[TowerTalk] Earthing a tower

[K8RI]

On 12/26/2012 6:14 PM, Jim wrote:
> Hello.
>
> I hope I have sent this correctly, as it's my first post.
>
> Is it necessary to earth a tower?

I'm going to answer this in my usual manner so please don't take offense.

Is it necessary? In literal terms, No, but if you have anything of value 
connected to it or on it, it would be highly advisable.

Lightning "tends" to strike the highest object around and if this object 
is conductive it makes an even better target. Grounding, or earthing 
will not prevent strikes, but will "tend" to bleed off the current 
"helping" to prevent it from damaging things connected to the tower.

Someone included a link to the polyphaser site.  Unfortunately it was 
broken at each line return.  That site contains a lot of valuable 
information on grounding/earthing so it is well worth reading.

It's worth noting that when it comes to lightning we are playing the 
odds and lightning is very unpredictable.  Each step we take increases 
the odds in our favor but never reduces our  risk to zero.

My two towers are grounded with a network of 32 or 33 (I forget which) 8 
foot ground rods Cadwelded(TM) to over 600 feet of bare #2 copper 
wire.(This was done when copper was a LOT cheaper)

I can say that the 100 foot tower has been hit directly at least 17 
times (visually verified) with no damage. I did lose a computer, 2-meter 
rig and a bunch of coax before installing the ground system.
So I'm a firm believer in a good ground, or earth connection/network.

73 and good luck,

Roger (K8RI)

>
> Regards,
> Jim zl2bmh at xtra.co.nz
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