New GFCI Tripping Breaker

Question

To preface, some of the wiring in the family home was done "creatively" but it is only about 30 years old. I have previously replaced outlets and discovered the master bathroom outlets, one GFCI and one regular outlet, were not functioning. I don't know how long they were not working, probably quite a while.

I replaced the GFCI first and was careful about the load and line terminals and wires, and attached the grounding wire attached to the previous GFCI. Because I am paranoid, I turned the whole house electricity off, and as soon as I turned power back on, one breaker switch tripped right away. It didn't even stay on long enough for me to determine any fault with the GFCI itself, my helper said the GFCI light very briefly flashed red but it was not the same as any of the error codes on the GFCI packaging/instructions. The breaker switch that is tripping is labeled "Family Room 2" and as far as I can tell, all other lights and outlets are functioning besides the two master bath outlets, master bath fan and lights all work still. There actually is a "Master Bathroom GFCI" and "Master Bedroom & Bathroom Outlets" labeled breaker switches but I have no clue if those are properly labeled.

Did I mix up the load and line wires somehow? Should I try replacing the regular outlet to see what happens? I just want to do all I can safely do before I call an electrician.

Answer 1

Very unlikely the GFCI is at fault. Mixing up line and load won't do this, for instance. But you can check.

Turn power off, take it out, isolate the wires that were connected to it, turn power back on. If the breaker does not trip, turn power off, reconnect the wires while leaving the GFCI hanging in space, not touching anything else, turn power on. If the breaker trips now, either the wiring to the GFCI is wrong, or the GFCI might be that rare 0.01% case of "bad" in an odd way.

If the breaker does not trip with the GFCI out in space, turn power off and put it back into the box. Turn power on. If the breaker trips now, a wire is being shorted from putting the GFCI into the box. Turn power off, take it out, and fix that.

Additional consideration since the labeling on the breaker that trips seems to be wrong - if any of the breakers involved has a "test button" indicating that it is itself a GFCI or AFCI you might have a case of a shared neutral, which would have to be resolved. And in any case you should map out the actual relationship of outlets to circuits and correct the labelling as needed.