Microwave keeps tripping breaker


Old 10-08-09, 04:03 PM
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Microwave keeps tripping breaker

I have an eleven year old home with a built-in microwave that keeps tripping a 15 amp breaker.

The funny thing is that it only trips the breaker if it is turned off by pressing the door release. There is another way to stop the microwave and that is by pressing the off button, that does not trip the breaker.

So if it is running and you hit the off button then the door release there is no problem. But if it is running and you hit the door release as a method of stopping it the breaker will usually trip, not always but usually.

I've replaced the breaker but it made no difference.

What's the deal?
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Old 10-08-09, 04:09 PM
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The microwave should be on a dedicated 20 amp circuit to begin with. It is possible the microwave, while running, along with other things on the circuit (lights, etc.), are peaking the breaker out. Stopping it with the door latch could cause an arc that sends it over the edge. Stopping it with the cancel switch may not be as much a load.
These are all probabilities, and others may have other ideas, so give 'em a chance.
Old 10-08-09, 04:54 PM
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Perhaps the door switch is broken and is shorting out to the case when you pull the door open.
Old 10-09-09, 06:58 PM
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I concur with ibpooks, kind of, but would suspect a faulty or misaligned interlock switches. Typically they are configured as such as one mode shorts across the magnetron line, but should only close after the series switches open.
Old 10-09-09, 07:50 PM
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"What's the deal?"

The deal is there is something wrong with the microwave. You have a two choices: Replace it or Repair it.

I'm assuming it is also 11 years old, so it probably isn't worth the cost of the repairs. This is probably not a do it yourself repair either. It is possible to have a radiation leak if the unit is not put back together correctly and there are some pretty high voltages at the magnetron.

In short, it is not safe to continue using it as is. Whatever is wrong is overloading the circuit that it is on and tripping the breaker. I know you know how to "work around" the problem but it is still not safe.

It's kind of like having an extension cord with a bare spot. It works great as long as I don't touch the bare spot. Sooner or later something will happen, you'll get busy and forget, and then...

Unplug it until you decide what to do.
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