> So when you buy a generic surge protected power strip, do they have the 3
> way MOV protection installed in them?
Yes, nearly all of them do -- even commercial grade products. For example,
two years ago, I ran a pair of dedicated 20A branch circuits into the shack.
Each branch was terminated into separate Leviton hospital-grade duplex
receptacles with "3-mode MOV protection." It was painful mistake because, I
paid about $45 ea. for the receptacles. About half the cost is due to the
MOV protection -- and the other half because of the superior quality
hardware used in hospital grade devices. I would have been better off
simply sticking with only hospital-grade receptacles without MOV protection.
Or, even industrial-grade receptacles for a few dollars each.
Going the SurgeX route is pretty expensive by typical ham budgets. I guess
its all a matter of what someone wants to pay for a given level of
protection. I would first put my money into a whole-house SPD, then later
consider a single-mode SPD for the shack, home theatre, etc.
----- Original Message -----
From: "Mark Robinson" <email@example.com>
To: <firstname.lastname@example.org>; <email@example.com>
Sent: Monday, January 03, 2011 2:18 PM
Subject: Re: [TowerTalk] Fwd: WHOLE HOUSE SURGE SUPRESSORS
> Mark N1UK
> ----- Original Message -----
> From: "Jim Brown" <firstname.lastname@example.org>
> To: <email@example.com>
> Sent: Monday, 03 January, 2011 1:50 PM
> Subject: Re: [TowerTalk] Fwd: WHOLE HOUSE SURGE SUPRESSORS
>> 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
>>> is equal across interconnected equipment on a branch circuit, there's
>>> issue. During a surge event, small amounts of resistance can create
>>> amounts of potential difference between grounded equipment.
>>> By storing the surge energy and slowly dissipating it onto the neutral
>>> 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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