What is "at a structure"?

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I would wager we're (note I say "we" and not "y'all") about the only bag of fruits and nuts who would think about a ground rod as a structure. Realistically, I can't envision a ground rod as ever getting 250.50 applied to it, so not much of an issue there. (I would agree that it's a structure, based on the definition.) :)

ptonsparky said:
mdshunk said:
Perhaps for a limit proposal, you might use some guidelines that are generally kept in mind for agricultural equipotential planes. Something like the pace of the average man, or the height of the average man from the soles of the feet to the tips of the fingers on the upstretched arms. Something around 7 or 8 feet sounds conservative to me.
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Maybe you might want to stretch this out to the average length of a Holstein from nose to hind legs. They are longer and would be most affected in this situation.
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I am really not understanding why this keeps revolving back to equipotential bonding? :confused:
 
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georgestolz said:
I would wager we're about the only bag of fruits and nuts who would think about a ground rod as a structure.
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Agreed.....I was just having some fun. :)

That could get messy, each time you drive a ground rod you would have to drive another one to ground the first one. Wait....that would keep us in work. ;)
 
Pierre C Belarge said:
Ground rods are equipment, like panels, switchgear, etc... they are manufactured and are not a structure.
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I respectfully suggest that is an opinion. :)

Lets say the 'equipment' is a large section of NEMA 3R switchgear sitting on a pad outside away from other buildings.

IMO that is equipment that is also a structure.

A light standard is equipment but is also structure to the NEC.

The lines blur and that is where an inspector must exercise judgment. :)
 
iwire said:
Agreed.....I was just having some fun. :)
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I know, me too. :)

Wait....that would keep us in work. ;)
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And looking like Ahnold too...

Pierre said:
Ground rods are equipment, like panels, switchgear, etc... they are manufactured and are not a structure.
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Pierre, to add to the blurry lines thing:

Have you seen a temp service built on a four-footed metal stand? Essentially, every component of it is manufactured, but it's still widely considered a structure in applying 250.50.
 
Ho!! Ho!! Ho!!!

Ho!! Ho!! Ho!!!

Bob
Are you respectfully trying to ruin my Xmas :-?

Just kidding ;)

I would say that a ground rod is not to be mistaken for a structure. I know that common sense does not pervade in the NEC, as you mentioned, an inspector has to try and use some "good" judgement.

I won't say I am so certain that I would eat crow, as we saw what happened yesterday when that was tried...HE! HE! HE!!!

Crow would really ruin the taste of my famous Ambrosia...which I just finished making.:)

P.S.
If the rod is a structure, due to building codes, would we need a bathroom and permanent cooking facilities at that structure????
 
iwire said:
Agreed.....I was just having some fun. :)

That could get messy, each time you drive a ground rod you would have to drive another one to ground the first one. Wait....that would keep us in work. ;)
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Wash, Rinse, Repeat.
 
Pierre C Belarge said:
Bob
Are you respectfully trying to ruin my Xmas :-?
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No not at all, I just wanted to keep it friendly. :)

I would say that a ground rod is not to be mistaken for a structure.
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I agree, as I said I was just having fun with the NECs open ended definition of structure.


I won't say I am so certain that I would eat crow, as we saw what happened yesterday when that was tried...HE! HE! HE!!!
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It's not that bad, and yesterday I figured I had a high chance of eating it.

P.S.
If the rod is a structure, due to building codes, would we need a bathroom and permanent cooking facilities at that structure????
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Now you confusing a structure for a building.

IMO a building is always a structure but a structure is not always a building. :)
 
georgestolz said:
mdshunk said:
Perhaps for a limit proposal, you might use some guidelines that are generally kept in mind for agricultural equipotential planes. Something like the pace of the average man, or the height of the average man from the soles of the feet to the tips of the fingers on the upstretched arms. Something around 7 or 8 feet sounds conservative to me.
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I am really not understanding why this keeps revolving back to equipotential bonding? :confused:
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Probably because this is the situation where you are most likely to encounter problems associated with having separately grounded metal structures that are not bonded together.

The problem with an electrode not bonded to your GES is that you could have a voltage difference between that electrode and your GES. But this is only a problem if there is some third item that interacts with _both_ of these electrodes.

So the question then falls to: "What could interact with both of these non-bonded electrodes, and would this be an issue?" Thus you get to dimensions related to things like the stride of a person or the distance that someone could reach, or the distance than an animal could reach.

-Jon
 
Jon, I understand what you are pointing out however I don't think it fits what George is asking about.

250.50 Grounding Electrode System.
If available on the premises at each building or structure served, each item in 250.52(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system. Where none of these electrodes are available, one or more of the electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.
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I am under the impression George wants to make a proposal to answer the question how far away does an electrode have to be before it is not available at the building or structure?
 
iwire,

Sorry I killed the joke. I think that the idea of a ground rod with its own lav is funny. I wonder if a welded stainless steel silo, buried directly in the ground, require additional grounding electrodes?

I get you on what George is asking, and I think that the reason that the discussion goes back to 'equipotential bonding' and 'stray voltage' is because these fields of work/study would provide a reasonable basis for the distance that George is trying to discover/define. They are not directly applicable, since this is a different application, but IMHO this field of research would provide a good set of ideas to figure it out.

-Jon
 
winnie said:
They are not directly applicable, since this is a different application, but IMHO this field of research would provide a good set of ideas to figure it out.
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Hi Jon, I think your right....if logic is involved. :)

I suspect that will not be the case, I suspect that some arbitrary distance will be chosen out of thin air.
 
I may be hard headed but a ground rod .......a structure?....after all of the posts...if someone asked me if a ground rod was a structure....I would still say NO!....250.50 or def.100.... I do not see it, sorry.
 
dcspector said:
if someone asked me if a ground rod was a structure....I would still say NO!....
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I certainly understand that position. :smile:

Let me ask this.

When you look at a pole holding up light fixtures do you see a structure?
 
I like to use the water pipe as a GE. But until the 2005 NEC it always required an additional electrode. I did a removeable building over a 500 ft deep well with a 100 hp motor. I didn't use ground rods as I ran a 4 wire feeder (I was wrong and many electricians make this mistake) so the bulding could be removed.
I had to drive two ground rods for the 16" well casing as the AHJ considered it a water pipe.

Even if the well casing is not a GE, I still bond to it.

I once did a service on a concrete dam that was 500 ft across and 125 ft high. I bonded to the metal outlet pipe and still had to install a ground rod. Dam, it was grounded.
 
A ground rod, by itself, is not a structure. A wooden or steel pole, by itself, is not a structure, or at least they wouldn't be a "structure served" if there were nothing electrical attached to them to "serve". A pole without a light is not a light pole, it could just as likely be a fence post without any fence. IMHO the operative word here is "served". You wouldn't need a ground rod at an outhouse, would you?

250.50 Grounding Electrode System.
If available on the premises at each building or structure served, each item in 250.52(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system. Where none of these electrodes are available, one or more of the electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.
 
iwire said:
I am under the impression George wants to make a proposal to answer the question how far away does an electrode have to be before it is not available at the building or structure?
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When it is sufficiently far away that a person cannot reach it from an electrode already in the 250.50 system.
 
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