Concrete encased electrode

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Dennis Alwon

Dennis Alwon

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Just got a call from a local inspector who just got back from a footing inspection and a concrete encase electrode. The electrician put 20' #4 in the footing and connected it to the rebar. We all know that 20' #4 is not necessary but that is what he did.

The problem is that the footing is set atop of crushed stone. I have never seen that before.....The code says direct contact with the earth. My guess is it is not compliant however it is better than 2 rods. I am not sure which way the inspector will go on this.


250.52(A)(3) A concrete-encased electrode shall consist of at least 6.0 m (20 ft) of either (1) or (2):
  • (1)
    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, installed in one continuous 6.0 m (20 ft) length, or if in multiple pieces connected together by the usual steel tie wires, exothermic welding, welding, or other effective means to create a 6.0 m (20 ft) or greater length; or
  • (2)
    Bare copper conductor not smaller than 4 AWG

Metallic components shall be encased by at least 50 mm (2 in.) of concrete and shall be located horizontally within that portion of a concrete foundation or footing that is in direct contact with the earth or within vertical foundations or structural components or members that are in direct contact with the earth. If multiple concrete-encased electrodes are present at a building or structure, it shall be permissible to bond only one into the grounding electrode system.
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Informational Note:
Concrete installed with insulation, vapor barriers, films or similar items separating the concrete from the earth is not considered to be in “direct contact” with the earth.
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What makes you think it is "better" than two rods?

there is no real question. It is not compliant as a CEE. the wire he put in is not a compliant GE either.
 
petersonra said:
What makes you think it is "better" than two rods?

there is no real question. It is not compliant as a CEE. the wire he put in is not a compliant GE either.
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Because there is contact on 2 sides I would bet that the concrete encase electrode in the case mentioned would have a lower ohm reading than 2 rods.

Why isn't #4 compliant--- Are you saying that because of the stone? I agree if one is not compliant then neither are compliant
 
roger said:
IMO stone is earth, and depending on location may be the only earth available.
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It does not say "earth". It says "the earth". If you dig out the dirt and put something else there it is no longer "the earth" it is in contact with.

In any case, the informational note makes it pretty clear that the foundation has to be in direct contact with the earth, and not sitting on something else.

OTOH, if he can get the inspector to accept the very weak argument that gravel is the same as "the earth", more power to the guy. However, it would probably be simple enough to just pound a couple rods and be compliant. He could still bond the rods to his wire and the rebar if he wanted to.
 
petersonra said:
It does not say "earth". It says "the earth". If you dig out the dirt and put something else there it is no longer "the earth" it is in contact with.
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So you're saying bedrock is not "the earth"? In many cases the site has been dug up (disturbed) before the footers are dug so we're not talking about virgin earth anyways.
 
If those stones are not encase in filter fabric, they will probably end up infiltrated with "earth" pretty quickly.

The definition of CEE does not specify it must be in contact with the earth on the bottom. Contact on the sides is sufficient.

Cheers, Wayne
 
wwhitney said:
If those stones are not encase in filter fabric, they will probably end up infiltrated with "earth" pretty quickly.

The definition of CEE does not specify it must be in contact with the earth on the bottom. Contact on the sides is sufficient.

Cheers, Wayne
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As much as I want to agree with you that the install is probably fine I cannot buy the argument that 2 sides are fine--- That is purely your personal feelings about it and that was my statement to the inspector. I told him you still had 2 sides and that was probably better than 2 rods anyway.

I am not sure it satisfy code as written.
 
petersonra said:
It kind of implies it but does actually say it, so I am inclined to agree it is not required.

however, virtually all basement walls are waterproofed on the outside and that would make it in appropriate as a GE.
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But the sides of the footing would be the Ufer, not the wall.
 
petersonra said:
from what I have seen the side of the footer are usually waterproofed. but my sample size is very small.
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One could have a situation where the bottom of the footer is on non-native drain rock (no fines), as is the inner side, and the outer side and outer top are waterproofed, or covered with filter fabric and more drain rock for the foundation drain assembly. Then none of the footer would be in direct contact with "the earth", unless you count the non-native drain rock as earth.

Cheers, Wayne
 
tom baker said:
Stones are a few eons from becoming earth
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No, they're earth as we breath. Dirt is just one part of Earth's layers but all layers including bedrock (which can be crushed by man's machines) is every bit as much "earth".
 
I am going to go with Roger on this one. Could always do a performance test after pour and add rods later if it fails.
 
tortuga said:
A ufer should test between 1 ohm and .25 ohms per the IEEE green book, section 4.2.3 2007 edition.
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I am sorry but there is no way a ufer is going to test between 1 and .25. If you had said between 1 and 25 that would have made more sense.
 
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