Sizing GEC

[johnson151]

I have a 100 amp service that will be fed from the power company with 1/0 AL. The grounding electrode is a rebar coming out of the concrete. I installed a #6 solid copper wire between the service panel and the rebar as the grounding electrode conductor. The inspector cited 250.66(B) and says that a #4 must be installed. The last sentence of this paragraph says "shall not be required be larger than #4awg" To me this says #4 is the maximum size I would need, and that I should size the GEC off of table 250.66 until conditions surpass what would otherwise call for larger that #4. The only evidence I can see that would support his argument is if that final statement means "is required to be #4".

He has asked a few other inspectors and they all say #4, but haven't been given a solid reference or piece of evidence to support it.
Can anyone else point me to what they may be referring too? Or, if I'm correct, is there a better reference or resource I can give to prove my case?
I found this video that seems pretty clear to me, but the only thing the inspector said was "is Mike Holt the AHJ?"

https://fb.watch/u_HJO0XW-1/

As for now, I'll just put in #4 from now on to avoid the fight, but I would like to know what the answer is.

Thanks in advance

 

[infinity]

I have a 100 amp service that will be fed from the power company with 1/0 AL.

Look at T250.66. For #1/0 AL the minimum size GEC is #8 copper. You 1, inspector 0.

 

[Elect117]

You are correct.

A concrete electrode can be rebar or 20' of #4 copper.

The grounding electrode conductor is sized based on 250.66.

#6 cu was fine. As infinity said, #8 would have been the minimum.

 

[Joe.B]

As the others have said, the inspector is wrong. There is benefit to using #4, you could theoretically upsize the service to 800 amps, or a million amps, and that #4 GEC would still be good. But the code is a minimum standard, you could always upsize everything and it would be "better" and provide more options. You could wire the entire house 10 gauge wire just so any circuit could be expanded... No one would do that though because it would be wasteful and cost prohibitive.

 

[infinity]

The inspector cited 250.66(B)

He has asked a few other inspectors and they all say #4, but haven't been given a solid reference or piece of evidence to support it.

Yes you had it correct. He and everyone else obviously misread what that section actually says.

250.66(B) Connections to Concrete-Encased Electrodes. If the grounding electrode conductor or bonding jumper connected to a single or multiple concrete-encased electrode(s), as described in 250.52(A)(3), does not extend on to other types of electrodes that require a larger size of conductor, the grounding electrode conductor shall not be required to be larger than 4 AWG copper wire.

 

[Lioneye]

You are correct.

A concrete electrode can be rebar or 20' of #4 copper.

The grounding electrode conductor is sized based on 250.66.

#6 cu was fine. As infinity said, #8 would have been the minimum.

Seems the inspector is confusing "Grounding Electrode" with "Grounding Electrode Conductor". And not that is applies here, but any GEC or bond smaller than #6 requires physical protection, so we usually never reduce below that.

 

[Dennis Alwon]

I agree with the others but I would have used #4 simply for the ease of a service upgrade. When I did a concrete encase electrode I installed the #4 where it could not be gotten to--in the concrete.