The short answer
Split the symptom first. Heat or damage at the plug and socket is an electrical-installation problem for an electrician. Arcing, scorching or burning smells inside the appliance mean disconnect it now and have the appliance itself inspected.
Sort what you have
- The plug is warm or the socket face is discoloured — An installation problem, and a hazard on its own.
- The circuit trips when the microwave starts cooking — An appliance fault until proven otherwise.
- Flashes or sparks inside the cavity — Stop the cycle and disconnect at once.
- A burnt patch on the waveguide cover — Evidence of arcing; the unit is out of service.
- A smell of burning that follows the appliance to another socket — Definitely the appliance.
- Not this fault: cold food and nothing else — Read the not-heating page instead.
Ranked for a counter-standing unit
- Overloaded or shared circuit, or a light-duty extension lead — First here, and the usual reason for warm plugs and nuisance trips.
- Carbonised food residue arcing in the cavity — Second, and entirely preventable by cleaning splatter when it is fresh.
- Metal or metal-trimmed dishes used in the cavity — Third, common in shared kitchens where nobody owns the habit.
- Worn socket or damaged cord — Fourth: cords are trapped behind counters and chafe.
- High-voltage component failure — Fifth, and the usual cause of a trip that happens only on cook.
- Ventilation blocked so the unit runs hot — Last, and it contributes to several of the above.
Deal with it in this order
- Disconnect first if anything is arcing, smoking or smelling — No further testing until the power is off.
- Move the unit to a known-good dedicated socket, if nothing is damaged — It separates the installation from the appliance in one step.
- Inspect the cavity and waveguide cover for scorching — A mark there answers the question without any instrument.
- Keep the appliance disconnected if the mark is there — That result ends the investigation and starts the phone call.
What to do
- Cancel the cycle and unplug the unit — Disconnection precedes every other step on this page.
About 5 min
- Take the unit off any extension lead and put it on a wall socket — The single most useful change for a counter unit.
About 10 min
- Look over the cord for crushing or chafing where it passes the counter — Damaged cords are common and are not repaired with tape.
Tools: torchAbout 10 min
- Clean carbonised residue from the cavity and the cover face — Carbon is what arcs; fresh splatter is not.
Tools: cloth, dish soapAbout 20 min
- Leave it disconnected and call if anything has scorched — A unit that has arced will arc again.
What applies regardless of unit type
Safety
Unplug the appliance or switch off its breaker before removing any panel. A capacitor can hold a charge after the power is off, and inside a microwave that charge is lethal, so the case stays on in every circumstance. Do not repair a damaged cord with tape, do not reset a tripping breaker repeatedly, and do not use a unit whose waveguide cover is scorched or holed.
Who to call
Call an electrician for a warm plug, a discoloured socket or a circuit that trips with several appliances running. Call an appliance technician for arcing, scorching, burning smells or a trip that happens only when a cook cycle starts. If flame appears in the cavity, keep the door closed, cut the power if that is safe, and call the fire service.
Other pages here
Page scope
Generalized across families and written for counter-standing units; the companion page covers mounted installations above a range. A family-specific or model-specific page, where one exists, is the more precise answer. Not here: internal test procedures, discharge methods, component identification and wiring detail, none of which belongs in an owner-facing page for this symptom.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
