[Top] [All Lists]

Re: [TowerTalk] ground rod depth problem due to rocky soil -- solutions?

Subject: Re: [TowerTalk] ground rod depth problem due to rocky soil -- solutions?
From: Jim Lux <>
Date: Fri, 16 Nov 2012 09:17:53 -0800
List-post: <">>
On 11/16/12 7:46 AM, K1TTT wrote:
My program doesn't do strap, so instead of 2" strap that the OP has, I
substituted 1" wire which gives a slightly smaller surface area... the OP
said he was going have 700' of buried stuff so that is what I used... of
course you can't bury in rock, but I can simulate it as a worst case, the 1'
of topsoil on top shows there isn't much difference.

From a transient behavior standpoint, I would imagine that the wire could be insulated it and would work about the same. 700 feet x 1/3 foot is around 230 square feet of surface area, or 22 square meters..

if it's separated by 1mm from the "earth", that's a capacitance of 8.85E-12* 22/1E-3 F or about .2 uF...

At a nominal 1 MHz (for lightning), that's an impedance of a bit less than an ohm...

and, because I'm a fan of Ufer grounds.. a 3x3x3 foot cube of concrete in soil with the top surface exposed has a surface area of 45 square feet, so its capacitive impedance is about 4 ohms.. a 5x5x5 cube is about 2 ohms.. so don't worry about the vapor barrier between concrete and soil. The concrete has lower inductance than the wire radials, too..


TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>