[TowerTalk] Grounding with Polyphaser lightning arrestors

[Jim Brown]

On Tue, 7 Oct 2008 07:30:48 EDT, K7LXC at aol.com wrote:

>One of the main reasons for lightning protection  is to keep the 
>transients out of the house/building so you want them installed  
>where the cables enter the house.

Yes.
> 
>Commercial installations typically have coax  shield grounds at 
>the bottom of the tower where the cables transition  from vertical
>to horizontal as well. Since your tower is so close to the  house, 
>I'd put my efforts and money into the building entry.

I'd bond shields at the top of the tower, at the bottom of the 
tower, and at the house, and I'd bond the earth electrodes at the 
tower to those at the house. 

Remember that arrestors like Polyphaser and ICE protect equipment 
by minimizing voltage between the shield and center conductor. In 
other words, they protect the equipment input. The EARTH connection 
diverts lightning current/voltage so that less of it flows into the 
equipment. 

The cable shield SHOULD be connected to the shielding enclosure of 
equipment. If it is not (that is, if the equipment has a pin 1 
problem), any lightning-induced current will flow through the 
circuitry and likely cause a (destructive) failure. Now, there 
could also be sufficient voltage drop across the chassis to cause 
problems, but a lot less than on a single circuit trace, or even a 
ground plane. 

73,

Jim Brown K9YC