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Old 09-03-2012, 11:51 PM   #1
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he everyone! i am getting ready to have a house built in NC. Today i was talking to a electrician and he told me that i would have to install a 4awg copper wire in the footings for grounding purposes. I have never heard of doing that before on my brothers house they only drove 2 ground rods. I plan on having a 200 amp service. Does anyone know if that it required now or if he is just making extra work for himself. Thanks a lot for your answers!

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Old 09-04-2012, 12:45 AM   #2
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It's called a Ufer ground.
In most cases it is better than ground rods.
You will have to get someone that knows the NC electrical code to tell you whether it is required or just one of the ways grounding can be done.

I would just go with it.

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Old 09-04-2012, 01:21 AM   #3
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If there is rebar in the concrete, then it is required.
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Old 09-04-2012, 05:51 AM   #4
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Oso and mpoulton are correct. Do a search on Ufer....goes way back to before WWII....

What they have found is that a concrete slab actually does a better job of providing a ground than a ground rod does.

My 2-story addition has one....before, I just had the single ground rod at the front of the house bonded to the metal plumbing and then a #4 wire running back to my load center. Well...with the addition, the load center was moved...

I ran another ground rod into the crawl space next to my slab (I didn't have too). I then ran at least 20' of #4 CU at the base of the footing (they want it about 2" from the dirt) intertwined with my rebar. One end is clamped to the ground rod in the crawl space....that ground rod also has the original ground wire that goes up to the front of the house.

The other end of that #4 CU comes up out of my slab along with a piece of ground rod. I also have the CU wire bonded to my rebar in a few places. For good measure, I have a clamp on the CU and rebar visible where it comes out of the slap....just so it's obvious the two are bonded. That #4 CU wire then goes to my load center.

Now....a topic of discussion that I hope the experts here will clarify....my drawings say Ufer ground....but no reference is made to the 20' of CU wire. My inspector and I had a discussion on this...I thought that the rebar all tied up and connected to the load center was the Ufer ground. He thought that the 20' wire was the Ufer ground. After the discussion, he would have been ok with just the rebar....but, to be on the safe side....I ran the 20' of CU.
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Old 09-04-2012, 06:12 AM   #5
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Quote:
Originally Posted by ddawg16 View Post

Now....a topic of discussion that I hope the experts here will clarify....my drawings say Ufer ground....but no reference is made to the 20' of CU wire. My inspector and I had a discussion on this...I thought that the rebar all tied up and connected to the load center was the Ufer ground. He thought that the 20' wire was the Ufer ground. After the discussion, he would have been ok with just the rebar....but, to be on the safe side....I ran the 20' of CU.
Well a ufer ground is a concrete encased electrode so either 20' of copper wire or 20' of rebar in your foundation will satisfy a ufer grounding system. It should be noted that in the event that you use the rebar and bury the connection to the wire it must be an approved clamp
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Old 09-04-2012, 06:16 AM   #6
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Well a ufer ground is a concrete encased electrode so either 20' of copper wire or 20' of rebar in your foundation will satisfy a ufer grounding system. It should be noted that in the event that you use the rebar and bury the connection to the wire it must be an approved clamp
Makes me glad I have it exposed....removes all doubt.

The reality is.....I'm easily meeting code...but what is more important to me? That it's done right.....I plan to be there a long time.....
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Old 09-04-2012, 06:19 AM   #7
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When the 20' #4 copper wire is embedded in the concrete pour below grade then it is the Ufer ground. A grounding electrode conductor (#6 copper) is run from it to the panel. When rebar was included in the concrete pour then the GEC is attached to a rebar below grade (should be 20' worth either one piece or bonded using the usual rebar tie wire) and run to the panel.

A copper wire buried horizontally next to the concrete footing is not a Ufer ground but may qualify as a "ground rod" depending on thickness and length.

Sometimes it is necessary to chip away at the concrete to get to a rebar to attach the GEC to.
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Last edited by AllanJ; 09-04-2012 at 06:27 AM.
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Old 09-04-2012, 06:20 AM   #8
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Grounding is one of the most important aspects of any electrical job! You have a smart electrician there, Listen to him!
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Old 09-04-2012, 06:28 AM   #9
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When the 20' #4 copper wire is embedded in the concrete pour below grade then it is the Ufer ground. A grounding electrode conductor (#6 copper) is run from it to the panel.
That the grounding electrode conductor is a #6 copper is NOT correct, it depends on the situation.
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Old 09-04-2012, 06:42 AM   #10
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Quote:
Originally Posted by Julius793 View Post
That the grounding electrode conductor is a #6 copper is NOT correct, it depends on the situation.
I 'think' it depends on the size of the load center.....

#6 is ok for 100A and smaller....
#4 for 150A and larger....

Please correct me if I'm wrong.
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Old 09-04-2012, 11:24 AM   #11
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250.66 Size of Alternating-Current Grounding Electrode
Conductor.
The size of the grounding electrode conductor
at the service, at each building or structure where
supplied by a feeder(s) or branch circuit(s), or at a separately
derived system of a grounded or ungrounded ac system
shall not be less than given in Table 250.66, except as
permitted in 250.66(A) through (C).





(A) Connections to Rod, Pipe, or Plate Electrodes.

Where the grounding electrode conductor is connected to
rod, pipe, or plate electrodes as permitted in 250.52(A)(5)
or (A)(7), that portion of the conductor that is the sole connection
to the grounding electrode shall not be required to be

larger than 6 AWG copper wire or 4 AWG aluminum wire.

(B) Connections to Concrete-Encased Electrodes.
Where the grounding electrode conductor is connected to a
concrete-encased electrode as permitted in 250.52(A)(3),
that portion of the conductor that is the sole connection to
the grounding electrode shall not be required to be larger

than 4 AWG copper wire.


Last edited by Stubbie; 09-04-2012 at 11:34 AM.
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