250.52(A)(3) Concrete-Encased Electrode

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iwire said:
MA is.



EC must do the work, EI must look at it and if that is not done the GC may have a very bad day.

If its a new footing for new construction and it has qualifying steel then it 'is available' even if that means breaking concrete.
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As Bob mentions,this is the way in MA,however I must add we have ran across a lot of EI questioning the size of the conductor.
 
Upstate South Carolina inspectors are on the lookout for CEE's. I have a standard note on my drawings warning the EC about this:

WARNING!! Article 250.52(A)(3) of NFPA 70: National Electrical Code. (NEC 2005) requires the use of a "Concrete-encased Electrode." BEFORE any reinforced concrete for this project is poured, the electrical contractor shall coordinate with other trades for the installation of this Concrete-encased Electrode. The electrical contractor is required BY LAW to install a Concrete-encased Electrode(s) to the rebar at the location of each building electric service. Failure to properly install this electrode will require removal of the concrete and to re-pour. Building inspectors are paying very close attention to this requirement and failure to comply will result in the failure to pass the appropriate building inspections and the denial of a certificate of occupancy.

Add to this my "null/void" note on every drawing. Both have received "attention" by both contractors and AHJ's.

ANY CHANGES, ADDITIONS, DELETIONS, ETC. WITHOUT THE EXPRESS WRITTEN PERMISSION OF THE ELECTRICAL ENGINEER SHALL CAUSE THESE DESIGN DOCUMENTS TO BE NULL AND VOID.


RC
 
The CEE (ufer) is only ?an electrode? if it is intentionally installed to the specific criteria of 250.52(A)(3). If the rebar is not intentionally installed as per 25.52(A)(3) it is simply reinforcing steel for the concrete structure and not an electrode. In this case it does not need to bond to other electrodes nor is it ?available? (250.50).

There really are 2 types of CEE?s listed in 250.52(A)(3). 250.52(A)(3) Includes 2 sentences of criteria. Read from the last conjunction ?or? in the 1st sentence to its end. This conductor does not have to connect to the rebar but it can, this conductor IS the electrode and if long enough can be the GEC as well. In other words this type of electrode does not require any steel.
 
tryinghard said:
The CEE (ufer) is only ?an electrode? if it is intentionally installed to the specific criteria of 250.52(A)(3). If the rebar is not intentionally installed as per 25.52(A)(3) it is simply reinforcing steel for the concrete structure and not an electrode.
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I strongly disagree.

It matters not why the steel is there or who installed it. If it meets the criteria of 250.52(A)(3) it is a CEE and we must use it.
 
This may sound like a simple question but,... what does " in direct contact with the earth " mean?? Does crushed stone count ??
 
iwire said:
I strongly disagree.

It matters not why the steel is there or who installed it. If it meets the criteria of 250.52(A)(3) it is a CEE and we must use it.
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Rebar is installed in concrete to reinforce it, this is its purpose, it does not have to be installed to 250.52(A)(3) but it can. It is not present and does not exist if it is 19? 11? (anything less than 20?) long while simultaneously not within and near the bottom of the footing and or is encased by less than 2? of concrete. This type of footing can be poured because the installer is choosing to not use the CEE rather a different one.

The #4 copper is specifically intended to be the electrode and must be installed as per 250.52(A)(3) every time. We can have less concern over this topic if all CEE?s are installed by a journeyman electricain as 20' of #4 cu or larger, connect it to steel anyway but get the hands of the non-qualified off our work.
 
Most work is ?design-build? type in that there are no specific plans drawn, regardless of dwelling or non-dwelling. With this the ground connection (electrode) is an issue of who, what, and how on nearly every job.

A likely scenario can be an out building say 10? x 10? that is actually a well house also. The GC can use short steel if desired therefore not have a single stick of rebar 20? long. The GC is not in violation but an electrode will still need to be provided. I do not believe it is the inspectors/electricians job to physically measure each steel to locate a 20?er with all the other criteria met. The electrical contractor should be prepared to answer what they will be using though.

Either type of electrode ? steel or #4 cu ? is in fact the responsibility of the electrician, so the electrician should furnish and install either one. I personally will use #4 cu.
 
tryinghard said:
Rebar is installed in concrete to reinforce it, this is its purpose, it does not have to be installed to 250.52(A)(3) but it can.
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I agree.

But that is not the same as you said here

The CEE (ufer) is only ‘an electrode’ if it is intentionally installed to the specific criteria of 250.52(A)(3). If the rebar is not intentionally installed as per 25.52(A)(3) it is simply reinforcing steel for the concrete structure and not an electrode.
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It does not matter if it was intentionally installed as the CCE or if it just ended up that way by random chance.

If it meets 250.52(A)(3) for any reason we must use it.
 
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iwire said:
Slabs do not count, only footings and foundations.
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Sure they do, footings and foundations are interpretive regarding physical dimensions. I just put a CEE in a few weeks ago at a new sewer lift station slab. This slab is over 4" thick and simply has a beveled deeper area at the edges.
 
tryinghard said:
Sure they do, footings and foundations are interpretive regarding physical dimensions. I just put a CEE in a few weeks ago at a new sewer lift station slab. This slab is over 4" thick and simply has a beveled deeper area at the edges.
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This is similar, I think, to what's commonly called a "monolithic" pour around here. The CEE is made a part of the GES for buildings and structures subject to the '05 NEC. :smile:
 
tryinghard said:
Sure they do, footings and foundations are interpretive regarding physical dimensions.
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We will have to remain in disagreement on that.

Footings and foundation are specific structures, I am sure it is possible some slabs are foundations but normally no they are not.

IMO rebar or copper in a slab can certainly be connected to the buildings electrical system but is not by definition a CEE per the NEC requirements.
 
iwire said:
We will have to remain in disagreement on that.

Footings and foundation are specific structures, I am sure it is possible some slabs are foundations but normally no they are not.

IMO rebar or copper in a slab can certainly be connected to the buildings electrical system but is not by definition a CEE per the NEC requirements.
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It is my understanding that part of the effectiveness of a CEE comes from the weight of the building pressing it to the earth - I wouldn't think that a slab would do this.
 
JohnJ0906 said:
It is my understanding that part of the effectiveness of a CEE comes from the weight of the building pressing it to the earth - I wouldn't think that a slab would do this.
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I don't follow. What difference would it make how much weight was on a segment of rebar totally encased in concrete, or a 20' length of cu encased in concrete? Isn't it more about the plane and its effect on grounding and stabilizing voltages and dealing with those nasty currents heading back to the substation through the earth? :smile:
 
wbalsam1 said:
I don't follow. What difference would it make how much weight was on a segment of rebar totally encased in concrete, or a 20' length of cu encased in concrete? Isn't it more about the plane and its effect on grounding and stabilizing voltages and dealing with those nasty currents heading back to the substation through the earth? :smile:
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Then why is it in the footer, and not in the slab?
Is I understand it, the weight improves the contact resistance.
 
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JohnJ0906 said:
Then why is it in the footer, and not in the slab?
Is I understand it, the weight improves the contact resistance.
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See 250.52(A)(4) as example to not needing building weight. The goal is to allow best low impedence path to earth for static lightning or overvoltages tyring to return to their source.

What is the minimum foundation or footing dimension and shape?
 
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tryinghard said:
What is a minimum footing dimension and shape?
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There is none, a footing may be larger or small.

But a footer or foundation has a specific function and that function is to support the weight of the building.

In general a slab is never used to be the support the building. Usually the ground level slab 'floats' in relation to the buildings foundation, it is often isolated by fiber board expansion material at all the edges.

I say in general as I have worked some jobs that had 'structural slabs' that were keyed into the buildings masonry walls to add additional support of old buildings with sinking foundations.

In this area you will recognize a structural slab as it will be very thick and have large rebar in massive quantities in it.

That said I have hardly seen it all so I would not be surprised if there are some areas that use the slab to support the building.

foot?ing (fʊt'ĭng)
n.
Secure placement of the feet in standing or moving.

A surface or its condition with respect to its suitability for walking or running, especially the condition of a racetrack.

A secure place for the feet; a foothold.
The act of moving on foot.

Architecture. The supporting base or groundwork of a structure, as for a monument or wall. Also called footer.

A basis or foundation: a business begun on a good footing.

Position or rank in relation to others; standing: Everyone began on an equal footing.

Terms of social interaction: neighbors on a friendly footing.

The act of making a foot for something, such as a stocking.

The sum of a column of figures.
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Where I work and play, the slab has a plastic/viscine liner under the slab to provide a vapor barrier. This alone would nulify the "slab" as an effective CEE.

A slab is a slab, and footings and foundations are footings and foundations.



If the building is being built on slab, remember there is not much depth to the slab, and the contact with the earth is could be determined as not being deep enough.
 
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