If both loads were on the same phase that would be a violation of the US NEC (NFPA 70) because use the load would be 40 amps..... And guessing we are taking 12a

If both loads were on the same phase that would be a violation of the US NEC (NFPA 70) because use the load would be 40 amps..... And guessing we are taking 12awg, way over allowed current. In hindsight I did not specify circut ampacity, or wire gauge. Still the question stands, how much current would you read at the panel on the neutral with those two loads on the line :-) (In my example you have two phases 120 degrees apart. Think US Residential split phase. The actual result is pretty awesome. It's a common test problem for new electricians.) I won't spoil the result because it's too cool when you get it.