HMMMM # 2

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pierre

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250.53(D)(2) requires a cold water grounding electrode to be supplemented with an additional electrode of a type such as .52(A)(2)-(A)(7).


250.52(A)(2)(2) permits structural steel to be considered effectively grounded if bonded to the cold water electrode .


So, if I bond the structural steel to the cold water electrode, does it "kill two birds with one stone"?

supplemental, and bonding.
 
Re: HMMMM # 2

I'd say not, because the metal frame of a building that is not grounded, but simply bonded to the cold water line, is not a supplimental grounding electrode. It's just a bonded hunk of steel in that case.

I do see the point, in that the code language does say that such a bonding arrangement makes the non-grounded steel qualify as grounded steel. "That's silly", is all I can think of at the moment, but that is what is says, isn't it? Crap.

[ October 24, 2005, 01:04 AM: Message edited by: mdshunk ]
 
Re: HMMMM # 2

I'd say yes, as long as the water-pipe, and the connection to it, qualifies as an electrode, such as connection within 5', 10' min. in the earth, etc..
 
Re: HMMMM # 2

I would ask this question:

If the cold water pipe was to be replaced with plastic in the future, would you still have an effective grounding electrode?

If not then I fail to see where it would be a supplemental grounding electrode as per the intent of the NEC.

In order to be a supplemental grounding electrode it must first qualify as an electrode on it's own.

This would circumvent the reason for supplementing the water pipe in the first place

I agree the words in 250.52(A)(2)(2) do state that bonding the building frame to the water pipe within the 5'rule would allow it to qualify as an electrode and 250.53(D)(2) allows it to supplement the water line.

I don't think it was the intent to allow the building frame supplement the water line if it couldn't be a stand alone electrode.

This needs to be changed!
It should only be allowed if 250.(A)(2)(1) was used.

[ October 24, 2005, 01:43 AM: Message edited by: hurk27 ]
 
Re: HMMMM # 2

As I have agreed that it does allow this as per the words in the NEC.

From my post above: I agree the words in 250.52(A)(2)(2) do state that bonding the building frame to the water pipe within the 5'rule would allow it to qualify as an electrode and 250.53(D)(2) allows it to supplement the water line.
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I still don't think it was the intent, as it deliberately circumvents the whole reason for supplementing the water pipe in the first place.

It's an error in the NEC that needs to be fixed.
 
Re: HMMMM # 2

I am confused as to what the problem is.

Most times the structural steel of the building is in itself a grounding electrode.

At some point if the water main was changed to plastic you are left with a legitimate GE.

250.52(A)(2) Metal Frame of the Building or Structure. The metal frame of the building or structure, where effectively grounded.
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IMO any metal frame of a building that is connected to the concrete footing / foundation is effectively grounded.

I must still be stuck on the 2002. :eek:

[ October 24, 2005, 05:40 AM: Message edited by: iwire ]
 
Re: HMMMM # 2

Basically what I am doing with the HMMM's is trying to point out that what has been accepted as a new code, with a particular intent, can be worded as such that maybe it is not what they really wanted to say.

Who knows, maybe the CMP already anticipated this and it is okay with them. There is only one way I know of to find out if this is so, with a proposal, and see how they react to the proposal.

I thought it was interesting how this change was written [250.52(A)(2)].
 
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