Lightning protection

[Skeleton Man]

Hi guys,

Can anyone reccomend a good product (preferably a power bar or simmilar) to
protect computer equipment against a lightning strike ? I'm looking for
something with a connected equipment warranty.. (ie. if my PC goes up in
smoke while connected to their product, they pay for the replacement)

While I'm at it.. is there any way you can insure just your PC and
associated equipment ? Insurance on the house itself (even just contents)
isn't possible right now, but I'd like to have some safeguard.. also, can
you insure against data loss ? (besides making a backup)

Chris

 

[DevilsPGD]

In message <[email protected]> "Skeleton Man"

Can anyone reccomend a good product (preferably a power bar or simmilar) to
protect computer equipment against a lightning strike ? I'm looking for
something with a connected equipment warranty.. (ie. if my PC goes up in
smoke while connected to their product, they pay for the replacement)

Not much will stop a lightning strike, but insurance is possible.

While I'm at it.. is there any way you can insure just your PC and
associated equipment ? Insurance on the house itself (even just contents)
isn't possible right now, but I'd like to have some safeguard.. also, can
you insure against data loss ? (besides making a backup)

In general, just pick up house insurance with low limit, this will do
the trick, just watch your exclusions.

As far as data loss, generally this is extremely expensive, you're much
better off learning to do a backup. It is cheaper to pay for off-site
backup services then to pay for insurance.

 

[Paul]

Hi guys,

Can anyone reccomend a good product (preferably a power bar or simmilar) to
protect computer equipment against a lightning strike ? I'm looking for
something with a connected equipment warranty.. (ie. if my PC goes up in
smoke while connected to their product, they pay for the replacement)

While I'm at it.. is there any way you can insure just your PC and
associated equipment ? Insurance on the house itself (even just contents)
isn't possible right now, but I'd like to have some safeguard.. also, can
you insure against data loss ? (besides making a backup)

Chris

I think some of the Isobars have insurance. Insurance is only valid
if the unit is plugged directly into the wall. (And the wall would
need a three pronged plug, as the safety ground has to be present
for it to work.) I'd want to find an account of someone actually
collecting on the insurance, as proof there really is effective
insurance.

http://www.tripplite.com/products/suppressors/isobar.cfm

Some have provision to run the telephone line through there,
which is handy if the computer uses a dial up modem. I don't
know what the best strategy is, if you are using ADSL or cable
modem. You could try running the phone line through it, for
ADSL, but I don't know if that affects the ADSL signal or
not.

Paul

 

[Jon Danniken]

Hi guys,

Can anyone reccomend a good product (preferably a power bar or simmilar)
to
protect computer equipment against a lightning strike ? I'm looking for
something with a connected equipment warranty.. (ie. if my PC goes up in
smoke while connected to their product, they pay for the replacement)

Belkin does, as do others. The way Belkin words their guarantee, is that
they will pay for any equipment damaged by a surge, but only if *every*
connection to the PC goes through their protection product. In other words,
the power line, and if you are connected to the phone or cable line, those
too have to pass through the protection device.

Jon

 

[DaveW]

Nothing will stop a lightening strike. You cannot just insure your PC. You
cannot insure against data loss (make a backup.)

 

[DevilsPGD]

In message <[email protected]> "DaveW"

Nothing will stop a lightening strike.

Either concrete or rubber will, although you do need a pretty good
thickness.

You cannot just insure your PC.

Incorrect. Even residential property insurance can be contents only,
and can be purchased in small enough increments that it will only cover
your PC.

Some surge protectors also include coverage, although you'll want to
read the terms closely.

You cannot insure against data loss (make a backup.)

Definitely incorrect (although this one will cost ya)

 

[Vester]

My home computers, modem, router, and television are all on
APC battery backup UPS
units. DSL sometimes works with the units
although my ISP says don't use a surge protector on the aDSL line.
The phone line from the wall jack to the modem is about six inches. I
have underground utilities which help. I've only lost one modem in
six years here in South Carolina, USA.

 

[w_tom]

Can anyone reccomend a good product (preferably a power bar or simmilar) to
protect computer equipment against a lightning strike ? I'm looking for
something with a connected equipment warranty.. (ie. if my PC goes up in
smoke while connected to their product, they pay for the replacement)

While I'm at it.. is there any way you can insure just your PC and
associated equipment ?

Many posts violate what is well known about surge protection. For
example, one assumed concrete might stop lightning. Hardly. Concrete
is considered a better conductor.

It is routine to suffer direct lightning strikes without failure.
But some have assumed:

Not much will stop a lightning strike ...

Correct. Effective protection means not even trying to stop
lightning. Effective protection is as Ben Franklin demonstrated in
1752. Did he block lightning from finding a conductive path through
wooden church steeples? (Notice that wood is also a conductor.) Of
course not. Franklin gave lightning a better and non-destructive path
to earth.

1) Lightning seeks earth ground. 2) Effective protection is about
conducting lightning to earth so that it does not find a destructive
path via DSL modem or computer - or church steeple.

Your telco connects to overhead wires everywhere in town. Its
computer may be threatened by hundreds of surges during each
thunderstorm. So what does your telco do where damage is never
acceptable?

Did those other posters forget to mention your telco installs a same
protector where phone line enters your building? Some claim that
protection is not possible or recommend a plug-in solution. Not one
post even mentions the effective protector installed by your telco ...
for free.

Sometimes protection does not work because the connection to
earthing is insufficient or missing. As with Franklin's experiment,
the lightning rod is not protection. Protection is the earthing.
Lightning rod or surge protection - are only as effective as their
earthing.

Meanwhile what is the most common source of modem damage? First an
electrical path is created from cloud, to AC electric, through modem,
out via phone line protector to earth ground. Then current flows
through everything in that path. Then something fails in that path.

How does your telco protect its computer connected everywhere to
overhead wires? Every wire in every cable connects to earth where it
enters the building. You must do same to protect your electronics.

Exampled is the 'whole house' protector installed by telco on phone
lines. But have you done same to AC electric? Every AC electric
wire either connects to earth ground directly or must make that
connection - 'less than 10 feet' - via a 'whole house' protector.

Responsible manufacturers such as GE, Intermatic, Leviton, Cutler-
Hammer, Siemens, and Square D make these protectors. How do you know
other plug-in protectors are not effective? 1) No dedicated wire for
that 'less than 10 foot' earthing connection. 2) Manufacturer avoids
all discussion about earthing.

Another claimed a protector needs a three prong wall receptacle.
Yes. Third prong is required for human safety. But third prong does
not provide earthing for protection. Among the long list of reasons
includes 'many times more than 10 foot' connection.

Every wire that enters a building must be earthed. That means cable
TV and satellite dish also must make a short earthing connection to
the same earthing electrode. Notice no protector even required.
Earthing is necessary for protection. Surges are not stopped. Surges
are earthed. Better earthing means better protection. The protector
is only as effective as its earthing.

'Whole house' protector can be purchases even in Lowes and Home
Depot - some for less than $50. And, of course, that earthing to
breaker box must meet and exceed post 1990 National Electrical Code so
as to make that 'less than 10 foot' earthing connection.

 

[Bud--]

The best information on surges and surge protection I have seen is at:
http://omegaps.com/Lightning Guide_FINALpublishedversion_May051.pdf
- the title is "How to protect your house and its contents from
lightning: IEEE guide for surge protection of equipment connected to AC
power and communication circuits" published by the IEEE in 2005 (the
IEEE is the dominant organization of electrical and electronic engineers
in the US).
And also:
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf
- this is the "NIST recommended practice guide: Surges Happen!: how to
protect the appliances in your home" published by the National
Institute of Standards and Technology (the US government agency formerly
called the National Bureau of Standards) in 2001

The IEEE guide requires some (not much) technical background. The NIST
guide is aimed at the unwashed masses.

Did those other posters forget to mention your telco installs a same
protector where phone line enters your building?

To get maximum benefit from telco, CATV, ... entry protectors they have
to be connected in a “single point ground” system - phone, CATV, ...
protector connected with a short wire to the power system earthing wire
at the power service. The problem created by not having a “single point
ground” are illustrated in the NIST guide starting pdf page 40.

How do you know
other plug-in protectors are not effective? 1) No dedicated wire for
that 'less than 10 foot' earthing connection. 2) Manufacturer avoids
all discussion about earthing.

Another claimed a protector needs a three prong wall receptacle.
Yes. Third prong is required for human safety. But third prong does
not provide earthing for protection.

Nonsense.
The IEEE guide (starting pdf page 40) explains that plug-in suppressors
work by CLAMPING the voltage on all wires (power and signal) to the
common ground at the suppressor. They do not work primarily by earthing.
The IEEE guide explains earthing occurs elsewhere.

Both the IEEE and NIST guides say plug-in suppressors are effective.

Note that all interconnected equipment needs to be connected to the
same plug-in suppressor, or interconnecting wires needs to go through
the suppressor. External connections, like phone, CATV, ... also need to
go through the suppressor. Connecting all wiring through the suppressor
prevents damaging voltages between power and signal wires. These
multiport suppressors are described in both the IEEE and NIST guides. As
John said, if a suppressor has a connected equipment warrantee, it
likely requires all circuits go through the suppressor. Not connecting
all wires through compromises the protection.

Suppressor ratings range from junk to very high.

With high ratings a suppressor is likely to protect from anything but a
very near hit. High ratings are why manufacturers can have connected
equipment warranties on some suppressors.

I have a couple of Belkin units, but here are other good brands.

'Whole house' protector can be purchases even in Lowes and Home
Depot - some for less than $50.

w_ has never provided a link to a $50 suppressor. Or provided the specs
for one.

 

[Mike Walsh]

Some modems have built-in surge protection e.g. my old 28.8 Zoom modem which has outlived several 56K modems. I still use the Zoom for fax since my last 56K modem died.

 

[Bud--]

He seems to go off when anyone mentions 'protection' in any form.

I believe he uses google-groups to search for "surge" and maybe
"lightning". Also "power supply" with a different spiel.

 

[Paul]

I believe he uses google-groups to search for "surge" and maybe
"lightning". Also "power supply" with a different spiel.

You can use Google Alerts, to have an email sent to you, every
time a certain word or phrase is used:

http://www.google.ca/alerts?t=8&q=protection

Paul

 

[w_tom]

The best information on surges and surge protection I have seen is at:http://omegaps.com/Lightning Guide_FINALpublishedversion_May051.pdf
- the title is "How to protect your house and its contents from
lightning: IEEE guide for surge protection of equipment connected to AC
power and communication circuits" published by the IEEE in 2005 (the
IEEE is the dominant organization of electrical and electronic engineers
in the US).
And also:http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf
- this is the "NIST recommended practice guide: Surges Happen!: how to
protect the appliances in your home" published by the National
Institute of Standards and Technology (the US government agency formerly
called the National Bureau of Standards) in 2001

When outright and intentional lies and myths are posted, nobody
cares who attacks the liar. Bud is the worst example. Let's take his
own citations as example. Bud intentionally misrepresents IEEE and
NIST. He cut and pastes this same response everywhere. He knows
exactly what my response will be and he never has been able to deny
reality.

Reality is that IEEE Standards are where recommendations are made.
And IEEE Standards are blunt about it. Earthing is the protection -
not a protector. For example IEEE Red Book (Standard 141) says"

In actual practice, lightning protection is achieve by the
process of interception of lightning produced surges,
diverting them to ground, and by altering their
associated wave shapes.

Other IEEE Standards repeat this - earthing is the protection. Bud
claims no protector need earthing. He claims his cited guides do not
disagree with IEEE Standards. They don't. Page 42 Figure 8 in his
first standard contradicts Bud. A plug-in protector has shunted (also
called clamping, connecting, bonding, diverting) a surge to earth
ground. Problem is the protector was too far away from building earth
ground - the protection. So it shunted that surge 8000 volts
destructively through the adjacent TV. Bud hopes you will not look
at Page 42 Figure 8. He will post spin to confuse the issue. But
Page 42 Figure 8 in his IEEE guide agrees exactly with IEEE
Standards. Protection is by earthing - not by a protector. And when
the protector has no earthing electrode to connect to, then it may
earthing that surge 8000 volts destructively via the TV.

Why does the telco install a 'whole house' protector where telephone
line enters your building? Because it can is properly earthed - will
then provide protection for telephone line appliances. Do what IEEE
Standards demand. Not cause damage as in Page 42 Figure 8.

But also hopes you never review his other citation Page 8 of 24
(paper page 6):

You cannot really suppress a surge altogether, nor
"arrest" it. What these protective devices do is
neither suppress nor arrest a surge, but simply
divert it to ground, where it can do no harm. So
a name that makes sense would be "surge diverter"
but it was not picked. So, for the rest of this
booklet, we will stick to the most popular "surge
protector".

How can this be? Bud who avidly promotes for plug-in protector
manufactures would not lie? Well last time his citations were uses
against him, then his replies were insults such as

And more drivel.

Then follows that post with no technical facts or repeats his
intentional misrepresentation of his only two citations.

Bud's citation Page 8 of 24 (paper page 6) even says a protector
must

... simply divert it to ground, where it can do no harm."

No earth ground means no effective protection. The protectors that
have no earthing - Bud promotes them. Others have simply used word
association to know plug-in protectors must work: surge protector
sound likes surge protection. Therefore it must be true.

But again, Bud's own citation demonstrates a protector too close to
appliance and too far from earth ground put 8000 volts destructively
through the TV.

'Whole house' protectors are earthed. Therefore facilities from the
US Air Force to commercial broadcasters, 911 emergency response
centers, and even hospitals install single point earthing AND use
'whole house' protectors.

Those who did not like being exposed in error may even post attacks
on this poster rather than cite science.

Cites is a 'whole house' protector already on phone line. Why did
those advocating grossly overpriced and ineffective plug-in protectors
not even know of that telco provided protector exist? How can they
recommend a protector that does not even cite each type of surge and
numbers for that protection? How can they recommend protection when
they don't even know how it was installed standard even long before
WWII?

Meanwhile Bud's knowledge apparently comes from the Internet. He
could not even get off his ass to visit any Lowes or Home Depot where
'whole house' protectors are sold - some for less that $50. Actually
he may have. But Bud's purpose is to pervert reality - promote
ineffective and so grossly profitable plug-in protectors that don't
even claim to protect from the typically destructive type of surge.
Obviously. No dedicated earthing connection. Even Bud's own citations
Page 42 Figure 8 and Page 8 of 24 contradict him.

Bud usual reply is to ignore how those citations say earthing is
necessary for protection. Bud cannot refute that because even IEEE
Standards demand earthing for protection. But then an engineer with a
few decades of experience learned this long ago. Real world design
experience; not denials based in promoting plug-in protectors from
internet knowledge.

A protector is only as effective as its earth ground. Even IEEE
Standards and Bud's own citations demonstrated that reality.

 

[Bud--]

When outright and intentional lies and myths are posted, nobody
cares who attacks the liar. Bud is the worst example.

Perhaps w_ could learn English.

Follow the discussion and see who is lying.
I encourage people to read the sources - the IEEE and NIST guides.

w_ has a religious belief (immune from challenge) that surge protection
must use earthing. Thus in his view plug-in suppressors (which are not
well earthed) can not possibly work. The IEEE guide explains plug-in
suppressors work by CLAMPING the voltage on all wires (signal and power)
to the common ground at the suppressor. Plug-in suppressors do not work
primarily by earthing. The IEEE guide explains earthing occurs
elsewhere. (Read the IEEE guide starting pdf page 40).

Reality is that IEEE Standards are where recommendations are made.
And IEEE Standards are blunt about it. Earthing is the protection -
not a protector. For example IEEE Red Book (Standard 141) says"...

w_ has to discredit anything that challenges his religious belief in
earthing.
But you have to be really stupid to say the recommendations of the IEEE
are not in the IEEE guide considering the IEEE guide (pdf page 4) says
the guide was peer-reviewed and represents the views of the IEEE.

And the "IEEE Recommended Practice for Powering and Grounding Sensitive
Electronic Equipment" (the Emerald book), an IEEE standard, recognizes
plug-in suppressors as an effective protection device. This is the most
appropriate IEEE standard for protecting electronics

Bud
claims no protector need earthing.

w_ is fond of making up what others claim. I repeat what the IEEE guide
says - plug-in suppressors work by clamping not earthing. The guide says
earthing occurs elsewhere.

Page 42 Figure 8 in his
first standard contradicts Bud. A plug-in protector has shunted (also
called clamping, connecting, bonding, diverting) a surge to earth
ground. Problem is the protector was too far away from building earth
ground - the protection. So it shunted that surge 8000 volts
destructively through the adjacent TV.

Lacking technical arguments w_ has to lie about sources that contradict
his dogma.
The illustration in the IEEE guide has a surge coming in on a CATV drop.
There are 2 TVs, one is on a plug-in suppressor. The plug-in suppressor
protects the TV connected to it. It reduces the voltage at a distant TV
from 10,000V to 8,000V. It does *not* contribute to damage of the second
TV, which is distant, not adjacent. The point of the illustration is "to
protect TV2, a second multiport protector located at TV2 is required".

This lie is repeated numerous times is w_’s rant.

Bud hopes you will not look
at Page 42 Figure 8.

Bud hopes you will read the IEEE guide. Start at pdf page 40.

But also hopes you never review his other citation Page 8 of 24
(paper page 6):...

What does the NIST guide actually say about plug–in suppressors?
They are "the easiest solution".

How can this be? Bud who avidly promotes for plug-in protector
manufactures would not lie?

w_ has to discredit anyone who challenges his dogma.
I can only agree with w_ when he said "It is an old political trick.
When facts cannot be challenged technically, then attack the messenger."
My only association with surge protectors is I have some.

No earth ground means no effective protection. The protectors that
have no earthing - Bud promotes them.

The statement of religious belief in earthing. Everyone is for earthing.
The only question is whether plug-in suppressors work.
And I don’t promote them. I only promote accurate information. I say
they are effective, not that I recommended them.

Others have simply used word
association to know plug-in protectors must work: surge protector
sound likes surge protection. Therefore it must be true.

Geez - and those idiots at the IEEE and NIST fell for it.

Those who did not like being exposed in error may even post attacks
on this poster rather than cite science.

w_ doesn’t like being exposed in error (as is evident) and posts attacks
on this poster rather that cite science. I cite science - links to 2
reputable sources that say plug-in suppressors are effective. Try to
find a source from w_ that says anything about plug-in suppressors.

Meanwhile Bud's knowledge apparently comes from the Internet. He
could not even get off his ass to visit any Lowes or Home Depot where
'whole house' protectors are sold - some for less that $50.

w_ requires others to post specifics. But he is immune. There is no
reason to believe the mythical $50 suppressor exists.

Bud usual reply is to ignore how those citations say earthing is
necessary for protection.

Everyone is in favor of earthing. But the only question is whether
plug–in suppressors work.

A protector is only as effective as its earth ground.

And the final statement of religious belief in earthing. The IEEE guide
explains plug-in suppressors work by clamping, not earthing.

Both the IEEE and NIST guides say plug-in suppressors are effective.
Read them for yourself.

Never seen - a link to a source that says plug-in suppressors are NOT
effective. Where is a link w__? Could it be that no one agrees with you?
And never seen - an explanation why the only 2 examples of protection in
the IEEE guide use plug-in suppressors.
Or why the NIST guide says plug-in suppressors are "the easiest solution".
Or why Emerald book includes plug-in suppressors as an effective surge
protection device.

All you get is a hysterical rant with w_'s opinions based on his
religious belief in earthing.


Bizarre claim - plug-in surge suppressors don't work
Never any sources that say plug-in suppressors are NOT effective.
Misattributes views.
Distorts and tries to discredit opposing sources.
Attempts to discredit opponents.
w_ is a purveyor of junk science.

 

[kony]

w_ is fond of making up what others claim. I repeat what the IEEE guide
says - plug-in suppressors work by clamping not earthing. The guide says
earthing occurs elsewhere.

No, it says they can be effective. It's like saying a steak
knife can be effective at driving off a burglar, but don't
be surprised if you happen upon a burglar that sees it and
laughs at you instead.

 

[Bud--]

No, it says they can be effective. It's like saying a steak
knife can be effective at driving off a burglar, but don't
be surprised if you happen upon a burglar that sees it and
laughs at you instead.

Everything I have read is that suppressors with high ratings will
protect against lightning induced surges short of a near direct strike.
The surge current to a plug–in suppressor is greatly limited by the
impedance of the supply wiring. It is easy to get plug-in suppressors
with high surge current ratings - so they will survive a few very
strong surges. It is also easy to get high Joule ratings - so they will
survive a large number of strong surges. That is why some manufacturers
can offer connected equipment warranties. Everything I have read
indicates suppressors with very high ratings, readily available, would
protect against anything but a lightning strike on a service drop to a
house (and are likely to even withstand that). Few people would expect
protection for a lightning strike to the house itself.

I said: “Suppressor ratings range from junk to very high.”
And “With high ratings a suppressor is likely to protect from anything
but a very near hit. High ratings are why manufacturers can have
connected equipment warranties on some suppressors.”
And that all signal and power wires have to go through the suppressor.
Seems to me that is adequate qualification.

You seem to think plug–in suppressors are not particularly useful. That
is certainly not what the IEEE and NIST guides say. You also insist
“effective” means 100%. By that definition steel frame buildings are not
”effective”, as has been recently seen. Nor are fuses, circuit breakers
or locks. I’m not sure anything is “effective”.

 

[kony]

Everything I have read is that suppressors with high ratings will
protect against lightning induced surges short of a near direct strike.
The surge current to a plug–in suppressor is greatly limited by the
impedance of the supply wiring.

So is the return path to ground. Remember that when there
is this higher impedance to ground, a larger % of the surge
ends up going through the equipment. Always "some" of the
surge does but with this raised impedance the % is more
significant.

 

[nobody]

You can get a full house surge suppressor installed by an electrician to
protect against surges, but nothing will protect against a direct or close
lightning strike, i was told.


Alan

--

----------------------------------------------------------------------
** Please use address alanh77[at]comcast.net to reply via e-mail. **

Posted using registered MR/2 ICE Newsreader #564 and eComStation 1.21

BBS - The Nerve Center Telnet FidoNet 261/1000 tncbbs.no-ip.com
----------------------------------------------------------------------

 

[Bud--]

So is the return path to ground. Remember that when there
is this higher impedance to ground, a larger % of the surge
ends up going through the equipment. Always "some" of the
surge does but with this raised impedance the % is more
significant.

The IEEE guide shows an example of how plug-in suppressors work,
starting pdf page 40. The voltage on all wires - power and signal - is
clamped to the common ground at the suppressor. The voltage difference
between wires connected to the protected equipment is clamped low enough
to not cause damage to the equipment. Surges do not go through the
equipment.

As explained at the bottom of page 40, connecting the surge to earth
does not primarily occur through the plug-in suppressor. In the example,
the “vast majority” of the surge current goes through the bond wire from
a CATV entry block to the power service earth connection. The guide says
further that the (US) NEC intends the bond wire to be the path to earth,
not the path through the plug-in suppressor. The current that does flow
through the suppressor goes from the CATV entry block, through the CATV
shield to the suppressor, through the ground and neutral wire to the
power service. The protected equipment is not in the path.

A shorter version of this was included in both my responses to w_.

One of the most useful applications for plug-in suppressors is when the
protected load connects to both power and phone, CATV, ... wires. The
suppressor prevents ground reference differences between the power and
signal wires at the protected equipment, as illustrated in the example .
According to the NIST guide, US insurance information indicates
equipment most frequently damaged by lightning is
computers with a modem connection
TVs, VCRs and similar equipment (presumably with cable TV
connections).
All can be damaged by surges causing high voltage between power and
signal wires.
The 2 examples of protection in the IEEE guide, both using plug-in
suppressors, are for a computer with phone connection and a TV system
with CATV, phone and satellite connections.

I think you have complained in the past that the ground reference level
at the plug-in suppressor is elevated. If the protected equipment has a
metal enclosure it is likely to be connected to a 3 wire plug. If the
enclosure has a path to a ground at a different potential, the ground
reference level at the equipment and suppressor would be shifted, but
the voltages would be clamped to the new reference level. If insulation
is in the path, a surge is a very short event and the voltage withstand
is much higher than normal. There are other possibilities, but in quite
a bit of reading no one has raised this as a practical problem.

And the same concern can be raised with a "whole house" protector.
Assume the power system is earthed with only a ground rod. If you have
a very good rod-to-earth resistance of 10 ohms and a modest 1,000A surge
earth current, the voltage from the power ground bar to `absolute' earth
is 10,000V. As a general rule, 70% of the voltage drop from a ground rod
is in the first 3 feet. From the power/signal ground system to earth
beyond 3 feet will be 7,000V or more. This can show up, for instance, in
basements. Or as the IEEE guide notes, at outside pad mounted
compressor/condenser units.

 

[kony]

The IEEE guide shows an example of how plug-in suppressors work,
starting pdf page 40. The voltage on all wires - power and signal - is
clamped to the common ground at the suppressor. The voltage difference
between wires connected to the protected equipment is clamped low enough
to not cause damage to the equipment. Surges do not go through the
equipment.

Wrong. Because your ground is at a relative impedance away
from earth ground, it does present a risk to equipment and
this is why more serious surge prevention does not only rely
on these plug-in protectors.