[Top] [All Lists]

Re: [TowerTalk] Adding ground rods, effect on ground resistance..

To: Jim Lux <>
Subject: Re: [TowerTalk] Adding ground rods, effect on ground resistance..
From: Alan Zack <>
Date: Mon, 17 Jan 2005 11:18:09 -0800
List-post: <>
Question please,
I have three 8 ft ground rods at the base of my tower, connected to each tower leg, tied together by a nr 2 wire plus tied to my rebar cage in the concrete (the rods are outside the concrete base) per my city bldg code. My coaxes pass through I.C.E. devices that are connected to the very bottom of the tower. The coax runs underground through a PCV tube to the house. At the house they pass through Polyphaser devices before entering the wall that are connected to another 8 ft single ground rod. There is 25 ft of coax between the base of the tower and where it enters the house.
Question, should these two grounds be connected (the tower ground rods and the house ground rod). Presently they are not. I was told by the Cel Tower installer who helped me with my tower installation that I should not connect them, that the rods at the tower base would handle any strike I had and I might make things worse by providing another path to the house by an additional ground wire between the tower and house. OK experts, what's your opinion? I can do it ether way, what is best?
TIA & 73

Jim Lux wrote:

----- Original Message -----
From: "Keith Dutson" <>
To: <>
Sent: Monday, January 17, 2005 9:32 AM
Subject: RE: [TowerTalk] There's 'ground', and then there's 'ground'

I read Polyphaser's technical note before installing my system. There is


lot of discussion about soil conductivity and how adding more rods will
improve conductivity.   Do you have an idea of HOW MUCH impedance would be

Keith NM5G

There's a heck of a lot of details that can go into this, but, it's easy to
establish the BEST that you can do, in a relative sort of way.

If the rods are "far" apart (basically on the order of 2 rod lengths), then
they're essentially independent, so the resistance of N rods in parallel is
the resistance of one rod divided by N.  (assuming same soil conditions,

If the rods are closer together, you get less improvement, culminating in
the situation where the rods are right next to each other, when the
resistance isn't much lower than a single rod.

The other factor to consider is the inductance of the wire(s) going to the
rod(s).  1 microhenry per meter is a nice rule of thumb number to use for an
isolated conductor... it might be twice or three times that, or half or a
third, but it probably won't be 10 uH/meter or 0.1 uH/meter..

You can also bury rods horizontally...  To a first order, it's surface area
in contact with the soil that's the important thing.


Alan Zack
Amateur Radio Station K7ACZ
Las Vegas, Nevada, USA
Quality Engineer, The Boeing Company, Retired
Aviation Chief Warrant Officer, U.S. Coast Guard, Retired
U.S. Coast Guard, Always Ready, Always There
Every hour, Every day, Around the Clock and Around the World


See: for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.

TowerTalk mailing list

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