Archived from groups: uk.comp.vendors,uk.comp.homebuilt,alt.comp.hardware,alt.comp.hardware.pc-homebuilt (
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Lem wrote:
> Stormsinger <support@wirednic.com> wrote:
>
>
>>modems are different. If the strike hits a telephone pole then
>>the resulting surge down the phone line can easily take out a
>>modem, and if you're unlucky your mobo as well. Usually though
>>your modem will act as a very expensive fuse.
>>
>>Buy a surge protection device that also protects modems and
>>you should be okay. IMHO Belkin are the best, but others may
>>have a different view.
>>
>>Look at it this way. A couple of years ago we had a massive
>>storm in our area - apparently there were 30,000 odd
>>lightening strikes over the county. (according to the
>>electricity people). Over a two week period, I replaced
>>several dozen modems for people who "suddenly couldn't get
>>online". My supplier ran out of stock! Even the local PCWorld
>>ran out (someone from there even phoned my business to see if
>>we had any modems left in stock that they could buy!!).
>>
>>You can save £30 or so and take the risk - its up to you in
>>the end.
>>
>
>
>
> See this posting to a second thread started with the same posting
> as this one. news:40EDC0A0.31DADBE8@hotmail.com
>
> It says the following.
The article below is misleading. They talk of earthing "all incoming
utilities" but fail to recognize that any incoming 'utility' is not simply
a single wire, as evidenced by their stating "even the CATV wire drops down
to earth ground." It's a coax cable folks, not a 'wire', and the wire in
the middle is not 'earthed' or else there's be no signal. It IS however,
'protected', to some degree, by the shield, which is what's earthed.
Power lines are more problematic. True, the incoming power line 'earth'
should be 'earthed', as they describe, but the others are not, or else your
incoming power would be a direct short to each other through this common
'earth' point.
The 'protection' for power and signal lines is an arc gap suppressor to
that common earth ground which, hopefully, arcs a lightning strike to earth
at that point rather than having it find earth through the devices, or you,
in the home so lucky you end up with only a few hundreds, or thousands, of
volts transients dancing around on the home wiring and your home equipment
with the brunt going through the arc gap suppressors.
Now you, as a human being, are probably safe from those remaining
transients, unless you have your finger stuck in a socket, but electronic
devices are not as they ARE plugged into the socket. And it is those
transients that an in-house transient/surge suppressor is meant to deal
with, not 'lightning strikes' per see.
It is true that small in-house 'protectors' are essentially useless if the
home utilities AREN'T properly protected (earthed) but the implication
derived from the small snippet that if the home has 'proper' incoming surge
suppression that it's then 'safe' for electronic devices (I.E. they're
sufficiently 'protected') is simply hogwash.
It should also be obvious that if the surge protector has no path to earth
then it's function is lost, which means the outlet(s) it's plugged into
must have the proper earth, or it's own wired earth. I.E. Using a '3 wire
to 2 wire adapter' on a surge suppressor disables the majority of it's
protection.
'Protection' is a multistage process. You have the 'protection' on the
utilities themselves, meaning the power company equipment/line outside the
home, which absorb the brunt of most faults. Then there is the protection
going into the home, which depends on the incoming line impedance to limit
the surge. And then you have protection (or lack thereof) from the
'remnants' left on the interior wiring.
> ====== QUOTE =======
>
> A plug-in surge protector is on the order of tens of times
> more money per protected appliance. Furthermore it does not
> even claim to protect from the typically destructive
> transient. Protectors do not stop, block, filter, or absorb
> destructive transients. Ineffective protector manufacturers
> get one to wish that is how they work. In reality, the
> protector is not protection. Protector and protection are two
> separate components of a surge protection system. Effective
> systems must include the protection. And the connection to
> protection is either a hardwire (less than 3 meters) or a
> protector (also part of a less than 3 meter connection).
>
> In short, the protection is called single point earth
> ground. Destructive surges may enter the building seeking
> earth ground. If not earthed (either by hardwire connection
> or by surge protector), then the destructive surge may find a
> path to earth ground via computer. One classic example is due
> to a direct strike to lines highest on utility poles - AC
> electric. Incoming on AC electric, through computer and its
> modem, then outgoing to earth ground via phone line. Many
> then *assume* the surge entered on phone line, damaged modem,
> then stopped - a violation of even primary school science.
>
> Effective protection means all incoming utilities are
> earthed before entering the building. All must be earthed to
> the same single point earth ground. That means even the CATV
> wire drops down to earth ground, connects ground block 'less
> than 3 meters' to that earth ground, and only then rises back
> up to enter building. Again, no surge protector required
> because earthing is accomplished by a direct and short
> hardwire connection.
>
> These concepts are explained further including some examples
> of 'whole house' protectors for AC mains at:
> "RJ-11 line protection?" on 30 Dec 2003 through 12 Jan 2004 in
> pdx.computing at
>
http://tinyurl.com/2hl53 and
> "strange problem after power surge/thunderstorm" in
> comp.dcom.modems on 31 Mar 2003 at
>
http://tinyurl.com/2gumt .
>
> Additional information on how surge protectors work, how
> they are rated, installed, etc was posted in:
> "Opinions on Surge Protectors?" on 7 Jul 2003 in the
> newsgroup alt.certification.a-plus at
>
http://tinyurl.com/l3m9 and
> "Power Surge" on 29 Sept 2003 in the newsgroup
> alt.comp.hardware at
>
http://tinyurl.com/p1rk
>
> One industry professional demonstrates how two structures
> are protected. Notice every wire entering each structure
> (building and tower) must first connect to single point
> ground. Even the buried phone wire carries a potentially
> destructive transient which is why even buried wires must
> enter building at the service entrance with the 'less than 3
> meter' connection to earth ground:
>
>
http://www.erico.com/public/library/fep/technotes/tncr002.pdf
>
> How do we identify ineffective protectors? 1) No dedicated
> connection to earth ground AND 2) manufacturer avoids all
> discussion about earthing. A surge protector is only as
> effective as its earth ground - the protection.
>
> Those ineffective protector manufacturers fear you might
> learn about the essential earth ground AND discover that
> plug-in protectors cost tens of times more money per protected
> appliance.
>
>
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