Microwave tripping breaker


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Old 10-08-22, 11:52 AM
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Microwave tripping breaker

So my microwave oven has always worked fine, even today when I reheated leftovers for 55 seconds. But a little while later when I set it for 47 seconds it tripped the breaker after 2. Itís a recently installed outlet so I took the MW to the other side of the kitchen and it tripped that one too. When I reset the breakers I saw they are both new. Back to its original spot the MW tripped the breaker again, this time after 5 seconds. It has always worked fine, even an hour ago.
 
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Old 10-08-22, 01:15 PM
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A consumer CANNOT be exposed to the short (micro) radio waves that a microwave oven generates while running so if the door is opened the microwave shuts down. There are at least two switches. One is power to the microwave section and the other is a fail-safe clamp.

When the door opens.... the one switch opens power to the microwave section and the other one dead shorts the high voltage. A common problem is that the primary switch doesn't disconnect power to the microwave and the fail safe clamps and creates a dead short.

A common problem on inexpensive microwave ovens and in particular GE units.
It's typically caused by switch mounting issues from cheap or damaged plastic mounts.
 
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Old 10-08-22, 03:49 PM
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Not a cheap model, a Panasonic Inversion something or other. Would the issue you describe take the 2-5 seconds before breaker tripping into account?
 
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Old 10-08-22, 03:54 PM
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I'm assuming a standard breaker is tripping.... is that correct ?
If not correct..... is it a GFI or AFCI breaker ?


On edit:
Are these GFI or AFCI or COMBO breakers ?
It needs to be determined if the microwave is leaking to ground or has an internal arcing problem.
Neither are very common.

Would the issue you describe take the 2-5 seconds before breaker tripping into account?
Yes. The fail safe shorts out the high voltage. You can hear the fan start and then you can usually hear when the HV starts as it creates a humming noise and the internal light usually dims slightly. If you were to select a lower temperature the HV would cycle.
 

Last edited by PJmax; 10-08-22 at 07:14 PM.
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Old 10-08-22, 06:06 PM
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Is the microwave on a dedicated circuit or are there other things on this circuit?

I know you said you tried it on two different circuits, so I am assuming at least one or both circuits have various other items on those two circuits. If so, that could be an issue.

You said there was a new breaker on this circuit. There are some possibilities here. Correct type, brand & amp breaker for the panel & circuit?
 
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Old 01-30-23, 07:28 AM
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PJmax
Are these GFI or AFCI or COMBO breakers?
Dixie2012
​​​​​​​Is the microwave on a dedicated circuit or are there other things on this circuit?
Sorry I ghosted my own thread for so long! Combo breakers, and the MW shares the circuit with outlets by the sink; I assume I could have had a standard breaker for the MW outlet otherwise. The electrician says these breakers are more sensitive than typical GFIs, and he replaced them with another brand. He tested them by running the MW from multiple outlets and it worked most of the time; it has worked fine for me so far, knock on wood. He says the cellar where the panel is located is really damp and that might have something to do with it. I think a French drain or other wet cellar mitigation might be a future home improvement project for me.
 
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Old 01-30-23, 07:00 PM
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Some GFI's do seem to trip quicker than others.
Also.... newer models are more reliable and accurate.
 
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Old 01-30-23, 08:14 PM
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A common problem is that the primary switch doesn't disconnect power to the microwave and the fail safe clamps and creates a dead short.
This was exact issue I had with my microwave oven once. Primary switch arced and contacts were welded together. I found primary switch is designed to carrying pretty much full operating current of magnetron and microwave stops by opening this switch when the door is open. My guess for the cause of failure is every time the door is open while microwave oven is operating, primary switch has to break high current, which is sure to arc. This will degrade contact points and eventually lead to arcing in closed position, which can weld them together.
Ever since I learned how this switch works, I don't open microwave oven while it is operating. I first press cancel/stop button before opening the door.

However, I doubt this is the cause of problem eddieo has. Safety circuit will blow fuse inside microwave oven. Sometimes it will trip the breaker too, but it will blow fuse for sure.

electrician says these breakers are more sensitive than typical GFIs, and he replaced them with another brand.
Was it GFCI receptacle that was replaced, or was it actually a breaker?
You cannot switch breaker to another brand. You must use breaker approved by the manufacturer of load center, which typically is the same manufacturer of the breaker.

If it was GFCI receptacle that was replaced, was GFCI tripping not the breaker? If it was actually breaker that was tripping and that breaker is not GFCI combo breaker, GFCI will be irrelevant in this case.
 
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Old 01-31-23, 01:45 AM
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The electrician says these breakers are more sensitive than typical GFIs, and he replaced them with another brand...
A word of caution here: This new brand breaker/s he used are they rated for the brand/model of your panel? Just because a breaker fits in a panel doesn't mean it is rated for that panel.
 
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Old 01-31-23, 04:22 PM
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Combo breakers,
​​​​​​​What the heck is a combo breaker?









 
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Old 01-31-23, 10:38 PM
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What the heck is a combo breaker?
I'm with CasualJoe on this one.

Do you mean "dual function" as in AFCI/GFCI breakers?

If a circuit's breaker is tripping it is trying to tell you something is not right.

Also as I stated in my earlier post - replacing a breaker in a panel with a different brand name could possibly be a hazard and should be avoided. You must only use breakers in a panel that the panel is rated for. The panel brand and model spec sheet should tell you the possible replacement breakers that you use in that panel. Only breakers that are rated for that panel can be used. Just because a breaker fits does not mean it will function correctly.

 
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  #12  
Old 02-16-23, 12:37 PM
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Panasonic inversion microwave has true variable microwave power settings. So start with the lowest power and see if it still trips the breaker. If you have a power measuring device (e.g. kill-a-watt) that could help too.

To see if the breakers are overly sensitive, plug in a hair dryer and put it on max power.
 
 

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