Q. On a 1,600A 277/480V service, is the neutral conductor from the utility transformer to the service disconnect considered a current carrying conductor if the only line-to-neutral loads is a 200A lighting panel supplying non-linear loads?
A. The neutral (grounded) service conductor for this installation is considered a current carrying conductor for conductor ampacity adjustment purposes because a major portion of the load consists of nonlinear loads [310.15(B)(2)(a) and 310.15(B)(4)(c)].
Got a Code question for Mike? Send it to him at firstname.lastname@example.org.