To my understanding that for new construction the EC is required to install a Ufer ground using # 4 AWG and connected to a 20 ft. length of rebar. Ok I got that, than the connection is completed to the meter pan. Now (assuming) that the concrete encased electrode is installed correctly and therefore you have a proper ground. What about the plastic barrier that is installed between the earth and the concrete? Would that not impeed the grounding method?
I also have seen that on some new homes here in FLorida, the EC connects the grounding electrode to a vertical rebar in the wall, is this acceptable?
Pretty straightforward.
If the concrete slab is not in direct contact with the earth, then it is not a CEE. If the plastic extends only under the central part of the slab but not under the perimeter foundation or footings, then it is a CEE.
Other things that will interfere with concreted being a CEE are Integrated Insulating Forms if they do not leave a substantial portion of the bottom surface in conact with the dirt, a gravel bed under the entire concrete structure, and waterproofing coatings adhered to the outer wall of the foundation.
In the case of vertical walls, as long as the rebar in the wall is properly bonded (deliberately tied to other rebar as described in the code) down to rebar in the foundation or footings, then you have a valid CEE. In fact, the code just requires the rebar mesh you bond to to be part of the same continuous mass of concrete that is in earth contact, not necessarily the rebar which is in the underground and contacting part of that mass of concrete.
Common sense should be enough to guide you in this if you know what the contractor did to create the CEE you are bonding to.
If you are of an experimental nature, you can use some of the standard techniques for testing ground electrode resistance to measure the resistance of a Ufer/CEE ground.
Just not the ones that are based on the assumption that the ground under test is located at a specific point.
