I recently ran a branch circuit to the exterior of the house to add a receptacle on the patio. The existing 15 amp breaker protected a circuit that had only three plug outlets and one switched ceiling light. The circuit is very lightly used. So I want to add GFIC protection in the form of a breaker in the service panel.The existing breaker is a single pole 15 amp breaker. It has only one wire to it (black). The 15 amp single pole GFCI breaker that I purchased to replace it has a white pigtail on it. I connected this to the buss bar and the existing black wire to the load lug on the new breaker. It trips as soon as I try to switch it on. Can anyone help? The directions that came with the GFCI breaker show a white wire attatched to the neutral lug on the breaker, but there was no white wire to the original breaker. Thanks. Dave.

Next to the white "pigtail" is a silver terminal, you need to find the neutral wire for the circuit you want to GFI protect, remove it from the neutral bar, and connect to this silver terminal.

Be sure to shut this circuit off, as if there is a load, you will break the neutral and now have 120 volts across that white wire and ground/neutral.

There are no white wires connected to any 1 pole breakers now because they are not GFI breakers, or Arc Fault breakers.

Not to confuse you, there may be white wires connected to a 2 pole breaker, in this case the white wire is being used as a hot, along with the black for a 240 volt circuit.

Thos this has always been allowed, code now requires that a white wire being used as a hot needs to be labeled as ahot , at both ends and anywhere the wire is exposed in a junction box.

Thank you very much tkrussel. I didn't know if I made myself clear enough, but you understood the problem and helped me fix it. I really appreciate your advice. I was confused about the neutral bar and the missing white wire from the circuit, as the instructions said to attach the pigtail to the bar.(And the white wire from this circuit was already connected to the bar) Followed black wire back to entry point and took white wire from circuit and connected it as you stated. Problem solved. Thanks again! Dave.