The NEC does not use THD level as the determining factor.

The NEC requirement states "major portion of the load consists of nonlinear loads".

PCs are non-linear loads and in Scott's example I would say that the major portion of the load is PCs.

In my opinion that is enough to have to treat the neutral as a CCC.:0

However that is just my opinion, Bob [Linked Image]

Bob Badger
Construction & Maintenance Electrician
Massachusetts