Paul is exactly right. I've spent the last 40 years in pro audio and
large sound systems, where lots of expensive equipment is
interconnected. We learned about the issues that Paul is talking about
the hard way, and came to the same conclusions that he is articulating.
The SurgeX products are specifically marketed to the pro audio world,
and are highly respected. I began specifying them for all of the large
systems I designed about 15 years ago. About the same time, I bought
them to protect the expensive gear in my home and office. About 7 years
ago, SurgeX began hiring me to teach classes on Power and Grounding at
industry conferences, and to write a tutorial on the subject. I'm still
teaching those classes, and recently updated the tutorial to cover power
systems outside North America. Less than 5% of the class content
addresses lightning protection or their products.
It's also ABSOLUTELY CRITICAL that everything connected to the power
system be properly bonded together per NEC. This includes EVERY ground
rod, the CATV ground, the TELCO ground, all antenna grounds, the shack
ground, conductive cold water, and any building structural steel.
BTW -- the SurgeX and Brickwall products are based on the same rather
interesting patent. Rather than being shorted out by an MOV, the surge
is stored in a large inductor, then discharged slowly back into the line
after the event. Thus, the surge protector does not raise the
potential of the equipment ground, where it cause failures of
interconnected equipment. An important limitation of this concept is
that it is not practical to build inductors rated for circuits of more
than about 30A.
73, Jim K9YC
On 1/3/2011 7:59 AM, Paul Christensen wrote:
> Surge diversion to the ground conductor can raise the ground potential
> unequally between equipment. If the rise and fall of the ground potential
> is equal across interconnected equipment on a branch circuit, there's little
> issue. During a surge event, small amounts of resistance can create large
> amounts of potential difference between grounded equipment.
> By storing the surge energy and slowly dissipating it onto the neutral (a
> conductor actually meant for carrying current), the surge event does not
> create a potential difference between grounded equipment:
> > From the descriptions in the above links, you can see why the ONLY place for
> "all three modes" of MOV protection is at the service entrance.
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