@fbelec, you’ve got the idea. To be honest, I had trouble following the original post, so it’s possible I was answering a scenario other than that which you were describing. The typical situation in which circuits may share a neutral is not two circuits on the same leg, which would be an illegal setup, but situations where two circuits are on opposing legs, with a shared neutral. This is legal and common, eg. 4-wire electric range hook-ups. In that case, which I was describing, the current on the neutral is simply the difference (“imbalance”) in the associated legs. The very reason it’s not legal to share a neutral between two circuits on the same leg is what you may have been describing, the currents would be summed, and the neutral would not be properly protected by the breakers. In my shop, I ran 12AWG 3C+GND to quad receptacle boxes, so that I could populate those boxes with both NEMA 5-20 (115V) and NEMA 6-20 (230V) receptacles, using one “hot” and the neutral for the NEMA 5-20’s and both hots (no neutral) on the NEMA 6-20’s. Which hot leg is used alternates in each box down the length of the circuit, and the current on the neutral ends up being just the imbalance on this circuit. I verified this with two commercial electrical contractors before doing it, and after some debate in their own offices, both agreed it was safe and legal. A residential electrician ended up doing the work for me, and he reported having done the same setup before.