Microwave sparking or arcing inside (all brands)
⚠️ This needs a qualified professional
This fault involves gas or mains electrical work. Don't attempt a DIY repair — UK law requires gas work to be carried out by a Gas Safe registered engineer. Below is what to check and describe to them, not step-by-step repair instructions.
Sparking or arcing inside a microwave needs to stop the appliance being used immediately — but the cause is very often something simple and removable, not a fault with the microwave itself.
What to check first (with the microwave switched off)
- Check for any metal — foil, a twist-tie, gold/silver trim on crockery, or a metal-flecked pattern on a plate — this is by far the most common cause of sparking and is completely harmless to the microwave once removed.
- Check the mica waveguide cover (a small rectangular panel, usually on a side or top interior wall, that protects the magnetron opening) for scorch marks, holes, or grease build-up — a damaged or heavily soiled cover is a very common cause of sparking that isn’t about what’s in the food.
- Check the interior generally for food splatter build-up, especially near vents — a build-up of burnt food residue can sometimes arc.
⚠️ Stop using the microwave if sparking continues
If you’ve removed all metal, the plate is safe, and the waveguide cover is clean but sparking continues, stop using the appliance. A damaged waveguide cover is an inexpensive, straightforward part to replace and often solves it, but if replacing it doesn’t help, don’t attempt anything further yourself — microwaves store high-voltage charge in an internal capacitor even when unplugged, and this can be dangerous. This is genuinely a case for a qualified appliance engineer, not a DIY repair.