The short answer
A microwave that trips its circuit or arcs inside is telling you something specific, and only two of the causes are owner business: what else shares the circuit, and what is inside the cavity. Everything past the cabinet screws is off limits, because the capacitor holds a dangerous charge long after the oven is unplugged. On a RecPro microwave the cause that ranks first is circuit shared or fed through an extension lead.
What you observe
- The breaker or protective device trips when the oven runs — A circuit-loading question first, an oven question second.
- Blue or white sparking inside the cavity while it runs — Arcing: metal in the cavity, damaged paint, or a carbonised waveguide cover.
- NEAR MISS — it runs normally but does not heat — That is a heating fault and belongs on that page.
Causes, most likely first on a RecPro microwave
- Circuit shared or fed through an extension lead — A microwave is one of the heaviest single loads in a kitchen. Ranked first on this microwave, because it explains most tripping complaints and it is free to test by moving the oven.
- Metal or foil in the cavity — Foil, a metal-trimmed dish, or a twist tie produces immediate visible arcing and can pit the cavity.
- Waveguide cover carbonised — The small cover on the cavity wall absorbs splatter, then carbonises and arcs against itself, with a burning smell.
- Protective device tripping rather than the breaker — A device tripping on a leakage fault is reporting something different from an overload, and it should not be reset repeatedly.
Check in this order, and why
- Note what else is on the circuit and whether an extension lead is involved — Most tripping complaints are resolved here and nowhere else.
- Stop immediately and look in the cavity for foil, metal trim or a twist tie — Arcing with metal present has an obvious cause and an obvious cure.
- Look at the small cover on the cavity wall for scorching or holes — A scorched cover explains arcing and a burning smell together.
What an owner can safely check
- Unplug the oven from any extension lead and run it from a socket of its own — If the tripping stops, the circuit was the cause.
About 15 min
- Stop the oven immediately, unplug it and remove everything metal from the cavity — Check for foil, metal trim on crockery, twist ties and skewers before running it again.
Tools: torchAbout 10 min
- Unplug the oven and inspect the waveguide cover on the cavity wall for scorching or holes — Clean gently if it is only soiled.
Tools: cloth, torchAbout 15 min
- STOP HERE if the next step needs a meter on live terminals or a panel off — That is where an owner check ends and a service call begins, whatever the ranking above says.
Before you open anything
Safety
Never remove the cabinet of a microwave. The high-voltage capacitor can hold a lethal charge long after the oven is unplugged, and nothing behind that cabinet is an owner repair at any skill level. Unplug the oven before cleaning the cavity or inspecting the cord. Never run a microwave empty, never run it with metal inside, and never use an extension lead. Stop immediately and unplug on any arcing, burning smell or smoke, and do not reset a protective device repeatedly to see whether it holds.
When to call a technician
Call, or retire the oven, on any burning smell, smoke, or arcing that continues after every piece of metal has been removed from the cavity. Call an electrician rather than an appliance technician if a protective device trips with the oven on a circuit of its own, because that is reporting a leakage fault in the installation. Stop using the oven in the meantime in every one of these cases: this is the one appliance page where continuing to use the machine while you decide is not an acceptable option.
Nearest pages of this class
What this page does not cover
This page is written for the RecPro microwave as a class, not for one family or model line. Where a family- or model-specific page exists for your unit it is linked above, it is the more specific answer, and it is the one to read first. Deliberately not here: part numbers, wiring colours, panel removal order and torque figures, which differ between families under the same nameplate.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
