I understand.A straight 240 load like A/C or a water heater does not need a neutral
OT....Yes, we understand that. The OP's question was:The neutral only carries the inbalance of the load between phases. So if there is a 40 amp load on phase A and a 30 amp load on phase B the neutral would carry 10 amps. If the electrician balances the loads across the phases the neutral carries little current.
Accidentally came across this while looking for something else. It's
from what's known as an AltStandata and is, as far as I know, a
code amendment effective officially only in Alberta.