Neutral sizing for main feeder from transformer

[highvolt65]

I need clarification on neutral sizing. Is it true that the neutral conductor can be 1/2 the size of a phase conductor? I know in the early version of NEC it could be half the size but I thought it was changed in the early
90's to say "must be same as phase conductor" Help please??

 

[don_resqcapt19]

It must be sized for the load and to clear faults. It must be the larger of what is required by 220.61 or 215.2(A)(1) which sends you 250.122. If most of the load is line to line the neutral can be a lot smaller than the ungrounded conductors, but there is no set rule, you have to do the load calculations.
Don