uffer

[leftcoastsparky]

Can anyone tell me the length of rebar and configuration for uffer i8n a slab. Thought it was 25' in 2 directions or something like that???? Thanks

 

[iwire]

250.52(a)(3)

 

[gndrod]

Can anyone tell me the length of rebar and configuration for uffer i8n a slab. Thought it was 25' in 2 directions or something like that???? Thanks

Would the 25' in 2 directions be a local adoption?

 

[hmspe]

The "Ufer" ground is named for Herbert G. Ufer, who developed the technique during World War II.

If there is a requirement for 25' and/or for bidirectional it would have to be a local amendmentn joints). Keep in mind that for a small building that all rebar in the footing will be tied together anyway, so in most cases the Ufer will be longer than 20' and will be "bidirectional".

 

[gndrod]

I should have asked the PO...In what local area are you at and is that their adopted requirement?

 

[Dennis Alwon]

To qualify as a ufer it must be 20 feet of either #4 bare copper or larger or 20 feet of 1/2" rebar or larger in either one continuous run or tied together

 

[don_resqcapt19]

You can't make a concrete encased electrode using a slab. The rebar or copper wire must be in a footing or foundation.

 

[jimport]

And in direct earth contact. Poly under the footer doesn't cut it.

 

[hmspe]

You can't make a concrete encased electrode using a slab. The rebar or copper wire must be in a footing or foundation.

In my opinion it would depend on the function of the slab. Parking areas and sidewalks would not be foundations (although if you turn one edge down it might qualify as having a footer) . A base for a specific piece of equipment or a pad for a stand-up service would meet the dictionary definition of a foundation.

Per m-w.com: foundation -- underlying base or support

Per dictionary.com: foundation -- the natural or prepared ground or base on which some structure rests (structure is "something built or constructed")

 

[acrwc10]

In my opinion it would depend on the function of the slab. Parking areas and sidewalks would not be foundations (although if you turn one edge down it might qualify as having a footer) . A base for a specific piece of equipment or a pad for a stand-up service would meet the dictionary definition of a foundation.

Per m-w.com: foundation -- underlying base or support

Per dictionary.com: foundation -- the natural or prepared ground or base on which some structure rests (structure is "something built or constructed")

If you are going to use definitions you must use them out of the code books not the dictionary, unless there is no definition of that term in the code books.

 

[ActionDave]

You can't make a concrete encased electrode using a slab. The rebar or copper wire must be in a footing or foundation.

And in direct earth contact. Poly under the footer doesn't cut it.

How does the poly under the footer make a difference? The rebar is still in concrete, underground; so it is still in direct contact with the earth, no?

 

[Dennis Alwon]

Here is the informational note in the 2011

Informational Note: Concrete installed with insulation, vapor barriers, films or similar items separating the concrete from the earth is not considered to be in ?direct contact? with the earth.

 

[hmspe]

If you are going to use definitions you must use them out of the code books not the dictionary, unless there is no definition of that term in the code books.

Absolutely correct. I searched electronic copies of both the 2008 NEC and the 2006 IBC and I did not find a definition of 'foundation' or 'footing' in either one. The terms are used many times, but as far as I can tell there are no definitions of these terms in either Code.