[TowerTalk] Three Lightning Protection Clarifications Please?

[DavidC]

> David, how far is your tower from the shack?

About 60-65 feet.

> I wonder about whether the tower ground should be connected to your
> house ground with something other than the shield of your coax cable(s).
> My thought is that if your tower is located a ways from the shack then as
> a charged cloud moves overhead (or if lightning strikes) the ground
potentials
> at the tower ground and the shack ground will be different. This will
cause
> current flow between the two and it'll take the least resistance path
which
> will be down the shield of your coax cables. It seems like it would be
better
> to keep everything more or less at the same potential by connecting both
> grounds together with some heavy wire/cable/strap, and placing ground rods
> between the tower and shack.  That way most of the current (either from
charge
> build up or during a lightning strike) flows along the ground cable
instead of on
> your coax.

Sure would make things more costly and more of a hassle.  Four more ground
rods at $10. each (Lowes), 60-65 feet more 0/0 or 0/2 wire, 60-65 feet more
trenching (though it is sandy here).

> Bob and I have gone round and round on this. He thinks it's a waste of
money,
> I'm not so sure. Does anybody else on this list have a strong opinion one
> way or another about this?  thanks,  Dave  K0QE

Just when I thought things had been simplified ... ;-)

I await the collective wisdom re. your proposal ... 73, DavidC  K1YP


> Thanks to all for the very helpful review of lightning protection
> and grounding principles!  Here is what I have learned from this
> and am about to apply.
>
> Context:
>
> The only reason I am extending the ground is because the shack
> entry point for antennas is 48 feet away from the service ground
> rod.
> I understand that I need to connect to that to avoid circulating
> currents.
> The tower will be heavily grounded so hopefully most of the energy
> will be absorbed there.  The ground here is said to be Alkaline
> (sand,
> some clay and limestone) and the test I just ran confirms that.
>
> Plans:
>
> I will go with copper ground rods and avoid complications.  The wire
> I
> have is stranded and each strand looks to be about #10.
>
> I am awaiting a reply from Harger as to the cost and part numbers I
> need for the CADweld moulds, starter and materials.  I am told that
> Harger is 1/2 to 1/3 cheaper than all other sources.
>
> I will have a grounding panel just outside the shack wall, about 24"
>
> from the wall, through which all of the antenna and rotor lines will
> be
> routed.  My one open-wire feedline will have both a disconnect knife
>
> switch and inline AEI lightning protection fuses.  The coax and
> rotor
> wires will have Polyphaser and MOV protectors.  The panel will be
> thoroughly bonded to the buried ground line that I will have
> extended
> from the service panel ground rod to the shack entry point 48 feet
> away.
>
> I think that about covers it.
>
> - Thanks! & 73, DavidC  K1YP
>
>
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