Remote Meter-Mains to Load Centers

[jtttat]

The Georgia Institute of Technology run length table in section 250-95 confuses me. If I have a meter-main 850 feet away from our distribution panel, then technically I can't run an effective ground fault path back to the main. I'm not certain I should bother pulling the ground wire.
Question: Does 250-81 apply here?

 

[charlie]

Re: Remote Meter-Mains to Load Centers

To find 250-95 I have to go back to the 1996 Edition of the NEC, is that what you are using?

 

[jtttat]

Re: Remote Meter-Mains to Load Centers

I'm aware of the 96 NEC book I was reviewing. I have the 99, & 02 on CD, yet found going to the hard back copy easier @ the time.

My point still stands: Does this Table by the Georgia Institute of Technology have any merit as to the length restrictions of the grounding conductor?

And do you think it necessary to run a ground conductor from a meter-pedestal mounted in a vineyard 850ft away from the load center to be mounted on a workshop?

[ July 22, 2005, 02:44 PM: Message edited by: jtttat ]

 

[charlie]

Re: Remote Meter-Mains to Load Centers

The reason I questioned the edition was the reorganization of Article 250. I highly recommend that you obtain a copy of the current NEC that is used in your area in hard copy.

OK, to address your question. I absolutely agree with the Georgia Tech model. You will need to not only install a grounding conductor with your phase conductors but you will need to increase the size of it to comply with 250.122(B) in the 2005 NEC (assuming that is the edition that you are required to comply with).

'05 250.122(B) Increased in Size Where ungrounded conductors are increased in size, equipment grounding conductors, where installed, shall be increased in size proportionately according to circular mil area of the ungrounded conductors.

You also question 250-81 which deals with the grounding electrode system in the 1996 Code. The meter/main will be installed on a separate structure and must be connected to a grounding electrode at that location. You are now feeding a second structure from there that is 850 ft away from the first structure. The grounding and grounded conductors must be kept separate unless you can meet the requirements of 250.32(B)(2) in the 2005 Code.

 

[jtttat]

Re: Remote Meter-Mains to Load Centers

I'll assume then that since I am installing a new ac service, which must be grounded, then I couldn't possibly meet 250.32(B)(2)" ?

If so, then how does that rule ever apply ?

 

[iwire]

Re: Remote Meter-Mains to Load Centers

Originally posted by jtttat:
I'll assume then that since I am installing a new ac service, which must be grounded, then I couldn't possibly meet 250.32(B)(2)" ?

If so, then how does that rule ever apply ?

You are free to apply 250.32(B)(2) on a new installation if you meet the rules in that section.

250.32(B)(2) may be the way to go at 850'. If you do use 250.32(B)(2) I would recommend running a full size grounded conductor.