Hello a circuit breaker or differential switch, acts by detecting a certain current difference between what enters and what leaves the differential If you connected a watch and took a pole of the differential and the other pole of another side, it is completely normal for this differential to operate since there the currents that enter and leave are not equal To avoid this, both the phase and the neutral (both) must be taken from the differential output or if the wish is not to pass through both poles must be taken upstream of the differential Regards