Derating service conductors

[jsathre]

Do I have to derate the service entrance conductors that are in PVC conduit from the utility transformer to the service located in the building when I have 4 conductors in each conduit of a parallel run (total of 8 conduits)?
Another estimator here is saying the adjustment factors do NOT apply based on Art. 310.15(B)(3)(a)(3).
Does anyone know the intent of this article? Does this article even apply (we are entering the building and the article states entering or leaving an outdoor trench)?
In this case derating the conductors will actually make a difference in the job.
Please send me your interpretation of this.

Thanks,
Jon Sathre

 

[Smart $]

The intent I believe is to ease derating for 4 CCC in conduit mostly when the neutral is counted as a CCC. Being [mostly] outside and underground, the safety impact of slightly warmer conductors is minimal. If the neutral does not count as a CCC, then there would be only 3 CCC and no derating for number of conductors would apply anyway.

Welcome to the forum :thumbsup:

 

[kwired]

Are you installing one conductor of each phase plus a neutral conductor in one conduit, or do you have all A phase in one conduit, B in one , C in one, and N in one? The first method is only considered to be three current carrying conductors unless the neutral would have high harmonic loading, the second method is four current carrying conductors in a raceway.