A microwave tripping the breaker comes down to one of two very different things: the circuit it is plugged into, or something failing inside the microwave itself. The first is a cheap, sensible fix. The second is one of the few household repairs you genuinely must not attempt yourself. Telling them apart starts with when it trips, and what else is running.
The common, harmless one: an overloaded circuit
Most of the time, this is just too much on one circuit. A microwave pulls around 12 amps and really wants its own dedicated 20-amp circuit. Plug it into a shared kitchen circuit alongside the kettle, the toaster and the coffee maker, and the moment two of them run together you sail past what the breaker allows, and it trips.
The tell is simple: if the breaker goes when other kitchen appliances are also on, but the microwave is fine on its own, the circuit is overloaded, not broken. The fix is a dedicated circuit, which is exactly what an over-the-range or built-in microwave is supposed to have, as we explain in what size wire and breaker does a microwave need?
The internal faults
The other possibility is a fault inside the microwave. The high-voltage side, the magnetron that makes the microwaves, plus the high-voltage capacitor and diode and the door safety switches, can short or fail and draw far too much current. The timing hints at which. A trip the instant you press Start often means a shorted door switch. A trip partway through cooking points more to a failing high-voltage component heating up. On a GFCI outlet, a microwave can also nuisance-trip, because it leaks a tiny bit of current that a sensitive GFCI reads as a fault, and a failing part leaks more.
Never open a microwave to fix it
This is the one to take seriously. Do not open a microwave to repair it. Its high-voltage capacitor can hold a lethal charge even after the microwave is unplugged and has been sitting for a while. A microwave is one of the very few things in your home that can electrocute you while it is switched off and disconnected. Internal repairs are strictly for a qualified appliance technician who knows how to discharge that capacitor safely, and honestly, for many microwaves the sensible answer is to replace the unit, since a new one often costs less than the repair.
What we can do
If the cause is the circuit, an overloaded or shared one, that is our side of the fence, and we will fit the dedicated circuit the microwave should have had. If the fault is inside the unit, we will tell you that plainly rather than open it up, so you can call an appliance technician or replace it. We test the circuit, the breaker and the outlet to work out which it is, as part of wiring and installations.
Related reading
- What size wire and breaker does a microwave need? for the dedicated circuit a microwave should be on.
- Why does my breaker keep tripping? for the wider picture on tripping breakers.
- Wiring and installations for adding a dedicated microwave circuit.
Why does my microwave trip the breaker when other appliances are on?
That is the classic overloaded-circuit sign. A microwave draws around 12 amps and wants its own dedicated 20-amp circuit. Sharing one with the kettle, toaster and coffee maker means that running two together exceeds the breaker’s limit and trips it. The fix is a dedicated circuit for the microwave.
My microwave trips the breaker even on its own. What does that mean?
If it trips by itself, the fault is more likely inside the microwave: a shorted magnetron, a failing high-voltage capacitor or diode, or a shorted door switch. A trip the instant you press Start often points to a door switch, while a trip partway through cooking points to a high-voltage component.
Can I open my microwave to fix what is tripping the breaker?
No, never. A microwave’s high-voltage capacitor can hold a lethal charge even after it is unplugged and left to sit. It is one of the few appliances that can electrocute you while switched off. Internal repairs are only for a qualified technician who can discharge it safely, and often replacing the microwave is cheaper anyway.
Why does my microwave trip a GFCI outlet?
Microwaves leak a tiny amount of current that a sensitive GFCI can read as a ground fault, which causes nuisance trips even on a healthy unit. A failing internal component leaks more and trips it for real. A dedicated, properly chosen circuit and outlet usually sorts the nuisance case.
Does a microwave really need its own circuit?
An over-the-range or built-in microwave should have its own dedicated 20-amp circuit, because its draw is too high to share. A small countertop unit is more forgiving but still should not run on the same outlet as other high-draw appliances at the same time.
Is a tripping microwave dangerous?
The tripping itself is the breaker doing its job. The danger is in trying to repair the microwave yourself, because of the stored high-voltage charge. Sort out an overloaded circuit with an electrician, and leave any internal fault to an appliance technician or simply replace the unit.
The next step
If your microwave trips the breaker mainly when the kitchen is busy, it probably needs a circuit of its own. Get a free quote or message us, and we will check the circuit and outlet, fit a dedicated circuit if that is the cause, and tell you honestly if the fault is one for an appliance technician instead.