concrete encased electrode

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buck33k

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250.52(A)3 seems to give two options for a concrete encased electrode.

Reinforcing bars (rebar) or rods, or a full 20' min. of 4awg copper conductor.

A 4" slab is poured for an outbuilding with NO rebar...fiberglass reinforced concrete. 20' of 4awg copper is laid under the slab in direct contact with the earth. Does this comply with 250.52(A)3?
 
buck33k said:
250.52(A)3 seems to give two options for a concrete encased electrode.

Reinforcing bars (rebar) or rods, or a full 20' min. of 4awg copper conductor.

A 4" slab is poured for an outbuilding with NO rebar...fiberglass reinforced concrete. 20' of 4awg copper is laid under the slab in direct contact with the earth. Does this comply with 250.52(A)3?
Click to expand...

I would say no unless it was in the footers, not the slab.
 
I agree with Dennis.

What you have discribed would not meet the requirements of a Concrete Encased Electrode.

A 4" thick slab is not a footing.

Chris
 
Thanks Dennis.

I did note "near the bottom of a foundation or footing".

Now some slabs have a trench dug around the perimeter to serve as a footing. The 20' #4cu (no rebar) in this location might be acceptable? I see how only under the slab area might not satisfy the requirements.
 
buck33k said:
Thanks Dennis.

I did note "near the bottom of a foundation or footing".

Now some slabs have a trench dug around the perimeter to serve as a footing. The 20' #4cu (no rebar) in this location might be acceptable? I see how only under the slab area might not satisfy the requirements.
Click to expand...

Some slabs are done as a monolithic pour. This means that the footer and slab are poured as one. It sounds like what you mentioned. I agree in that case the footing cee would be acceptable.
 
"located within and near the bottom of a concrete foundation or footing..."

Leaves room for interpretation :)

I would say if the perimeter bevels or is cut down below the slab bottom portion it would be a foundation.
 
buck33k said:
20' of 4awg copper is laid under the slab in direct contact with the earth. Does this comply with 250.52(A)3?
Click to expand...

It must be encased by at least 2" of concrete to qualify as a CCE. If you do this, then you then it must be bonded to all other qualifying electrode to form your grounding electrode system.(250.50 2005 NEC)
 
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