GFIC tripping.

[Strange1]

Here's the situation. When the microwave is used for an extended length of time or when it is activated several times in succession, the house GFIC breaker will trip. The microwave is on another circuit and it does not trip. When the GFIC breaker trips it doesn't have over 6 amp load. No other circuits causes this to happen. Any Ideas on what might be causing this and how to troubleshoot it. I have the electrical tools necessary for testing and have wired and/or repaired many buildings in my time but this has me stumped. I assume it has something to do with the balance on the hot and common leg. Thanks

Jack

[HayZee518]

why don't you remove the gfci breaker and install a standard breaker and replace the outlets with gfci receptacles. this way when one trips it doesn't take out the whole line. the microwave uses a transformer and a dc rectifier called a bridge rectifier. the bridge rectifier conducts on one-half of the sine wave for each cycle. this might be where the problem is because when one side of the line is going positive, the other side is seeing zero volts. this may be the imbalance the gfi is seeing. the transformer takes the 120 volts and drops it for use with the electronics. the magnetic field across the iron is induced in the secondary at 180 degrees out of phase with the input.

[Strange1]

Thanks Hayzee. Thought it might be something like that. As an afterthought tho, I wonder why it just started doing it when the microwave is a couple of yrs old? Also, I just remembered that the outlet in the garage, which is on the GFIC has 2 fridges plugged into it. Should I run another circuit to the fridges? Also the GFIC had tripped a number of times before when a lot of other things in the garage was on that circuit too. I dropped a new line from a diff circuit for those other usages in the garage but the fridges are still on the CFIC ine and are a long way from the outlet to the other circuit so would be a bit difficult to change where they are pluggedin . With that thought tho, could the CFIC breaker be getting weak. Thanks again.

Jack

[HayZee518]

It is a posibility that they are getting weak especially from all the nuisance tripping. As far as the fridges go. change the outlets to standard ones. code says that at least one receptacle be gfci. power tools are notorious for tripping gfci-s.

[Strange1]

Thanks again. Will try a few things to see if I can resolve the prob.

Jack