Can 3 4/0 Alum. conductor triplex underground rated be in stalled in PVC conduit with a # 4 copper ground wire. If it meets 40 % fill single phase 120/240 volt. I'd say so want other views on this.?
I don't see a problem Ernie as I understand your discription. I don't know of anything in the code that would prohibit using a copper equipment grounding conductor with an aluminum feeder. and I'm assuming that the triplex consist of all insulated conductors. See Ya in Troy in December.
Ground not a Problem , Neutrals insulated not a problem, I was curious about the Tri-Plex being in conduit underground?? Conductor fill for one thing I think would be different? Is tri-plex rated to be installed in conduit?? underground . I;ve also seen it done but wondered????