inside the microwave cavity can result in electrocution, or even a fire inside the microwave by igniting flammable materials inside the appliance.

What would make a microwave spark inside?

Build up of Food and Grease

If there is a lot of food debris inside your microwave, it can lead to sparking! This happens when food particles are left in the microwave through many cooking cycles and become carbonized.

How do I know if my microwave is unsafe?

6 Signs It's Time to Replace Your Microwave
  • Smoke, sparks, and burning smells.
  • Food isn't cooking properly.
  • It makes horrible sounds as it cooks.
  • The door doesn't seal properly.
  • The keypad doesn't function.
  • It's over 10 years old.

Is your Microwave catching fire or sizzling? Easy Fix!

When should you throw out your microwave?

On average, microwaves last 7-8 years.

What is the life expectancy of a microwave?

The average microwave oven lasts about seven years with normal use, yet even less with heavy use and poor maintenance. A large family may find themselves replacing their appliance every four to five years as they become more reliant on its use to heat snacks and leftovers or to defrost meals.

Should I replace my microwave if it sparks?

Faulty waveguide cover

If the cover is damaged it can lead to concentrated spots of energy that can cause sparks. If any part of your microwave is damaged, it's recommended that you purchase a new one or get professional help.

What does a faulty magnetron sound like?

A screaming or screeching sound that's hard to ignore is usually caused by a defective or worn-out magnetron.

What happens when a microwave diode goes bad?

Microwave Does Not Heat

This generates enough power so that the magnetron is able to provide the cooking energy within the oven. A failure in the diode will result in a lower A/C voltage reaching the magnetron, which may not be sufficient. Diode failure is often accompanied by visible signs of a burn out.

How to tell if a waveguide is damaged?

If your microwave oven is sparking or 'arcing' during cooking it may be that the waveguide cover is damaged. Usually the cover is made of a material called mica.

Can a microwave cause an electrical fire?

Overheated food is a primary reason microwaves catch fires. It could be as simple as popcorn being microwaved for a minute or two longer than necessary or frozen meals being cooked too long. Besides this, faulty wiring or electrical shorts can cause a microwave fire, just like other appliances.

Why are things burning in my microwave?

Food-based fires in a microwave almost always happen because someone overestimated or mis-entered the cook time. An extra three minutes can be the difference between a nicely baked potato and a charred, smoky mess.

When should I replace my microwave waveguide cover?

Answer: The waveguide cover protects the gap where the microwaves enter the oven cavity from where they are produced by the magnetron. Additionally, it stops moisture and food particles from getting into the "workings" of the microwave. Replace the waveguide cover if it is burnt, chipped, or cracked.

Is it normal for a microwave to get hot on the inside?

Cooking foods in a Microwave Oven for an extended period of time can cause heat to transfer to the internal oven walls and floor as well as the external cabinet.

What are the symptoms of a bad magnetron in a microwave?

One of the most common issues with a malfunctioning Magnetron is the lack of heating. If your microwave is running but not producing heat, it could be due to a faulty Magnetron, burned-out filament, or a malfunctioning high-voltage diode.

How much does it cost to replace a magnetron in a microwave?

Magnetron Replacement

The magnetron is the heating technology that powers your microwave. Without it, your food is as good as cold. Replacing a microwave magnetron costs between $100 and $200 on average.

Why is my microwave making noise when not in use?

This could be caused by a faulty motor, worn-out bearings, or loose parts. Faulty control panel: In some cases, a malfunctioning control panel can cause the microwave to make unusual noises even when it's not in use.

Why did my microwave spark inside?

The electromagnetic waves bouncing around inside the microwave oven cavity will strike the metal object, producing a spark and a crackling sound. This is why it's important to only use microwave-safe plates and containers when heating up food or beverages.

Can you still use a microwave after it catches on fire?

If the fire warped the microwave door or frame such that the door no longer seals perfectly, then the microwave should be replaced. If the plastic around the door is not distorted, then it's probably fine.

How do I know if my microwave is bad?

When to replace the microwave? Common signs that your microwave needs changing
  1. Making funny noises.
  2. Smells like electrical burning.
  3. Isn't cooking food in the usual time or cooking unevenly.
  4. Needs help to work properly – such as a spoon to hold the door closed.
  5. Keypad has stopped working.

What is the best microwave brand?

As the best microwave overall, we chose the Panasonic Microwave Oven; it combines a 1,200-watt motor with a compact exterior. If you're looking to save money and space, the Commercial Chef Countertop Microwave is the best budget microwave: simple but effective, much like microwave cooking itself.

Is it OK to use a 20 year old microwave?

Microwaves older than 10 years or with faulty doors should be replaced immediately in order to reduce radiation exposure while you cook.

Is it worth fixing a microwave?

If the cost of repairing a microwave comes close to or exceeds the price of a new one, it might make more financial sense to replace it. However, if the costs of repairing are relatively low and the microwave isn't too old, it could be worth repairing the microwave.

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