Actually, 'wear out' is an effective way of describing it.  Otherwise, your
description of joules is very accurate.  Each hit 'consumes' so many joules,
when the limit is reached or surpassed, the suppression capability of the
unit is dead.  Since most hits are small and go unnoticed, the only safe
practice is to invest a little extra for a suppressor that automatically
shuts down when the unit can't absorb any more surges.  My units are from
various manufacturers, but I like Power Sentry Power Blocker @ 1020 joules
for my desktop, and Woods TrueProtection @ 800 joules with coax cable
protection for my sound system. I use an  APC uninterruptible power supply
on the server/router/modem.  All will permanently shut down if they become
defective.  The APC ups can be repaired of course, but you throw the
suppressors away when shut down, this is permanent and I am not referring to
the circuit breaker that pops when the unit exceeds 1800 watts.

All of them explicitly say they have lightning protection, which is not
automatic with a surge suppressor.  A really bad lightning strike might jump
any suppressor, but a cheap one offers no protection from even a feeble hit.

Tom Turak

-----Original Message-----
From: Dan Kucherich [mailto:[log in to unmask]]
Sent: Sunday, June 02, 2002 3:19 PM

Thanks,  I haven't heard of joule rating as a standard, although
I remember joule units from physics class.  What I see on specs
for surge protectors is MOV, which I don't know what that refers
to (v probably stands for voltage).


> > Do surge power strips "wear out"?.  When they've taken a few
surge 'hits'
> > to they lose their effectiveness for attenuating power
spikes?
> >

>
> Hi,
>   The surge protection doesn't "wear out" as you put it, but
they can be
> rendered ineffective. The protection device will try to clamp
any surge
> voltage to a "safe" level, right up to the point it self
destructs (from
> overheating). The amount of energy it can absorb before this
happens is
> called a joule rating. Better protectors have a higher joule
rating (the
> protection devices are physically larger inside the unit), so
they can
> withstand a bigger "hit", before overheating to the point of
> self-destruction.
>   There is no simple way of testing them, to see if they are
still
> functioning properly, so if you have any doubts, you should
just replace them
> (and maybe move the questionable ones to less valuable
equipment, or stuff
> that is not likely to be hurt by surges...incandescent lights,
or things with
> just a motor, like fans for example, are not too susceptible to
surges).

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