If it's a Y system, all loads touching the neutral, the neutral current, if the harmonics are so bad that the currents never overlap will just add up as (phase A current)+(phase B current)+(phase C current)= current on the neutral. Makes you ask "why bother with neutrals anymore?" Or 3 phase power.... You don't get this problem on a single phase 240V centertapped system, current spikes on both sides happen at the same time.
