[TowerTalk] Fw: w7ekb & ground rods

[Jim Lux]

On 1/19/15 9:30 AM, Brian Carling wrote:
> I have not heard of this concrete ground before. Is it made with conductive concrete?
>

No.. but regular concrete is more conductive than most soil (not to 
mention that concrete often has reinforcing steel in it, which makes it 
more conductive, too)

Look up "Ufer Ground"  (after the inventor's name)
or "Concrete Encased Grounding Electrode". (what they call it in the 
electrical code)

Basically, you have at least 20 feet of wire or other conductor in the 
concrete that serves as the connection.  You can use the rebar as a 
conductor: there are Ufer grounds where they just bring one of the rebar 
rods up through the surface and you connect to that.  More commonly, 
it's just a bare copper wire 23-25 feet long (so that you have 20 feet 
in the concrete, and 3-5 feet sticking out to connect to the electrical 
panel ground, or the conduit feeding the electrical panel.

So you have really good contact between the wire and the concrete 
(because it's cast in place), and also good contact area between the 
concrete and surrounding soil (because it's big, and it's heavy).

In my area (Southern California), a single rod can't serve as the system 
ground,  you have to use a Ufer ground, or one of the other substitutes. 
Cold water pipe also can't be used as the sole ground (too much plastic 
pipe these days).