3-Phase MCCBs for 2-Phase Applications

Where you see the feed-through jumper requirement is when you have the device known as a Motor Protective Switch, which is providing the dial-adjustable thermal overload protection of a motor. Devices designed for that use have a thermal trip sensing element that features something called a "differential trip bar". This is a counter spring trip bar that will bias (skew) the trip point of the thermal setting if there is an imbalance in the 3 phases, causing it to trip faster than it normally would. This is because if you have an imbalance of current in a 3 phase motor, it causes the motor to heat up disproportionately to the amount of current flowing. So without the biased early tripping, the motor may suffer damage even though the overall current is still under the thermal trip point.

That issue of course means nothing to a 1 phase load, but a 3 pole device used on a 1 phase load may end up falsely tripping because of that feature. Therefore if you use one of those type devices on a single phase load, you must loop a conductor out of one phase and back through the 3rd, so that equal current is flowing on all 3 sensing elements. It doesn't matter that it is the same current as is being seen by the previous element, it only matters that there is no differential.

So now the issue for you is to determine what you are referring to as a "circuit breaker". It's common in places outside of North America for Motor Protective Switches to be referred to and used as "Circuit Breakers", whereas here in the US we cannot do that if it is not used directly on a motor. So if what you have is a Molded Case Circuit Breaker (MCCB) or Mini-Circuit Breaker (MCB), then you should not have to loop back with a jumper, it will not have the differential trip bar feature.