Conduit Under Building - Encase in Concrete or Direct Buried

[designer82]

Section 300.5 of the NEC doesn't have much in requirements regarding running a conduit under a building. It basically says just run it in a raceway (concrete encased or not)

This is for a school project where we need to run a single conduit underground, from main electric room to another electric room.

So my question is whether you would suggest to encase it in concrete or just run direct buried in PVC 80 or RGC.

Thanks

 

[augie47]

90%+ of the installs I see are simply PVC, normally Sch 40 with occasional turn-ups in rigid.

 

[Flanative]

I wired schools for many years and the spec book for schools is usually very thick. One of the things that always dictated our burial depths under slabs was we could only penetrate a footer from under neath going vertical. No horizontal pass thrus. All the slabs were monolithic with bell footers. So just below the lowest footer was our. elevation. Unless we had to go lower to avoid conflicts with the plumbers runs. All was sch 40 piping to rgc elbows painted with bitumastic paint as no pvc could pass thru the slabs. We used rgc nipples painted as well to extend up from the 90 to one coupling height above the slab.

 

[JoeStillman]

In my world, that would be PVC Sch 40 encased in concrete (dyed red) with RGS ells and nipples.