Underground Conduits Without Concrete Encasement

[Alecto]

If I'm running underground conduits not encased in concrete, do I have to keep them all on a single row or can I stack them in two rows with spacers still without concrete encasement?

Or is that when you need to encase in concrete when you have more than one row?

Thanks

 

[ron]

How are you deciding the ampacity of the feeders? Most folks will follow the Figure B.310.15(B)(2)(2) and 310.60(C)(3) for one of those configurations rather than having to calculate Neher McGrath custom calcs

 

[Alecto]

I meant like if you have something like this with multi-rows, does that necessitate encasing in concrete?

But I think the answer is no bc the NEC shows many variations like that in the Annex and notes "with" or "without" concrete encasing. So I think maybe I answered my own question.

 

[ron]

I meant like if you have something like this with multi-rows, does that necessitate encasing in concrete?

But I think the answer is no bc the NEC shows many variations like that in the Annex and notes "with" or "without" concrete encasing. So I think maybe I answered my own question.

View attachment 20801

You do not need concrete. However, you have to decide what the ampacity of the conductors are because regular dirt acts like a blanket and doesn't disapate heat well, so sometime we encase in concrete just to wick heat away.
Make sure you are using either one of the prescriptive tables for ampacity or doing the Neher McGrath calculations. Not the regular tables like overhead

 

[Dale001289]

I meant like if you have something like this with multi-rows, does that necessitate encasing in concrete?

But I think the answer is no bc the NEC shows many variations like that in the Annex and notes "with" or "without" concrete encasing. So I think maybe I answered my own question.

View attachment 20801

Concrete encasement, usually colored red, is largely for safety to prevent accidental contact from backhoes, shovels etc. Depth requirements are lesser as well, see NEC Tables 300.5 and 300.50.