Ufer, Connection of copper to rebar

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Rex Hungerford

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Electrician
Is it permissible to use an acorn connectors to clamp a #4 bare copper conductor to the steel rebar, concrete encased electrode and permanently cover that connection in the footer.

I would assume an irreversible compression connection would be legal. Was not sure about the Acorn.

Are there any studies to show a connection in the concrete, our out of the concrete oxidizes less over time. Is there a best place to make the connection.
 
Whatever you use to connect the GEC to the rebar has to be listed for both the conductor size/type and the rebar. An irreversible connection is not required but is permitted. Connections of the GEC to a CEE are not required to be accessible after installation so they can be encased in the concrete.
 
The acorns that we used are listed for db and encased in concrete. I don't know if they all are or just the ones we use,
 
This is from the IAEI Magazine

Question​

Are there any UL Listed direct burial brass acorn clamps for use with rebar on a UFER ground? Will there be a galvanic issue with the dissimilar metals?

Answer​

Yes, UL has Certified (Listed) acorn-type grounding clamps for use on rebar to connect the grounding electrode conductor between steel rebar and the bronze clamp.

Grounding clamps are investigated for compliance with the ANSI/UL 467, the Standard for Safety for Grounding and Bonding Equipment. To reduce electrolytic action between dissimilar metals, UL 467 requires that metal parts in a bonding or grounding path be galvanically compatible. When determining this, UL evaluates all possible combinations of the grounding and bonding device along with its rated electrodes, etc. A suitable plating or coating process delivers the required corrosion resistance.

The guide information details how to identify clamps Certified (Listed) for use on rebar. It states: “Ground clamps intended for use with rebar are marked with the size of rebar with which the clamp is intended. Rebar sizes may be specified in fractions, such as 1/2, 5/8, etc., or a number, such as 3, 4, 5, etc., where the number represents the numerator of the fraction when stated in eighth-inch increments, e.g., 4 = 4/8.” Regarding direct burial identification, it states: “Ground clamps and other connectors suitable for use where buried in earth or embedded in concrete are marked for such use. The marking may be abbreviated ‘DB’ (for ‘Direct Burial’).”
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“Ground clamps and other connectors suitable for use where buried in earth or embedded in concrete are marked for such use. The marking may be abbreviated ‘DB’ (for ‘Direct Burial’).”
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Does DB mean that it's listed both concrete encasement and direct burial in dirt?
 
Does anyone have an opinion on the following process
Apply a think film of deox at rebar copper wire contact point
Use an Acorn to clamp a bare copper to the steel rebar.
After deox and clamping tight of acorn, use liquid tape over contact area.

My thought is to try and keep galvanic reaction low and to keep as much oxygen out as possible, to also inhibit rust and corrosion at the contact area.
 
Rex Hungerford said:
Does anyone have an opinion on the following process
Apply a think film of deox at rebar copper wire contact point
Use an Acorn to clamp a bare copper to the steel rebar.
After deox and clamping tight of acorn, use liquid tape over contact area.

My thought is to try and keep galvanic reaction low and to keep as much oxygen out as possible, to also inhibit rust and corrosion at the contact area.
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IMO none of that is necessary and I wouldn't be doing it unless it were part of some job specification. There is no issue with copper to steel contact. For example copper EGC's are connected to steel all of the time.
 
California residential homes require a simple plaster ring with cover plate to be used as an inspection means to evaluate the condition of the attached grounding clamp and its attachment .
 
Another C10 said:
California residential homes require a simple plaster ring with cover plate to be used as an inspection means to evaluate the condition of the attached grounding clamp and its attachment .
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Do they require that for all installations because they not allow the GEC connection in the concrete?
 
Another C10 said:
California residential homes require a simple plaster ring with cover plate to be used as an inspection means to evaluate the condition of the attached grounding clamp and its attachment .
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Really? That's a CA wide requirement? I'm not so sure about that, maybe a local AHJ thing? I'd love to see that code reference because if that's true there's a lot of non-compliance going on.
 
infinity said:
Does DB mean that it's listed both concrete encasement and direct burial in dirt?
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It does, a separate marking is not required by the UL standards and any grounding connector marked as suitable for direct burial use is also suitable for use in concrete.
 
Joe.B said:
Really? That's a CA wide requirement? I'm not so sure about that, maybe a local AHJ thing? I'd love to see that code reference because if that's true there's a lot of non-compliance going on.
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If its a mechanical clamp it requires an inspection port. If it is a permanent connection such as irreversible compression or CAD welded, then you do not need an inspection port. Where the new footer is going into the home I am specking, there is no good place for an inspection port. Hence, I want to have the acorns buried in the footer so I don't have to have a a view port. In a round about way, I am trying to make a mechanical clamp a permanant connection. Most residential electricians don't have a multi thousand $ hydraulic compression tool.
 
Another C10 said:
California residential homes require a simple plaster ring with cover plate to be used as an inspection means to evaluate the condition of the attached grounding clamp and its attachment .
Click to expand...
I assume you mean only if the rebar is stubbed up out of the foundation and a GEC attached to it above grade. 250.68(A) would require accessibility then. But if the copper goes directly into the foundation and is connected to the rebar there, 250.68(A) has an exception on the accessibility.


Cheers, Wayne
 
Joe.B said:
Really? That's a CA wide requirement? I'm not so sure about that, maybe a local AHJ thing? I'd love to see that code reference because if that's true there's a lot of non-compliance going on.
Click to expand...
I can imagine why an inspection port of any earth conductor attachment would be desired, so as to check on if necessary, especially in earth quake country other than maybe a CAD welded earth grounding grid, I think that's one of the only conditions maybe where buried encasement of earth ground splices are accepted.

I remember once on a stand alone switch gear pad that fed treatment water pumps, I had to provide a inground inspection well with cover for the Earth ground splice from rod to gear. Why could I not just encase and bury that splice.
 
Another C10 said:
I can imagine why an inspection port of any earth conductor attachment would be desired, so as to check on if necessary, especially in earth quake country other than maybe a CAD welded earth grounding grid, I think that's one of the only conditions maybe where buried encasement of earth ground splices are accepted.

I remember once on a stand alone switch gear pad that fed treatment water pumps, I had to provide a inground inspection well with cover for the Earth ground splice from rod to gear. Why could I not just encase and bury that splice.
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There are best practice methods, then there are code requirements. I agree that inspection port would be best, but as far as I know it's not a code requirement. What is a code requirement is that a splice or connection has to be non-reversible. Pretty sure a clamp encased in concrete is commonly considered non-reversible.
 
Joe.B said:
There are best practice methods, then there are code requirements. I agree that inspection port would be best, but as far as I know it's not a code requirement. What is a code requirement is that a splice or connection has to be non-reversible. Pretty sure a clamp encased in concrete is commonly considered non-reversible.
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There is a code requirement for the GEC connection to the CEE to be accessable so the " inspection port" is required unless the point is in the footing.
 
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