[TowerTalk] Lightning arrestor in towers

K8RI on TT k8ri-on-towertalk at tm.net
Sun Jun 19 19:33:00 PDT 2011

On 6/19/2011 7:58 AM, HansLG at aol.com wrote:
> I just wonder if I can get some input.
> I was thinking putting a "stick (conducting)" on top of my tower well above
>   any other installation. Connect the "stick" to a heavy wire that is well
> grounded in the other end. The idea is that a lightning preferable will hit
> the "stick" and be safely conducted to the ground similar what you do with
> a  house.

If you note the top antennas  in 
http://www.rogerhalstead.com/ham_files/Tower29.htm they are 30 feet 
above the top of the tower.  The cross boom, antennas, and mast have 
taken a number of direct hits. It's difficult to really know from 
neighbors reports which antennas or where on the tower any specific bolt 
struck. there is enough information to know that the *stuff* "on top" 
has taken more than one or two hits. It's also obvious that some strikes 
were to lower antennas.

All coax shields are grounded to the tower at the top and the bottom. 
They are also grounded where they enter the house through a grounded 
bulkhead as well as where they enter the shop.  Each leg of the tower is 
tied into the ground system which radiates out from the tower as well as 
running to those grounded bulkheads.  Also each tower ground is tied 
into the over all ground system.  The shop and house each have their own 
electrical service and grounds, but those too are tied into the overall 
ground system as the computers in the house and shop are tied togather 
via CAT5e or CAT6 and the ham stations all tied together as each station 
feeds antennas on each tower. Were the system grounds not all tied 
together lightning strikes would tend to follow either coax, control 
cables, network cables, or telephone cables from one building to the other.

The mast at the top of the towers goes through at least 2 thrust 
bearings that provide side support, but no vertical load support. There 
are 4 coax runs from the antennas mounted on the mast. These run through 
bulkhead connectors at the top of the tower. So the mast serves as a 
lightning rod "of sorts".  It's more a case of every thing being well  

The ground system itself consists of 32 or 33 8' copper clad, steel 
ground rods Cad Welded (TM) to over 600 feet of bare #2 copper wire.


Roger (K8RI)
> A few days ago I did have a hit on my house and the lightning protection
> worked except for a surge protector and a battery charger located near the
> corner that was hit. Everything else survived.
> 73
> Hans - N2JFS
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