Is it dangerous when a microwave sparks?
Yes. Sparking means the microwave energy is arcing to something it should not reach. It can burn holes in the cavity, damage the magnetron and start a fire. A single spark from a forgotten piece of foil is easy to fix. Sparking that keeps coming back is a fault.
Common causes
These are the usual causes, starting with the ones you can check yourself.
At a glance
| Cause | Who fixes it |
|---|---|
| Metal in the cavity | You can check this |
| Food and grease build-up | You can check this |
| A burnt or dirty waveguide cover | Technician |
| Chipped paint or rust on the walls | Technician |
| A damaged turntable support or stirrer | Technician |
- 1
Metal in the cavity
You can check thisFoil, metal containers, plates with gold or silver trim and twist ties all cause sparks. Some dishes have metal in the glaze that you cannot see. Use only dishes marked microwave safe.
- 2
Food and grease build-up
You can check thisSplashed food and grease on the walls and ceiling can burn and arc, especially near the waveguide cover. Clean the cavity with warm soapy water and dry it well.
- 3
A burnt or dirty waveguide cover
TechnicianThe waveguide cover is a small panel, usually on the right-hand wall or ceiling, that lets the microwaves into the cavity. Grease soaks into it and burns. A cover that is dark, soft or holed needs replacing.
- 4
Chipped paint or rust on the walls
TechnicianBare metal or rust spots inside the cavity can arc. Small chips can be repaired with the right microwave cavity paint. Large rusted areas usually mean the microwave is at the end of its life.
- 5
A damaged turntable support or stirrer
TechnicianA cracked roller ring, a metal part out of place or a damaged stirrer fan cover can cause arcing. A technician checks these when the source is not obvious.
What you can safely check yourself
- Stop and unplugStop the microwave as soon as you see sparks and unplug it.
- Remove any metalTake out foil, metal-trimmed dishes and anything with a wire or clip.
- Clean the cavityOnce cool, wash the walls, ceiling and door with warm soapy water. Pay attention around the waveguide cover. Do not remove any screws.
- Look for damageLook for chipped paint, rust spots or a burnt waveguide cover. If you see any, do not use the microwave until it has been checked.
- Test with waterHeat a cup of water on full power for one minute and watch. Any sparks mean it needs a technician.
When to stop and call a technician
The sparks continue with nothing metal inside, the waveguide cover is burnt or holed, there is a burning smell or smoke, or the microwave trips the power. Do not open the casing to look for the cause.
Still having trouble with your microwave?
Our technician comes to your home, usually the same day. The R450 call-out falls away if you go ahead, and you get a fixed price in writing before any work starts.
How a technician diagnoses it
- Find the arc pointThe technician inspects the cavity, waveguide cover, stirrer and turntable parts for burn marks.
- Replace or repairA burnt waveguide cover is replaced and damaged cavity paint is repaired where that is safe.
- Check the magnetronArcing can damage the magnetron, so its output is checked too.
- Fixed priceYou get a fixed price in writing before any work starts.
Is it worth repairing?
Usually worth repairing when
- Only the waveguide cover is burnt
- The cavity paint has small chips
- It is a built-in or combination microwave
Consider replacing when
- The cavity is rusted through
- Sparking has damaged the magnetron on a basic model
- The door or seal is damaged