On Tue, 14 Mar 2006 05:42:44 GMT, Curious George <cg@email.net> wrote:

>On 13 Mar 2006 00:49:46 -0800, "w_tom" <w_tom1@usa.net> wrote:
> 
Blah, Blah, Blah,...
[vbcol=seagreen]
>The issue is whether a HDD is at significant risk of catastrophic
>damage due to power anomalies of any kind regardless of ANY attempts
>of protection, especially multiple levels i.e. best efforts of
>electrical protection.  With properly wired building & and utility
>power a UPS or line conditioner is never taking a direct lightening
>hit.  You're missing the mark trying to argue whether plug in
>protection is a substitute for properly wired utility power, telco,
>buildings, & power panels.  Still, that we agree on ground protection
>for direct lightening strikes doesn't mean I can't take exception with
>you're exceptionally sloppy terminology, mendacious posturing, &
>irrelevant argument.

I don't know if I can run with such an elite group, but I'll give it a
go...

To protect a home from lightning the manufacturers  (SQ D, GE, ITE,
ect.) all work under the guidance of the NEC here in the US. The NEC
Art #110-3B states that if the code book (NEC) doesn't exactly answer
the question at hand that the manufactures instructions will be
followed. Now in lightning suppression, the standard guidelines are
you must clear the fault within 16 mSec (milliseconds) or 1/60 of a
second. Ring any bells? AC in the US is 60 Hertz or sixty cycles every
second. The fault curve is based on I squared T in other words square
the current times the time it takes to open the circuit (clear the
fault) and protect your washer, dryer, TV, ect. Lightning can product
hundreds of thousands of amps! But for a very short period of time.
That is why those things (SQ D, GE, ITE, ect) don't work for
electronics, they are too slow.

Now electronics, the rule of thumb is to clear the fault in 4 mSec.
Why is this number significant? The AC hertz is dispersed on a Sine
wave which starts at 0volts travels to its positive peak then to 0
volts then to its negative peak then back to 0 volts - this is one
cycle which takes 16 mSec to complete. 4mSec would be to the positive
peak of the sine wave. So there you have it, to protect your
electronics you must clear the fault (open the AC line) before the
sine wave reaches its first peak on the AC from the time of the fault.
This is also why there are so many fuse types to pick from. They are
selected to clear the fault in specific time ranges.

Tripplit, Belkin, Sola, ect... are good at what they do. Are you ready
for it? They sense the flow of electrons and watch for the change in
flow and trip if the change is too great well ahead of the actually
destructive current. That hokie joules number is actually a IMPRESSED
current number and not actually what the device will handle. These
devices can work in the 1mSec range and that is why they give such a
large protection value. They know they will work fast enough to
protect.

A funny sidebar, some of the cheap ones are built for mortality, in
other words if they are subjected to any faults they protect by
destroying themselves. NEVER use a device that you THINK MIGHT HAVE
BEEN subjected to a fault (of any kind). If you read closely you'll
see that exact statement in the instructions.

So there's my 3 cents worth.


if it hurts... take a pill!

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