"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?

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?

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'.

check the curves for the breaker?
how do i do that?
what is the curve of a breaker?
are they like a womans curves?

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.

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.

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).]

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

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.

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.

George.
thanks for your post.
ya the length of conductor is not in the ground. It runs through the house to the water pipe and rods.

ya the code is silent on the lenth of conductor but not the size.
So if the code is silent on the length how can the AHJ infoce it?

That is why they call it AHJ, because they have the last word on it. Hell there are parts of the country still working on 1999 code because their AHJ didn't adopt the 2002.

I would ask the AHJ to give me a quote reference for the NEC bieng enforced in your area. Unless there is a legally adopted local code requirement, he cannot ask for some thing that is not code.
As was noted above the ground rods do not help the circuit breaker trip in a fault condition.

why don't ground rods help?
if it's less then 25 ohms it's all good right.
if you drive two no need to test for 25
and that could meen you still might have more?

bucketman -

"why don't ground rods help?"...because ground rods are for directing lightning strikes and high voltage line surges (Poco problems) to ground...this current is not part of your circuit wiring and thus does not pass through your circuit breaker.

Another point - if you look at Table 8, it shows the resistance on a #4 conductor over a distant of 1,000 feet to be .508! ....that's .0508 for 100 ft....do the arithmetic...this resistance is so low as to have NO affect on a lightning strike going to earth.