Concrete and rebar cage a good ground?

[HighPotential]

I haven't delved into the issue much, but now we have an issue here as to whether the rebar cage inside of a concrete column sunk 30 ft into the ground is a good ground. If the conrete is wet, I can see how it would be, but if for some reason the dirt dries out, my suspicions are that the dry concrete would not provide a path from the rebar cage to earth. Anyone checked into this issue?

 

[busbar]

Search on "Ufer ground."

 

[DougMSOE]

Concrete itself is a fair ground, but you are on the right track. The salts in the concrete give the column its low resistance. If the ground dries out, it might not be a good ground.
Look in the Green book from IEEE. Depth of the ground is nor nearly as important as the width (how spread out) the ground is.