Insulated Copper Stinger Thru Foundations Question

[RM1386]

Random question, but our company's electrical engineers always write "PVC Sleeves shall not be used in Concrete" in the grounding section of the electrical commodities specification. I've always heard this was because if you don't seal the hole caused when you cut the pvc, it can trap moisture and cause issues with the foundation down the line. So, usually we support the Ground Wire (4/0) with a section of rebar driven into the ground so it doesn't get knocked over and lost during concrete foundation placement. Am I overlooking something else with why not to use PVC? Is there a better, more efficient way to do this than using rebar, then having to go chip around the rebar, cut the bar, then patch with grout?

Info- this is on industrial power projects and we are both engineering the job and constructing it. I could probably get the engineer to revise the spec, but I'm just wondering if i'm overlooking something.

 

[infinity]

What's an "insulated copper stinger"?

 

[RM1386]

What's an "insulated copper stinger"?

It’s a length of green insulated copper wire (typically 4/0 or larger for industrial sites) that extends from the buried ground grid up thru a foundation (typically 6’ past top of foundation) in order to ground equipment and steel on the foundation to the grid that’s in place.

 

[retirede]

Since the equipment’s power circuit includes a GEC, what you’re doing is completely unnecessary.

 

[RM1386]

That’s certainly one camp of thought, and I’ll play devil’s advocate and take the equipment out of the equation, what about all the steel structures for everything non-electrical?

 

[hbiss]

That gets connected to the building GEC. Matter of fact it's required. If you want to bond your buried grid to the steel also, you can do that too.

-Hal

 

[RM1386]

That gets connected to the building GEC. Matter of fact it's required. If you want to bond your buried grid to the steel also, you can do that too.

-Hal

I guess I got sidetracked and got way off topic with my previous comment- talking about using the equipment’s power circuit as the GEC and saying it was unnecessary, but the reality is even using that theory, there are still things that require connection to the grid (I’m talking power plants, not everything under one roof) that are out on their own and away from anything that’s got a power circuit to use as the conductor. For example, a spare GSU XFMR foundation or a spare HV breaker foundation. Just wondering if anyone had any better ideas than pvc sleeves, vertical rebar, or bringing the conductor up outside of the foundation and creating a tripping hazard across half the foundation.

 

[retirede]

I guess I got sidetracked and got way off topic with my previous comment- talking about using the equipment’s power circuit as the GEC and saying it was unnecessary, but the reality is even using that theory, there are still things that require connection to the grid (I’m talking power plants, not everything under one roof) that are out on their own and away from anything that’s got a power circuit to use as the conductor. For example, a spare GSU XFMR foundation or a spare HV breaker foundation. Just wondering if anyone had any better ideas than pvc sleeves, vertical rebar, or bringing the conductor up outside of the foundation and creating a tripping hazard across half the foundation.

But to Hal’s point, the foundation should already be a part of the grounding electrode that gets bonded at the service. How many more times do you need to connect to it?

If you have to do it and aren’t allowed to use PVC, sleeve it with something acceptable….EMT, rigid, pool noodle, whatever.
(JK about the pool noodle )

 

[hbiss]

... there are still things that require connection to the grid (I’m talking power plants, not everything under one roof) that are out on their own and away from anything that’s got a power circuit to use as the conductor. For example, a spare GSU XFMR foundation or a spare HV breaker foundation.

Ok, I think I know what you are talking about. Plant equipment like transformers and breakers situated away from any buildings. (Think substations.) It's common for some to have buried ground grids, particularly under where someone might stand to operate a switch for example. But without seeing an example of how the conductor needs to be run and the configuration of the foundation, I really can't suggest anything.

-Hal

 

[brantmacga]

What if you had the rod busters turn up rebar at said equipment for you to connect to?