Conduit in ground - are adjustments necessary for current carrying conductors

[Plano12345]

Quick question:


I am performing an adjustment to previous made plans to move an electrical service to a new locaiton.


I am running conduit in the ground from the electrical service to roadway illumination. I have a situation where I have 11 conductors (1 ground and 10 for 5 breakers) in a single conduit run in the ground.

As this is in the ground (earth) and not in a raceway or cable, is there an adjustment factor necessary for the ampacity based on the number of current carrying conductors I have?

Based on reading the charts, it appears I do not.

Thanks!

 

[jaggedben]

Yes there is, 310.15(B)(3)(a).
(That's the 2011 code numbering).

A conduit is a raceway.

 

[kwired]

Yes there is, 310.15(B)(3)(a).
(That's the 2011 code numbering).

A conduit is a raceway.

Even if they were direct buried conductors, I think adjustment factors still apply if they are all in close proximity to one another. Put them in separate trenches or somehow make sure there is a maintained separation and then you have a different installation where adjustments need not apply.

Also keep in mind that ambient temp adjustment for underground conductors will generally allow for increased ampacity. Number of conductors in raceway or cable still needs adjustment though. You just have one adjustment that decreases and another that increases the conductor ampacity. Not very often the ambient temp underground is higher than 86F.