Another UFER Ground Thread

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socal_j

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Did a search and couldn't find this particular question asked/answered.

Concrete Encased Electrode Art. 250.52.(A)3 refers to 20ft length of rebar or #4 wire placed horizontally in footing. However, does the 20ft length refer to the dimension of the concrete contact with earth or just the length of rebar/wire? I have seen drawings for a pier footing (24"D x 4ft Deep) require a #4 wire coiled in bottom 20ft long. This does make sense to me. The purpose of the CEE is to provide additional contact with earth, not just coil a wire up and encase it in a small amount of concrete.

If you had a footing that was less than 20ft in length (say a pump pad that was 3'x5'), and it had #4 rebar in it, would this require a CEE?

What if the same size pad had a web of #4 rebar all tied together that was >20' even though direct earth contact wasn't >20'. Does this require a CEE?

If the same pad was 5' x 6' and had a loop of #4 bar around the perimeter that was >20', would this require a CEE?
 
You measure the individual lengths of all of the pieces of rebar tied together and if it's 20' or more in the footing then it qualifies as a CEE.
 
I think it would be more technically correct to ask whether the footing in each of those situations qualifies as an electrode and must be used, or does not qualify as one and a different electrode type must be used.
 
socal_j said:
Do you have anything that spells this out? Code reference?
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Here's the reference as Hv noted:

250.52(A)(3) Concrete-Encased Electrode. 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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