The short answer
On TM models the electrical complaint that turns up most is not inside the appliance at all: it is the outlet, the plug or the circuit. A standard household branch circuit is 15 A or 20 A at 120 V, and a microwave sharing one with the rest of a kitchen will trip it under load. Establish what the circuit is doing before anybody looks inside the appliance.
What the supply side looks like
- The breaker trips when the appliance is asked to heat — Under load rather than at random, which is the distinction that matters.
- The plug or the outlet is warm after a run — Act on this. Heat at a connection is a fault rather than a characteristic.
- Lights dim briefly when the heat starts — A report about the circuit, worth passing to an electrician.
- It trips only when something else in the kitchen is running — A shared-circuit finding, and a free one.
- A smell of hot plastic near the outlet — Isolate the appliance and stop using that outlet until it has been looked at.
Supply causes, in order
- A circuit carrying more than it should — It leads because it explains the trips, the dimming and the timing together, and because it is free to establish. The appliance in this case is not faulty at all.
- A poor connection at the outlet or the plug — A loose contact makes heat, and heat at an outlet is the symptom owners most often describe as a warm plug. It is the finding that justifies stopping immediately.
- An extension lead or an adaptor in the path — Neither belongs in front of an appliance that draws what this one does, and both are common causes of exactly these symptoms.
- Something in the cavity — Metal or a damaged cover produces flashes and a smell without troubling the breaker, which is how a cavity fault and a supply fault get separated.
- A fault drawing current inside the appliance — Last. It is what remains when the circuit is proved good and the appliance still trips it, and it is a technician matter from that point on.
Establish the circuit, then the appliance
- Note whether the trip happens as the heat starts or at random — It is the single most informative observation on this page and it costs nothing.
- Run the appliance with nothing else on in the kitchen — If it holds, the finding is the shared circuit rather than the appliance.
- Feel the plug and the outlet after a run, with care — Warmth is a finding. Stop using that outlet and have it looked at.
- Remove any extension lead or adaptor from the path — Plug the appliance directly into a wall outlet, which is the only correct arrangement for it.
- Stop resetting a breaker that will not hold — A breaker tripping repeatedly under load is reporting a condition, and resetting it in a loop ignores the report.
Before you open anything
Safety
Do not run this appliance from an extension lead or an adaptor. Do not keep resetting a breaker to get through a meal. If the plug, the outlet or the cord is warm, discoloured or smells, isolate the appliance and leave that outlet alone until an electrician has seen it. Unplug the appliance or switch off its breaker before removing any panel, because a capacitor can hold a charge after the power is off.
When to call a technician
Observing when the trip happens, testing with the kitchen quiet, and removing adaptors are owner work. A warm outlet, a breaker that will not hold, or dimming lights are an electrician’s call rather than an appliance technician’s. Call an appliance technician when the circuit has been proved good and the appliance still trips it.
Other faults covered for TM models
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
