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#261 - 01/05/01 09:11 AM SQ. D GFI Circuit Breaker  
Bob Hinshaw  Offline
Junior Member
Joined: Jan 2001
Posts: 5
Tipp City, Ohio, USA
I have a 15 amp GFI circuit breaker that trips everytime the microwave oven is started. The microwave is not on the same circuit as the cb, and no matter what circuit in the house or garage I plug the microwave in, when it is turned on it trips the cb. If the microwave is off, everything works fine. I have changed out the GFI cb with a new one and it still does it. The only way it will work, is with a standard cb. Also, with the microwave plugged in a GFI receptacle, it does not trip it, but will still trip the GFI cb that is on another circuit. The microwave is new. Any suggestions??????????

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#262 - 01/05/01 11:09 AM Re: SQ. D GFI Circuit Breaker  
sparky66wv  Offline
Joined: Nov 2000
Posts: 2,236
West Virginia
Don't know if this is any help, but I've been having a tough time even getting SQ D GFCI Circuit Breakers... Something about a recall, I've been told by my local supplier. And I was also told that the problem with them is inadvertant tripping. The symptoms you're having sounds like the problem that started the recall, but I'm really in the dark here and I'm really guessing big time.

Any additional comments, guys?

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#263 - 01/05/01 12:41 PM Re: SQ. D GFI Circuit Breaker  
RobertW  Offline
Junior Member
Joined: Jan 2001
Posts: 2
A micro oven doesnt have to be on a gfci circuit.If you microwave is in the can be pluged in to a dedicated single 20 a recp. the reason your gfi trips on another circuit doesnt make sense.If the micro is pluged in to another is possible you may think its on a diffrent circuit but it could be fed downstream from the gfci breaker or device.

#264 - 01/05/01 07:08 PM Re: SQ. D GFI Circuit Breaker  
Bennie R. Palmer  Offline
Joined: Nov 2000
Posts: 72
Milwaukie, OR 97267 USA
Bob: This is an interesting event. There is always a logical explanation for all effects of electricity. Unfortunately, I do not have an immediate answer, or possibly no answer.
I will investigate the power supplies of micro-wave ovens. I think they present a non linear load. This can produce a distorted sine wave. I will also look at frequencies this produces, and see if there can be some relationship with the sensing system of the other non related device.
Keep us informed if you discover a more sensible resolution, or cause.

#265 - 01/05/01 08:55 PM Re: SQ. D GFI Circuit Breaker  
jeff1  Offline
Junior Member
Joined: Dec 2000
Posts: 2

My 1 & 1/4 cents worth ( darn Canadian money )....most microwaves will operate ok on a 15 amp circuit....but with the power output increasing every year ( 800-900-1000-1100 watts ) it may be best to have a 12 gauge 20 amp circuit dedicated for the micro only.
We have run into this with many of the newist micros on the market. A standard outlet and breaker is often best :-)


#266 - 01/06/01 08:36 AM Re: SQ. D GFI Circuit Breaker  
sparky  Offline
Joined: Oct 2000
Posts: 5,311
I had a situation where a neutral was bad, but it only showed up under a load condition.
I'd be inclined to crank up that wave, and do some metering.... [Linked Image]

#267 - 02/24/01 03:17 AM Re: SQ. D GFI Circuit Breaker  
silverbk  Offline
Joined: Feb 2001
Posts: 60
Your problem sounds likeit could be an improper splice. I have seen experienced electricians that do not understand the principal behind a GFCI circuit and splice it incorrectly. It's possible that your ground and neutral are bonded together somewhere in the house. In any event I would suggest getting a shortstop and start looking at your junction boxes.

#268 - 02/26/01 09:48 PM Re: SQ. D GFI Circuit Breaker  
elec3  Offline
Junior Member
Joined: Feb 2001
Posts: 1
Thief River Falls, MN,USA
The mic should be on a dedicated cicurit.But if you wish to GFCI the mic try a type B GFCI

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