310.4 -- "1. Be the same length,"
All phases are not required to be all of the same length, for example, All of Phase A can be 15 feet, all of Phase B can be 17 feet, all of Phase C can be 19 feet, and all of the neutrals can be 23 feet.
Lengths for these SEC's all depends on the overall length of the run --- to the service point at the overhead or lateral.
