Ufer Ground

[robertearl]

They will be pouring the slab for my shop soon and I am working with the inspector as I will be doing my own electrical. He suggested to me to do a Ufer ground instead of driving in rods. He told me to get 20 feet of #4 stranded copper and tie it to the re-bar and turn one end up through the concrete to tie to. My question is, they are putting down a vapor barrier for the slab and I am wondering how this will work as a ground if there is a large plastic sheet insulating the slab? Is the area around the side of the slab where there is no plastic enough for the ground? I ask the inspector and he said that according to the code, it would work fine.


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[kbs2244]

I share your doubts.
Ask him.
Maybe he didn't think about the plastic.
The idea is to get to moist dirt.
That is why the rods are 10 feet long.

 

[robertearl]

I did ask him if it would work with the vapor barrier and he said that according to the code, it would. Just have some doubts.


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[mrb]

heres some good info http://www.ashireporter.org/articles/articles.aspx?id=1676

 

[rockwithjason]

the vapor barrier kills the ufer ground idea. the slab must be in continuous contact with the earth in order for a ufer ground to work.

 

[robertearl]

If the vapor barrier is only under the floor and not the footings, how about I run the wire down the rebar in the footings.

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[rockwithjason]

if the footings are big enough it might work. you need a lot of contact area to get the proper conductance. sounds like a judgement call for the inspector.

 

[Stuart in MN]

An Ufer ground is supposed to be in the footing anyway. Assuming your vapor barrier is only underneath the slab you should be okay.