2014 NEC 680 26.

[Risk Management]

I am an electrical inspector in upstate NY. I have been on this end of the electrical field since 1994. Prior to that I was both line foreman & field planner supervisor with a local utility up here. Prior to that I served in the USN for 22 years. The last 10 as Chief Warrant Officer -Electrician. I have also taught Code classes at the local Community College.

I have read the 2014 ROP on 680.26. Sure was some controversy on nonconductive perimeter bonding.. Still is in 2017 I imagine.

Never claiming to know every thing I have a question regarding conductive inground pools. Actually on the perimeter bonding. Both the NEC handbook as well as Soars concentrate on the conductivity of concrete. That is understandable it is porous. I accept terminating the #8 bare to the steel mesh reinforcing at 4 points in lieu of 12 x 12 copper grid.

My concern is that neither the NEC or Soars discuss the conductivity of quarry tile perimeters. They seem to be more and more popular in this area. Having struggled with grounding neutrals on "Y"" distribution systems around dairy farms I know rock is not the best conductor. That said I have required the 12 x 12 #8 copper grid under the quarry tile perimeters. Safe than sorry.

Anyone have any input on this? Sime of the tile run 1 - 3 inches thick.

Thanks

 

[FionaZuppa]

perhaps you read it wrong. and perhaps i may not fully understand your question.
i am looking at 2017 version.

non-conductive encapsulation. very different than the bonding grid being located under plastic pavers. unless the decking is formed and poured concrete 6"+ deep, how would the decking bonding grid ever be encapsulated?

rock pavers dont matter, what ever the deck grid is per NEC 680.26 it goes under the grade 4-6in.


if you are asking about pool shell in 680.26, it looks like pools that have shell of glass or vinyl needs to have a shell grid of copper #8.

for decking grid in 680.26 it says for non conductive shells the decking grid does not need to be bonded to the shell grid.

 

[Dennis Alwon]

The perimeter grounding only requires a #8 that follows the contour of the pool. It must be 18-24" away from the pool edge and 4-6" below subgrade.

I don't know what the resistance is of these different stones but I wire it based on the NEC. Years ago the perimeter bonding require a mesh setup but no longer and unless you are still under that code cycle it would not be proper for you to enforce something that is not required or because you think it is better. I understand your concern but forcing contractors to do that is not, IMO fair game...LOLIs the mesh better? I don't know that either....

 

[FionaZuppa]

The perimeter grounding only requires a #8 that follows the contour of the pool. It must be 18-24" away from the pool edge and 4-6" below subgrade.

I don't know what the resistance is of these different stones but I wire it based on the NEC. Years ago the perimeter bonding require a mesh setup but no longer and unless you are still under that code cycle it would not be proper for you to enforce something that is not required or because you think it is better. I understand your concern but forcing contractors to do that is not, IMO fair game...LOLIs the mesh better? I don't know that either....

680.26(B)(2) - non conductive shells do not need permimeter 4 points
680.26(B)(2)(2) - uses the plural word "conductors", which to me still sounds like a grid, but this section states that at least one #8 is to be used. is this "at least one #8" referenced as the "required" conductor?
680.26(B)(2)(b) - i believe the mention of encapsulated is as example; epoxy coated rebar.


in 680.26 i no see any direct verbiage stating what the perimeter grid layout should be (rebar or copper). that said, a single #8 copper loop does seem acceptable.

all the above said, the OP was asking about what to do for the "non-conductive" pavers that could be 3" thick. the pavers dont matter is all i can say.