grounding electrod conductor through concrete slab

[marcs11]

Can any tell me if it is a code violation to run a # 3/0 copper conductor connected to a grounding electrode through a concrete floor with no sleeve where it is not subjected to physical damage.
Thanks

 

[ActionDave]

Not a violation as described. Why do you ask?

 

[marcs11]

I have a AHJ asking me to jack hammer up 6 inch's of concrete to sleeve it in PVC. My comment was does any one sleeve a ufer ground or a concrete encased electrode. I kindly asked for him to site the code article. No replay as of yet but will let you know. I was not able to find anything in the code that would prohibit the grounding electrode conductor coming through the slab under the panel.
I appreciate you comment
Marc

 

[mgookin]

I have a AHJ asking me to jack hammer up 6 inch's of concrete to sleeve it in PVC. My comment was does any one sleeve a ufer ground or a concrete encased electrode. I kindly asked for him to site the code article. No replay as of yet but will let you know. I was not able to find anything in the code that would prohibit the grounding electrode conductor coming through the slab under the panel.
I appreciate you comment
Marc

Sounds like you got a plumbing inspector on the job. If it were copper pipe it would have to be isolated from the concrete for electrolysis purposes.
Heck in electric we lay 20' of it in the trench before we place the concrete. Ask him if that's supposed to be isolated!

 

[frank everingham]

frank

frank

if the conductor has an outer coating, thhn, thwn, it is allowed. if the conductor is bare copper it will need to be sleeved with pvc where it leaves the slab because of the corrosive nature of air, copper and concrete at the same point. even rigid metal conduit will break down eventually when it exits the concrete

 

[mgookin]

if the conductor has an outer coating, thhn, thwn, it is allowed. if the conductor is bare copper it will need to be sleeved with pvc where it leaves the slab because of the corrosive nature of air, copper and concrete at the same point. even rigid metal conduit will break down eventually when it exits the concrete

Frank:
Do you have a code section to support that?

 

[frank everingham]

Frank:
Do you have a code section to support that?

if the conductor is bare, and there is no protection where the conductor leaves the pour, I write up the violation under110.11 and 300.6. since there is no air movement in the pour there is no break down of the copper conductor. rerod in the pour lasts forever. .they are both metals. see100.2

 

[kwired]

if the conductor is bare, and there is no protection where the conductor leaves the pour, I write up the violation under110.11 and 300.6. since there is no air movement in the pour there is no break down of the copper conductor. rerod in the pour lasts forever. .they are both metals. see100.2

just because they are both metals doesn't mean they react the same to a particular agent. There is a reason we galvanize some steel components or use stainless instead of mild steel. Not so common is applications subject to anhydrous ammonia - galvanizing doesn't hold up in that environment, neither does copper. Severe corrosive locations still may use coated rebar because uncoated likely will not last, it may take longer to corrode then if exposed though.

 

[mgookin]

if the conductor is bare, and there is no protection where the conductor leaves the pour, I write up the violation under110.11 and 300.6. since there is no air movement in the pour there is no break down of the copper conductor. rerod in the pour lasts forever. .they are both metals. see100.2

300.6 does not apply to conductors.

What do you do when the footing crew lays 20' of bare copper wire in the footing trench?

 

[kwired]

300.6 does not apply to conductors.

What do you do when the footing crew lays 20' of bare copper wire in the footing trench?

He is saying the point of emergence from the concrete is where there is a problem. I do agree 300.6 doesn't apply though. I can see 110.11 applying - but fail to see this being any more deteriorating condition in most applications then a copper wire emerging directly from the soil. Seen a lot of copper water pipe in contact with concrete over the years with no problems. But put a copper pipe in contact with a zinc coated fastener or strap and you have a problem waiting to happen.

 

[jap]

He is saying the point of emergence from the concrete is where there is a problem.

I think Mgookin is saying bare copper laid in a footing ditch also has to emerge from the concrete somewhere also.

JAP>

 

[gadfly56]

if the conductor has an outer coating, thhn, thwn, it is allowed. if the conductor is bare copper it will need to be sleeved with pvc where it leaves the slab because of the corrosive nature of air, copper and concrete at the same point. even rigid metal conduit will break down eventually when it exits the concrete

So where do you stop? Push the sleeve 6" down, and now the copper/concrete interface is 6" below the rest of the slab. Unless you instruct them to fill the hole with pitch or something you will never get rid of the air-copper-concrete interface.

 

[jap]

So where do you stop? Push the sleeve 6" down, and now the copper/concrete interface is 6" below the rest of the slab. Unless you instruct them to fill the hole with pitch or something you will never get rid of the air-copper-concrete interface.

Only if your concrete slab is more than 6" thick or over a footing that is, otherwise you'd be in the dirt after the 6" sleeve.

JAP>

 

[gadfly56]

Only if your concrete slab is more than 6" thick or over a footing that is, otherwise you'd be in the dirt after the 6" sleeve.

JAP>

OK wisenheimer, :roll: but I think you get my drift.

 

[winnie]

I think that mgoodkin hit the nail on the head, this is a plumbing but not an electrical issue.

Take a look at this document from the CDA:
https://www.copper.org/applications/plumbing/techcorner/problem_embedding_copper_concrete.html

There is no corrosion concern for copper in concrete or copper penetrating concrete.

Steel _does_ have a concern where it exits the concrete, because a passivation layer forms on the steel fully covered by the concrete. The passivation layer is _stable_ iron oxide formed in the alkaline environment of the concrete which prevents further oxidation. Where the steel exits the concrete the passivation layer ends and there is a focused area where you can get lots of corrosion. But this is not a concern with copper, it is simply stable in concrete (unless various contaminants are present, eg sulphur compounds).

It appears that the _plumbing_ requirement for sleeving is based not on corrosion but on abrasion associated with expansion and contraction. If you have a thin pipe subject to temperature changes because of flowing water, abrasion is a bigger concern than if you have a solid constant temperature wire.

-Jon

 

[jaggedben]

We have 250.64(A) that addresses aluminum conductors, and nothing that directly addresses copper conductors. To my knowledge there is no meaningful corrosion issue with bare copper conductors.