Quote Originally Posted by JohnT
Wet concrete is a pretty good conductor. Connecting the rebar to the bonding grid or putting a bonded metal mesh in the concrete does a fairly good job of connecting the concrete to the bonding system when the concrete is wet.
I agree that wet concrete is a good conductor on the surface, but when concrete gets wet, I could be wrong but I would not expect the moisture to get all the way down to the rebar which is 2-3" below the surface. The concrete surface is somewhat porous but not as much to allow moisture to get down 2". What I could imagine is that when the concrete cracks it could allow some of the moisture to reach the rebar and then it would make a difference.