Mwave has been there for several years and worked just fine. The past few months, it has started to occasionally (1 time in 20 or so) throw the breaker. 1,000 watt Mwave on a 20 amp breaker, neither of which is more than a 6 or 8 years old. Nothing else on the breaker but the Mwave. Ideas?

Problems with microwave my first guess, or issue with breaker, or a wire issue (often at a connection)

Try microwave on other circuit for a bit, see if there is still issues, if there is, then it is the microwave.

Trying other appliances on the dedicated line, or moving the microwave to another line is a good suggestion to troubleshoot your problem. Anything else costs good money.

The microwave is a built in so putting it on another circuit would be difficult. There's no receptacle on the circuit so can't try other appliances. I guess I'll try replacing the breaker first, or swapping it with a known good breaker.

Got a multimeter?

I do.

You're good to go... piece of cake*. 8D


*Safety ALWAYS first.

If the only device on the branch circuit is the microwave and the branch circuit is a 20 amp circuit you should not be seeing a problem.

That's the theory of it. However, since circuit breakers react to amperage, not voltage, I suspect that the microwave's motor is starting to bind up during startup which draws more current than the normal inrush current which if it lasts for a long enough period could trip the breaker.

I would really need to put an ammeter around the wire and just stop and stop the microwave until I could trap the failure

Quote:

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That's the theory of it. However, since circuit breakers react to amperage, not voltage, I suspect that the microwave's motor is starting to bind up during startup which draws more current than the normal inrush current which if it lasts for a long enough period could trip the breaker.

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That sounds believable. I bought a new breaker today and will try that. If it continues, then I have to assume it is the Mwave? Don't have an ammeter, but it does seem to happen when the Mwave starts up.

There is more than just a microwave generator in a microwave oven. System electronics, light, plate rotator, exhaust fan and microwave stirrer. A problem with any of these could cause the overload. Hopefully, it's just a failing breaker.

Yeah. I hope the same thing.

You don't have to remove or unplug Microwave to try on a different circuit, a Troubleshooter may remove microwave wire from breaker, then place wire on another Breaker. Swap temporarily so you are not losing something else,