Ground Ring as GE

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I'm looking for claification of Sec 250.52 (4). A colleauge is interpretting it as you only need 20' of wire to make a ground ring. I see it as the conductor needs to go around a building, but only 20' is required to be bare. Can anyone clarify?
 
A ground ring can not be shorter than 20' in length

all of it must be in contact with the earth

it must encircle the builing or structure.

it does not appear to be economically sound unless there are no other alternatives (IMO)
 
I see it as the conductor needs to go around a building, but only 20' is required to be bare.
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If you read 250.52(A)(4) it says:

"A ground ring encircling the building or structure, in direct contact with the earth, consisting of at least 20 feet of bare copper conductor not smaller than 2 AWG."

So the ground ring must encircle the building or structure and be not less then 20 feet of bare copper #2 AWG.

For example, I have a panel mounted on a post for an irrigation pump and related equipment, and I choose to use a ground ring for my grounding electrode, I must encircle the post with at least 20 feet of bare #2 AWG to meet the requirements of 250.52(A)(4).

Here is another example:

I have 5000 square foot building and I choose to use a ground ring I must encircle the building with a #2 AWG bare conductor all the way around the building to meet the requirements of 250.52(A)(4)

Hope this helps,

Chris
 
what kind of building could be encircled by 20 feet of wire?

not even a portapotty.

this is one of those things in the code that never made much sense to me. my guess is that it might well be something done by someone for a very rare and specific purpose, but is certainly not a practical option for any normal situation.

I also don't see any requirement that all of the wire be bare or that it all be #2 or larger, just that 20 feet of it is bare and at least #2. It does say the ground ring has to be in direct contact with earth, but so one might argue if insulated it does not meet that requirement.
 
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what kind of building could be encircled by 20 feet of wire?
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It also says "structure". If you look at my example of the irrigation pump panel located on a post you could see a structure that could be encircled by less then 20 feet of wire.

Chris
 
As the currently is worded, your interpretation is the correct one. However, it wouldn't make any sense to circle a building with a ground ring with only 20' bare. The interpretation your co-worker has would probably be as effective...
 
tom baker said:
Not only encircle the buildig but 30 inches deep. A ufer is far better at essentially no cost.
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Not that I disagree, but where are you coming up with the 30'' depth?
 
The 'minimum' of 20 feet is for small structures such as Raider1's example or even a transformer. The conductor is required to be bare and encircle the building or structure. I have pictures of a ground ring that is a little over 2000 feet long. One of my students is working on a project where the ground ring is sized at 750 AWG.

The ground ring is the "ELECTRODE" [even though it is a conductor - 250.52(4)], hence it is required to be bare and in contact with the earth.

The grounding electrode conductor that connects the ground ring (electrode) is permitted to be ... "The conductor shall be solid or stranded, insulated, covered, or bare", as per 250.62.
 
[FONT=&quot]According to CMP 5 there is some magic about having the ground ring encircle a building or structure. I submitted a proposal to permit the use a a 20' length of bare #2 that does not encircle a building or structure to be used as a grounding electrode but it was rejected. I think that the amount of contact area is what makes an effective grounding electrode and not the fact that it encircles a building or structure. In fact, based on the theory that ground rods are the most effective when they are separated by a distance equal to twice the length of a single rod, I would expect that a straight length of bare copper 20' long would be more effective that a 20' length that encircled a building or structure.
Don
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I question the reason(s) why the bare wire is circular in relation to the structure vs straight. Does anyone know if lightning will strike more/less likely from the earth because of the circular shape of the conductor,rather than a straight line? Thinking perhaps that maybe part of the "reject" by CMP? Any engineers or lightning experts to weigh in on this?
 
When the code says encircle,are they wanting you to tie the ends together to make a complete circle? If so,would you have to cadweld them together or a listed clamp?
 
travis301 said:
When the code says encircle,are they wanting you to tie the ends together to make a complete circle?
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I would say no, the NEC does not require a continuous circle.

Type "define:encircle" into the google search engine, and the first definition it turns up is "surround".

For example, if a gang of ruffians encircle you, demanding your money or your life, they need not be holding hands. Kinda destroys the mental image, actually. :D
 
Is a ring of smoke continuous? A ring of fire? A nose ring? A ring of ships in the harbor?

Even jewelry rings can be made non-continuous, for artistic or one-size-fits-all purposes.

Given the lack of a requirement for continuity from the NEC definition in 250.52(A)(4), falling back on the english language itself in this case is just like a ring itself - it has a hole in it. :)

JMO,
 
George if your correct Don would not have had to put in a proposal and CMP 5 would not have turned it down.

I have installed a ground ring or two and they are always drawn as a complete circle, that is part of it's supposed effectiveness.
 
Bob, to be honest, I've never installed one, and I'm sure most engineers/designers do insist on a continuous ring.

I'm just saying I don't think the existing code text could be 100% without a doubt used to enforce a continuous ring.

I do also see a middle ground where someone could insist on a circular shape (non-cont.) circling a building and not a straight line, based on the code text.

Don's proposal should have passed, IMO.
 
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