Welcome to deregulation where we don't want the government
to do standards. As a result, simple standards cost big
bucks.

UL1449 defines testing a surge protector so that it does not
kill humans. Surge protector can fail during some of these
tests and still pass because the only requirement is that
protector not threaten human life. Transistor safety is
irrelevant to UL1449 - or the principles on which all UL
standards are created. Underwriter's Laboratory is about
protecting human life. It does not care whether the product
does as advertised.

Some will cite ANSI/IEEE C62.1 standards. These are
waveforms to simulate surge transients. C62.1 also does not
mean the surge protector does anything. How does a waveform
standard provide surge protection? But again, anything to
sell a plug-in protector. They will hype C62.1 so that the
naive feels this is an effective protector. Too much junk
science reasoning only because a numerical standard is
printed. One should first learn what that standard says.
Most do not when they recommend a surge protector.

A common mode transient inside a building seeks earth
ground. It can seek earth via one or all wires. This being
different from a differential mode transient that requires two
wires. An AC power line transients will be earthed by the
neutral, but other AC wires will continue into the building.
However if the 'whole house' protector earths those other
wires, then common mode surge become irrelevant. However all
incoming wires must have some connection to earth for common
mode transient protection.

Earth has resistance. But more important, wire also has
impedance. Now some numbers. Read multiple times if necessary
since those numbers put surge protection into perspective and
expose junk science myths. For example, a 20 amp copper wire
of 18 meters may appear as 0.2 ohms resistance, but may also
appear as 130 ohms impedance to a surge transient. This wire
*impedance* is why a surge protector must make a less than 3
meter connection to earth.

For example, lets say a 100 amp surge arrives at computer
and adjacent plug-in surge protector. Surge protector
attempts to shunt (divert, connect) that transient to earth
ground via safety ground wire. But that would be 100 amps
times 130 ohms or 13,000 volts. Computer and adjacent surge
protector at something less than 13,000 volts relative to
earth! IOW the surge will find other, destructive paths to
earth such as through modem via phone line. This is typical
modem damage - surge entering on AC mains and leaving to
ground on phone line (UK has a different variation).

Surge arrived on AC hot (black or brown) wire. Adjacent
surge protector shunted surge to green safety ground wire.
Surge protector, being too close to transistor and too far
from earth ground, has contributed to surge damage. Modem
often being a victim because it makes a good conductive path
to earth ground.

Now lets say same 100 amp surge encounters a 'whole house'
protector with a 3 meter earth ground connection. That would
be maybe 4 ohms impedance (and something less than 0.01 ohms
resistance). IOW surge voltage from hot wire to earth ground
is only 400 volts. Voltage at service entrance so low that
1000 and 2000 volt protection abilities built into appliances
are not overwhelmed. Furthermore, that 18 meter wire between
breaker box and appliance NOW becomes part of the surge
protection solution rather than part of the problem.
Impedance in those 18 meters makes it that much more difficult
to find earth ground via the appliance - because surge was
earthed by a 'whole house' protector.

Of course that earth ground rod may not be the best earthing
connection. No matter how big that earth ground, we can never
get an excellent earth ground. Therefore better built homes,
before the foundation is laid, install an Ufer ground with
footings or a halo ground around the entire building. This
makes earth beneath the building equipotential but for cost of
copper wire. Very effective earthing at so little cost.
However that copper wire loop can never be a perfect
conductor; wire has impedance. So we want central earth
ground to be a single point connection and the best earthing
in the facility. Of course we can never make a perfect and
best conductive single point ground.....

Concepts of single point earthing are similar to why Hi-Fi
components require single point grounding to eliminate hum and
why A/D converters in so many electronics have a single point
ground between the analog and digital circuits AT the A/D
converter. Single point ground is a concept that requires
understanding electronic circuit theory and electrical
principles.

These factors combine to make surge damage completely
avoidable. Earthing for no surge damage is so easy if
installed when the building is first built. Even so, we can
install an effective earth ground, in most cases, by superior
single point grounding techniques just at the service
entrance. It may not be fully effective against the 200,000
amp direct strike. But then most people never confront this
rare surge in their lifetime.

My experience demonstrates earthing a direct strike with
only 1 three meter ground rod. Damage to unprotected circuits
was to everything. Damage on the protected circuits -
nothing. Nothing except the utility meter that was partially
damaged and failed later when the surge was earthed through
meter. But this installation was more typical of a best
protected facilities. This one facility has a less than 1
meter connection to a single earth ground rod in conductive
soil. That distance to earth ground determines how much or
little of a surge will seek earth ground inside the building.

As noted previously, once inside the building, a surge will
find too many destructive paths as even demonstrated by an
IEEE paper. Concepts of surge protection were demonstrated in
most papers of the 8 Nov 1998 issue of IEEE Transactions on
Electromagnetic Compatibility. For example, one was a
Norwegian maritime station installed to withstand the EMP of
nuclear war. But so poorly earthed as to be damaged by a
direct lightning strike. Authors demonstrated how earthing
need be repaired.

Legendary application notes are provide by the benchmark in
surge protection - Polyphaser:
http://www.polyphaser.com/ppc_pen_home.asp
Does Polyphaser hype their product line? Of course not.
Polyphaser earns their profits on providing real surge
protection. Most who recommend surge protectors have never
even heard of Polyphaser - which exposes how little they
really knew. Polyphaser discusses earthing - extensively.
Earthing so critical that one product has no earth ground
connection. Instead the protector mounts directly on earth
ground - because distance to earth - 0 meters - is that
critical.

Polyphaser even demonstrates how a direct strike to buried
cable some distance from the building results in transistor
failure - because incoming wire was not properly earthed to a
single point bulkhead:
http://www.polyphaser.com/datasheets/PTD1028.pdf
Lightning strikes somewhere across the street close to the below
grade West cable vault. ... The first line of defense is the
telco protection panel, but the panel must be connected to a low
resistance / inductance ground. There was no adequate ground
available in the telephone room.

Also note that serious surge protectors have little or no
warranty. Polyphaser offers no warranty which is but another
characteristic of better products.

Concepts of earthing for surge protection demonstrated in
this figure from an industry professional. Note that even
buried wires can source an incoming transient. Both structures
have their own central earth ground. All wires connect to
that earth ground before entering structure - either by direct
wire connection or via a surge protector:

http://www.erico.com/erico_public/pd...es/Tncr002.pdf

Other concepts:

http://lists.contesting.com/_towerta...st/032935.html

http://lists.contesting.com/_towerta...il/004413.html
http://www.psihq.com/iread/ufergrnd.htm
http://scott-inc.com/html/ufer.htm
http://www.psihq.com/iread/strpgrnd.htm
http://www.xantrex.com/support/docserve.asp?id=337
http://www.cinergy.com/surge/ttip08.htm
http://www.ipclp.com/html/aud_ho_faq.html
http://www.telebyteusa.com/primer/ch6.htm (see section 6.4)
http://www.citelprotection.com/citel/tech_article.htm

None of this is mentioned or implied by plug-in protectors
because they are not selling effective surge protection. They
are selling a product that is grossly overpriced (especially
considering how few joules are installed), that avoids all
mention of common mode transients, and that costs on the order
of 10 to 50 times more per protected appliance compared to
'whole house' protectors.

Where do most computer 'experts' get their education on
surge protection? From boxes on retail shelves. Electrical
concepts necessary to understand effective protection are not
taught to nor understood by too many computer experts. For
example, one need not even understand how to use a 3.5 digit
multimeter to get A-plus Certified - to be a certified
computer repairman. Insufficient electrical knowledge is why
so few understand a concept well proven and demonstrated
repeatedly since the 1930s - surge protection.

Surge protectors are not surge protection. Surge protection
is earth ground. A surge protector is only effective when it
makes a connection to earth ground - as those so many
professional comments repeatedly demonstrate. The most
important point that no plug-in protector will ever mention -
a surge protector is only as effective as its earth ground.

Vanguard wrote:
I'm not an electrical engineer but find this topic interesting. Could
you please define what you mean by a "common mode" surge. I thought
that meant the impulse was on both wires (line and neutral) and that a
surge only on 1 wire was a "normal mode" surge. There are probably more
technical explanations of common mode signals but the one at
http://www.explan.co.uk/antisurge/modes.shtml seems to suffice (if you
neglect the resistance to ground which apparently you do in claiming
that slamming the surges to ground does not affect data transmission
which uses ground as the reference).

Say I have a common mode surge headed at my house (same impulse on both
wires). At the service entry, the neutral is grounded to earth. Are
you saying the impulse on the neutral still continues into the house?
Then what was the point of grounding the neutral wire at the service
entrance? And wouldn't this disqualify all your arguments regarding
shunting the surge to ground if the shunt that already and permanently
exists where the neutral wire is bonded to ground at the service entry
doesn't work to eliminate the surge? Why would I expect a surge
arrestor to do any better than a solid heavy gauge wire in shunting the
surge to ground?

If the surge is grounded on the neutral wire and doesn't proceed further
and only the surge on the [hot] line gets through, why would that still
be considered a common mode surge if the [companion] surge is now
missing on the neutral wire?

Also, do you know of any online links to ANSI, IEEE, and UL
specifications (that I don't have to pay for)? As I mentioned, this is
not my career but an interest as a result of my career and hobbies
(i.e., it's not what I do but it can affect what I do). When I have
gone hunting for the specs, it seems I end up as some site that wants me
to pay for the documentation. For example, I want to find out about
UL1449 referenced by a product, I go to http://www.ul.com and click the
link for "Standards", and I get redirected to somewhere else
(http://snurl.com/28fb) where I can buy a copy of the standard for $265.
Yeah, right, like consumers are going to spend more than what the
product costs to find out what the standard means. What the hell good
are any of these standards when they are quoted by manufacturers but the
consumers have to no way to know what they are? And you wonder why
consumers don't know this stuff.