Our old microwave started tripping the breaker every 3rd or 4th time we would use it. I tried other outlets and they would also trip. So, I figured it was the appliance and bought a new microwave. It's rated at 15 amps and it's plugged into a 20 amp dedicated circuit. It worked fine for about a week but now it's tripping the breaker. First every 3rd or 4th time, now almost every time I start it. I've tried plugging the new microwave into different outlets and it trips the breakers on those too.

Anybody got any suggestions?

 

When wiring our house, my handy dandy wiring guide said to put the microwave on it's own circuit with a 30 amp breaker. I ran 10 ga. wire for this circui & it has never tripped the breaker.

 

Running a residential microwave that is cord and plug attached on a 30 amp circuit violates code. What wiring guide was that???

PeterBub, can you give us all the electrical specs that are on the sticker inside the microwave?

 

Just a thought.. although the circuit is 20 amps maybe it's not dedicated and now there exists another load somewhere on the circuit that is causing the breaker to over amp and trip. I have seen non-professional electrical work that has been done where outlets that are supposed to be dedicated are shared with combinations of other devices.

Try running the microwave while there is as little other power usage as possible lights, tv's, dishwasher, etc. See if it still trips and let us know.

 

I know it's not common, but since the breaker has been tripped so many times, I'd swap it out to be sure it isn't a weak breaker.

 

Yeah, I thought about the breaker being bad, but it seemed coincidental that two different breakers tripped when I tried different outlets. But changing the fuse is something I was going to try.

The specs on the microwave are:
Power Supply: 120V 15A single phase with grounding 60HZ, AC.
Power Consumption: 1400 W
Output Power: 1000 W
Frequency: 2450 MHZ

Thanks to everybody that's been responding.

 

If it is not broken, it should only pull about 11.7 amps. There will be a surge the first time the power supply for the magnetron is energized. I would suspect something else is on the circuit with the microwave. If you have a circuit tracer you can use it to chase down what else might be on the circuit.

 

I'm betting that this circuit is not really "dedicated." Shut off the breaker and test everything in the house to see what doesn't work any more.

 

Egg on my face... Instead of looking it up, I went from memory. It does say 20 amp, 120 volt dedicated circuit. Many appologies. My memory is like a GFI that's been tested one too many times.
The wiring guide is Advanced Home Wiring from Black & Decker. I did the whole house with it & the only trouble I had is with the 3 way swiches in the garage. I must have something wired wrong somewhere. When the switch near the overhead door is used to turn the lights off, the one in the house will not turn them back on. It was also one of the last circuits that I ran. Go figure...

 

I checked the circuit. I couldn't find anything else hooked in other than the microwave, so I switched out the breaker with a new one. The microwave hasn't tripped the new breaker for the last two days, so it seems that the culprit was a faulty breaker.

Thanks to everyone for their help.