Why does a GFCI breaker trip when another breaker is accessed?

Question

I just bought a new house, and on the first day there realized a breaker was tripping. It is one of only two GFCI breakers in the box. It's 20 amp with a bedroom/bathroom on it. I tested every outlet on that circuit to make sure they were wired correctly, and they were. I reset the breaker and thought it was fixed.

Long story short, as it kept tripping and I kept investigating, I realized that it trips whenever something is plugged in to a circuit controlled by another breaker (one with my back porch, family room, and bar top outlets on it). Within the breaker box they are on top of each other: the GFCI that trips is above the regular breaker that seems to be causing the tripping. Only the GFCI trips, not the regular circuit breaker.

What would you all suggest?

Answer 1

From the description, it sounds like the neutral may be shared between the two circuits, which you can't do with a GFCI. The GFCI is looking for an imbalance of current on the hot and neutral lines, so if the neutral is shared with another circuit, there will be some current returning on the neutral that did not go out on the hot.

If you can trace the circuit and find the connection between the neutrals on the two circuits, and isolate them, that would be the easiest and cheapest fix. If the neutral is shared via a multiwire branch circuit from the breaker and can't be split, you can change the gfci breaker to a standard breaker and install a gfci outlet after the neutral splits for the two branches. And I'm also seeing two pole gfci breakers which would allow you to replace the two breakers with one that provides gfci coverage to both circuits and should handle the shared neutral, which may be a good fall back option if you can't locate the shared neutral.

Answer 2

Your neutral wire is shared between both circuits. Just pigtail the two hots and hook it up to your GFCI breaker. That's the easiest fix.