Separating 3-phase Circuit

[mromanini]

Hello,

Is there a section of NEC code that prohibits separating a 3-phase circuit into separate underground conduits? The purpose of this would be to reuse existing 3/4'' conduits on a retrofit project rather than excavate a hillside to run a new 2 1/2'' conduit.

 

[LarryFine]

Welcome to the forum.

PVC conduit, probably okay; metallic conduit, definitely not.

 

[mromanini]

Thank you.

Any special precautions? Should all components (hubs, troughs, etc.) be non-metallic as well?

 

[LarryFine]

Any special precautions? Should all components (hubs, troughs, etc.) be non-metallic as well?

Ideally, or slots cut between holes, effectively rendering all conductors entering through a single hole.

Added: An alternative is to make holes in a plastic panel installed in a hole cut in the metal.

As a perfectionist, I would use PVC boxes, lock-nuts, and no metal clamps that encircle the conduits.

 

[mromanini]

Got it, thank you for the help.

Any idea if there is a section of NEC that touches on this?

 

[augie47]

Got it, thank you for the help.

Any idea if there is a section of NEC that touches on this?

300.3, 300.20

 

[don_resqcapt19]

The only thing that really talks about this is the exception to 300.3(B)(1), but that only talks about parallel installations.
I think that 300.3(B)(3) should permit this, but Code Making Panel 3 is on record as saying it doesn't.