Ufer?

[Wingrider]

No mention of moisture barrier

No mention of moisture barrier

This discussion of what makes a proper Ufer seems moot when considering most buildings have the slab poured on a moisture barrier. If the slab is on a plastic barrier of some sort, then the Ufer is not a proper grounding technique. I find very few buildings poured on natural dirt.

 

[iwire]

This discussion of what makes a proper Ufer seems moot when considering most buildings have the slab poured on a moisture barrier. If the slab is on a plastic barrier of some sort, then the Ufer is not a proper grounding technique. I find very few buildings poured on natural dirt.

A 'proper' Ufer is never in the slab, it is in the footings or foundation.


From 2011 250.52(A)(3)

Metallic components shall be encased by at least
50 mm (2 in.) of concrete and shall be located horizontally
within that portion of a concrete foundation
or footing that is in direct contact with the earth or
within vertical foundations or structural components
or members that are in direct contact with the earth.
If multiple concrete-encased electrodes are present at
a building or structure, it shall be permissible to bond
only one into the grounding electrode system.

 

[infinity]

This discussion of what makes a proper Ufer seems moot when considering most buildings have the slab poured on a moisture barrier. If the slab is on a plastic barrier of some sort, then the Ufer is not a proper grounding technique. I find very few buildings poured on natural dirt.

That's a good point but I'm guessing that it depends on where you are. Around here the footing is almost never poured over a plastic barrier. And what Bob said.

 

[Strathead]

:?Silly question guys/gals. What's a Ufer?

Thanks

Not a stupid question actually.

 

[Strathead]

And the code section requiring that dielectric would be ......

FYI, I am not going to even bother to look. "suitable for the purpose", "where subject to damage", etc. gives the AHJ the authority to make this determination all over the code book. the previous email shows that galvanic action between copper and steel is a possibility. If you choose to install them touching and your AHJ allows it fine. I have definitely been directed not to by more than one AHJ. As a matter of fact it was the structural inspector that disallowed the copper and rebar touching because it was the deteriotion of the rebar he was concerned with. I pick my battles and this one is not worth it.

 

[iwire]

FYI, I am not going to even bother to look. "suitable for the purpose", "where subject to damage", etc. gives the AHJ the authority to make this determination all over the code book.

In general if people cannot provide a code cite I tend to consider it hear say.

the previous email shows that galvanic action between copper and steel is a possibility.

The NEC allows a bare EGC in steel conduit

The NEC allows steel straps to be used with aluminum RMC.

The NEC allows cast AL fittings, conduit bodies and boxes to be used with steel conduits.

I pick my battles and this one is not worth it.

Well I hear you there and it is often easier to just comply.

 

[George Stolz]

I would pick that battle myself. To each their own.

To comply without argument is often to perpetuate a myth; I'd rather discuss it and stand on solid ground than to subsidize a wive's tale. That road leads to more failed inspections than challenging an inspector, IMO. It's why we have a written book.

If they feel it's a problem they're more than welcome to submit a proposal to the NEC to fix it.

 

[Strathead]

I would pick that battle myself. To each their own.

To comply without argument is often to perpetuate a myth; I'd rather discuss it and stand on solid ground than to subsidize a wive's tale. That road leads to more failed inspections than challenging an inspector, IMO. It's why we have a written book.

If they feel it's a problem they're more than welcome to submit a proposal to the NEC to fix it.

What is a wive's tale? Dissimilar metals cause deterioration. Current flow exacerbates the action. So does moisture. Concrete, especially in the ground will stay moist forever. Here is another article specifically addressing bridges and the detrimental affect of corroding rebar along with confirmation that copper steel contact needs to be prohibited. It is for bridges, but applies to rebar and concrete. So if the structural inspector who is the one I indicated has jambed me up on this, decides he does not want copper an steel contacting each other, who am I to dispute it?

 

[George Stolz]

Look, I'm not saying punch the guy in the face for his insolence. I'm saying, "Show me a code reference and I would be happy to oblige." Most buildings I wire feature roofs, and do not feature DOT trucks spreading salt everywhere. I have a really hard time picturing substantive damage to the steel from a piece of #4 resting on it. Even if there were enough electrolyte to cause an initial reaction (which has yet to be shown), as soon as enough reaction had taken place to remove some steel the electrical connection between the two would be severed and the reaction would stop. I can't picture more than 5% of the circumference disappearing before it solved itself.

I could be off base with my feeling, but I would expect an inspector to substantiate a red tag with a citation to back him up.

 

[Gac66610]

250.52(A)(3) direct contact with earth ... didn't think about it til i read this in iwire post
we have a house that a builder (first house for him) put the foundation on a bed of 1.5", to 2" gravel (why, i dont know seems the same as sand to me)
the weeping tile going around the house will be at the same level as the footings with gravel covering it and the footing,
so the footing with the CEE (footings) IMO will not be "in direct contact with earth"

I'm thinking i may need some ground rods driven, do you believe i should, or am i over thinking this?

 

[Strathead]

Look, I'm not saying punch the guy in the face for his insolence. I'm saying, "Show me a code reference and I would be happy to oblige." Most buildings I wire feature roofs, and do not feature DOT trucks spreading salt everywhere. I have a really hard time picturing substantive damage to the steel from a piece of #4 resting on it. Even if there were enough electrolyte to cause an initial reaction (which has yet to be shown), as soon as enough reaction had taken place to remove some steel the electrical connection between the two would be severed and the reaction would stop. I can't picture more than 5% of the circumference disappearing before it solved itself.

I could be off base with my feeling, but I would expect an inspector to substantiate a red tag with a citation to back him up.

This was in California schools about 8 years ago. It may have been in the specs as well, but at those schools the specs are written rather strictly and that definitely wasn't a battle worth happening. The cost would have been far greater than the $15 clamp and afew pieces of PVC in the long run. However, I am curious, do you feel that tying copper to rebar with nothing more than steel tie wire would be an effective means of establishing the UFER?

 

[infinity]

However, I am curious, do you feel that tying copper to rebar with nothing more than steel tie wire would be an effective means of establishing the UFER?

If there is 20' or more of #4 cu then IMO it's not required to be connected together at all. (See post #12)

If you're attaching a GEC then a proper clamp is required.

 

[ptonsparky]

I believe the inspector just wanted the CCE raised & held in place by wire tying it to the rebar, not for a Ufer connection. We do not know the size of the rebar in the footing.

Moderator:
For some reason I can't see all the posts here that I get notified of. I may just be impatient.

 

[ptonsparky]

Now I see post 31 & 32.

 

[Strathead]

If you're attaching a GEC then a proper clamp is required.

this was what I meant

 

[bobbymari]

this is a classic inspectors preference they do not need to be tied together anywhere in nec code. 20' of rebar is addequate . When it doesn't cost too much to give em what they want best to just do it. Although I just ran accross an inspector that was suggesting I modify a 3 gang meter pak installation to put in a main breaker in front of it . Reasoning? There was none, time for your supervisor bud. By the way it wasn't modified and passed no problem. If it doesn't change your plan by much just do it.

 

[Strathead]

this is a classic inspectors preference they do not need to be tied together anywhere in nec code. 20' of rebar is addequate . When it doesn't cost too much to give em what they want best to just do it. Although I just ran accross an inspector that was suggesting I modify a 3 gang meter pak installation to put in a main breaker in front of it . Reasoning? There was none, time for your supervisor bud. By the way it wasn't modified and passed no problem. If it doesn't change your plan by much just do it.

What do you mean they don't need to be tied together? the GEC has to be tied to rebar or run separately 20' in the footer.

 

[bobbymari]

i was stating that if they were run seperatly "tied" was the wrong choice of words

 

[jghrist]

OK this morning the inspector required the 20 foot bare copper to be tied to the rebar in the footer. I tied it with tie wire while he looked at the rest of the job. I asked what do you tie it to when there is no rebar in the footer? He said you need saddles to hold it up off the dirt. Doesn't make sense to me, current path is thru the dirt eventually anyway. I was not going to argue, he holds the axe, and I have to deal with him for the rest of the job, the building side anyway.

The wire has to be encased by at least 2" of concrete [250.52(3)(2)]. Either tying to rebar or holding off the dirt with saddles will do this.

 

[George Stolz]

If there is 20' or more of #4 cu then IMO it's not required to be connected together at all. (See post #12)

If you're attaching a GEC then a proper clamp is required.

Agreed.