In short
On a Kucht microwave, arcing inside the cavity is most often waveguide cover burnt or greasy. Stop the oven, remove whatever is inside, and look at the cavity and the waveguide cover before running it again. If it arcs with a clean, empty cavity and a cup of water, stop using it.
What this looks like
- Bright flashes or sparks inside the cavity while it runs — Arcing. Stop the oven immediately and look at what is inside before anything else.
- Rust or bare metal showing in the cavity — Damaged cavity coating will arc, and it is not something to paint over with an ordinary paint.
- The breaker trips when the oven runs — Either the circuit is overloaded or the oven has an internal fault. Neither is fixed by resetting it repeatedly.
- NEAR MISS — no sparks, but the oven does not heat — An oven that runs cold without arcing is a heating fault, and that page covers it.
The causes in order of likelihood
- Waveguide cover burnt or greasy — There is a small removable cover on the cavity wall that protects the opening where the energy enters. It absorbs splatter, and once that splatter carbonises it starts to arc — which burns the cover further, which makes the arcing worse. It is at the top because the evidence for it is visible from outside, and because the alternative explanations all cost money. Pro-style equipment is over-built in the mechanism and under-forgiving in the install, which is why placement and clearance rank above component failure here.
- Cutlery left in a bowl — It is the single most common cause of arcing, and it is entirely preventable: the fix is to look at what goes in rather than at the appliance. Second here: common enough to matter, and still answerable without a tool in your hand.
- An extension lead that cannot carry the load — A microwave draws heavily while it runs, and sharing a circuit with a kettle, a toaster or a second heating appliance is enough to trip a breaker with nothing wrong in the oven at all. Third: the checks above will usually have found the fault before this one is reached.
- Internal high-voltage fault — The capacitor in a microwave can hold a dangerous charge long after the oven is unplugged, which is why the outer cabinet must never be removed by an owner, however simple a video makes it look. It ranks last on the evidence rather than on its importance: when it is the answer, it is unmistakable.
Work through it in this order
- Check whether the arcing always happens in the same place — Arcing at one fixed point points at the cover or the cavity rather than at the food. First, and it costs nothing but a minute of attention.
- Run a short test with a cup of water in a plain ceramic mug — No arcing with a clean cavity and a plain mug means the oven is fine and the dish was not. Follow with this: it either confirms the second cause or clears it for good.
- Check whether the oven is on an extension lead or a multi-way adaptor — Microwaves belong in a wall socket of their own, not on a shared lead. Leave this one until the cheap checks are done; it is the slowest of the three.
Owner-side checks, in order
- Clean the cavity and the cover with warm soapy water once the oven is unplugged and cool — Do not remove the cover unless the manual describes it as a user-replaceable part.
Tools: cloth, mild detergentAbout 20 min
- Remove everything metallic and run a short test with water in a plain mug — Stand by the oven and stop it at the first sign of a spark.
Tools: plain ceramic mugAbout 15 min
- Plug the oven directly into a wall socket and run it alone — If the breaker holds, the circuit was the problem rather than the appliance.
About 15 min
- STOP HERE if the next step needs a meter on live terminals — That is the line between an owner check and a service call, and it is not a line worth crossing for a fault that is already narrowed to two causes.
Safety first, and it is not boilerplate
Safety
Unplug the oven first and let it cool. Do not remove the cabinet, do not attempt to discharge anything inside it, and do not test for leakage with a consumer meter — none of those is a safe or meaningful thing to do at home. Never operate an oven with a damaged door, latch or inner panel.
Where the owner fix ends
Call when the arcing has a fixed location and the cover and cavity are already clean, or when anything on this page is accompanied by smoke. Unplug it first and leave it unplugged.
Nearby pages
What this page leaves out
This is the generalized page for Kucht microwaves. If a page exists for your particular family or model line, it is linked from this section and it outranks this one for your unit. What is deliberately absent: part numbers, connector pinouts and the service-manual sequences, which are family-specific and wrong the moment they are generalized.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
