Concrete encased electrode

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don_resqcapt19

don_resqcapt19

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If you have re-bar in the footing that qualifies as a grounding electrode, would you be permitted to install 20' of #4 bare copper and not make a connection to the re-bar?
Don
 
I would say, yes, based on both methods are acceptable grounding electrodes. However, why would you do that if rebar was available to tie in to? It would be a lot less wire to use.
 
Don......now you have me thinking. Are you implying that the rebar would have to be used because it is "available"?
 
don_resqcapt19 said:
If you have re-bar in the footing that qualifies as a grounding electrode, would you be permitted to install 20' of #4 bare copper and not make a connection to the re-bar?
Don
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I would say yes because it says or in the article.

(3) Concrete-Encased Electrode An electrode encased by at least 50 mm (2 in.) of concrete, located within and near the bottom of a concrete foundation or footing that is in direct contact with the earth, consisting of at least 6.0 m (20 ft) of one or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm ( 1/ 2 in.) in diameter, or consisting of at least 6.0 m (20 ft) of bare copper conductor not smaller than 4 AWG.
 
Tom,
Don......now you have me thinking. Are you implying that the rebar would have to be used because it is "available"?
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Yes that is exactly how I see it. The rule says that you have to use all of the electrodes that are present. The installation of the copper does not make the re-bar go away.
250.50 Grounding Electrode System
All grounding electrodes as described in 250.52(A)(1) through (A)(6) that are present at each building or structure served shall be bonded together to form the grounding electrode system. Where none of these grounding electrodes exist, one or more of the grounding electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.
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Don
 
You would be satisfying the article by bonding the # 4 to the other electrodes. A CEE can be either or.
 
Concerning 250.52(A)(3): My thought is that the "or" between the reference to rebar and the reference to a #4 copper wire means that you can use one or the other to satisfy the code requirements. You wouldn't have to use both. Now, you could use both if you wanted to.
 
ditto derek's reply.

As far as a good connection to the CEE, have seen it turn concrete floors into a proven effective ESD sink (if that's a consideration.)

Found an article which discusses your particular item, meaning the use of 'available' and whether it 'shall' be done. Looks like "I don't know" and yes.
 
If you stub your piece of rebar up and it doesn't get inspected in the dirt then you need to have another stub up over 20' away so you can show a resistance reading between them to the inspector, if he wants one.

And I disagree that you have to use the rebar unless it was planned as a concrete encased electrode. Without intent to design I say it's not a concrete encases electrode but just a piece of rebar in the concrete.
 
wireman71 said:
And I disagree that you have to use the rebar unless it was planned as a concrete encased electrode. Without intent to design I say it's not a concrete encases electrode but just a piece of rebar in the concrete.
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There is nothing in the code the states the concrete-encased electrode must be created for the purpose of grounding a service. It states that in the event a concrete enacased electrode is present, it must be bonded.
 
IMO if the rebar is present then you're only required to use a CEE not necessarily the rebar. If you prefer the use 20' of #4 over the rebar you can. The CEE can be the rebar or the #4 conductor.
 
bphgravity said:
I would say the new last sentence in Section 250.52(A)(3) would give you the permission to NOT have to bond the rebar. (2008 NEC)


See this discussion over at the ICC forum:

http://www.iccsafe.org/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=11;t=001382
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Hi Bryan,

I saw the 'discussion' at the ICC forum. Very interesting variations of interpretation sure is entertaining. In the early 70's in Sacto county, UFER grounds in residential were mandatory in new construction. One 20' rebar stubbed up was good then and appears to still be per the new 2007 CA code cycle. Article 250.52(A)(3) 2008 further defines in detail that allows bonding one concrete encased footer (20' x 1/2"[#4]rebar) to the GES. What's currently used in FL?
 
If the rebar that is present in the footings meets the requirements from 250.52(A)(3) that it is required to be used as a grounding electrode.
If a 4 WG bare was also in the footing it to is a grounding electrode and would need to be used.
 
Don- A code proposal is in order, the language could be and/or. Sometimes a code proposal is a good way to find the panels intent.
 
I'm all for using a concrete encased electrode. I'd much rather use one than have to drive ground rods. Now if I could just get general contractors on board with that idea...
 
wireman71 said:
I'm all for using a concrete encased electrode. I'd much rather use one than have to drive ground rods. Now if I could just get general contractors on board with that idea...
Click to expand...


How do you get around the fact that using a CEE is required if there is 20' of 1/2" or larger rebar present in the footing?
 
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