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#93331 - 05/16/05 08:55 AM Electrical grounding clamps and there use
Joe Tedesco Offline
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Registered: 10/07/00
Posts: 2749
Loc: Boston, Massachusetts USA
From the field:

Quote:
I have a question regarding electrical grounding clamps and there use.

Question: Can you use an aluminum grounding clamp on a bronze, brass, or copper grounding rod?

References in the 1999 NEC Article section 250-8, 250-10, and 250-70 covers grounding clamps and stipulates exothermic welding, listed clamps, pressure connectors, listed lugs, or other listed means. Also it states that grounding clamps shall be listed for the material of the grounding electrode.

Please provide me with your interpretation of the NEC code for the use of aluminum clamps use.

Thank you,

Robert
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#93332 - 05/16/05 09:16 AM Re: Electrical grounding clamps and there use
Roger Offline
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Registered: 05/18/02
Posts: 1716
Loc: N.C.
Joe, 110.14. The clamps listing would then come in to play.

Roger
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#93333 - 05/16/05 09:24 AM Re: Electrical grounding clamps and there use
Alan Nadon Offline
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Registered: 03/10/05
Posts: 399
Loc: Elkhart, IN. USA
Not sure about the listing of clamps but, section 250-64 (A) should be checked if the aluminum is going to be used outdoors within 18 inches of the earth, also there are some other restrictions.

Alan--
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#93334 - 05/16/05 10:55 AM Re: Electrical grounding clamps and there use
Roger Offline
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Registered: 05/18/02
Posts: 1716
Loc: N.C.
Alan, 250.64(A) would not apply to the clamp.

BTW, the references seem to be pre 2002 and I don't have access to any editions except 02 and 05 right now.

Roger

[This message has been edited by Roger (edited 05-16-2005).]
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#93335 - 05/16/05 06:04 PM Re: Electrical grounding clamps and there use
renosteinke Offline
Cat Servant
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Registered: 01/22/05
Posts: 5316
Loc: Blue Collar Country
I believe the general code cautions regarding "suitable for environment" and "dissimilar metals" come into play here. In other words, such a use is forbidden, due to the certainty of galvanic corrosion.
Remember, electricity takes ALL paths. Every ground rod has some current passing through it, in inverse relation to it's comparative resistance to the utility neutral.

I have never seen such a clamp made of aluminum. I question whether it is hard enough to 'bite' into the rod.
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#93336 - 05/17/05 04:33 PM Re: Electrical grounding clamps and there use
e57 Offline
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Registered: 05/27/03
Posts: 2876
Loc: S.F.,CA USA
I have only seen these for pipe in Al/NiCa/zink/tin? ( T-6 Al, I think), they are not "really" just Al, just look it.

Dont think I have seen that material for rods.
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#93337 - 05/17/05 04:34 PM Re: Electrical grounding clamps and there use
e57 Offline
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Registered: 05/27/03
Posts: 2876
Loc: S.F.,CA USA
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Mark Heller
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#93338 - 05/17/05 06:45 PM Re: Electrical grounding clamps and there use
renosteinke Offline
Cat Servant
Member
Registered: 01/22/05
Posts: 5316
Loc: Blue Collar Country
Thank you, e57....that link answers all my concerns, and I must say I'm surprised to see that it not only exists, but may be used on a copper rod..so brass or bronze ought not be a problem either.
Learn something new everyday....
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#93339 - 05/17/05 07:05 PM Re: Electrical grounding clamps and there use
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9036
Loc: Estero,Fl,usa
I have some of those clamps and they are stamped for CU. I just thought they were a zinc alloy.
I guess they are doing wonders with aluminum these days.
I did get slapped around by roofers when I said al and cu were "dissimilar". I was told they have linear expansion rate problems but they don't eat each other.
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