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Re: [TowerTalk] whole house surge protectors

To: "Tower Talk List" <>
Subject: Re: [TowerTalk] whole house surge protectors
From: "Jim Brown" <>
Date: Wed, 16 Apr 2008 08:33:59 -0700
List-post: <">>
On Tue, 15 Apr 2008 19:55:47 -0400, WA3GIN wrote:

>Whole house protects the big gear like AC compressors, HVAC blowers, for 
>sensitive electronic gear like your HDTV, Ham Radio, PC you are required to 
>installed end-point surge protectors.

A good "whole house" surge protector is a very good way to protect against 
lightning and other transients coming in on the power line. 

99'9% of all local surge protection uses MOVs. MOVs are LOUSY surge protectors 
for several reasons. 1) They fail after they have absorbed enough joules, and 
can fail destructively (catch fire, explode, etc.). They can also fail open. 2) 
MOV surge protectors are nearly always wired to short the surge to the green 
wire. That raises the voltage on the green wire to the voltage of the strike. 
Any equipment connected to the "protected" equipment, but not plugged into that 
very same protected outlet is almost certain to be BLOWN UP by the strike, 
because it's ground is at a much lower potential!  

Shunt mode protectors like MOVs DO work in whole house systems IF building 
wiring is properly grounded and the protectors are properly installed, because 
when they short the spike to ground, the voltage on ground for the whole 
building is raised, not just one outlet. 

>I put all the expensive stuff on UPS which provided further protection, i.e. 
>low and high voltage protection as well as spike and surge...

>Plenty of good gear available commercially.

Plenty of LOUSY JUNK available commercially. 

MOV surge protectors are a lousy idea, and they CAUSE more problems than they 
solve. They are, however, the direct equivalent of exotic loudspeaker cables -- 
their only good function is to transfer money from the pockets of their 
customers to the pockets of those who build and sell them. 

As Jim Lux has noted, the only GOOD protection to use on a branch circuit is a 
series-mode surge protector. The best ones I know of are made by SurgeX, a very 
good US company based near Philadelphia. They are widely used in the pro 
audio/video world to protect equipment and systems much more costly than our 

Full disclosure:  I have done some technical writing for SurgeX, and SurgeX 
me to teach workshops for them on Power and Grounding, but not to sell or 
endorse their product. In fact, I began specifying SurgeX units for all the big 
audio/video systems I design (that's my job) nearly ten years ago, and at least 
five years before they hired me to do writing or teaching. I also BOUGHT SurgeX 
units to protect equipment in my home, office, and ham station. 

The tutorial, as well as slides from my lectures, are on my website.


Jim Brown K9YC


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