[TowerTalk] Conductive Concrete and Grounding

[Gary Schafer]

Randy wrote:
  It *will* cause concrete to explode
> exactly like wood, trees, etc., i.e.
> the sudden vaporization of the moisture within causing a violent 
> expansion thereof. 

  Personally, I wouldn't want
> such a system in either
> a residential setting for safety of persons and equipment, nor would I 
> want it in a tower base
> for structural considerations. 
> 73 de KZ4RV
> 
> Randy
> 

Ufer grounds can be quite effective if done properly. But they should 
not be the only ground used.

In a tower base you already have a connection into the concrete if you 
have J bolts that the tower is bolted to.
The rebar should be bonded together when using a Ufer ground (as it 
should be in the tower base). That will prevent arcs within.

Concrete retains lots of moisture so it makes a pretty good ground.

I have seen a couple of tower bases cracked / split from lightning going 
into the J bolts. But these were on installations with no ground rods 
attached!

I also saw a large chunk of concrete that was blown apart on a sea wall 
near where my boat was tied. Lightning hit a palm tree a few feet away 
and found a small existing crack in the concrete on its way to ground.

Ufer grounds are fine if installed properly and other ground systems are 
also used.