ECN Forum Forums Code Related Discussion NEC & other Code issues ungrounded 2400 volt feeders

2400 volt ungrounded customer owned feeder from OCP .
Run underground in PVC

, Equipment ground required ?? Shield as ground ???

2017 NEC Part X.
I'd prefer EGC. But I think Shield allowed in some cases.
Code section with answer Please.

If EGC required sized by 250.122.

Yoopersup