conduit derating

[jcelect]

when running emt for branch circuits, 3 phase 208v, 3 hots & neutral will be used, counting as 4 conductors. not clear on derating over 4 & with cost of tubular steel is bigger better :roll:

 

[charlie b]

Re: conduit derating

For most installations, this will count as 3 current-carrying conductors. The neutral will not be counted, and de-rating is not required. The exception would be an installation that has a significant amount of non-linear loads (i.e., high harmonic content). Please note, however, that there is no standard, accepted value for what constitutes a ?significant? or ?major? amount of non-linear loads.