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#84968 - 05/20/03 11:47 PM Re ground?
ga.sparky56 Offline
Member

Registered: 11/24/02
Posts: 582
Loc: young harris georgia usa
Is it ever permissible to re ground a grounded conductor on the load side of the service disconnecting means? I'm talking drive a ground rod and reground.

I know it's permitted in 250.32(B) at out buildings,but outbuildings aside, is there a code art. that specifically adresses this?

To further clarify,I'm not saying bond to any enclosures or anything of the sort.Just drive a ground rod,and say for example take a piece of # 6 bare cu. from it to a subpanel and land it in the neutral bar (not bonded to the panel),or for that matter take a piece of #12 barecu. from said rod to a jbox,break the neutral(or grounded conductor) and reground it.

Code aside, what electrical problems would this create?

No I'm not legally insane,just want to settle an arguement. I think I know the answer but need clarification.

Russell

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2014 / 2011 NEC & Related Books and Study Guides
#84969 - 05/21/03 03:44 AM Re: Re ground?
Redsy Offline
Member

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
I know there is controversy surrounding the POCOs utilizing the earth as a conductor.
By doing what you describe, you would be creating an additional earth current. I think this would, to varying degrees, result in a voltage gradient that could cause "step voltage" hazards.

[This message has been edited by Redsy (edited 05-21-2003).]

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#84970 - 05/21/03 04:09 AM Re: Re ground?
George Corron Offline
Member

Registered: 05/16/01
Posts: 728
Loc: Lorton, Va USA
Supplementary grounding is permitted per Article 250-54 (99 ref.). You can NOT use the earth as a return, but are allowed to supplement anywhere you feel necessary.

One example of this is parking lot lights. You must carry your equipment ground with you, but if you are in an area with thunderstorms and lightning, you are wise to add a ground rod at each pole base.

Remember the basic theory behind ground rods is equipotential plane, long runs or sensitive equipment your plane can get a bit stretched. Supplementals are not utilized enough, just make certain you are not replacing the equipment ground.

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#84971 - 05/21/03 05:10 AM Re: Re ground?
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
See 250.24(A)(5). Rebonding the grounded conductor is rarely permitted. The second building example is one place where it is permited, but in general you can't connect the grounded conductor to earth after it leaves the service disconnect enclosure.
Don
_________________________
Don(resqcapt19)

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#84972 - 05/21/03 07:43 AM Re: Re ground?
George Corron Offline
Member

Registered: 05/16/01
Posts: 728
Loc: Lorton, Va USA
Don,
Thanks, I obviously read his post too quickly. You do NOT rebond the neutral, but can supplement the EGC, or GEC if you like, anywhere you believe necessary.

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#84973 - 05/21/03 02:35 PM Re: Re ground?
BGaquin Offline
Junior Member

Registered: 05/08/03
Posts: 16
Loc: Sterling, VA
If I understand your question “is it ever permissible to reground a GROUNDED CONDUCTOR “The Neutral” in most systems. Other than the one item you mentioned the answer is no. The examples listed are for re-grounding a grounding conductor.

A Neutral/grounded conductor that is grounded downstream from the main disconnect, can cause current to flow on the ground system. The equipment grounding conductor will be in parallel with the neutral/grounded conductor. This will effect to operation of ground fault devices, can cause Power Quality issues and in some instances be a life safety issue

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#84974 - 05/21/03 03:35 PM Re: Re ground?
kale Offline
Member

Registered: 11/08/02
Posts: 168
Once again, the --GEC, EGC, grounded conductor, grounding conductor-- terminology problem raises its ugly head.

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#84975 - 05/23/03 07:00 PM Re: Re ground?
ga.sparky56 Offline
Member

Registered: 11/24/02
Posts: 582
Loc: young harris georgia usa
Thanks for the replies guys.

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#84976 - 05/24/03 04:36 AM Re: Re ground?
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
The issue is conceptual.

One can have a number of SDS's 'reground' within a structure, or 250.32 a 3-wire feeder to an outbuilding close to the 'supply' building.

Either/Or ends up with gauss or stray voltage bettween the two methods

Then the PQ guys get the biz.....

This is due to the NEC's stance that the earth is not a conductor, despite other international methods

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#84977 - 05/24/03 05:16 AM Re: Re ground?
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
 Quote:
One can have a number of SDS's 'reground' within a structure,


Isn't this different then regrounding the grounded conductor downstream?

In the case of an SDS you have a new/created neutral that must be grounded.

In the opening post it was regrounding a conductor that was already grounded.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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