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Re: [TowerTalk] Different lightning ground question.

To: Jim Lux <>
Subject: Re: [TowerTalk] Different lightning ground question.
From: Gary Schafer <>
Date: Mon, 17 Jan 2005 19:02:21 -0500
List-post: <>

Jim Lux wrote:
----- Original Message -----
From: "Dudley Chapman" <>
To: <>
Sent: Monday, January 17, 2005 11:17 AM
Subject: [TowerTalk] Different lightning ground question.

Keith's comment below reminded me of a question I had about horizontal ground rods on lightning protection systems. Current wisdom seems to suggest that if it is impossible to drive ground rods vertically, that laying them out horizontally underground is the next best thing. This sounds reasonable, but I am wondering what the difference is between a horizontal ground rod and the thick bare conductor leading up to it. Both are thick copper conductors running horizontally. Another way to ask the question is, if I substituted a 10 foot piece of #8 wire for a 10 foot horizontal ground rod, what would be the difference?

Absolutely no difference...well... you'd need a bit more length of wire to
equal the surface area of a 5/8" rod.  Say 20 ft of bare AWG8.

You can also bury a metal plate.  All covered in the various codes and

If there is no

difference, then just bury thick wire radials and be done with it. It


save on all the worry about joints except where the wire is bonded to
whatever is being protected.

Sure would, and that sort of thing is why UFER grounds (concrete encased
grounding electrodes) exist.

There is not much difference in effectiveness for different amounts of surface area for ground rods. It is the length that counts.

As far as differences in buried horizontal wires verses driven ground rods, there are two reasons to drive rods:

First, there is better contact with a rod driven into undisturbed soil than what you get by digging a hole and back filling it with a rod planted in it. Same of course is true for burying horizontally. The soil has been disturbed.

Second, when a rod is driven it gets down to where there is more moisture than if it is buried in a rather shallow trench.

Burying radials is ok if you can not drive a rod in.
It is also good to bury interconnecting leads between ground rods. It gives more connection to the soil.

Gary  k4FMX


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