underground pvc or metal

[jjavier]

Hi, what do you recommend in underground bank conduits, metal or pvc? Our first idea is pvc condut (sch 80 outdoor), but I don´t know if it is the best solutions outside the trench at the ac combiner boxes. What do you think will be easy to install or cheaper?

 

[Carultch]

Hi, what do you recommend in underground bank conduits, metal or pvc? Our first idea is pvc condut (sch 80 outdoor), but I don´t know if it is the best solutions outside the trench at the ac combiner boxes. What do you think will be easy to install or cheaper?

I see no reason to use anything other than PVC SCH40 in an underground duct. You might use SCH80 risers, or perhaps RMC risers, depending on the potential for physical damage, but underground, there is no need for anything more than PVC40.

 

[peter d]

Hi, what do you recommend in underground bank conduits, metal or pvc? Our first idea is pvc condut (sch 80 outdoor), but I don´t know if it is the best solutions outside the trench at the ac combiner boxes. What do you think will be easy to install or cheaper?

By "metal" I assume you mean rigid metal conduit or intermediate metal conduit, since you can't use EMT in the ground. PVC conduit is a small fraction of the cost of RMC/IMC both in material and labor cost. Not sure why you would even consider it unless you had some unique circumstance. :huh:

 

[ohm]

Hi, what do you recommend in underground bank conduits, metal or pvc? Our first idea is pvc condut (sch 80 outdoor), but I don´t know if it is the best solutions outside the trench at the ac combiner boxes. What do you think will be easy to install or cheaper?

You might want to look at Table 300.5 if you're going to dig a trench. 18" is the min. depth for PVC (without 2" of concrete over it).
If you can only dig down 6" use rigid or IMC, but much more expensive.

Roads and driveways etc. require 24" for PVC, rigid or IMC and yes, when PVC emerges from the ground sch 80 is required

 

[electrofelon]

and yes, when PVC emerges from the ground sch 80 is required

If i may nitpick a bit, That is actually not specifically required in the nec. Yes On many job specs, interpreted that way by some inspectors, and probably a good practice. Iirc, the only place sched 80 is specifically required is on poles.

 

[69gp]

The Schedule 80 is required to be used where the conduit would be subject to damage and even that I have seen is not enough to protect the wiring in some cases. I have seen where sickle bar mowers have cut through 2" sch 80 pvc 2" above grade under an array. I have seen where sch 80 has been cut clear through with flexible steel wire. This is all on large commercial systems where you are not getting the best workers doing the vegetation management. Oh by the way have you ever seen what an array looks like after a tracked skid steer with a brush hog on it pushes 2500 pound ballast blocks 2 to 3'?. Not a pretty site.