[TowerTalk] Lightning protection grounding

[Eric Gustafson]

<199904162316.QAA19069@toontown.mmsi.com> <3717D309.F63E80B8@erols.com>
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Hi Dave,

I found the web site for the company you mentioned.  They seem to
be selling the idea of preventing a lightning strike by means of
a "static dissipator".  The idea for this indeed seems appealing.
Because of this there are now a number of companies touting this
technique.  However, since I have been standing under a tower
when the dissipation array mounted on it was struck, you can
understand my skepticism regarding this method of lightning
protection.

To get an idea of how the supplier feels about the efficacy of
this method, ask for some technical support.  Tell them that you
have an antenna at the top of a 70 foot wooden pole.  Tell them
that the antenna feedline is the only conductive path from the
antenna to ground.  Tell them that you can mount their dissipator
just above your antenna.  Then ask them what size ground
conductor they recommend for you use to connect the dissipator to
the earth terminal at the base of the pole.  If they recommend a
conductor larger than #14, then they actually believe the
dissipator is likely to get struck.  After all, if the dissipator
does what is claimed, the ground conductor could safely be #24 or
even smaller wire because it is never going to have to carry any
fault current.  Let us know if they _do_ recommend a very small
conductor to groound the dissipator!  But be sure to ask them if
their warranty covers your losses in case of a protection system
failure.

Save your money on the "dissipator" and put a nice efective earth
terminal system at the base of the tower (if it isn't already
grounded for lightning) to carry the strike current when the
tower is hit.  If you want to try to force the lightning to pick
a safe place to attach to your tower system, do as Bob suggests
and put a standard air terminal up high enough to be
"unmissable".

73, Eric  N7CL


>Date: Fri, 16 Apr 1999 20:17:13 -0400
>From: Dave Jordan <wa3gin@erols.com>
>
>Eric,
>
>I have seen a fairly inexpensive static dissipater by Lightning
>Prevention Sytems of N.J. The air terminal goes for about $100.
>

>Eric Gustafson wrote:
>
>>
>> Hi Dave,
>>
>> What kind of static discharge device do you have in mind?...
>
>


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