Grounding electrode at a seperate building

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Richard DeBernardo

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Does a remote panelboard (120/240 volt, 10 circuits) need a seperately driven ground rod if an insulated equipment grounding conductor was installed with the feeder conductors between the remote panelboard and the main service? The second question is can a seperately driven ground rod at the remote panelboard take the place of the insulated equipment grounding conductor that could have been installed with the feeder conductors?

Thanks,
Rich
 
Yes and maybe
You must always drive a ground rod at the separate structure whether you have an EGC or not. If you choose not to have an EGC you may do so if there is no metallic pathway between the buildings. Art. 250.32 (B)(2)
 
Dennis Alwon said:
Yes and maybe
You must always drive a ground rod at the separate structure whether you have an EGC or not. If you choose not to have an EGC you may do so if there is no metallic pathway between the buildings. Art. 250.32 (B)(2)
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There is one exception, if only one branch circuit supplies the building or structure and the branch circuit includes an equipment grounding conductor, but the OP does not qualify for this anyhow...
 
Richard DeBernardo said:
Does a remote panelboard (120/240 volt, 10 circuits) need a seperately driven ground rod if an insulated equipment grounding conductor was installed with the feeder conductors between the remote panelboard and the main service?
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Yes, unless the remote panelboard is located within the same building that the panelboard receives its' supply from.

Richard DeBernando said:
The second question is can a seperately driven ground rod at the remote panelboard take the place of the insulated equipment grounding conductor that could have been installed with the feeder conductors? Thanks, Rich
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We call that "regrounding the neutral" at a separate building, where I work. Be careful here. You would not want to create a high-resistance path. The grounded conductor would have to be bonded to the grounding electrode system as per 250-32. Look at the limitations of 250-32 in effect, including metallic piping paths that would carry current. :)
 
For what it's worth using the grounded conductor as a grounding means at a separate structure will likely be a violation starting in 2008.
 
iwire said:
For what it's worth using the grounded conductor as a grounding means at a separate structure will likely be a violation starting in 2008.
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That will be alright with me. I've been to lots of day camps, Boy Scout, Girl Scout camps and the like where there are many little cottages each with a feeder and a water service. So many of these have regrounded neutrals and 3-wire feeders, and there is almost always a complaint of a big blue spark at the drinking fountain. :)
 
wbalsam1 said:
. I've been to lots of day camps, Boy Scout, Girl Scout camps and the like where there are many little cottages each with a feeder and a water service.
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How is this different then any residential street in the USA that has metal water distribution?
 
iwire said:
How is this different then any residential street in the USA that has metal water distribution?
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Really, that's a great question. I don't know if I'm smart enough to answer it. I will venture to say that in my limited experience, there seems to be a better percentage of safer installations at services than feeders in my area. I think the objectionable current/objectionable voltage/parallel paths/ conditions are less likely to occur in service entrance installations around here than they are to occur in feeder services to these little remote cottages, etc.

I fully agree with the notion that the systems are identical in theory but somewhere in practice it's just different. Sorry I don't have a better answer, Bob. Teach me. That's what I'm here for. :)
 
First know that I was not trying to give you a hard time.

You just provided the opportunity to bring up this subject.

I don't know the answer, but its an issue I am interested in.

IMO the change in the code had more to do with peoples gut feelings more than any statistical proof there was a problem.

Maybe Ryan will jump in I believe he was a submitter asking for this code change. :)
 
I'm glad to see somebody asked this question, we have just this situation where I work. On a newly installed building grounds building a local electrical contractor installed a 100 amp main lug panel to serve the heat, lighting,and general receptacles. After he completed the work I noticed that he hadn't bonded to the building, the building is all steel, and when the other contractor installed the footings for the building I didn't see them install any grounding system. So I assumed that the electrician would drive a couple of 8ft rods and bond the sub panel and building steel all together. Art250.32 states that the EGC is to be run with the phase wire then bonded to the structures metal. But if there is no provision to bond and ground are you required to set up a bonding system?
Bill
 
iwire said:
Maybe Ryan will jump in I believe he was a submitter asking for this code change. :)
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Well...my ears were burning, so here I am.

Mike and I made this proposal for a few reasons.

The first argument that always comes up is "how is this different than a service"? The answer is...its not. That is the problem.
Why does the code require no objectionable current on the electrical system as a general rule, then require the objectionable current at the service? This proposal was made to get rid of using the nuetral to connect to enclosures. We don't use the nuetral at other locations because of objectionable current, why do we do it here?

In 2011, I plan on making a proposal to 250.24 that would allow an equipment bonding jumper to the service, if that is desirable.

Perhaps next will be a proposal to the NESC to require it.
 
ryan_618 said:
Perhaps next will be a proposal to the NESC to require it.
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I agree that would be very good, but...

I think the POCOs in this country would not even touch this with a million mile pole.
I think that it would open the proverbial "can of worms" for them. As to why are not existing installations changed as well... a multi-billion dollar issue, maybe even a mega-billion dollare issue.

Don't let that stop you from providing a proposal, I would love to see it.
 
ryan_618 said:
In 2011, I plan on making a proposal to 250.24 that would allow an equipment bonding jumper to the service, if that is desirable.

Perhaps next will be a proposal to the NESC to require it.
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Is this really an issue though? We have "objectionable current" flowing on millions upon millions of services throughout the nation. I'm just curious what the problem is.

As for the NESC, that seems like a very wishful thinking. Getting the utilities to stop using an MGN system seems like the challenge of a lifetime.
 
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