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Re: [TowerTalk] Lightning Damage

To: "Tower Talk List" <towertalk@contesting.com>
Subject: Re: [TowerTalk] Lightning Damage
From: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 18 Aug 2009 09:46:57 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On Tue, 18 Aug 2009 08:13:23 -0700, Michael Tope wrote:

>BTW, I am not familiar with series suppressors 

Series-mode suppressors have been developed that are quite 
effective on power line branch circuits. They work by storing the 
strike voltage in a very large inductor, then discharging it 
slowly once the strike event has past. The principal virtues of 
series-mode suppressors are that 1) they don't force the strike 
current onto the ground conductor, which raises the voltage of the 
ground relative to other grounds, and causes destructive failure 
of interconnected equipment; 2) they are not sacrificial -- that 
is, they do not have a limited life, so they can take the largest 
strike that can occur on a branch circuit (per IEEE data) without 
damage. 

SurgeX is the mfr of series mode surge suppressors that are widely 
used in the pro audio/video world to protect expensive equipment. 
I have been doing consulting work for them since 2004 (technical 
writing, teaching at industry conventions, customer technical 
support). For at least five years before that, I was specifying 
their products for every installation and buying them to use in my 
own home and office. 

It is impractical to build protectors using their technology for 
circuits rated at more than about 30A, and their methods are 
applicable only to power circuits. I recommend whole house shunt 
mode protection at the service entrance and series-mode products 
on branch circuits. 

For more about series mode suppressors see www.surgex.com  and my 
own tutorial on power and grounding for audio and video systems at 
http://audiosystemsgroup.com/publish 

BTW -- the SurgeX products are based on a patent licensed 
initially to three companies, each of which was granted rights to 
promote the product in a particular market. SurgeX bought rights 
to the the pro audio/video market, and has been very well 
respected in that world.  One of the other licensees used the name 
Brick Wall. I don't recall the name of the third company. 

Now -- the REALLY critical issue with shunt-mode protectors is 
where the "cold" lead goes. If it goes to the wrong place, it will 
blow up equipment, just like MOV suppressors on power circuits do. 
The key is to give them a "zero length" path to the star ground. 
That's why "whole house" suppressors at the service entrance are a 
good idea and MOVs on branch circuits are a recipe for disaster.  

73,

Jim Brown K9YC


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