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Reread that PC World article with care. UL1449 2nd edition
does not claim a surge protector is effective. UL1449 only
says the protector does not harm humans. Article even says
that. A protector with ineffective components could still be
approved for UL1449 if it does not harm humans. Computer
protection is completely irrelevant to Underwriters Labs.
Surge protectors meet two important criteria. 1) Protector
must be sufficiently sized to remain functional after each
surge. 2) Protector must make a short conductive connection
to common earth ground so as to provide that protection.
Many plug-in protectors are grossly undersized - as
indicated by their joules number. Review manufacturer data
sheets and their charts such as:
http://www.europechemicon.de/ecc01/Products/varistor/va-pulselife-e-010928.pdf
For surges of constant value, then more joules means a
protector will survive more surges. The relationship is
exponential. For example, a plug-in protector rated at 345
joules may actually use as little as 115 joules in protection
and never more than 230 joules. Assume this 115 joules only
survives two or three same size surges. Then the properly
sized 1000 joule 'whole house' protector might survive for
well over 100 such surges.
Notice that numbers are provided in this post. To disagree,
another will have to provide better numbers. That is the
problem with so many posts about MOV protectors. They provide
no numbers - only parrot myths they have heard. Provide here
even were the charts from MOV manufacturers. That is damning
evidence that says joules are important.
BTW, how does a protector fail? It degrades. No protector
properly sized fails by vaporizing or burning. That failure
mode is not even listed on those charts or by manufacturer
data sheets. Vaporization must never happen to a properly
sized protector. IOW notice how many plug-in protectors are
not just undersized. They are grossly undersized - completely
ineffective.
Why did I mention an undersized 345 joules protector? Look
at the joules claimed even on plug-in UPS protectors. It too
is undersized. But then the manufacturer did not even claim
to provide protection from the destructive type of surge. He
only says enough so that those myth purveyors will make wild
assumptions and will recommend that UPS as if it was an
effective surge protector.
Effective protector must not be close to transistors and far
from earth ground. A minimally effective 'whole house'
protector for residential AC electric is about 1000 joules and
50,000 amps. It costs about $1 per protected appliance.
Compare that to how much for the grossly overhyped plug-in
protectors? To be sized equivalent, the plug-in protectors
would be rated 3000 joules.
Art wrote:
> "sdlomi2" <sdlomi2spamfree@yahoo.com> wrote in message
> news:10ft3a08crs71c2@corp.supernews.com...
>> How much surge protection, in joules, does one actually need
>> for home computing system, including all-in-one pscf-machine?
>> Are certain brands preferable to others? TIA, s.
>
> There's an article in the latest (August) issue of PCWorld on
> what they refer to as "PC Myths". One, in particular, deals
> with surge suppressors and, according to PCWorld, refutes the
> notion that a pricey surge protector affords more protection
> that the cheapo models. The article contains a statement from
> a presumed expert that the number of joules is *not* a reliable
>indication of quality and all that's important is that the
> device is UL 1449 rated. All this, of course, seems to fly in
> the face of everything we've previously read or heard on this
> subject. Here's the link to the article:
>
http://www.pcworld.com/news/article/0,aid,116572,pg,5,00.asp
>
> Art
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