Concrete-Encased Electrode Size

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Desert Sparky

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Electrical Engineer
I've read dozens of threads on the forum regarding this topic, but I've not seen an answer to the following specific question:

Assume I'm bonding all grounding electrodes together present at my building, to include building structural steel, cold water piping, concrete-encased electrode, and (2) ground rods per NEC 250.50. Per Table 250.66, my GEC should be #1/0 based on service entrance conductor size.

Does my concrete-encased electrode also need to be #1/0, or can it be #4 AWG as described in 250.52(A)(3) and just be bonded to the rest of the grounding electrode system with a #1/0?
 
roger said:
250.66(B) #4 is fine
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My understanding is that 250.66(B) describes the size of grounding electrode if that grounding electrode is only connected to a concrete-encased electrode (and nothing else). My question is about the size requirements of the concrete-encased electrode itself when there are multiple grounding electrodes present and bonded together (and our grounding electrode is larger than #4).
 
Regardless of what size the GEC must be the jumper (connection) to the CEE never has to be larger than #4 and the jumper (connection) to any rods never has to be larger than #6
 
Desert Sparky said:
My understanding is that 250.66(B) describes the size of grounding electrode if that grounding electrode is only connected to a concrete-encased electrode (and nothing else). My question is about the size requirements of the concrete-encased electrode itself when there are multiple grounding electrodes present and bonded together (and our grounding electrode is larger than #4).
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To have a CCE you need 20' of rebar or 20' of #4 copper.
 
Desert Sparky said:
My question is about the size requirements of the concrete-encased electrode itself when there are multiple grounding electrodes present and bonded together (and our grounding electrode is larger than #4).
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I'm not sure I understand your question. As Dave stated there are two ways to have a CEE, either the rebar or a bare copper conductor.
 
infinity said:
I'm not sure I understand your question. As Dave stated there are two ways to have a CEE, either the rebar or a bare copper conductor.
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The CEE in this scenario is bare copper conductor; as such, does the size of this CEE have to match the size of the GEC? Or is it acceptable to bond a #4 CEE to a grounding electrode system installed with a larger GEC (in my case, a #1/0)?
 
Desert Sparky said:
The CEE in this scenario is bare copper conductor; as such, does the size of this CEE have to match the size of the GEC? Or is it acceptable to bond a #4 CEE to a grounding electrode system installed with a larger GEC (in my case, a #1/0)?
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No the connection to the #4 CEE can be larger than #4. It can also be smaller than the #4 CEE when the service conductors are very small.
 
Desert Sparky said:
The CEE in this scenario is bare copper conductor; as such, does the size of this CEE have to match the size of the GEC? Or is it acceptable to bond a #4 CEE to a grounding electrode system installed with a larger GEC (in my case, a #1/0)?
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We're trying to explain that the GEC to the #4 cu CEE need not be larger than the same #4 cu.
 
Desert Sparky said:
The CEE in this scenario is bare copper conductor; as such, does the size of this CEE have to match the size of the GEC?
Click to expand...
No. A CCE is either 20' of rebar or 20' of 4AWG in the footer of the building. The conductor connecting to the CCE never needs to be larger than 4AWG
Desert Sparky said:
Or is it acceptable to bond a #4 CEE to a grounding electrode system installed with a larger GEC (in my case, a #1/0)?
Click to expand...
Sure.
 
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