Electrode sizing

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ATOMMYD

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Here is my problem. I had an inspection on a 400 amp residential service in broward county. The electrode conductor was sized at 2/0 figuring that if I had to run the service to FPL than I would run 500kcmil The inspector told me that I could size the wire to FPL wire size which was much smaller than what we would have to run . I could have used a #4 solid and been good. The code reads we size the wire according to the wire size of the service entrance conductor. Is the inspector correct. And if he is correct will I be able to argue this in other cities and counties
Thanks...
 
infinity

infinity

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Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Re: Electrode sizing

Stars is correct. As Ryan had asked it would depend on what type of electrode(s) you were using. A metal underground water pipe or building steel would require a #1/0 copper, a concrete encased electrode would require a # 4 copper and the two ground rods would only require a #6 copper conductor.
 
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eprice

Senior Member
Location
Utah
Re: Electrode sizing

Atommyd,

I agree that in your specific case, where the grounding electrodes are 2 ground rods, 250.66(A) allows you to use #6 copper conductors.

However, I think you are asking a more general question. Utility companies often run smaller service conductors for a particular size service than what the NEC would require. I believe you are asking whether this smaller actual size can be used on table 250.66 rather than the size which the NEC would require for the service? I believe the answer to that question is no. Table 250.66 bases sizing of the GEC on the size of the service entrance conductors. If you look at the definitions section, the conductors that the utility might possibly be installing are either service drop conductors or service lateral conductors, but never service entrance conductors.
 
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stars13bars2

Senior Member
Re: Electrode sizing

Sorry Ryan, I didn't mean to steal your thunder. You did all the work to set it up. After that it was too easy to pass up.
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Re: Electrode sizing

I agree with eprice that the real question here is if we size the GEC by our service entrance conductors or the power company conductors.

I also agree with eprice that we must size the GEC based on the service entrance conductors that are under NEC jurisdiction. The size of the utility companies conductors are of no significance to us under the NEC.
 
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