I'm not an electrical contractor, but I'm a pretty experienced DIYer having done a lot of residential wiring on my own homes - under permit. I'm stumped on a current problem, so I'd appreciate any troubleshooting tips.


My home has 200 amp service. From the main service panel, I have run a 50 amp sub-panel to the other end of my basement.

The bathrooms and exterior outlets run from a GFCI breaker in the main service panel.

From the sub-panel, I have a 15 amp dedicated circuit supplying the microwave in the kitchen.

The subpanel was installed about 5 years ago - and inspected. All has been well until a few days ago.

Now, when one turns on the microwave (a dedicated circuit from the sub-panel), the GFCI breaker (in the main panel) supplying the bathrooms and exterior outlets flips off.

Any explanations or ideas?

Thanks for indulging me.
gary comfort
reston, va 20191