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Joined: Oct 2004
Posts: 72
B
Member
"AHJ says if grounding elctrode conductor is longer then 100' up size from #4 to a #2."
no code was refferanced.

Why?
what would he be thinking?
has any one seen this in nec 2002 or 2005?

Joined: Feb 2002
Posts: 182
B
Bob Offline
Member
This is not a code problem. Its an engineering problem. If the grounding conductor is too long the impedance may cause a delay in the opening of the breaker. The 100 ft is a rule of thumb. To know if there is a problem you would need to caculate the fault current and check the curves for the breaker. How long is the conductor?

Joined: Oct 2004
Posts: 72
B
Member
Are rules of thumb enforceable violation?
NEC says nothing about rules of thumb, right?
article 250 said nothing about it.
is something wrong with 250.66? No

it's a residence with a 200amp service
4/0 alum
grounding electrode conductor from service to with in 5' of whare water enters the house.
a distance of 85'.

Joined: Oct 2004
Posts: 72
B
Member
check the curves for the breaker?
how do i do that?
what is the curve of a breaker?
are they like a womans curves?

Joined: Feb 2002
Posts: 375
G
Member
bucketman ---

The AHJ is asking you to either increase the conductor size or provide engineering showing your size is correct.

While the code may be silent on the issue, I think he is within the spirit of the code.

Joined: Oct 2004
Posts: 72
B
Member
250.66 doesn't seem vary silent.
it seems to be directly to the point.
now I've been doen these service changes for a few years and never had the AHJ call me on the 80 some feet of ground condutor be to long.
i just can't see the AHJ call me for something thats not in the code.

Joined: May 2002
Posts: 1,716
R
Member
Bucketman, I agree with you, as far as the GEC there is no restriction to length as you have said and in fact if the #4 GEC is bare it becomes part of the "Electrode" and the GE's function won't be improved to any great performance level by increasing the conductor size.

With this length of #4 copper in the ground, and if we were talking about a rod, the conductor would probably provide more of a GE than the rod itself.

Bob, the GE and GEC would play no part in the operation of an overcurret device.

Roger



[This message has been edited by Roger (edited 03-02-2005).]

Joined: Aug 2003
Posts: 1,374
R
Moderator
I think the AHJ is acting well beyond the scope of his/her authority.


Ryan Jackson,
Salt Lake City
Joined: Oct 2004
Posts: 72
B
Member
ya, talked to the AHJ to day befor I ripped out all that #4 and he said it was just a consern of his that it be up sized.
So the #4 stands...

But next time I'll just pull #2 because its cool.
I do think it's a good wiring practice and a good Idea and it cant heart but the $$$.

"I think the AHJ is acting well beyond the scope of his/her authority."

That was my hole thought. It was a you can't make me thing.

thanks all for the posts. keepem comen.

Joined: Feb 2002
Posts: 375
G
Member
1) It is not clear that the GEC is in the ground. I assumed it was not.

2) If there are no real concerns about the length, then the diameter does not matter. And we would not have a table of GEC related to service conductor.

The code is silent on the issue of maximum length of the GEC before meeting the grounding electrode.

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