The test button on a QO-GFI or HOM-GFI breaker will not trip the breaker; is the breaker bad?
QO and HOM GFI circuit breakers
First ensure that the breaker is properly installed in an energized panel with the pigtail connected to the neutral bar.
If the breaker will not trip when the test button is pressed with the load wires connected, disconnect the load wires and try again. If it trips with load wires disconnected, the breaker is good. If it still will not trip with the load wires disconnected, replace the breaker. See next paragraph for explanation.
The test feature injects test current through the ground-fault sensor in the opposite direction of load (and ground leakage) current. Therefore, if there is 3-4 mA of ``standing leakage`` in the circuit, the 7-8 mA of test current will vectorally sum to 3-4 mA, which is below the 6 mA tripping threshhold of the breaker. If there is a ground fault in the circuit, the fault current will be in the same direction as the load and leakage current, so it will provide the specified protection.