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Sci.Electronics.Basics -> Re: Surge / Ground / Lightning
There are 12 messages in this thread.
You are currently looking at messages 1 to 12.
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On Mon, 5 May 2008 09:28:05 -0700 (PDT), trader4@optonline.net wrote:
>On May 5, 10:54 am, "Dave" <no...@nohow.not> wrote:
>> I wonder why, since electrical codes in North America
>> and Britain require a ground connection at each outlet;
>> computer power cords are 3 wire?
>>
>> (snip)
>>
>> hot neutral ground
>
>
>Meanwhile, I'm still waiting for an explanation from w_ about how
>surege protection inside that computer can work? Where is that
>direct connection to earth ground, without which w_ says surge
>protection is impossible? Does the computer have a mythical earth
>ground inside? The answer is it doesn't. It is acting under exactly
>the same limitations and uses the same components, typically MOVs to
>do what a plug-in surge supressor does. w-'s answer to this is to
>claim that electronics, appliances, etc do not use MOVs, a claim
>previously smashed, because of course they do. Plus it really has
>nothing much to do with the question anyway, because the computer,
>appliance, etc still HAS NO DIRECT EARTH GROUND, without which w- says
>protection is impossible.
I'm curous to know how surge suppression can work without a ground
(earth) of any sort. Does the "black box" detect overvoltage and
disconnect the power like an earth leakage safety switch?
This might be fine for a TV, but surely not for a computer.
I don't recall any computer I've owned that did not have a three wire
connection to the mains. That and a MOV is OK for smallish surges, but
I believe that for a large surge, the sort that will blow a telephone
off the wall, one needs a large, short-path earth for the surge
detector to dump the extra power down.
I've got a few plug in protectors here and there to sop up a small
spike, but when a storm is within a few km, I pull the phone wire out
of the ADSL router, and the plug out of the mains. If I'm working at
the time, I might just keep a watch on the weather radar and count
lightning fashes to thunder times. It's rare that I get interrupted. I
have underground power and phone lines so that gives a little extra
protection, I believe. I've been told that Australian phone lines are
the most vulnerable, and the most urgent to protect or disconnect.
I hope to be going wireless soon which obviates this problem.
jack
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Author: Mike TomlinsonDate: 14:19 05-05-08
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In article <2seu14tkjc068ph626ahu4akieb1pqa38f@4ax.com>,
spamfree@spam.heaven writes
>I'm curous to know how surge suppression can work without a ground
>(earth) of any sort.
Surge suppressors usually have three MOVs: one between phase and
neutral, and one each from phase and neutral to earth.
On properly grounded outlets, such a suppressor can deal with an
incoming surge on phase or neutral in an effective manner by conducting
and diverting current to the other leg AND to ground, but their
effectiveness when used on ungrounded outlets is reduced, since the path
to ground doesn't exist.
w_twat chooses to conveniently ignore this fact and continues to peddle
his unique brand of lies, misrepresentation and FUD in his own
inimitable style, which another poster has described as "hostile".
It's telling that w_ was unable to understand that people perceive his
posting style as hectoring or hostile, which should give you some idea
of his mental state :)
Best place for w_'s posts is in the killfile.
--
(\__/) Bunny says NO to Windows Vista!
(='.'=) http://www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.html
(")_(") http://www.cypherpunks.to/~peter/vista.pdf
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Author: Phil HowardDate: 15:25 05-05-08
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In alt.tv.tech.hdtv spamfree@spam.heaven wrote:
| I'm curous to know how surge suppression can work without a ground
| (earth) of any sort. Does the "black box" detect overvoltage and
| disconnect the power like an earth leakage safety switch?
Without a ground of any sort, not all types of surges can be protected against.
But some can.
If the surge is a differential one (some use the term transverse), then what
the surge suppressor can do is cancel it out by effectively short circuiting
it to itself. A differential surge involves two wires with the voltage on
each being of opposite polarity and equal level. The MOV component inside
the suppressor will normally not be conductive. But when the voltage is high
enough, it becomes a conductor. The arrival of a high voltage differential
surge will result in the MOV between those 2 wires to become conductive.
If the surge is a common mode one, AND if the surge has a slow rise time,
then a device that is interconnected to other wires or other devices can
be protected by allowing the surge to pass to all devices at the same level.
As long as the rise is not too fast, keeping all the incoming wires, and all
the interconnected devices, at the same level results in insignificant current
flows. That surge will either reflect back from the protected equipment to
the suppressor, and from there go back through all the connected wires (which
could be more than where the surge arrived from).
Most strikes have lower energy levels at high frequencies than what would
cause damage. The exact frequency level that needs to be considered depends
on the internals of the equipment. For example, where it has inductance to
one end of a sensitive component like a CMOS chip, and no inductance to some
other end, this could result in a very brief fast rise of voltage high enough
to damage the CMOS chip. In some cases an LC circuit can actually increase
the voltage level of high frequency components (at the resonant frequency).
For example if you have energy at some voltage at 200 MHz, an LC series
circuit resonant at 200 MHz will result in a higher voltage being present
at the connection between the L and the C. So even in cases where there is
not enough energy at high frequency in a surge to cause direct damage, it
can still happen on some devices (think of them as having a lower threshold
of damage to simplify this).
| This might be fine for a TV, but surely not for a computer.
If everything the computer is connected to is protected at a common point
in the same surge suppressor, you can have this kind of protection, even
on a computer. That does mean if you have a phone line connected to a
modem, you need to protect both the phone line itself and the power to the
modem, in common with the computer.
| I don't recall any computer I've owned that did not have a three wire
| connection to the mains. That and a MOV is OK for smallish surges, but
| I believe that for a large surge, the sort that will blow a telephone
| off the wall, one needs a large, short-path earth for the surge
| detector to dump the extra power down.
Such a surge is likely to have high levels of high frequency energy. The
effective protection against these rare events is a combination of somewhere
to divert the energy (like a ground path), and something (like an inductor)
to ensure the energy does get diverted.
One problem is that at the point of use, an alternate ground path is not
practical. The grounding wire of the power circuit coule be as much a source
of the surge as the neutral wire would be. The place to put the diversion
system is at the entrance to the building. Most surges that come in by other
paths besides the entrance to the building are induced surges that will not
have so much energy and even less at high frequencies.
Still, I have seen three incidents in which an induced surge damaged a device
that was not connected to anything at all (in two cases they were battery
powered devices, and in the third, it was disconnected before the storm but
suffered damage anyway).
| I've got a few plug in protectors here and there to sop up a small
| spike, but when a storm is within a few km, I pull the phone wire out
| of the ADSL router, and the plug out of the mains. If I'm working at
| the time, I might just keep a watch on the weather radar and count
| lightning fashes to thunder times. It's rare that I get interrupted. I
| have underground power and phone lines so that gives a little extra
| protection, I believe. I've been told that Australian phone lines are
| the most vulnerable, and the most urgent to protect or disconnect.
| I hope to be going wireless soon which obviates this problem.
Disconnecting provides even better (but still not 100%) protection. Yes, the
underground wiring helps. I don't know the issues with Australian phone lines.
I do the wireless thing myself and feel much more comfortable with it. Most
of the past damaging surges I've seen come in do that on phone and cable wires,
and much less often on power wires. That may be due to the more sensitive
aspect of equipment where it connects to these wires.
--
|WARNING: Due to extreme spam, I no longer see any articles originating from |
| Google Groups. If you want your postings to be seen by more readers |
| you will need to find a different place to post on Usenet. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |
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Author: w_tomDate: 02:42 06-05-08
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On May 5, 1:05 pm, spamf...@spam.heaven wrote:
> I'm curous to know how surge suppression can work without a ground
> (earth) of any sort. Does the "black box" detect overvoltage and
> disconnect the power like an earth leakage safety switch?
>
> This might be fine for a TV, but surely not for a computer.
>
> I don't recall any computer I've owned that did not have a three wire
> connection to the mains. That and a MOV is OK for smallish surges, but
> I believe that for a large surge, the sort that will blow a telephone
> off the wall, one needs a large, short-path earth for the surge
> detector to dump the extra power down.
>
> I've got a few plug in protectors here and there to sop up a small
> spike, but when a storm is within a few km, I pull the phone wire out
> of the ADSL router, and the plug out of the mains. If I'm working at
> the time, I might just keep a watch on the weather radar and count
> lightning fashes to thunder times. It's rare that I get interrupted. I
> have underground power and phone lines so that gives a little extra
> protection, I believe.
This will address some of your questions only in summary. Details
are provided in other posts.
First, much of this stuff was learned by earliest 20th century
hams. They would disconnect their antenna, put the lead inside a
mason jar, and still suffer radio damage. Even mason jars could not
stop or block lightning. But then the antenna was earthed, then damage
stopped. It's just like Franklin's lightning rod (air terminal).
Protection has always been about diverting "it to ground, where it can
do no harm". Disconnecting did not provide sufficient protection.
That wire had to be earthed.
Protection for the TV, computer, and all other appliances is same.
Computers contain some of the most robust protection. Computer grade
UPSes can output electricity so dirty (when in battery backup mode) as
to even harm some small electric motors. But computers are so robust
as to make even that 'dirty' electricity irrelevant. Do not assume
computers have less internal protection. Intel ATX standards require
computers to be more robust than what is standard for other
appliances.
No protection exists by disconnecting - the black box. Air is a
best insulator. Lightning travels through 3 miles of air to contact
earth. What magic black box do you own that can stop what three miles
of sky could not? Protectors do not stop, block, or disconnect from
lightning. Furthermore, a lightning surge does damage too fast. A
fastest disconnect relay takes milliseconds. Lightning surges do
damage in microseconds. Two of so many reasons why protection is not
achieved by disconnecting.
Try damming a river to stop a flood. Dam gets swept away. Move
that dam off to the side; call it a dike. Open a large channel
downriver. Protecting by disconnecting, blocking, or absorbing surges
is akin to that dam - useless. Instead, install (and earth) a 'whole
house' protector - akin to a large channel downriver. And then
install dikes - internal protection inside appliances or other
supplementary protection.
Even dikes (supplementary protectors) are useless without that large
channel downriver - the properly earthed 'whole house' protector.
MOVs are routinely installed where direct lightning strikes are
earthed - without damage to MOVs. MOVs used in properly sized 'whole
house' protectors. But when a plug-in protector is sold to maximize
profits (not for protection), then grossly undersized protectors also
create another problem - scary pictures:
http://www.hanford.gov/rl/?page=556&parent=554
http://www.westwhitelandfire.com/Articles/Surge%20Protectors.pdf
http://www.ddxg.net/old/surge_protectors.htm
http://www.zerosurge.com/HTML/movs.html
http://tinyurl.com/3x73ol or
http://www3.cw56.com/news/articles/local/BO63312/
Routine is for direct lightning strikes to be earthed by a 'whole
house' protector. Routine is for a properly sized protector to earth
surges AND remain functional. A protector damaged by a direct
lightning strike - grossly undersized - is designed in direct
violation of MOV manufacturer's specs. MOV manufacturers are quite
clear about this. MOVs must only fail by degrading; not fail by
vaporizing. MOVs also do not work by sopping up surge energy. But
grossly undersizing a plug-in protector and a resulting explosive
damage gets the naive to recommend an obscenely overpriced protector.
Yes, grossly undersizing a protector can get the naive to recommend
more ineffective protectors.
An effective protector earths direct lightning strikes AND remains
functional. An effective protector means nobody knew the surge even
existed. But no explosive failure means some here would not recommend
that protector.
Above described secondary protection. Homeowners should also
inspect their primary inspection system:
http://www.tvtower.com/fpl.html
Buried wires do not provide effective protection. An industry
professional provides this application note. Notice even underground
wires must be earthed before entering the building. Even underground
wires can carry surges, destructively into the building. Any wire
that enters the building - overhead or underground - must connect to a
single point earth ground either directly (ie cable TV, satellite
dish) or via a protector (ie telephone, AC electric). The app note
shows two structures. Any wire into either structure first connects
to that structure's single point earth ground:
http://www.erico.com/public/library/fep/technotes/tncr002.pdf
And finally, it is posted multiple times including a reference to an
article for EE entitled "Protecting Electrical Devices from Lightning
Transients". That safety ground and neutral wire cannot provide
earthing for a long list of reasons.
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Author: w_tomDate: 03:02 06-05-08
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On May 5, 2:19 pm, Mike Tomlinson <m...@jasper.org.uk> wrote:
> On properly grounded outlets, such a suppressor can deal with an
> incoming surge on phase or neutral in an effective manner by conducting
> and diverting current to the other leg AND to ground, but their
> effectiveness when used on ungrounded outlets is reduced, since the path
> to ground doesn't exist.
Include facts taught in first year electrical engineering OR
described in both 'top of the front page' articled in Electrical
Engineering Times on 1 Oct and 8 Oct 2007 entitled "Protecting
Electrical Devices from Lightning Transients" at:
http://www.planetanalog.com/showArticle.jhtml?articleID=201807127
http://www.planetanalog.com/showArticle.jhtml?articleID=201807830
That wire from wall receptacle is too long, has too many sharp
bends, has spliced, is bundled with other wires, etc. More reasons
why that safety ground wire is not earth ground wire. Protectors
without earth ground is not effective as Mike says. And AC wall
receptacle does not provide an earthing connection - wire too long -
too much impedance. Page 42 Figure 8 also demonstrates that problem
resulting in 8000 volts being earthing, instead, through the adjacent
TV.
Breaker box earthing wire goes over top of the foundation and drops
down to an earthing electrode. Compromised protection. Wire is too
long and has sharp bends. Better protection means wire goes through
foundation and down to that earthing electrode. Few meters less wire
and without those sharp bends means improved protection. Why? See
"Protecting Electrical Devices from Lightning Transients".
If earthng wire must be every meter shorter, then how does a
receptacle safety ground wire do earthing? Safety wire has maybe 30
or 50 sharp bends, numerous splices, and maybe 15 meters too long?
Low impedance connection to earth typically means 'less than 10
feet', or then even shorter for even better protection.
Obviously wall receptacle safety grounds do not provide earth
ground. But then Mike Tomlinson also did not understand the
engineering numbers in that EE Times article entitled "Protecting
Electrical Devices from Lightning Transients". Note the numbers.
Wall receptacle safety grounds cannot provide a low impedance
connection to earth ground. Engineers would know this. Mike
Tomlinson obviously does not.
Literally every incoming wire must make that short (low impedance)
connection to earth ground. If that earthing wire is not separated
from other wires (if that earthing wire is inside a bundle of romex
cables), then that earthing wire induces surges on those other wires.
Just another reason why safety ground is not earth ground. Just
another engineering fact that Mike Tomlinson read and did not
understand.
AC wall receptable is not an effective earth ground. Protectors
best make a less than 3 meter (low impedance) connection to earth
which wall receptacles just cannot provide.
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Author: bud--Date: 13:00 06-05-08
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w_tom wrote:
>
> But when a plug-in protector is sold to maximize
> profits (not for protection), then grossly undersized protectors also
> create another problem - scary pictures:
> http://www.hanford.gov/rl/?page=556&parent=554
w_ can't understand his own hanford link. It is about "some older
model" power strips and says overheating was fixed with a revision to
UL1449 that required thermal disconnects. That was 1998. There is no
reason to believe, from any of these links, that there is a problem with
suppressors produced under the UL standard that has been in effect since
1998.
But with no valid technical arguments all w_ has is pathetic scare tactics.
For reliable information on surges and protection read the IEEE and NIST
guides. (Both say plug-in suppressors are effective.)
--
bud--
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Author: w_tomDate: 21:23 06-05-08
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On May 6, 1:00 pm, bud-- <remove.budn...@isp.com> wrote:
> w_ can't understand his own hanford link. It is about "some older
> model" power strips and says overheating was fixed with a revision to
> UL1449 that required thermal disconnects. That was 1998.
Bud will only challenge the hanford link because he cannot challenge
those 'scary pictures'. One is a Boston building fire last year
created by a plug-in protector. Another is a fire marshal describing
why plug-in protectors can create house fires. And pictures from fire
departments showing a problem seen too often.
And then Bud posts a half fact. UL1449 was created on 28 Aug 1985 -
not in 1998 as Bud claims. Why would Bud do this? Profits are at
risk - another fact that Bud must avoid admitting.
So where is this plug-in protector spec that claims to provide
protection? Oh. It does not exist because plug-in protectors do not
even claim to provide this protection. Bud refuses to post a
specification for one simple reason. There is no plug-in spec that
claims what Bud is posting. So Bud posts insults. In reply, this is
what Bud is really promoting - these 'scary pictures':
http://www.hanford.gov/rl/?page=556&parent=554
http://www.westwhitelandfire.com/Articles/Surge%20Protectors.pdf
http://www.ddxg.net/old/surge_protectors.htm
http://www.zerosurge.com/HTML/movs.html
http://tinyurl.com/3x73ol or
http://www3.cw56.com/news/articles/local/BO63312/
Pictures of protectors typically located on a pile of desktop papers
or buried in dust balls on a rug.
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On May 6, 2:42=A0am, w_tom <w_t...@usa.net> wrote:
> =A0 =A0This will address some of your questions only in summary. =A0Detail=
s
> are provided in other posts.
>
> =A0 First, much of this stuff was learned by earliest 20th century
> hams. =A0They would disconnect their antenna, put the lead inside a
> mason jar, and still suffer radio damage. Even mason jars could not
> stop or block lightning.
I'd love to see a reference for this. In that time frame, lightning
was already fairly well understood. I find it hard to believe any ham
would try to use a mason jar in this way. Sounds more like some urban
legend to me.
But then the antenna was earthed, then damage
> stopped. =A0It's just like Franklin's lightning rod (air terminal).
> Protection has always been about diverting "it to ground, where it can
> do no harm". =A0Disconnecting did not provide sufficient protection.
> That wire had to be earthed.
>
> =A0 Protection for the TV, computer, and all other appliances is same.
> Computers contain some of the most robust protection. =A0Computer grade
> UPSes can output electricity so dirty (when in battery backup mode) as
> to even harm some small electric motors. =A0But computers are so robust
> as to make even that 'dirty' electricity irrelevant. =A0Do not assume
> computers have less internal protection. =A0Intel ATX standards require
> computers to be more robust than what is standard for other
> appliances.
>
And guess what component is used as part of that robust protection?
MOVs, which W_ denies are used in electronics/appliances. Once again,
I'll ask the same question W_ refuses to answer. How is it that MOVs
or any other component can offer protection when used in a PC power
supply, but are useless in a plug-in surge protector? According to
W_, surge protection is impossible unless there is a direct and short
connection to earth ground. Does the PC power supply come with a
built-in earth ground?
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Author: bud--Date: 11:40 07-05-08
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w_tom wrote:
> On May 6, 1:00 pm, bud-- <remove.budn...@isp.com> wrote:
>> w_ can't understand his own hanford link. It is about "some older
>> model" power strips and says overheating was fixed with a revision to
>> UL1449 that required thermal disconnects. That was 1998.
>
> Bud will only challenge the hanford link because he cannot challenge
> those 'scary pictures'.
w_ only provides those ‘scary pictures’ because he has no valid
technical arguments.
Still missing - a link to any source that says UL listed plug-in
suppressors made after 1998 are a problem.
> Another is a fire marshal describing
> why plug-in protectors can create house fires.
The fire marshal said: "More modern surge suppressors are manufactured
with a Thermal Cut Out mounted near, or in contact with, the MOV that is
intended shut the unit down overheating occurs.[sic]"
>
> And then Bud posts a half fact. UL1449 was created on 28 Aug 1985 -
> not in 1998 as Bud claims.
It is really hard to understand how someone could be stupid enough to
not know the difference between a creation date and a revision date.
From w_'s hanford link:
"Underwriters Laboratories Standard UL 1449, 2nd Edition, Standard For
Safety For Transient Voltage Surge Suppressors, now requires thermal
protection in power strips. This protection is provided by a thermal
fuse located next to the MOV."
The fire marshal says the same thing (above)
If w_ had any knowledge of the field he would know UL 1449, 2nd Ed was
effective in 1998.
> Bud refuses to post a
> specification for one simple reason.
Posted often and ignored. Another of w_'s favorite lies.
> In reply, this is
> what Bud is really promoting - these 'scary pictures':
> http://www.hanford.gov/rl/?page=556&parent=554
The lie repeated. But w_ is a fan of Josef Goebbels and thinks if you
repeat a lie often enough, people will believe it.
Still missing - a link to another lunatic that says plug-in suppressors
are NOT effective.
Still missing – answers to embarrassing questions:
- Why do the only 2 examples of surge suppression in the IEEE guide use
plug-in suppressors?
- Why does the NIST guide says plug-in suppressors are "the easiest
solution"?
- Why do all but one of w's "responsible manufacturers" make plug-in
suppressors?
- Why does SquareD say in addition to their "whole house" suppressors
"electronic equipment may need additional protection" from plug-in
suppressors.
- Why aren't airplanes crashing daily when they get hit by lightning (or
do they drag an earthing chain)?
–-
bud--
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Author: w_tomDate: 20:14 07-05-08
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On May 7, 8:07 am, trad...@optonline.net wrote:
> According to W_, surge protection is impossible unless there is
> a direct and short connection to earth ground. Does the PC
> power supply come with a built-in earth ground?
Again trader reads only what he wants to see. Surge protection
without that short connection to earth ground is *ineffective*.
trader, who understands propaganda in the Rush Limbaugh tradition,
changes the message - uses the word 'impossible'. Misrepresenting
reality is trader.
PC power supply has no built-in earth ground. How do others know?
They learned before knowing. For example, they read both front page
EE Times articles entitled =93Protecting Electrical Devices from
Lightning Transients". trader did not. Those electrical concepts
were too complex. trader knows rather than first learn technology.
Had trader learned facts before posting, he would have read what
IEEE Standards also said (and is posted elsewhere). Defined by the
IEEE is effective protection - with numbers:
> Still, a 99.5% protection level will reduce the incidence of direct
> strokes from one stroke per 30 years ... to one stroke per
> 6000 years ...
What do 'whole house' protectors use? Enough MOVs so that protector
is sufficiently sized. So that direct lightning strikes does not
destroy the protector.
What do MOVs need to provide effective connection? That short (ie '
less than 10 foot') connection to earth.
What provides surge protection? Earth ground - where surge energy
is harmlessly dissipated.
What does the effective MOV do? Connects to earth so that surge
energy gets dissipated harmlessly rather than destructively inside the
building.
What must those MOVs inside appliances do (and why did Apple stop
using them after Apple II)? Those MOVs must somehow stop or absorb a
surge that even three miles of sky could not stop. So few joules will
somehow absorb all that energy. Such little devices will block what a
sky could not?
What happens when MOVs are too close to appliances and too far from
earth ground? Page 42 Figure 8 from another IEEE citation - surge
earthed 8000 volts destructively through the adjacent TV.
Provides were numerous professional citations that say this. Where
does trader even post technical numbers? He does not. trader is like
most who recommend plug-in protectors. They need not first learn
facts. They know. Their proof is by using insults =96 just like Rush
Limbaugh.
A protector is only as effective as its earth ground.
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Author: Michael A. TerrellDate: 20:27 07-05-08
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w_tom wrote:
>
> A protector is only as effective as its earth ground.
And you are only as lucid as your drugs allow.
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
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w_tom <w_tom1@usa.net> wrote:
>... Surge protection without that short connection to earth ground
>is *ineffective*.
Wrong, wrong, wrong (say it 3 times and it's true :-)
Nick, ex-K3VZW, BSEE, MSEE, Senior Member, IEEE
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