ECN Forum Forums Code Related Discussion NEC & other Code issues Ufer

As I understand, the 05 NEC will now require the steel in the concrete slab to be connected to the other available grounding electrodes. This is something that I have not had to do before, but is being required on a job I am presently bidding. I searched some of the other posts to the ECN forums and several mentioned having the footing contractor stub up a piece of rebar to connect the GEC. How and where should this connection be made. I typically run the GEC from the ground rod up the exterior face of the building into the meterbase or CT cabinet. Could the rebar be stubbed up so as to be outside the building? Should it be inside the building? What type of connector or connection is used to attach the #4 copper GEC? Mechanical? Exothermic?

Around here they turn up the rebar into a block core and paint the block green so it doesn't get poured solid when they pour the doweled cells. (a Florida thing)
This gets a blank cover on it on the outside and they fish the #4 down to it from the panel. Use an acorn.
A more elegant solution is to hook the #4 directly to the rebar in the footer and hope nobody breaks it before you set the panel.

excuse the ignorance, but what does Ufer stand for?

It stands the H. G. Ufer, who wrote a paper on an installation of a made ground electrode on 24 buildings in Arizona. The installation met a 5 ohms maximum value. the year was 1942.

From his tests and papers, the CMP accepted into code the "Ufer" type of electrode.

Rick Miell

Just a small point here, but in your original post, you used the term "available". That is exactly what the change for the 2005 is...removing the words "if available" and replacing them with "if present". In regards to your question, the connection can be mechanical with listed fittings (there are some different types available), or you could do it exothemically if you really wanted to.

What about the benefits / drawbacks of stubbing the steel up either inside the wall cavity (seems like the connection would be better protected from corrosion and could be made accessible) or just outside the exterior face of the wall (easier to run the GEC up into the meterbase). Any thoughts?

I do not think that an acorn connector is rated for rebar. There are other rated types of connectors, one that resembles a water pipe clamp, and another parallel type of clamp/connector. Both are rated for rebar & concrete encasement.
Rick

I would say keep it inside, for reasons that you describe.

Ilsco specifically says #5 rebar in the description of the BGRC-58
It better be legal or there are a few million homes in Florida that are in violation. This is the standard way to install a Ufer and Ufer is the electrode of choice here.

http://ebusiness.ilsco.com/webapp/w...gId=-1&catalogId=1&categoryId=89

I have searched the web for mechanical grounding connectors that are listed for use with rebar. Of the few that I found that specifically mention rebar, the description stated that they comply with UL 467. I don't see any other listing that differentiates them. Does anyone know if all mechanical grounding connectors that comply with UL 467 can properly be used to attach a GEC to rebar?