Ground to water main

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acrwc10

Master Code Professional
Location
CA
Occupation
Building inspector
I have a 400a Homeline main panel that has two 200a breakers in it, they are fed from factory installed paralleled 3/0. I ran a #2 to the water main, and the inspector wants a larger conductor. My argument is for the paralleled 3/0 a #2 is what code calls for. His argument is that it is 400a panel and the ground needs to be based on 400a. I should add this is an underground fed panel, and the utility conductors are 350 AL. Any comments would be appreciated.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I say #2 is all you need. Note 1 T. 250.66. Table 8 has 3/0 at 167800 cir mil. Multiply by 2 and you get 335600 cir mil. This is equi. to 350 KCM. Table 250.66 allows #2 for 350 KCM copper
 

A/A Fuel GTX

Senior Member
Location
WI & AZ
Occupation
Electrician
Dennis, I used Table 5 for my calc. I get confused here. I'm sure someone will steer me straight on this:wink:
 

acrwc10

Master Code Professional
Location
CA
Occupation
Building inspector
I say #2 is all you need. Note 1 T. 250.66. Table 8 has 3/0 at 167800 cir mil. Multiply by 2 and you get 335600 cir mil. This is equi. to 350 KCM. Table 250.66 allows #2 for 350 KCM copper

Thanks, this is how I sized my ground. Now I just have to convince the man incharge of this.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Dennis, I used Table 5 for my calc. I get confused here. I'm sure someone will steer me straight on this:wink:

The insulation has nothing to do with it. You only have to use Table 8-- the conductor itself.

Yes the inspector is asking about the GEC and perhaps he did it incorrectly.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
I see a situation which exemplifies NEC vs NESC vs manufacturer specs and I don't think there is an easy answer. The inspector is caught being regulated by the NEC. The "factory" 3/0s are part of the listing/labeling of that gear and are not required to be NEC specs. The utility installs to the POCO requirement and NESC, not NEC.
Not necessarily taking the inspectors side, but walking in his shoes, he has a service which according to NEC should have a minimum conductor of 400 kcmil Cu or 600 kcmil AL (310.15(B)(6)). Using "his" Code rules a 1/0 grounding electrode conductor is needed.
There are obviously different points of view with all the specifics involved, but, having faced the same situation, I followed the same steps. The most conservative action no doubt but one which he probably feels is best based on NEC alone.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Gus those parallel 3/0 conductors are service entrance conductor and the code doesn't state whether or not it is part of a listing. I have to disagree with you on this one but I see where you are coming from. With a buss I have no question 1/0 is required but not with the conductors.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Gus those parallel 3/0 conductors are service entrance conductor and the code doesn't state whether or not it is part of a listing. I have to disagree with you on this one but I see where you are coming from. With a buss I have no question 1/0 is required but not with the conductors.

Dennis, My whole point is a position anyway and it sure may be wrong.
As far as the 3/0s, you may be correct, I was ass-u-ming from "they are fed from factory installed paralleled 3/0" (emphasis mine)
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Dennis, My whole point is a position anyway and it sure may be wrong.
As far as the 3/0s, you may be correct, I was ass-u-ming from "they are fed from factory installed paralleled 3/0" (emphasis mine)

I think they are installed from factory installed 3/0 but I don't see why it matters who installs it.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
not to argue the point, but if they were "factory installed" I would look at them the same as I would lines in a motor starter, etc and assume they were not necessarily sized by NEC
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
not to argue the point, but if they were "factory installed" I would look at them the same as I would lines in a motor starter, etc and assume they were not necessarily sized by NEC

I want to argue the point. :grin: They are installed to NEC standard whether they were deliberately or by design it does not matter When a buss bar is used we must assume the one wire size since they are not parallel conductors. But you are correct in that we have a difference of opinion. The difference is that I am correct. :grin::grin::grin:

Anyway that is my opinion.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Well I know that I am a nobody. However, I see where Gus is coming from and had me thinking. Dennis I agree with your posts per NEC.

Boy, that's taking the middle of the road. ;)

Emily Dickinson said:
[FONT=Geneva,Arial,Helvetica,helv,sans-serif]I'm nobody! Who are you?
Are you nobody, too?
Then there's a pair of us ? don't tell!
They'd banish us, you know.
[/FONT] [FONT=Geneva,Arial,Helvetica,helv,sans-serif]How dreary to be somebody!
How public, like a frog
To tell your name the livelong day
To an admiring bog!
[/FONT]
 
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