I have attached some romex to an existing light fixture in my garage. I ran it to a pair of switches and an outlet that I have mounted on the outside wall of my garage. I have separated the outlet so that each switch controls one of the plug-ins. One plug-in is going to power a small pond pump while the other is going to some decorative lighting. I want to control these devices separately. Up to this point, everything is working fine.
I want to add some protection (since water will be everywhere) by upgrading the existing circuit breaker to a GFCI Breaker. It is my understanding that a GFCI Breaker has both the line and the neutral of the circuit connected directly to it and it has it’s own pigtail connection to the neutral. I have installed a GFCI Breaker before but it was to a new circuit that I ran all of the wires for myself. I can find the line wire easy enough since it is attached directly to the existing breaker. It is the neutral that I am having some problems with. I disconnected every neutral wire in my Main Panel and attached the garage’s line wire to the GFCI Breaker and the GFCI Breaker’s pigtail to neutral. I tested each neutral wire until I found the one that did not trip the GFCI Breaker immediately upon hook-up. I reconnected all of the neutrals and everything was working fine by my early afternoon finish time only to wake up the next morning to a tripped GFCI Breaker that would not reset. Something must be keeping it tripped. (By the way, nothing is hooked up to this new circuit yet.) I reinstalled the original 20 amp breaker and everything came back to life.
I do not know what I have done wrong. Did I choose the wrong neutral? Why did it work for hours with no problems if I did? My garage has some fluorescent lights and I have been told that GFCI and fluorescents do not mix.
I am considering installing a GFCI Receptacle between the light fixture that I grabbed power from and the switches that I installed to control the plug-ins, but that would be an absolute last resort.
Please help.

 

Your procedure for choosing the right neutral may have been flawed. Just because it doesn't trip the GFCI doesn't necessarily mean that it was the right neutral, especially if no current was flowing at the time. You might have the right neutral, but you might not.

Here's what I suggest. Shut off your new breaker, remove the black and white wires from it. Go to the new switch box and temporarily connect the white and black wires together, deliberately creating a short circuit. Now go back to the panel. Use your ohmmeter to test for continuity between the black and white wires. If you get continuity (i.e., near zero ohms), then you have the right wire. Don't forget to remove your deliberate short before hooking it back up.

If the GFCI still trips after verifying the right wire, then you must have a real ground fault. You can isolate this by disconnecting one thing at a time from the circuit until it no longer trips.

I have no explanation for why it worked for a while. Perhaps dew or some other moisture got into a box overnight, creating a ground fault. If so, you will need to put in more protection against moisture

As you said, you could have done this much more simply, and much less expensively, by simply putting a GFCI receptacle between the ceiling lights and the two switches.

 

If i understand this correctly, you took power from an existing light fixture in your garage, which should be switched, so the tap you installed to provide power to the other devices will not work unless the light is switched on. As far as the wiring is concerned, you should have run a 3-wire to your new switch box, and 2-wire from there to each of the additional devices. You should have spliced and pigtailed the two hots in the 3-wire to the hot in the existing switch leg of your garage light. As far as the breaker is concerned, the GFCI breaker should have replaced the existing breaker that controls the garage light you tapped off of, with both the hot and neutral wires going into the breaker. Check to see that the hot and neutral are not reversed at the breaker, and if you still have a problem after checking this and backtracking your new wiring, please post back.

 

EMS, thanks for pointing that out that potential problem. I assumed that there was constant power at the ceiling light, perhaps with a switch loop providing the switching, or perhaps the lights are operated by a pull chain.

 

Actually John has the correct scenario.
I forgot to mention that the existing light fixture that I grabbed power from is constant hot with the existing light turning on & off with a pull chain. I did not want to have to turn on multiple switches to activate these two outdoor devices.
I will have to wait til later in the week when I have some more time but I will take your advice to short the connections at the new switch and use my ohmmeter to determine the correct neutral and post back with the results.
Thank you.

 

I did as John suggested and shut off the main panel, shorted the line & neutral wires at the constant on light fixture in the garage where I grabbed power from and then disconnected every neutral from my Main Panel for testing. The neutral that read a direct short on my ohmmeter was the same wire I had used initially.
The house is 15 years old and the previous owner ran lots of things off of similar circuits and it would be impossible to narrow down what may be tripping the GFCI Breaker I originally installed.
The fix I implemented was my last resort idea from the first post. I cut the romex between the constant on light fixture and my new pair of switches and installed a GFCI Receptacle facing into the garage (I did not expose this fixture to the outside of the garage like I did the switches and the corresponding outlets). While this was my last resort – I feel now that it is the best way to accomplish the protection to the pond pump & lights without knocking out my whole garage & laundry room if it happens to trip.
Thanks all for the help.