footing basement-codes on grounding

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Old 08-18-09, 06:19 AM
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footing basement-codes on grounding

Can anyone here help me out with what the NEC has to say about grounding a footing in regards to where and how it is turned out to run to the meter base and the panel? I talked with our inspector yesterday, and he sounded like he was going to be pretty easy to get along with, however the conversation did lead to more questions. He said he needed to see the rebar sticking out of the footing where the ground attaches. Explained to him that the basement will have poured walls, and asked if we could turn out the point of attachment for the ground closer to ground level so back-filling or water due to the weather would not be an issue with him being able to see it at the rough in inspect. Unless he comes out for an inspect prior to the rough in, there really is no way he can see the rebar in the walls/footing, but it is there. The rebar is all tied together and run in the footing and all through the walls, over 1000 ft of rebar. He said whatever was easiest for us, so long as he could see the rebar coming out and the ground attached to it.

After talking with the inspector I asked my contractor yesterday while he was here framing up the walls and he told me we probably don't really want rebar sticking out, it will over time rust and also will rust through into the concrete. Makes sense. So what is the best way to tie into the rebar to turn out for the ground, and does the NEC code specify any height in regards to where it has to turn out. Is there something to tie into the rebar inside the wall that can be stubbed out just below where we will grade to, or may tie braided copper around the rebar inside the wall and run out the concrete and just have the inspector come out to see it is there prior to pouring the walls?

Appreciate any help/advice here.
 

Last edited by william; 08-18-09 at 08:26 AM.
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Old 08-18-09, 09:33 AM
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Originally Posted by william View Post
we probably don't really want rebar sticking out, it will over time rust and also will rust through into the concrete.
The UFER (foundation) ground is usually done using a piece of copper, brass or stainless rebar turned out of the wall or up from the footing right under where the main panel will be. You can then use a brass clamp on the protruding rebar to attach the grounding electrode conductor (GEC) to the main panel.

does the NEC code specify any height in regards to where it has to turn out.
No, only that inside the wall the embedded conductors or rebar be "near the bottom" of the concrete wall or footing. With a standard rebar cage, this is not a problem because the metal goes to the full depth.

Is there something to tie into the rebar inside the wall that can be stubbed out just below...
Yes, an alternative to turning a rebar out is to embed at least 20 feet of #4 AWG bare copper wire into the concrete footing (near the bottom) and tie it to the rebar cage with the usual rebar wire twists. Leave enough copper protruding to reach the main panel. However, this method isn't really the best in my opinion because it's too easy to cut or break the soft #4 wire dangling out of the wall through the rest of the construction process. A 1/2" rebar poking out is much more durable.
 
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Old 08-18-09, 10:20 AM
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Originally Posted by ibpooks View Post
The UFER (foundation) ground is usually done using a piece of copper, brass or stainless rebar turned out of the wall or up from the footing right under where the main panel will be. You can then use a brass clamp on the protruding rebar to attach the grounding electrode conductor (GEC) to the main panel.
That was the answer I was looking for, would seem it will make for cleaner look with the point of attachment stubbed out just below the meter base and box. Thanks so much for the reply.

Think the electrical and plumbing supply store should have what I need if lowes does not have it, I may possibly already have what I need. So basically I can tie to the rebar at several points a length of copper rod(guess a piece of copper ground rod might work) and run out just under where the meter base and disconnect will be and also run one in for the panel and connect my ground wire with the clamps to those rods. Pretty sure I have some ground rods from old satellite installs, is there a specific size I need?

Footing is poured with two runs of rebar sitting on chairs all tied together for the entire run, that rebar is under 12-14 inches of concrete and ties into the walls and they are cross tied all the way around, should make for a pretty good ground system.
 
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Old 08-18-09, 10:31 AM
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Originally Posted by william View Post
guess a piece of copper ground rod might work
Yes, that would work just fine. Take a rod and bend an L at the end to poke a few inches out of the wall. Embed the rest in the concrete and tie it to the steel.

is there a specific size I need?
At least 1/2" diameter.
 
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Old 08-18-09, 10:36 AM
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Originally Posted by ibpooks View Post
At least 1/2" diameter.
Glad I asked that question, think what I have from installing satellites was probably only 3/8ths. Will definitely check though. Thanks again for your help, really appreciate it.

William
 
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