Bonding Requirements for Underground Raceways

[tcoogler]

My question is this: Our project has several U/G raceways that are Schedule 40 PVC, with GRC factory 90's at all stub up's. These GRC 90's are required per the project specification. Today, I was told by the Electrical Superintendent that is was an NEC code requirement to have GRC raceways installed vertically from the GRC 90, up through the slab...He said it was a grounding issue. I can find no requirement in the Code (BTW, this projet is under the 2008 NEC. I've looked in both the 2008 and 2011 Code, but to no avail.) that specifically addresses this issue. Is the GRC riser from the GRC 90 required by the NEC? Any help or clarification would be greatly appreciated.

Finally, I have seen this requirement in the Army Corps. of Engineer specifications on previous projects. My thought is that maybe our Electrical Superintendent is confused about what is a specification requirement and what is a Code requirement. Thoughts?

Thank you,

TCoogler

 

[augie47]

Look at 250.86
They must be bonded. Locally that is normally accomplished by continuing the run in a metallic conduit to a grounded box or panel.

 

[texie]

To clarify, are you saying that the metal 90 is buried below grade and you are going to exit the slab with PVC? If so, you do not have to bond the metal 90-see 250.86 Exception #3.

 

[infinity]

The section that Texie provided gives you two options under the exception, elbow 18" below grade or encase in 2" of concrete. The third otion as Augie mentioned is to continue the run with a metallic conduit from the elbow.

 

[dicklaxt]

The extension of using RMC is the best option as PVC becomes brittle with age and is very vulnerable to breakage.I realize thats not the question just a thought.

The 90 degree elbow is to stop possible abrasion and cut thru by/of the pull rope when runs are long or wire is the big stuff requireing a lot of ooomp to get around the corner,

dick