I have tossed this around various groups for a month and the answers were all over the map. The THWN marked conductors are certainly OK in pipe underground so the safety issue seemed minimal to non-existant. The licensed EC made the decision to use it and the AHJ said it was OK so I figured it was NOMB.
Bear in mind I also had no real authority to say they couldn't. I was just an observer.
In fact I just took my required my CEU law course and I would face a $1500 fine for impersonating the AHJ if I did say something.
That's my story and I'm sticking to it. ;-)
They did strip the last 10' that goes through the turns so I wouldn't bet you couldn't pull that out if that was your concern. I can't imagine why they would want to and if they did replace it they could go back with #6 if they wanted to since this is only supposed to be a 60a service and they are only using about 5 of it. (two 15a circuits)
