[Amps] MOVs on HV PS

[Jim Brown]

On Mon, 05 Mar 2007 19:40:20 +0000, Rick Stealey wrote:

>If I understood W8JI recently, Tom said MOVs should not be installed in a 
>piece of equipment, forcing the surge to green wire ground, but rather 
>should only be at the service entrance (or single point ground?).  

I haven't seen Tom's advice on this, but I strongly agree with it (for that 
matter, I almost never disagree with him on anything). If you live in an 
area that gets much lightning, I also recommend a series-mode surge 
suppressor on branch circuits that feed expensive equipment. The best ones 
carry the SurgeX brand. They aren't cheap, but they are worth the money. 
They're especially designed for use in professional audio and video 
systems. I use them to protect my office computers, my audio and video 
gear, and my ham gear. 

There's a discussion of the technical reasons for these recommendations in 
a Power and Grounding tutorial "white paper" that I wrote a few years ago 
for audio professionals, and it applies equally to ham radio. 

http://audiosystemsgroup.com/SurgeXPowerGround.pdf

The executive summary for the reasons why is that when the surge is 
conducted by MOV's to the green wire, the green wire rises to the potential 
of the surge. This can blow up equipment powered by other branch circuits 
that is connected to "protected" equipment. 

Disclaimer:  While I do some occasional consulting work for SurgeX, I 
formed my professional opinion of them and their products long before doing 
any work for them, and I have long specified their products for all of the 
projects I design. 

73,

Jim Brown K9YC