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[TowerTalk] Lightning ground for tower with ufer ground

To: TT Forum <towertalk@contesting.com>
Subject: [TowerTalk] Lightning ground for tower with ufer ground
From: Beat Meier <mbe_ml@swiss-wireless.com.ar>
Date: Thu, 10 Apr 2008 19:13:02 -0300
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Hello

After several posts and reading a lot of the forum about tower grounding 
the opinions seems to differ a lot.
I'm now almost ready to install my grounding system but I'm in doubt.
First of all I will have a lot of electronic at the tower (embedded 
system,wifi stuff at 2.4GHz and 5.8GHz).
And where I live horizontal grounding is much more better than vertical 
grounding...
Analyzing the earth has given me that the best value is in 1m deep
What I have:

0. Tower triangle 30cmx30cmx30cm (tower height 66m) and 6 concrete bases 
every 1m³ of concrete with rebar cage
3x in a distance of 20m of the base (G1.1, G1.2, G1.3)
3x in a distance of 35m of the base (G2.1, G2.2, G2.3
Something like this


          G2.1                                G2.2


                   G1.1         G1.2


                              B


                            G1.3


                            G2.3



                              Garage (20m from base)

                                                           House (55m 
from base)


The only connection are the power lines from the garage to the base no 
other connection.
I will connect the base with the garage with a wire and and a lightning 
protector but this is an other "article" ...

1. The tower base has too a 1m³ concrete with 4 connections of stainless 
soldered to the rebar cage below earth.
    the tower base of steel has 3 connections of stainless soldered 
above earth.

2. I have now opened from Base (B) to G1.1 and from Base to G1.2 a 
trench of 80cm deep.
The idea is to connect a copper wire from Base to G1.1 and from Bae to 
G1.2 to use so 3m³ concrete ...

Now my questions.

What should this wire be? Most articles here in the list says you should 
use a #4 (which is AWG4 I guess).
What I've read in several books is you must use #0 to put in earth.
My problem is now ok the greather the better but #0 is very very 
expensive here.
Now the question is: Can I use AWG2, AWG3 or even AWG4? I cannot buy 
solid wires only stranded (7x3mm for example for AWG0)
I think the usage of AWG0 is because it should alive very long in earth 
(apart that is disapates better the current)

So in the fact that I have 2x20m horizontal wires what should I use?
Do I have to put ground roads between B and G.1.1 and B and G1.2 for 
lightning protection grounding system?
What is better:
   2 radials more at the base
or
  use the other 2m³ concrete and go from G1.1 to G2.1 and from G1.2 to G2.2
and if it's better to go from G1.1 to G2.1 can I use a wire which is 
smaller than that comes from the base?
What do you think? What is better for a lightning protection of the 
equipment?

It would be nice to here much answers. I'm since a lot of time 
investigation and time goes on and my tower is still
not elected :-(
Now I really want to go on but I don't want to burn my equipments ...

Thanks a lot for your time and ideas!

Beat

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