Schedule 40 PVC and cable temperature ratings

[fosilfuel]

We have a newly installed Schedule 40 PVC Conduit running underneath a concrete slab. If we pull a 4/0 THWN Type TC cable rated at 90C through the PVC, will we have to derate the cable temp rating to 75C?

Also what's the best way to protect the PVC? It's rising out of the concrete on one side and dirt on the other.

Thanks and any help would be appreciated.

 

[rbalex]

It will depend on the "marking." From the 2010 UL Whitebook:

RIGID NONMETALLIC SCHEDULE 40 AND SCHEDULE 80 PVC CONDUIT (DZYR)
USE AND INSTALLATION
...
Unless marked for higher temperature, rigid nonmetallic conduit is intended for use with wire rated 75?C or less including where it is encased in concrete within buildings and where ambient temperature is 50?C or less. Where encased in concrete in trenches outside of buildings it is suitable for use with wires rated 90?C or less.
...