CEE with tinned copper - your thoughts?

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txinspect

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I apologize in advance for the length, and if this question has been asked before. My repeated searches have yet to turn up anything.

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Ok folks, now another question has arisen and we have the usual debate with people taking one side or the other...which will probably happen here as well...lol.

Anyway, I post this question for your thoughts and prehaps someone already knows where to find the correct information for what is listed as approved for a CEE. I haven't had time to check ASTM, UL, etc.

Here's the question:

Can tinned copper be used as a CEE?

As we all know the code says: Bare Copper

250.52 (A)(3) Concrete-Encased Electrode.

An electrode encased by at least 50 mm (2 in.) of concrete, located within and near the bottom of a concrete foundation or footing that is in direct contact with the earth, consisting of at least 6.0 m (20 ft) of one or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (1⁄2 in.) in diameter, or consisting of at least 6.0 m (20 ft) of bare copper conductor not smaller
than 4 AWG. Reinforcing bars shall be permitted to be bonded together by the usual steel tie wires or other effective means.

However, it does not say bare tinned or untinned copper.

The reason this is coming up is....we see a lot of ground rings on radio towers where the engineer is spec'ing tinned copper because of its corrison resistance and ease of weld.

So let's post the code section for ground ring:

250.52 (A)(4) Ground Ring. A ground ring encircling the building or
structure, in direct contact with the earth, consisting of at
least 6.0 m (20 ft) of bare copper conductor not smaller
than 2 AWG.

Once again, I only see bare copper mentioned here. Bare tinned or untinned? The code is silent.

So, are we saying that because of the engineer's seal on the ground ring....tinned copper can be used in this application; however, tinned copper cannot be used for a CEE?

I've got a retired, well respected former Chief Elect Inspector of a large city saying that the tinned copper cannot be used as the CEE because it is not approved for this use.

So help me out folks.....Goggle searches have only turned up engineered ground rings thus far. Before I dig in a little deeper, does anyone already have this info?

For the record, I do know that bare tinned copper carries a little more resistance, so its not quite as good as untinned....but from what I have seen on the charts....the difference is minimal at best (0.02).

Thanks for reading!

TXInspect
 
"Bare" means not insulated or covered. Do you feel "tinning" the copper no longer makes the conductor bare? I would not have any problem with "tinned" copper used for grounding purposes of any kind.

I believe the NEC considers a "tinned" conductor as "COATED".
 
I agree with you both. I am on the side that believes that tinned copper is fine for use as a CEE. However, the other side is primarily using the argument that tinned copper is not listed for such use.

Anyone else care to share their thoughts?
 
Tinned copper is commonly used on GEC at cell sites to protect against corrosion from rain, rain tends to be slightly more acidic than tap water and is more corrosive.
 
txinspect said:
I agree with you both. I am on the side that believes that tinned copper is fine for use as a CEE. However, the other side is primarily using the argument that tinned copper is not listed for such use.

Anyone else care to share their thoughts?
Click to expand...
I would, and I'd like to see how bare copper is "listed for such use" and where tinned copper lacks the same listing.
 
tom baker said:
Tinned copper is commonly used on GEC at cell sites to protect against corrosion from rain, rain tends to be slightly more acidic than tap water and is more corrosive.
Click to expand...

Thanks, Tom.

But is it listed or labeled for use in this application?

I was hoping to find somewhere that it is.

I see in spec'd in a variety of applications at radio towers. The problem is they all have engineers' seals on them.

One of the contenders against the use of tinned copper as a CEE said that when the engineer puts his/her seal on it....it is their responsibility and can be installed; however, it is still not approved for this use.

I could be wrong, but I would tend to believe that if engineers across the country spec tinned copper for use as a ground ring or CEE then there has been a study that has proven that tinned copper is safe and effective.

That's what I am looking for....

Thanks,

TXInspect
 
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LarryFine said:
I would, and I'd like to see how bare copper is "listed for such use" and where tinned copper lacks the same listing.
Click to expand...

Thanks Larry.

I believe you mean you would like to see where "untinned" copper is listed for such use.

I maintain that we have bare "untinned" copper that people are generally used to calling bare copper....then we have bare "tinned" copper.

As Bryan pointed out under NEC code definition...they are both bare copper.

Conductor, Bare. A conductor having no covering or electrical
insulation whatsoever.
 
I?m not sure why the notion of an engineer?s seal comes into this discussion. I will say that an engineer sealing and signing a document cannot turn a code violation into an acceptable installation. We are not empowered to make our own rules. An engineer?s seal does not certify that something is acceptable, nor that it meets code or is equal to something that is described in code. All the seal says is, ?This word was done by me or under my supervision.? Put another way, the seal says, ?If something goes wrong, blame me.?

The code does give us certain instances in which we can make judgments, in lieu of selecting values from a table. For example, suppose that instead of saying ?bare copper,? the code said ?bare copper or a conductor of equivalent resistance.? An engineer could then perform a calculation of the resistance of two possible electrodes, one being bare copper wire and the other being tinned copper wire. The engineer could make a judgment as to whether the two are sufficiently close in resistance values as to make them equally acceptable, and could document that judgment in a sealed and signed report.

But that is not what the code says. I would have no objection to the use of tinned copper in the two applications described above. In my view, the word ?bare? in the phrase ?bare copper? simply means ?no insulation.? What is desired here is metal in contact with dirt or with concrete. I think that tinning does not remove the essential nature of an uninsulated wire.
 
charlie b said:
I?m not sure why the notion of an engineer?s seal comes into this discussion. I will say that an engineer sealing and signing a document cannot turn a code violation into an acceptable installation. We are not empowered to make our own rules. An engineer?s seal does not certify that something is acceptable, nor that it meets code or is equal to something that is described in code. All the seal says is, ?This word was done by me or under my supervision.? Put another way, the seal says, ?If something goes wrong, blame me.?

The code does give us certain instances in which we can make judgments, in lieu of selecting values from a table. For example, suppose that instead of saying ?bare copper,? the code said ?bare copper or a conductor of equivalent resistance.? An engineer could then perform a calculation of the resistance of two possible electrodes, one being bare copper wire and the other being tinned copper wire. The engineer could make a judgment as to whether the two are sufficiently close in resistance values as to make them equally acceptable, and could document that judgment in a sealed and signed report.

But that is not what the code says. I would have no objection to the use of tinned copper in the two applications described above. In my view, the word ?bare? in the phrase ?bare copper? simply means ?no insulation.? What is desired here is metal in contact with dirt or with concrete. I think that tinning does not remove the essential nature of an uninsulated wire.
Click to expand...

Thanks, Charlie....that was what I wanted to hear from the engineering perspective.

TXInspect
 
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