I had to install 3 x GFCI breakers in my panel to bring my kitchen up to code following a kitchen remodel (lucky for me I have 3 separate circuits in my 10x10' kitchen !). Two of the breakers switch on fine and test OK. One of the breakers trips immediately when switched on. I have tested the breaker on another circuit and it works fine. I have also checked the wiring on the 3 outlets which seem to be in order and have also worked fine for the last 2 years that they were installed.

The circuit had no loads on it when tested. Does anyone know why this might be happening ? Are there any tools that could help me isolate the problem area ?

Brgds

The breaker that trips was tested on another circuit, so that proves the breaker is fine. Have you tested the circuit on another GFI breaker?

Likely the circuit has a ground fault that is being detected. Could be a nick by a nail or screw into a cable.

Disconnect all receptacles so that all wring is cleared, reconnect circuit to a working breaker, and test. As one section of cable is tested, and the breaker does not trip, keep re-connecting sections of cable, until the breaker finally trips. This will help find the faulty section of cable.

One thing to watch out for, is to not let any bare grounds touch the neutral terminals at receptacles, that will trip a GFI also.