In 2 cities right next to each other, Ufers are required to be installed in 2 different ways. One inspector wants the Cu tie wired right to the rebar. The other wants the Cu totally away from the rebar in the footing, but bonded together above the slab. Up until now I just have tried to remember which guy's city I'm working in.
Who's right???

[This message has been edited by electure (edited 06-20-2001).]

I think Ufer himself allowed the copper to be under the concrete. But in a wet area, the copper could possibly corrode away.

The place that is right is the one that requires a stainless steel rod to be welded to the rebar and left sticking out for the purpose of attaching the copper GEC.

what is the rationale? is the voltage gradient affected either way?

Searched "Ufer" and got an article published by Chris Scott in December of 1989 in Radio World magazine. According to the article, Mr. Ufer's findings were published in IEEE Transaction paper #63-1505.
"After much research and testing Mr. Ufer advised the Army to make connection to the steel bar that would internally reinforce the concrete foundation. He had determined that concrete was more conductive than all but the best soil, and that this improved semiconducting characteristic would enhance surface area contact with the surrounding soil. The wire ties normally used would be extra secure, and attention would be given to bonding or welding the lattice- type network together." We use this type system often doing design. The cage is wired together and a piece of CU is brought out to the steel column. This is all tied to the building ground loop, etc, to have a better than adequate grounding system.