My GFCI outlet keeps tripping when my microwve oven is plugged in. There is also a regular toaster plugged in which does not cause trip. Both ae located near a sink, thus the GFCI. The microwave and toaster have been plugged into this outlet for over a year with no problems. Help please.

 

I see two possible problems. One possibility could be as simple as a bad GFCI receptacle. The second possibility could be a problem with the microwave oven. Since your toaster doesn't trip the GFCI, I am thinking it's a microwave oven problem.

 

Thanks CasualJoe, the microwave works on a regular outlet so I do not think it is that. The GFCI is only a year old and the toaster works fine on it. Not sure what is going on here.

 

You probably have a fault in the microwave oven. The GFCI receptacle detects ground faults as low as 5 mA so yes, it may work fine in a non-GFCI protected outlet, but that doesn't mean it doesn't have a problem. If the outlet you have plugged into is a non-GFCI protected outlet and it is on the kitchen countertop, it needs to be GFCI protected.

 

A regular outlet is protected by an OCPD - an Overcurrent Protection Device - that is designed to open the circuit when more power is being drawn on the ungrounded conductor than the device is built to allow. The OCPD - a fuse or circuit breaker - may take some time to open, and require a significant amount of power draw over the allowable amount.

A GFCI is designed to open the circuit when too little power is being returned on the grounded conductor. In addition to the small amount of "lost" power required to trip it, the GFCI may open the circuit in only a few milliseconds. It depends on the amount of power gone MIA.

Totally different forms of protection. The problem sounds like it's in your microwave.