Isolated phase installation

[Sometimeselectric]

In an isolated phase installation, with all of the A phase conductors in one pipe, all of B phase in one pipe, all of C phase in one pipe.... do you derate for more than one currrent-carrying conductor in a raceway, or are they considered one conductor?
300.3(B)(1) refers you to 300.20(B) which talks about them like a single conductor.

If this is a service, would your grounded conductor be reduced to the 12 1/2% and only require one conductor?

ex: 2000A service, fed with six 750MCM aluminum per phase in 6" PVC, and then a 2" PVC with one 600MCM for the grounded conductor.

Thanks!

 

[Frank DuVal]

This PVC conduit going into PVC boxes/enclosures?

 

[infinity]

Derating applies to the 6 CCC's in each raceway. Since they're isophase you can use a single smaller neutral calculated at 12.5% as you've noted.

 

[Sometimeselectric]

PVC conduit into open bottom gear.
If it were going into a metal box with the saw kerf cut between knock outs, I suppose a PVC box connector would be the only way to go?
A lock nut could heat up I imagine.
We saw this heating issue while doing thermal imaging on drilling rigs, where they had individual DLO cables with steel CGBs going into metal enclosures.

Thank you infinity, it seemed like that would be the case.
I might have been over thinking/wishful thinking that!