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Re: [TowerTalk] Radiating Lightning Rod

To: "Towertalk" <>
Subject: Re: [TowerTalk] Radiating Lightning Rod
From: "Jim Brown" <>
Date: Tue, 02 Jun 2009 20:15:37 -0700
List-post: <">>
On Tue, 2 Jun 2009 21:49:49 -0000, Jim Hargrave wrote:

>Grounding: The tower has a ground rod that was driven into the ground below
>the Hole before the concrete was poured. This rod comes up through the
>concrete and is attached to the tower legs at the base. 

>My Equipment box and Prop Pitch rotor are mounted about 4 ft up from the
>concrete pad. The box is a double wall exterior wx proof box. It is attached
>to two legs of the tower with Stainless steel saddle clamps. Also I have a
>#4 stranded copper wire connecting the box to the ground rod below.

>I drove a ground rod into the ground at the bottom of the house foundation
>beam. This protrudes above the concrete slab about 4 inches. In addition,
>the foundation concrete reinforcement steel is also bonded to this ground
>rod. This rod comes up in the wall just behind my operating desk.

One CRITICALLY important thing I don't see in your post is that ALL of those 
ground rods must be bonded together by a very low impedance path, and ideally 
they should be bonded together outside your house. AND, they must also be 
bonded to the power system ground rod(s), again by a very low impedance path. 

This is critical because EARTH is a lousy conductor, so a lightning event can 
establish rather large potential differences between those ground rods, and 
in turn to the points in your home where they are connected. This is one way 
that fires start, and that equipment is destroyed by strikes. 


Jim Brown K9YC


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