[TowerTalk] Different lightning ground question.

[Jim Lux]

----- Original Message -----
From: "Dudley Chapman" <chief at thechief.com>
To: <towertalk at contesting.com>
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
specs.

 If there is no
> difference, then just bury thick wire radials and be done with it.  It
would
> 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 a concern with a small diameter copper wire (like AWG8) and that
has to do with inadvertent destruction (a misplaced shovel or plant stake
might sever it, while a grounding rod will just deform or stop the shovel).
If there is any corrosion concern, an AWG8 will corrode away much faster
than a 5/8" diameter rod.

>
> I do see the difference when it comes to vertical ground rods, since it's
a
> better way to deliver copper down into the packed earth.  But that
> horizontal case puzzles me.
>
> Dudley - WA1X
>
Be puzzled no more...