[TowerTalk] Ground Rods

[Eric Gustafson]

>Date: Sat, 17 Oct 1998 07:58:44 -0400
>From: LYN <designserv@ipass.net>
>

Snip...  for brevity

>
>Now to the effects of orientation: It seems to me that a ground
>rod oriented vertically may be considered to have more or less
>equal pie-shaped wedges of earth connected to all the points for
>a full 360 degrees around the rod, while a rod in a horizontal
>orientation has wedges on the top side which quickly terminate
>in the air at the surface of the earth.  This being the case, it
>seems to me that the horizontal rod would have fewer long
>wedge-shaped resistors connected in parallel and would thus have
>greater net resistance.

True.  Particularly for the purpose of dumping large amounts of
charge into the earth in a short time without developing a
damaging potential gradient at the earth's surface.




>Someone mentioned that RF and lightning tend to travel outward
>from the rod near the earth's surface.  These same people tell
>me that the series inductance in the ground rod keeps the far
>(deep end) of a vertical rod from being effective as a ground
>for lightning and rf.

Depending on the soil conditions, rod lengths (depths) to 30 feet
and more (longer being more effective than shorter) are effective
for lightning earth terminals.  If you are depending on a ground
rod for minimizing RF losses, you are making a different kind of
mistake.



>That argument doesn't influence me because the series inductance
>in the rod is going to be there whether the rod is vertical or
>horizontal.  Their argument would imply that a one-foot long
>vertical ground rod would be just as good as an eight-foot long
>vertical ground rod and I don't believe it.  They would seem to
>suggest that an array of short vertical ground rods would be as
>good as an array of long vertical ground rods.  I don't believe
>that either.
>
>Now, I've been wrong before and may be wrong this time, but that
>is my $.02 until I get a chance to examine empirical data which
>proves otherwise.  Guess I may have a little ostrich blood in my
>genes somewhere, but I will try to examine the available evidence
>before I put in my next ground system.
>
>Thanks for asking for ideas.  Now I'll get off my soap box.
>
>Good luck and have fun.
>
>Lyn, W4WDN


I don't think you are far off the mark this time Lyn.

73, Eric  n7CL

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