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lightning protection

H

Halfgaar

Jan 1, 1970
0
Hi list,

Is there a way to reasonably reliably protect electronic equipment from
indirect lightning hits? I have an extensioncord (well, not really an
extensioncord, I just don't know what else to call it) with
surgeprotection. It says: "max clamping voltage: 750V with standing surge
current 1250A". Can this do the trick, or is it only to protect the
equipment from a faulty powergrid?

TIA

Halfgaar
 
H

Halfgaar

Jan 1, 1970
0
w_tom said:
Ben Franklin demonstrated the concept in 1752. Lightning
traveled miles through non-conductive air to obtain earth
ground. Is some silly opto-isolator or point of use surge
protector going to stop, block, or absorb lightning? Of
course not. But effective protection has been demonstrated
repeatedly since before WWII. Effective protection does what
Franklin did in 1752.

Lightning seeks earth ground. Divert lightning to earth
before it can strike the church steeple. Well proven by
centuries of experience.

Electronics has the same problem. If lightning finds a
circuit path to earth via household electronics, then surge
damage result. Again well proven is to earth the surge, at
service entrance, before surge can enter a building.

It's called 'whole house' surge protectors. But surge
protectors are not surge protection. A surge protector is
only as effective as its connection to surge protection -
earth ground. No short connection to earth ground (which is
the problem with plug-in or point of use surge protectors)
means no effective connection.

A surge protector is only as effective as its earth ground.
Surge protectors are simple science - often hyped into myth.
The art of protection is earthing - not a surge protector.
Which again demonstrates why 'point of use' protectors are so
ineffective. Since they don't provide effective protection,
then there is no dedicated (less than 10 foot) connection to
earth AND those ineffective protectors avoid all discussion
about earthing.

Just as Franklin demonstrated. Surge protection is about
earthing a surge. That is what a surge protectors does.
Connect all wires to earth ground only during the surge (which
is why a surge protector must have a less than 10 foot
connection to earth).

The most common source of destructive surges (even to
modems) is AC electric. Surge enters on the one utility that
typically has no protection. Telephone line has and CATV
should have 'whole house' protection. But AC electric - the
utility highest on pole and most struck - makes a direct
hardwire connection even to modem ICs.

What does a surge seek? Earth ground. Any appliance that
makes a connection from AC electric to earth ground becomes a
complete surge circuit. Modems and portable phone base
stations are easily destroyed. Incoming on AC electric.
Outgoing to earth ground on phone line (because telco already
installs 'whole house' protector on phone line).

Two minimally sized 'whole house' protectors are sold in
Home Depot - Intermatic EG240RC or IG1240RC, and Siemens
QSA2020. Never seen any effective surge protectors sold in
Sears, Walmart, Lowes, Kmart, Staples, or Office Max.
Obviously. They don't have a dedicated connection to earth
ground AND avoid all earthing discussions. They don't even
claim to protect from the typically destructive type of surge.

Just a few introductory concept about protection. Will not
even discuss so many erroneous facts posted in the
www.penlight.org FAQ. Discussion for another post. But this
is the fundamental fact. A surge protector is only as
effective as its earth ground. Surge protectors don't stop,
block, or absorb surges. They only shunt - connect all wires
together - during the surge. That shunting is protection only
if connected less than 10 feet to earth ground.

Is it also impossible to protect against indirect hits? I know that direct
hits are fatal, but a few days ago, I saw an add in the paper from a
company which sells protectors for indirect hits. You don't just buy the
device, but also an insurrance. If anything is damaged, they'll pay the
damages. Is this possible, or just a trick to get people to buy those
things? After all, not everyone who buys such a thing gets hit by lightning
(well, their equipment...), so maybe the devices are fake and they just
make money on the insurances.

Halfgaar
 
H

Halfgaar

Jan 1, 1970
0
I have read the faq at penlight. A few more question have come up.

I have this "extensioncord" with, I quote, "full three line surge
protection" and "overload protection" and as I said it says "max clamping
voltage: 750V with standing surge current 1250A". It has a button which
says "press to reset" and a device with an indication light. Is the latter
the surge protection and the former the overload protector?

I have an amplifier connected to it which outputs clicks in the speakers
when lights and the like are turned off/on. It used to do that before I had
the surge protector, and it still does. Isn't it suposed to suppress that?
I do have it connected to the ground.

And finally, how can I check if the surgeprotection actually works?

Halfgaar
 
F

Fred Abse

Jan 1, 1970
0
Lightning seeks earth ground. Divert lightning to earth before it can
strike the church steeple. Well proven by centuries of experience.

A lightning bolt can carry as much as 30,000 amps. One tenth of an ohm
will drop 3000 volts. What is the resistance to ground of the usual type
of lightning rod?

ISTR a guy down at Langmuir Lab being interviewed. He was researching the
effectiveness of different types of lightning conductor, all the way from
soimple blunt ones to the "sophisticated" types using radioactive sources
to ionize the surrounding air. His comments were something on the lines
of: "We can't really get meaningful results, because the lightning seems
to prefer to strike the trees."
 
F

Fred Abse

Jan 1, 1970
0
The ony thing that works is to optically isolate the phone line .
Trouble is that the telco doesen't like that !

Reminds them that they're going to have to dig up all that copper and put
fiber in sometime soon :)
 
T

tube2ic

Jan 1, 1970
0
I have an amplifier connected to it which outputs clicks in the speakers
when lights and the like are turned off/on. It used to do that before I had
the surge protector, and it still does. Isn't it suposed to suppress that?
I do have it connected to the ground.

Your surge protector will not suppress clicks from low amplitude spike
in the AC mains due to noisy fluorescents or other loads.
 
F

Fred Abse

Jan 1, 1970
0
It went for the better earth ground.

What's the proper name for those glassy tube things that lighning strikes
make in sandy soil? I forget.
 
H

Halfgaar

Jan 1, 1970
0
tube2ic said:
Your surge protector will not suppress clicks from low amplitude spike
in the AC mains due to noisy fluorescents or other loads.

You're saying that the flourescents don't produce a high amplitude spike?
But will the surgeprotector probably still protect my equipment from those
high amplitude surges?

Halfgaar
 
T

tube2ic

Jan 1, 1970
0
Halfgaar said:
You're saying that the flourescents don't produce a high amplitude spike?
But will the surgeprotector probably still protect my equipment from those
high amplitude surges?

Halfgaar

Relative to lightning, a fluorescent will not produce a high enough
pulse to fire your surge protector. If your fluorescent is ignited
using a Ballast and starter instead of the newer electronic ballast,
then if your mains is 220V, the ballast produces a surge of about
600-700V to ignite the tube. Once the tube is ignited, the tube itself
acts like a regulator and maintains the voltage at around 110V with
the ballast dropping the rest.
It is the 600-700V spikes produced when your tube ignites that you
hear on your stereo. However by the time it reaches your surge
protector, the energy is already dissipated and will not be strong
enough to fire the suppressor.
It should still protect you against a lethal surge such as an indirect
hit from lightning.
 
H

Halfgaar

Jan 1, 1970
0
w_tom said:
Spike from a power line that do not appear with lightning's
intensity is noise. Typically so small that surge protectors
ignore those transients. Typically so small that internal
protection in appliances are more than sufficient.

If suffering frequent power line transients, then you are
frequently replacing things far more susceptible to damage
such as dimmer switches, cheap radios, and GFCI outlets.
Plug-in surge protectors are typically so undersized that
frequent transients would degrade a plug-in protector in
months. Joules determines how long a protector lasts.
Plug-in protectors are typically undersized - often grossly
undersized.

Meanwhile, those power line transients would occur too
quickly for an electromechanical device, such as that
overcurrent protector, to be effective.

Provided previously was one example of why outlet safety
ground wire is not effective earth ground - induced
transients. Another major reason: wire has impedance. Low
wire resistance is why that outlet safety ground is effective
for human safety. But wire impedance is why that same outlet
safety ground is not an earth ground.

Numbers: that 50 foot of 20 amp wire may measure 0.2 ohms
resistance. But same wire might measure 130 ohms impedance to
a surge. Suppose an adjacent, plug-in protector is trying to
earth a trivial 100 amp surge. 100 amps times 130 ohms means
adjacent computer and surge protector would be something less
than 13,000 volts relative to earth ground. A surge shunted
by adjacent surge protector will seek other destructive paths
to earth such as through computer modem.

Now put a surge protector in AC breaker box - a 'whole
house' surge protector. Same trivial 100 amp surge would be
something less than 400 volts relative to earth. That 50 foot
of wire between 'whole house' protector and computer now
contributes to computer protection! Protector at wrong end of
50 foot wire could only contributed to adjacent appliance
damage.

Bottom line - outlet safety ground is not earth ground
because 'a too long' wire has excessive impedance. Because
ground wire is bundled with other wires. Because the
connection to earth has too many splices and sharp bends. Too
many fundamental electrical reasons why outlet safety ground
is not earth ground. Too many reasons that say a plug-in
surge protector has all but no earth ground. No earth ground
means no effective surge protection.

Plug-in protectors avoid all discussion about earthing since
effective protection is not even claimed. Why raise an issue
that would hurt their grossly excessive profit margin?
Currently, many use junk science reasoning - that a surge
protector and surge protection are one in the same. Surge
protector is simply a shunting device - nothing more. It does
not and cannot stop, block, or absorb a surge. Surge
protection is earth ground. Surge protector is ineffective
without a 'less than 10 foot' connection to the 'system's most
critical protection component - single point earth ground.


For reasons of human safety, even ineffective plug-in
protectors must meet UL1449 2nd Edition. For reasons of
transistor safety, a surge protector must complete a less than
10 foot connection from AC mains to single point earth ground.

Single point earth ground is typically the earth ground rod
that breaker box connects. That rod is required by post 1990
NEC requirements. However many older homes don't have an
earth ground let alone on necessary for surge protection.
Single point earth ground is the point where all incoming
utilities connect to the same earth ground rod, ring, plate,
or whatever is installed.

Where does a 'whole house' protector connect to AC main.
Measure distance from that connection, through surge
protector, to single point earth ground. Less than 10 feet.
Shorter means even better protection.

BTW, that penlight.org FAQ contained many fundamental
technical errors. It was not written by an engineer with
technical experience on the subject.

This is complicated matter. A short answer please :): Does a point of use
surgeprotector has any use when you connect it to the safety ground (as the
one I have is designed to)?

And you say that with many power transients, the protector breaks down fast.
But in the penlight faq, it says that surges happen all the time. If the
protector nullifies all the surges, then it must be dead very soon, right?
And if it is a shunting device, shoudn't I notice power cutt-offs all the
time?

Something else I thought of: Some devices say something about FCC rules,
that it doesn't create harmfull interference and that it must accept any
harmfull interference received. I'm not sure if this is just for radio
equipment. Is it? Or does it have anything to do with surges?

Halfgaar
 
H

Halfgaar

Jan 1, 1970
0
tube2ic said:
A good quality surge supressor, would have at least one common mode
choke (A black ferrite ring) with thick wire wound on it with 4 wires
connected across the input. At least 2 high voltage capacitors and a
fairly big (the size of a dime) thing that looks like a capacitor
(which is probably an MOV-Metal Oxide Varistor). Also it should have a
three pin plug. No doubt there are other designs as well.
While a good ground is a good thing, it is not necessary to get too
paranoid about it. Just make sure that it is connected to the socket
that you are using. You can check by connecting a meter between phase
and ground and between phase and neutral. If the difference is no more
than 2 Volts, your ground is adequate.

I'll check the parts sometime.

Won't measuring the phase and the ground create a leakage so that the "earth
leakage breaker" (I don't know what it's called in English) will disconnect
power?

Halfgaar
 
T

tube2ic

Jan 1, 1970
0
Halfgaar said:
I'll check the parts sometime.

Won't measuring the phase and the ground create a leakage so that the "earth
leakage breaker" (I don't know what it's called in English) will disconnect
power?

Halfgaar

No. A voltmeter is high impedance. If you use a lamp then it would
probably trip. (Depends on your system)
 
T

tube2ic

Jan 1, 1970
0
Halfgaar said:
I seem to be getting several conflicting answers here.

Basicly, all I'd like to know is: can I trust the surge protector (or
"parasite eliminator" or something as the manufacturer calls it) in my
extension cord (or power strip or whatever) to protect my equipment? Does
it at least do *any* good, or can I just leave it out?

This discussion is getting somewhat big, so I'd like a definate answer :)

Halfgaar

Halgaar,
It is unfortunately the nature of a newsgroup to give you anything but
a definite answer.
I strongly urge you to read this brochure for the layman by National
Institute of Standards and Technology (US Dept of Commerce).
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf

You should also look at the website of your local utility company for
information. These are un-biased independent bodies which tell it
plain vanilla.

To give credit to Tom, he is not telling anything that conflicts too
much with what I am saying. It is the details that are off and can
mislead a layman. The facts that he quotes from application notes are
obviously correct. The only thing that he doesn't get is that surge
protectors are classifed into grades, classes and work in different
modes, based on their design, scale, type of protection. What he is
talking about are service panel surge protectors for whole house or
even a metering-panel protector that is installed by utility companies
in areas of strong lightning activity. What you are asking about are
called plug-in surge protectors. They do work if they are properly
designed. Unfortunately with the information you have provided, there
is no way to tell if yours is properly designed. Should you leave it
out? Maybe not because even if it does half of what it's supposed to
do, it's still better than nothing. But is it guaranteed to work? Hard
to say. You have to be aware of the risks.

Also it is always dangerous to have independent earth grounds due to a
phenomenon called ground bounce. All grounds have to be tied to a
common point to earth ground using special very thick bonding
conductors that are low impedance which nullify all the effects he
keeps talking about. (Little knowledge is a dangerous thing). Do you
seriously imagine that Utilities, Telcos and Government agencies do
not give any though about these things? There is a regulation/standard
for everything.

Thirdly all lightning rods are not created equal. There are types
which are proven to be ineffective. As a layman you cannot rely on the
say so of a manufacturer. You need to look for unbiased information
from organizations such as the National Lightning Safety Institue
http://www.lightningsafety.com

We need to keep things in perspective. To protect multi-million
dollars of equipment, you need to spend hundreds of thousands of
dollars in surge protection. To protect a thousand dollar appliance
you need to spend a hundred or less.
Is the hundreds of thousand dollar protector better than the hundred
dollar one? You bet your life it is. So are you going to go buy the
former? A fine fool you will look if an indirect lightning stike
destroyed your thousand dollar protector in saving your 300 dollar TV.

Lastly, lightning as a phenomenon is still not understood fully. There
are several groups of researchers that are at loggerheads with each
other. So until there is agreement by the experts, there will always
be conflicting opinions.

Hope this helps. I will not post further to this list as I have a new
project. I have to design lightning protection for some mobile
wireless equipment that will keep me in the lab zapping equipment for
several weeks. Ta Ta Halfgaar all the best in your quest.
 
F

Fred Abse

Jan 1, 1970
0
"earth leakage breaker" (I don't know what it's called in English)

Depends where you live:

"Ground fault current interrupter" (GFCI) in North America.

"Earth leakage circuit breaker" (ELCB), now obsoleted by "Residual
current circuit breaker" (RCCB), or "Residual current device" (RCD), in
the UK.
 
H

Halfgaar

Jan 1, 1970
0
w_tom said:
I still don't know what your 750 volt 1250 amp device is.
But we know it is not an effective surge protector. Posted
previously on 26 Jul:

If it does not have the less than 10 foot earth ground
connection OR it does not even discuss earthing, then it
probably provides no such protection. Identifying ineffective
protectors is that simple. Furthermore implied, it is an
electromechanical device. Again, cannot protect from hardware
destruction. Too slow. Remember the microsecond destruction
followed eons later by the millisecond response of that
device?

It might be doing something else. But it is not protecting
electronics from potentially destructive transients.
Conditions repeated in that first paragraph make it obvious
what the device cannot do.

In the meantime, where are contradictory responses. Only
one provided blunt technical facts that say that device
provides no transient protection AND could not do so. Facts
with numbers such as microsecond destructive transients that
cannot be stopped by a millisecond responding device.

First provide some specific claims, with technical numbers,
that says what the device does. Currently, we don't even know
what it is suppose to do. Claims without numbers is more akin
to junk science. What technically does that parasitic device
even claim to do? We know what it cannot do. What does it
claim to do?

I don't really know what it's supposed to do. It was written on the box, at
least in some stupid metafor, but I don't have the box anymore.

And about the 10 ft, Tube2ic doesn't seem to think it's all that important.

I think I know all I can find out here. I'll do some more research and
hopefully find out some more.

Thanks to all for your time.

Halfgaar
 
Halfgaar said:
Is it also impossible to protect against indirect hits? I know that direct
hits are fatal, but a few days ago, I saw an add in the paper from a
company which sells protectors for indirect hits. You don't just buy the
device, but also an insurrance. If anything is damaged, they'll pay the
damages. Is this possible, or just a trick to get people to buy those
things? After all, not everyone who buys such a thing gets hit by lightning
(well, their equipment...), so maybe the devices are fake and they just
make money on the insurances.

I don't know about your particular case, but I tend to view these as
paying for the insurance not surge protection. Given that most power in
UK cities comes in underground I am extremely dubious about the value
of these devices in my enviroment. I would rather pay for better quality
plugs, sockets and cable.

I have seen one of these fail to protect its load, turned out the
"electrician" had wired up between the red & blue busbars (across
2 phases of a 3 phase line) and stuck 400V at practically unlimited
current up an alegedly 240V feed. The smoke was impressive.

Regards, Dan.
 
H

Halfgaar

Jan 1, 1970
0
w_tom said:
Halfgaar only said something about impedance after it is put before
him multiple times - with numbers. He did not even challenge those
numbers. Instead he responded without numbers because either 1) he
did not understand the circuit involved, or 2) did not even know basic
circuit theory.

Provided were numerous facts from other sources include an industry
benchmark - Polyphaser. If you dispute this, then go to the web sites
of people who come from where the work gets done and confront
lightning most - such as rec.radio.amateur.antenna. Or those two
threads in the discussion among engineers in the newsgroup misc.rural
cited previously. They also use numbers. They too don't have
problems with the need for short connection to earthing. But then
they too have training AND experience with circuit theory, MOV
datasheets, wire impedance, etc. Just more facts that those who
promote plug-in protectors cannot be bothered to read or learn.

Halfgaar even cites a NIST *.pdf document. But it is written for
layman - no numbers. It makes reference to good grounding, but does
not detail that good grounding - probably because they regard the
concept too complex for layman. If Halfgaar really understood the
science behind that web site, then he would have understood that what
was posted here and what was in that NIST pdf document are in
agreement. I provided the numbers and basic science. Most important,
Halfgaar cannot use the NIST site to claim anything I said was
incorrect. They simply cited trends without numbers - a general
direction. And they too keep refering to the most important function
is surge protection - earth ground. I refined the details AND put
numbers to it. Remember what they kept saying - importance of earth
ground. They just did not define good earth ground. I did. It
includes that less than 10 foot connection.

This is a common problem, which is why junk science is so easily
promoted. Numbers that say where and why wire impedance is so critical
is not challenged and probably not understood. So instead the comment
was "that's not correct" without any engineering facts. That
challenge to the bottom line has no technical facts in support -
therefore nothing more than rumor. Missing contradictory facts nor
any numbers and equations to challenge what was posted alone should
have been enough for any layman's ears to rise up and ask why those
numbers could not be challlenged.

Most distressing question from any American. That the government
should require such things. Evil thinking. Government regulation is
only required where industries have displayed a total disregard for
the purpose of their principles, purpose of their business, and
responsibility to customers and stockholders. It is why railroad and
auto industry regulations exist. It is why the American accounting
industry cannot be trusted and must be permenantly regulated like
those other industries.

But most standards - especially the good ones - are by private or
non-profit industry standards - ie UL, CBEA, IEEE, EIA, ISO, etc.
Even standared for ATX power supplies are superior and have no
government regulation (even though many layman are so naive as to buy
computer power supplies that violate standard of even 30 years ago).
The electrical engineering and computer industry have much less
regulation than most because it has been so responsible. However,
that does leave oppurtunity for plug-in manufacturers to 'lie by
telling half truths' which they do so freely. Halfgaar has simply
demonstrated why they can sell ineffective plug-in protectors.
Halfgaar has not even defined the hows and whys of common mode verse
differential mode transients - which is critical to understand
background in that NIST pdf document.

That 'less than 10 foot' is essential. And it is quite simple. If
the ten foot wire is too long, then a surge will go off finding other
destructive paths to earth ground inside the building. Nothing
complex here. Principles even demonstrated by Franklin in 1752.
Either the flood gets a short path downstream (single point earth
ground), or it backs up into all other creeks, storm sewers,
basements, and low lying streets (everything inside the house).

I'm Halfgaar, I believe you got me mixed up with Tube2c.

Granted, It's very hard to dismiss what you're saying, seeing as how you
explain everything in detail. But as I said, I think I've found out
everything I can here. I'll just keep in mind what you've said when for
example asking about it in specialist-electronicshops (not the household
electronics shops, they don't know anything).

Also what worries me, is that if you're right, then there is no
(inexpensive) way to protect against surges and that plugin protectors are
(almost) all just junk. There will be a lot of people who feel safe but
actually are not.

Halfgaar
 

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