Many surge suppressors on the market (I'm only talking about the MOV
type here, not the fancy induction style) have little indicator lights
to tell you if the thing is still providing protection. How do they
do this? I thought the only way to test a MOV was to send a surge
through it, and then you will only know what condition it was in
before you sent in the surge. What is the circuit diagram for one of
these indicator LEDs, and is this a way to test any MOV or MOV device?

Thanks.

<grizdog@gmail.com>
>
> Many surge suppressors on the market (I'm only talking about the MOV
> type here, not the fancy induction style) have little indicator lights
> to tell you if the thing is still providing protection. How do they
> do this?


** There is a fuse wire link in series with the MOV.

If the MOV blows all to hell, then so does the fuse.

The light ( usually neon ) indicates that the fuse is blown.



........... Phil

On Wed, 22 Aug 2007 14:38:42 +0000, grizdog@gmail.com wrote:

> Many surge suppressors on the market (I'm only talking about the MOV
> type here, not the fancy induction style) have little indicator lights
> to tell you if the thing is still providing protection. How do they
> do this? I thought the only way to test a MOV was to send a surge
> through it, and then you will only know what condition it was in
> before you sent in the surge. What is the circuit diagram for one of
> these indicator LEDs, and is this a way to test any MOV or MOV device?
>

You're right, there's no way to test an MOV, and any indicator that
claims to indicate the status of the MOV is nothing but marketing hype.

Cheers!
Rich

"Rich Grise" <rich@example.net> wrote in message
news:pan.2007.08.22.19.10.56.883211@example.net...
> On Wed, 22 Aug 2007 14:38:42 +0000, grizdog@gmail.com wrote:
>
>> Many surge suppressors on the market (I'm only talking about the MOV
>> type here, not the fancy induction style) have little indicator lights
>> to tell you if the thing is still providing protection. How do they
>> do this? I thought the only way to test a MOV was to send a surge
>> through it, and then you will only know what condition it was in
>> before you sent in the surge. What is the circuit diagram for one of
>> these indicator LEDs, and is this a way to test any MOV or MOV device?
>>
>
> You're right, there's no way to test an MOV, and any indicator that
> claims to indicate the status of the MOV is nothing but marketing hype.
>
> Cheers!
> Rich
>
>
A typical MOV has a capacitance of 100-2000 pF, which is an impedance of
about 1.3 - 26 Megohms at 60 Hz. This is barely enough to light a neon lamp
at 120 VAC. But it could provide enough current to drive a transistor and
indicator lamp. However, a failing MOV gradually increases its leakage, and
it would take a sophisticated circuit to analyze that.

I think Phil is right, except that the indicator is probably across the
MOV, so it lights if the fuse is OK. I know *my* surge suppressor has a
green light that indicates "protection", so I think that's how it must
work. I don't really want to take it apart (unless it goes bad).

Paul

grizdog@gmail.com wrote:
> Many surge suppressors on the market (I'm only talking about the MOV
> type here, not the fancy induction style) have little indicator lights
> to tell you if the thing is still providing protection. How do they
> do this? I thought the only way to test a MOV was to send a surge
> through it, and then you will only know what condition it was in
> before you sent in the surge. What is the circuit diagram for one of
> these indicator LEDs, and is this a way to test any MOV or MOV device?
>
> Thanks.
>

In some failures, the indicator light can indicate that the
MOV is bad, but it can never indicate that the MOV is good.
So if the light tells you it is bad, believe it. If the light
tells you the MOV is good, it could be lying to you.

Ed

"Paul E. Schoen"
> I think Phil is right, except that the indicator is probably across the
> MOV, so it lights if the fuse is OK. I know *my* surge suppressor has a
> green light that indicates "protection", so I think that's how it must
> work. I don't really want to take it apart (unless it goes bad).


** The light can be made to work in the opposite sense - ie as a warning
the MOV has been damaged - by having a resistor ( say 50 kohms) across the
MOV and the neon plus 100 kohms wired across the fuse link.

This will operate the neon in both open and shorted MOV conditions, if the
link goes open.



........ Phil

On Aug 22, 10:38 am, "griz...@gmail.com" <griz...@gmail.com> wrote:
> ...
> I thought the only way to test a MOV was to send a surge
> through it, and then you will only know what condition it was in
> before you sent in the surge. What is the circuit diagram for one of
> these indicator LEDs, and is this a way to test any MOV or MOV device?

As others have noted, an MOV is 'protected' by a thermal fuse. If a
surge is so large as to cause MOV to vaporize, then a major human
safety threat exist (see scary pictures). A thermal fuse is placed in
series with MOVs in a desperate hope to disconnect an MOV before it
vaporizes Vaporizing MOV is a complete violation of MOV manufacturer
specs AND a human safety threat.

Think about it a minute. MOV is so grossly undersized as to
vaporize or be disconnected. It leaves the appliance to fend for
itself from surges? Yes, the fuse does not disconnect appliances.
Fuse leaves the appliance to protect itself from a surge.

So why is that appliance working while the protector failed? Surge
was too small to overwhelm protection inside the appliance. But MOV
protector was so grossly undersized as to be permanently destroyed.

By undersizing it, a plug-in protector manufacturer gets the naive
to recommend a grossly undersized protector. Effective protectors
earth surges AND remain functional - do not blow the fuse. Any
properly sized protector remains functional after a surge. So that
'failed' protector light says what about the protector? Grossly
undersized?

Another problem when that fuse does not disconnect fast enough:
http://www.hanford.gov/rl/?page=556&parent=554
http://www.westwhitelandfire.com/Articl ... ectors.pdf
http://www.ddxg.net/old/surge_protectors.htm
http://www.zerosurge.com/HTML/movs.html
http://tinyurl.com/3x73ol or
http://www.esdjournal.com/techpapr/Phar ... 0FIRES.doc

IOW many plug-in protectors will fail even on smaller surges to
avoid those scary pictures. Failure also promotes sales among the
naive.

How to test an MOV? Apply a 1 ma current source to it and measure
its voltage. Remember, a vaporized MOV is a complete violation of
manufacturer specifications. MOVs must degrade; never vaporize. When
has an MOV degraded excessively? When that voltage during a 1 ma
current is more than 10% of its rated voltage. See the datasheet. A
fully degraded MOV remains functional - does not vaporize.

So again, if a surge was so large as to trip that indicator lamp,
then the protector was grossly undersized - completely ineffective.
If a power strip protector is reported defective by its indicator
light, then you have no business buying more of those grossly
undersized devices. Otherwise even the house is a risk per those
scary pictures. See the Gaston County Fire Marshall report to
appreciate the threat - the fifth citation.

On Aug 22, 10:38 am, "griz...@gmail.com" <griz...@gmail.com> wrote:
> ...
> What is the circuit diagram for one of
> these indicator LEDs, and ...

http://www.zerosurge.com/HTML/movs.html
Notice that all MOVs are remove and indicator light says protector is
good. Its not good. All MOVs are removed. Lights can only report a
catastrophic failure; not report the protector as good.

Thanks, everyone.

w_tom wrote:
> On Aug 22, 10:38 am, "griz...@gmail.com" <griz...@gmail.com> wrote:
>> ...
>> I thought the only way to test a MOV was to send a surge
>> through it, and then you will only know what condition it was in
>> before you sent in the surge. What is the circuit diagram for one of
>> these indicator LEDs, and is this a way to test any MOV or MOV device?
>
> As others have noted, an MOV is 'protected' by a thermal fuse. If a
> surge is so large as to cause MOV to vaporize, then a major human
> safety threat exist (see scary pictures). A thermal fuse is placed in
> series with MOVs in a desperate hope to disconnect an MOV before it
> vaporizes Vaporizing MOV is a complete violation of MOV manufacturer
> specs AND a human safety threat.

Vaporizing is a scare tactic.

MOVs have an energy (Joule) rating. They do not protect by absorbing
surge energy, but in the process of protecting they absorb enengy. When
they have absorbed an energy equal to their rating, they will conduct at
successively lower voltages, eventually conducting at 'normal' voltages
and overheating. UL has, since 1998, required disconnects for
overheating MOVs. Plug-in suppressors have their current limited by the
significant impedance of the branch circuit.

>
> So why is that appliance working while the protector failed? Surge
> was too small to overwhelm protection inside the appliance. But MOV
> protector was so grossly undersized as to be permanently destroyed.

For w_, all plug-in surge suppressors are "grossly undersized". In fact
suppressors with very high ratings are readily available at rather low
cost. And apparently a surge that can destroy a MOV won't damage
protection inside an appliance? Hallucination.


>
> By undersizing it, a plug-in protector manufacturer gets the naive
> to recommend a grossly undersized protector. Effective protectors
> earth surges AND remain functional - do not blow the fuse. Any
> properly sized protector remains functional after a surge. So that
> 'failed' protector light says what about the protector? Grossly
> undersized?

"Grossly undersized" red herring again.

>
> Another problem when that fuse does not disconnect fast enough:
> http://www.hanford.gov/rl/?page=556&parent=554

The hanford link describes overheating as being a problem with "some
older model" power strips and says overheating was fixed with a revision
to UL1449 that requires thermal disconnects. Overheating was fixed, for
UL listed suppressors, in 1998.

>
> IOW many plug-in protectors will fail even on smaller surges to
> avoid those scary pictures. Failure also promotes sales among the
> naive.

Competently manufactured suppressors engineer the fuses/thermal
disconnects to open only when the MOVs fail. (They fail by conducting at
too low a voltage and overheating.) w_, apparently, buys only cheap
no-brand Chinese suppressors.

>
> How to test an MOV? Apply a 1 ma current source to it and measure
> its voltage.

I agree this is the way to test a MOV.

> So again, if a surge was so large as to trip that indicator lamp,
> then the protector was grossly undersized - completely ineffective.

The "grossly undersized" red herring again. Grossly undersized applies
equally to service panel suppressors, which will also be disconnected if
their ratings are exceeded.



w_ believes that plug-in suppressors to not work. Instead of using
technical arguments, he doesn't have any, he is using scare tactics.

For accurate information on surges and surge protection read:
http://omegaps.com/Lightning%20Guide_FI ... May051.pdf
- "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/prac ... gesfnl.pdf
- "NIST recommended practice guide: Surges Happen!: how to protect the
appliances in your home" published by the US National Institute of
Standards and Technology in 2001

The IEEE guide is aimed at those with some technical background. The
NIST guide is aimed at the unwashed masses.


The author of the NIST guide, who was the surge guru at the NIST, has
said "in fact, the major cause of TVSS [surge suppressor] failures is a
temporary overvoltage, rather than an unusually large surge."

--
bud--

w_tom wrote:
> On Aug 22, 10:38 am, "griz...@gmail.com" <griz...@gmail.com> wrote:
>> ...
>> What is the circuit diagram for one of
>> these indicator LEDs, and ...
>
> http://www.zerosurge.com/HTML/movs.html
> Notice that all MOVs are remove and indicator light says protector is
> good. Its not good. All MOVs are removed. Lights can only report a
> catastrophic failure; not report the protector as good.

This link is an anti-MOV propaganda piece by a manufacturer whose
suppressors do not use MOVs.

But removed MOVs are indeed a problem in areas where MOV theft rings are
active. Check with your local police to see if there is a ring active in
your area.

Lights indicate MOVs have been disconnected. Because MOVs have been
disconnected there is no "catastrophic failure".

It is very unlikely the light would be on and the suppressor would not
be functioning. (Provide an example of how.)

--
bud--

On Aug 26, 7:04 pm, bud-- <remove.BudN...@isp.com> wrote:
> This link is an anti-MOV propaganda piece by a manufacturer whose
> suppressors do not use MOVs.

Bud will not admit the only reason he is here. He promotes for plug-
in protectors manufacturers, follows me everywhere posting replies,
and now makes a comment that is completely irrelevant to the
discussion.

Demonstrated was that lights did not even report missing
protection. MOV protectors are removed and light still says protector
is OK. The picture demonstrates exactly what we are discussing here.
Lights report a failure so catastrophic due to protector being
undersized.

The picture demonstrates that the lights will not report all failure
conditions. They created a failure and lights said protector was OK.
Demonstrated is that lights report only one type of failure - that
should not happen and that is too common when plug-in protectors are
grossly undersized.

Bud fears you might learn this major problem with plug-in protectors
- undersizing. He will post replies incessantly to confuse you - so
that you will also ignore these scary pictures.

These pictures come from sources who are not selling anything - a
contradiction to what Bud is doing. Indicator lamps also will not
warn of this failure. These scary pictures of current technology plug-
in protectors are too common. Threat is not because MOVs are bad.
Effective protectors are designed to provide protection; not located
in fire risky locations and not to maximize profits:
http://www.hanford.gov/rl/?page=556&parent=554
http://www.westwhitelandfire.com/Articl ... ectors.pdf
http://www.ddxg.net/old/surge_protectors.htm
http://www.zerosurge.com/HTML/movs.html
http://tinyurl.com/3x73ol
Notice the last 'scary picture' - a recent report from the Gaston
County Fire Marshall. Why would anyone place these things on a rug
or adjacent to desktop papers?

Of course Bud will reply incessantly to get the last word. He must
say anything so that your eyes will glaze over; so that you will not
remember which MOVs protectors are so ineffective. The indicator
light only reports failure when the protector was so grossly
undersized that those "scary pictures" were more probable.

bud-- wrote:
> w_tom wrote:
>
>> On Aug 22, 10:38 am, "griz...@gmail.com" <griz...@gmail.com> wrote:
>>
>>> ...
>>> I thought the only way to test a MOV was to send a surge
>>> through it, and then you will only know what condition it was in
>>> before you sent in the surge. What is the circuit diagram for one of
>>> these indicator LEDs, and is this a way to test any MOV or MOV device?
>>
>>
>> As others have noted, an MOV is 'protected' by a thermal fuse. If a
>> surge is so large as to cause MOV to vaporize, then a major human
>> safety threat exist (see scary pictures). A thermal fuse is placed in
>> series with MOVs in a desperate hope to disconnect an MOV before it
>> vaporizes Vaporizing MOV is a complete violation of MOV manufacturer
>> specs AND a human safety threat.
>
>
> Vaporizing is a scare tactic.
>
> MOVs have an energy (Joule) rating. They do not protect by absorbing
> surge energy, but in the process of protecting they absorb enengy.

Yes.
1) The mechanism by which they change from high resistance to
low resistance requires absorbing energy. 2) Staying in the low
resistance mode requires energy absorbtion. 3) Any energy they
absorb cannot reach the device(s) they are protecting.

Absorbing surge energy is the only way an MOV can work.
It cannot provide protection without absorbing surge energy.
That does not mean it absorbs the entire surge energy.
Where does the surge energy go? Some is absorbed and
dissipated in the source path, some in the MOV and some
in the return path.

This is a point w_tom has missed in the past when he insists
that point of use MOV's don't absorb surge energy. They most
assuredly do. If they did not absorb, they would not switch to
low resistance. When they do switch, they absorb I^2R, per ohms
law. They clamp the voltage that the device "sees" to some level
by absorbing energy. They do not absorb the entire energy that
the surge contains - just the amount of energy they "see"
that falls into their operating specs.

> When
> they have absorbed an energy equal to their rating, they will conduct at
> successively lower voltages, eventually conducting at 'normal' voltages
> and overheating. UL has, since 1998, required disconnects for
> overheating MOVs. Plug-in suppressors have their current limited by the
> significant impedance of the branch circuit.
>
>>
>> So why is that appliance working while the protector failed? Surge
>> was too small to overwhelm protection inside the appliance. But MOV
>> protector was so grossly undersized as to be permanently destroyed.
>
>
> For w_, all plug-in surge suppressors are "grossly undersized". In fact
> suppressors with very high ratings are readily available at rather low
> cost. And apparently a surge that can destroy a MOV won't damage
> protection inside an appliance? Hallucination.
>
>
>>
>> By undersizing it, a plug-in protector manufacturer gets the naive
>> to recommend a grossly undersized protector. Effective protectors
>> earth surges AND remain functional - do not blow the fuse. Any
>> properly sized protector remains functional after a surge. So that
>> 'failed' protector light says what about the protector? Grossly
>> undersized?
>
>
> "Grossly undersized" red herring again.
>
>>
>> Another problem when that fuse does not disconnect fast enough:
>> http://www.hanford.gov/rl/?page=556&parent=554
>
>
> The hanford link describes overheating as being a problem with "some
> older model" power strips and says overheating was fixed with a revision
> to UL1449 that requires thermal disconnects. Overheating was fixed, for
> UL listed suppressors, in 1998.
>
>>
>> IOW many plug-in protectors will fail even on smaller surges to
>> avoid those scary pictures. Failure also promotes sales among the
>> naive.
>
>
> Competently manufactured suppressors engineer the fuses/thermal
> disconnects to open only when the MOVs fail. (They fail by conducting at
> too low a voltage and overheating.) w_, apparently, buys only cheap
> no-brand Chinese suppressors.
>
>>
>> How to test an MOV? Apply a 1 ma current source to it and measure
>> its voltage.
>
>
> I agree this is the way to test a MOV.
>
>> So again, if a surge was so large as to trip that indicator lamp,
>> then the protector was grossly undersized - completely ineffective.
>
>
> The "grossly undersized" red herring again. Grossly undersized applies
> equally to service panel suppressors, which will also be disconnected if
> their ratings are exceeded.
>
>
>
> w_ believes that plug-in suppressors to not work. Instead of using
> technical arguments, he doesn't have any, he is using scare tactics.
>
> For accurate information on surges and surge protection read:
> http://omegaps.com/Lightning%20Guide_FI ... May051.pdf
> - "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/prac ... gesfnl.pdf
> - "NIST recommended practice guide: Surges Happen!: how to protect the
> appliances in your home" published by the US National Institute of
> Standards and Technology in 2001
>
> The IEEE guide is aimed at those with some technical background. The
> NIST guide is aimed at the unwashed masses.
>
>
> The author of the NIST guide, who was the surge guru at the NIST, has
> said "in fact, the major cause of TVSS [surge suppressor] failures is a
> temporary overvoltage, rather than an unusually large surge."
>
> --
> bud--

Nicely stated.

Ed

On Aug 28, 11:31 am, bud-- <remove.BudN...@isp.com> wrote:
> I recommend people interested in accurate information read the IEEE
> and/or NIST guides. Both say plug-in suppressors are effective. Neither
> guide includes w_'s scary pictures. The only 2 examples of surge
> protection in the IEEE guide use plug-in suppressors.

So let's quote that IEEE guide that shows how plug-in protectors
might work AND what happens when it is not properly earthed. Page 42
Figure 8 in
http://omegaps.com/Lightning%20Guide_FI ... May051.pdf
shows what happens when the plug-in protector does not earth a surge.
Due to a plug-in protector too far from earth ground and too close to
the TV, therefore the TV earths that surge - 8000 volts destructively.

The effective protector earths surges. The effective protector is
not protection. Protection is earth ground. Numbers are posted in
reply to above ehsjr's 27 Aug post. In that example, earth may
dissipates (absorbs) 60 million or 100 million watts. But what
happens to that energy when the protector does not have that 'less
than 10 foot' earthing connection. Where is that surge energy
absorbed? Bud conveniently forgets that fact.

The protector without properly earthing - on Page 42 Figure 8 - it
earths that surge 8000 volts destructively through an adjacent TV.
That is effective protection? Bud hopes you ignore what his IEEE and
NIST citations state. Protectors work by earthing. No earth ground
wire? How then does it earth that surge? It does not. Plug-in
protectors don't even claim to provide protection in numerical spec
sheets. What kind of protection is that? Ineffective - but so
profitable.

On Aug 27, 10:13 pm, ehsjr <eh...@bellatlantic.net> wrote:
> Absorbing surge energy is the only way an MOV can work.
> It cannot provide protection without absorbing surge energy.
> That does not mean it absorbs the entire surge energy.
> Where does the surge energy go? Some is absorbed and
> dissipated in the source path, some in the MOV and some
> in the return path.
>
> This is a point w_tom has missed in the past when he insists
> that point of use MOV's don't absorb surge energy.

w_tom never said "MOVs do not absorb energy". Even wire absorbs
energy - which is what I post everytime in response to ehsjr's
intentional misquotes. What are functions of an MOV and of wire?
Both are shunt mode devices. Both operate by shunting (diverting,
connecting, clamping, conducting) electrical current (and energy)
elsewhere. Both absorb energy when performing their job. But neither
function is to absorb all energy - as ehsjr repeatedly claimed.

If we increase MOV joules, then MOV absorbs more energy? Of course
not. If we increase the gauge of wire, then it absorbs more energy?
No. In both cases: as MOV joules and wire gauge increase, then the
device absorbs less energy - because that is what we want it to do.
The function of wire and MOVs: absorb less energy and shunt more
energy.

If MOVs are grossly undersized, then absorbed surge energy increases
massively. That unacceptable operation causes an MOV to vaporize. A
vaporized MOV exceed manufacturer acceptable ratings. Undersized
protectors - too few joules - can also create these scary pictures:
http://www.hanford.gov/rl/?page=556&parent=554
http://www.westwhitelandfire.com/Articl ... ectors.pdf
http://www.ddxg.net/old/surge_protectors.htm
http://www.zerosurge.com/HTML/movs.html
http://tinyurl.com/3x73ol or
http://www.esdjournal.com/techpapr/Phar ... 0FIRES.doc

When too much current passes through an MOV, then its voltage
increases. That unacceptable voltage increase is when an MOV is
grossly undersized - has too few joules. We increase MOV joules so
that an MOV does not absorb more energy; just as we increase wire
diameter.

From manufacturer data sheet: An MOV for 120 volt operation rated
at 25 joules (241KD09 is an 11 mm MOV disk) see voltage climb quickly
past 800 volts during a 2500 amp surge because it is undersized - too
few joules. That peak 2 million watt surge dissipated in that MOV
means its life expectancy is 1 surge (does not vaporize). If we
increase to a 72 joules MOV (241KD18 is a 22 mm disk)). Then a 2500
amp surge creates an MOV voltage of 550; only 1.4 million watts
dissipated in that MOV. Larger MOV means increased life expectancy
and less energy absorbed by the MOV. Better protectors (more joules)
absorb less energy.

What happens if we use five 72 joule MOVs? 110 amps through each
MOV means each MOV voltage is 320 volts - 35,000 watts per MOV or
0.175 million watts total. Increasing from 25 joules to 360 joules
means MOV absorbs 11.5 times less energy. Meanwhile, the 360 joule
protector is now rated for about 3000 surges. Increases joules also
means life expectancy increases exponentially.

Why do some foolishly claim a protector is only for one surge? Why
did a plug-in protector manufacturer charge so much for so few joules?

When joules increase, MOV absorbs less energy AND MOV life
expectancy increases massively. The purpose of an MOV is not to
absorb 'more' surge as ehsjr claimed. More joules means the MOV
absorbs 'less' energy AND lasts longer - just like increasing wire
size.

ehsjr and this poster have argued this for maybe seven years. ehsjr
insisted MOVs provide protection by absorbing the entire surge. MOVs
do not. Is ehsjr finally backing off that claim?

MOVs are shunt mode devices. Like wires, MOVs are not perfect
conductors; absorb a minority of a surge. Whereas that large MOV
might dissipate 1.4 million peak watts, a same surge may also
dissipate 60 or 100 million peak watts into earth. What makes an MOV
effective? Earth ground is the protection. Earth ground is where
maybe 40 or 70 times more energy is dissipated.

A protector without earth ground means no effective protection.
Earth is where the brunt of a surge energy is absorbed; not inside an
MOV as ehsjr once repeatedly claimed.

What makes an MOV effective? MOV resistance drops so that a surge
is shunted to and dissipated by earth ground. Demonstrated above is
how the 72 joule MOV absorbs 30% less energy compared to a 25 joule
MOV. As MOV joules increase, then absorbed MOV energy decreases.

Where is most all surge energy dissipated? Not inside an MOV. Above
numbers make that obvious. Effective protection means most surge
energy is dissipated in earth. But since MOVs are not perfect, then
MOVs (like wires) absorb some of that energy. I was posting this to
ehsjr seven years ago. ehsjr still misrepresents what w_tom has
posted.

w_tom wrote:
> On Aug 27, 10:13 pm, ehsjr <eh...@bellatlantic.net> wrote:
>
>>Absorbing surge energy is the only way an MOV can work.
>>It cannot provide protection without absorbing surge energy.
>>That does not mean it absorbs the entire surge energy.
>>Where does the surge energy go? Some is absorbed and
>>dissipated in the source path, some in the MOV and some
>>in the return path.
>>
>>This is a point w_tom has missed in the past when he insists
>>that point of use MOV's don't absorb surge energy.
>
>
> w_tom never said "MOVs do not absorb energy".


You most certainly did:

Quoting what you wrote on 15 Apr 2006 00:04:07 -0700
under the subject "Re: surge protector question" in the
alt.engineering.electrical newsgroup:

"Shunt mode protectors do not to suppress, absorb,
dissipate, or arrest energy as ehsjr repeatedly
claims over so many years. "

The full post, including header data, is shown at the
bottom, between the lines of asterisks.

You've gone too far with your accusations this time.


> Even wire absorbs
> energy - which is what I post everytime in response to ehsjr's
> intentional misquotes.

You are the master of intentional misquotes. I have never
intentionally misquoted you, and I doubt that I have ever
done it unintentionally. You have done it often, intentionally.


> What are functions of an MOV and of wire?
> Both are shunt mode devices. Both operate by shunting (diverting,
> connecting, clamping, conducting) electrical current (and energy)
> elsewhere. Both absorb energy when performing their job. But neither
> function is to absorb all energy - as ehsjr repeatedly claimed.

I have *NEVER* stated that the MOV function is
to absorb *all* energy. That is a blatant lie.

What I *have* said, consistently, is that an MOV
will absorb whatever surge energy it "sees" at its
leads that is within the MOV's specs, until it dies
or until the voltage drops below the spec.

<snip>

>
> ehsjr and this poster have argued this for maybe seven years. ehsjr
> insisted MOVs provide protection by absorbing the entire surge.

Blatant lie. I have *NEVER* said "MOVs provide protection
by absorbing the entire surge".

<snip>

>
> Where is most all surge energy dissipated? Not inside an MOV. Above
> numbers make that obvious. Effective protection means most surge
> energy is dissipated in earth. But since MOVs are not perfect, then
> MOVs (like wires) absorb some of that energy. I was posting this to
> ehsjr seven years ago. ehsjr still misrepresents what w_tom has
> posted.
>

The post I quoted from you at the begining of my reply proves
you are the one who misrepresents what you have said.
You've hoisted yourself on your own petard.

Ed




*****************************************************************************
Subject:
Re: surge protector question
From:
"w_tom" <w_tom1@usa.net>
Date:
15 Apr 2006 00:04:07 -0700
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Because "energy will be absorbed & dissipated when current flows
through a resistance" then the purpose of wire is to absorb and
dissipate electrical energy. Surge protectors, like wire, will
dissipate some energy when performing their function: to conduct,
shunt, divert, transport that electricity. Shunt mode protectors do
not to suppress, absorb, dissipate, or arrest energy as ehsjr
repeatedly claims over so many years. Although some energy is
dissipated (neither wire nor protectors are perfect conductors), well,
a one hundred joule protector will absorb how many joules in a
lightning strike? (One joule is one volt and one amp for one second:
how many in lightning?) How many joules will that 100 joule protector
suppress, absord, or arrest?

A wire diverts (conducts) energy to my vacuum cleaner. How many
joules has its power cord suppressed, absorbed, dissipated, or
arrested? About 3700 joules. Well that proves it. The purpose of a
power cord is to absorb electricity. Meanwhile the power cord carries
another 3,456,000 joules into the vacuum cleaner. Irrelevant. That
wire dissipated / absorbed energy. Absorbing enery must be its
purpose.

When ehsjr posts this same refrain, a credible source is cited in
reply. This time the National Institute of Science and Technology is
quoted from in their publication 960-6 entitled "Surges Happen! How to
Protect the Appliances in your Home.":

>> You cannot really suppress a surge, altogether, nor "arrest"
>> it. What these protective devices do is neither suppress nor
>> arrest as urge, but simply divert it to ground, where it can do
>> no harm. So a name that makes sense would be a "surge
>> diverter"


ehsjr wrote:

>> You *still* don't understand that energy will be absorbed &
>> dissipated when current flows through a resistance?
>> P = I2 * R
>> where P is the power dissipated in the resistance of the
>> protector, I is the current through the protector, and R
>> is its resistance.
>> QED - the protector will dissipate surge energy.
>>
>> To say it will only divert a surge is blatantly wrong.
>> You cannot get around the laws of physics, no matter
>> how often you post that incorrect idea.
>>
>> The remaining points below in your post, predicated
>> on that misconception, are wrong.

*****************************************************************************

w_tom wrote:
> On Aug 28, 11:31 am, bud-- <remove.BudN...@isp.com> wrote:
>
>>I recommend people interested in accurate information read the IEEE
>>and/or NIST guides. Both say plug-in suppressors are effective. Neither
>>guide includes w_'s scary pictures. The only 2 examples of surge
>>protection in the IEEE guide use plug-in suppressors.
>
>
> So let's quote that IEEE guide that shows how plug-in protectors
> might work AND what happens when it is not properly earthed. Page 42
> Figure 8 in
> http://omegaps.com/Lightning%20Guide_FI ... May051.pdf
> shows what happens when the plug-in protector does not earth a surge.
> Due to a plug-in protector too far from earth ground and too close to
> the TV, therefore the TV earths that surge - 8000 volts destructively.

Yes - let's cite it *accurately*, and note that when you read
all of the information,the IEEE guide clearly indicates that
point of use protectors can be of value in protecting your gear.
First, figure 8 is on page 33, not on page 42 as you indicated.
The last line in the text description for figure 8 says: "A second
multi-port protector as shown in figure 7 is required to protect TV2."
The last line in the text description under figure 7 says: "The
multiport protector shown at the TV set can greatly decrease the
voltage between the AC ground and the coax cable, preventing damage
to the set."

That is from the IEEE guide you are recommending, and it clearly
shows that point of use protectors can be of value in protecting
your equipment.


>
> The effective protector earths surges. The effective protector is
> not protection. Protection is earth ground. Numbers are posted in
> reply to above ehsjr's 27 Aug post. In that example, earth may
> dissipates (absorbs) 60 million or 100 million watts. But what
> happens to that energy when the protector does not have that 'less
> than 10 foot' earthing connection. Where is that surge energy
> absorbed? Bud conveniently forgets that fact.
>
> The protector without properly earthing - on Page 42 Figure 8 - it
> earths that surge 8000 volts destructively through an adjacent TV.
> That is effective protection?

Why don't you read the whole thing? It *plainly* tells you that
a second multi-port protector is *REQUIRED*.


> Bud hopes you ignore what his IEEE and
> NIST citations state.

Where do you get off stating what Bud hopes?

> Protectors work by earthing. No earth ground
> wire? How then does it earth that surge? It does not. Plug-in
> protectors don't even claim to provide protection in numerical spec
> sheets. What kind of protection is that? Ineffective - but so
> profitable.
>
>

Again, you bash plug-in protectors, when the very guide
you cite says: "The multiport protector shown at the TV set
can greatly decrease the voltage between the AC ground and
the coax cable, preventing damage to the set."
See figure 7, page 32.

Quoting Section 5.1 page 38:

"Most plug-in AC protectors use MOVs rated for 130 V AC RMS, and
have a surge limiting voltage of ~330 V peak for the 500A test
pulse. So, plug-in protectors tend to provide lower limiting
voltages (better protection for equipment) for moderate incoming
surges. The gap widens when more realistic surges, and the effects
of wiring, are considered."

Repeating for emphasis: *better protection for equipment*.

Continuing the quote:
"Section 2.3.2 pointed out how rapidly the lead length raises the
effective limiting voltage of hard-wired protectors for large current
impulses. For a typical installation with 20 inches (50 cm) leads,
the effective limiting voltage at the panel would be ~1160 V for a
10 kA impulse (see Table 1). In a well-constructed plug-in protector,
the load is connected directly across the MOVs (Figure 6B), and there
should be negligible voltage drop in the MOV leads. So for the same
10,000 A surge current, the load can actually see a ~400–500 V
effective limiting voltage (with 130 V MOVs), much smaller than
allowed by the hard-wired protector, and much more protective for the
equipment."

Repeating for emphasis: *much more protective for the equipment*

Continuing the quote:
"Well-designed and well-built plug-in protectors will actually
withstand the 10,000 A (8x20 μs) surge current, and that is
rating required by NFPA 780-2004 for plug-in protectors.
However, the UL 1449 Standard only requires plug-in protectors
to withstand, without damage, ~20 500 A surges. Inexpensive
protectors using the 6C type of circuit are designed to respond
to overload by opening the protective fusing shown in Figure 6C,
sometimes at surge currents barely over the 500 A limit. Because
the UL 500 A surge withstand requirements are relatively weak, it
is important to have both a hard-wired protector at the service
entrance and a plug-in protector at the critical loads."

Repeating for emphasis: *it is important to have a hard-wired*
*protector for the service panel and a plug-in protector at*
*the critical loads*

Tom, the guide you cited *clearly* recommends plug-in protectors.
It states thay provide better protection. If you are honest with
yourself, you will stop bashing them, and perhaps recommend them,
as the IEEE guide does, in conjunction with the ideas you have
put forward about a single point grounding system with a short,
straight connection to an effective electrode grounding system.

Ed

On Aug 29, 2:53 am, ehsjr <eh...@bellatlantic.net> wrote:
> Continuing the quote:
> "Well-designed and well-built plug-in protectors will actually
> withstand the 10,000 A (8x20 s) surge current, and that is
> rating required by NFPA 780-2004 for plug-in protectors.
> However, the UL 1449 Standard only requires plug-in protectors
> to withstand, without damage, ~20 500 A surges. Inexpensive
> protectors using the 6C type of circuit are designed to respond
> to overload by opening the protective fusing shown in Figure 6C,
> sometimes at surge currents barely over the 500 A limit. Because
> the UL 500 A surge withstand requirements are relatively weak, it
> is important to have both a hard-wired protector at the service
> entrance and a plug-in protector at the critical loads."

That right. It's important to have hard-wired protector at the
service entrance that has that short connection to earth ground. And
$2000 or $4000 worth of plug-in protectors? Remember we must install
them on dishwasher electronics, dimmer switches, and most critical
appliances such as bathroom GFCIs and smoke detectors. Or maybe those
critical devices are best protected by a 'whole house' protector that
is properly earthed.

As the guide says repeatedly, a protector works by earthing. If the
earthing is not sufficient, then how does a plug-in protector put more
current into an earth ground what would not accept that current
initially? It does not.

How do we make better protection? We enhance what provides the
protection. We upgrade the earthing.

Without that 'whole house' protector, then those supplemental
protection - plug-in protectors - are not sufficient. How
insufficient? Again the scary pictures demonstrate the problem of
grossly undersized plug-in protectors you are recommending:
http://www.hanford.gov/rl/?page=556&parent=554
http://www.westwhitelandfire.com/Articl ... ectors.pdf
http://www.ddxg.net/old/surge_protectors.htm
http://www.zerosurge.com/HTML/movs.html
http://tinyurl.com/3x73ol or
http://www.esdjournal.com/techpapr/Phar ... 0FIRES.doc

And that is what the guide is also noting. Plug-in protectors alone
are not effective. The guide says plug-in protectors can work IF
massive cautions are taken. Meanwhile what does your telco do to
operate during every thunderstorm? Do they disconnect their switching
computers to protect them from lightning? Of course not. Those
computers are connected to overhead wires all over town and must not
suffer damage.

They use properly earthed 'whole house' protectors on every incoming
wire - and no plug-in protectors. To have effective protection
without spending massively, the telco uses a 'whole house' protector
AND better earthing.

How did the Orange County FL emergency response center stop damage?
They also did not waste money on plug-in protectors that are also a
fire hazard. Instead they upgraded the earthing. Why upgrade the
earthing? Even the IEEE guide says it. Protectors don't stop or
absorb surges as ehsjr had claimed even on 29 May 2005. Earthing
provides the protection. Orange County stopped surge damage by not
using plug-in protectors AND by enhancing the earthing. They spend
money where money would be useful which meant upgrading earthing:
http://www.psihq.com/AllCopper.htm

Why do you recommend protectors that the guide even warns as poor?
Meanwhile the IEEE defines the only thing that provides protection in
their Red Book (Standard 141) and in many other standards. No they
don't recommend plug-in protectors. IEEE recommends the only thing
that provides protection - earth ground:
:> 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.

Yes one can supplement protection with grossly undersized and
massively more expensive plug-in protectors. And then the guide also
shows why plug-in protectors will fail to provide protection.

Meanwhile Page 42 Figure 8 of the other citation also shows what
telcos know. A protector too close to appliances and too far from
earth ground many even earth the surge 8000 volts destructively
through an adjacent TV. Therefore telcos that operate without damage
during every thunderstorm put the protector within feet of earth
ground AND up to 50 meters distant from electronics. Why 50 meters?
That separation also makes the earthed protector more effective. The
protector adjacent to an appliance may even earth that surge
destructively through that appliance. How curious. We engineers saw
this happen even 20 years ago.

We engineers also knew that protectors do not work by absorbing all
the surge energy - as ehsjr repeatedly claimed seven years ago.

On Aug 29, 1:04 am, ehsjr <eh...@bellatlantic.net> wrote:
>> w_tom never said "MOVs do not absorb energy".
>
> You most certainly did:
> Quoting what you wrote on 15 Apr 2006 00:04:07 -0700
> under the subject "Re: surge protector question" in the
> alt.engineering.electrical newsgroup:
>
> "Shunt mode protectors do not to suppress, absorb,
> dissipate, or arrest energy as ehsjr repeatedly
> claims over so many years. "

ehsjr reads selectively. ehsjr ignores this phrase:
> ... as ehsjr repeatedly claims over so many years.

ehsjr repeatedly claimed an MOV absorbs all surge energy. No. MOVs
only absorb a minor part just like wire is also not perfectly
conductive. To make it easier for ehsjr to grasp the concept, these
phrases were also used:
> MOV absorbs energy just like a wire
and
> even wires are not perfect conductors.

ehsjr repeatedly claimed MOVs absorb ALL surge energy. His
reasoning was that MOVs are rated in joules, joules measure energy,
therefore MOVs must stop surges by absorbing all surge joules.

Joules do not measure the energy of a surge. Joules are the ball
park measurement for a protector's life expectancy. More joules means
a more conductive MOV, long life expectancy, and less energy
absorbed. ehsjr never understood that and repeatedly denied it.

Lurker may note how ehsjr cannot get over being wrong seven years
ago.

Even in 29 May 2005, ehsjr did not udnerstand how a protector works.
In "Help With a MOV (Varistor?)" in sci.electronics.basics, ehsjr
posted:
>w_tom wrote:
>> MOVs don't stop, block, or absorb surges to keep them out of
>> equipment.
>
> MOVs absorb the surge energy they are exposed to at their
> terminals. E=I*R applies. The MOV absorbs electrical energy
> and converts it to heat energy, as long as it is working. They
> absorb whatever amount of the total surge energy they are
> exposed to across their terminals, again, only as long as they
> are working.

MOVs do not absorb whatever amount of surge energy they are expose
to. MOVs dissipate a small amount of energy while shunting
(diverting, conducting, clamping) massive energy elsehwere - where
that energy will not be destructive.. The majority of energy shunted
by an MOV is dissipated in earth - not absorbed by the MOV. But even
in May 2005, ehsjr was still claiming MOVs absorb all that energy.

And so we have the phrase "... as ehsjr repeatedly claims over so
many years." Lurkers should appreciate the integrity of those who
promote plug-in protectors as 'magic box' solutions. ehsjr has so
little electrical grasp as to assume a shunt mode protector absorbed
whateever energy they are exposed to. MOVs work by *shunting* that
energy elsewhere; not by absorbing "the total surge energy".

w_tom wrote:

Your response contains lies about what I have posted.
You've gone over the line. I can no longer give you
the benefit of the doubt that maybe you misunderstood
what was said. There is no longer any doubt, and it
demands the reponse below identifing lies in your post.



> On Aug 29, 1:04 am, ehsjr <eh...@bellatlantic.net> wrote:
>
>>> w_tom never said "MOVs do not absorb energy".
>>
>>You most certainly did:
>>Quoting what you wrote on 15 Apr 2006 00:04:07 -0700
>>under the subject "Re: surge protector question" in the
>>alt.engineering.electrical newsgroup:
>>
>>"Shunt mode protectors do not to suppress, absorb,
>>dissipate, or arrest energy as ehsjr repeatedly
>>claims over so many years. "
>
>
> ehsjr reads selectively. ehsjr ignores this phrase:
>
>>... as ehsjr repeatedly claims over so many years.
>
>
> ehsjr repeatedly claimed an MOV absorbs all surge energy.

LIAR. You know damn well that I have never claimed that an
MOV absorbs *all* energy.


> ehsjr repeatedly claimed MOVs absorb ALL surge energy.

LIAR.

>
> Even in 29 May 2005, ehsjr did not udnerstand how a protector works.
> In "Help With a MOV (Varistor?)" in sci.electronics.basics, ehsjr
> posted:
>
>>w_tom wrote:
>>
>>> MOVs don't stop, block, or absorb surges to keep them out of
>>>equipment.
>>

So in May 2005 you said: "MOVs don't stop, block or absorb surges
to keep them out of equipment."

And in August 2007 you say:
" w_tom never said "MOVs do not absorb energy" "

So were you lying then, or are you lying now?


> But even
> in May 2005, ehsjr was still claiming MOVs absorb all that energy.

LIAR.


You want to lie about someone else, that's your affair.
Stop lying about what I have posted.

Ed

w_tom wrote:
> On Aug 29, 2:53 am, ehsjr <eh...@bellatlantic.net> wrote:
>
>>Continuing the quote:
>>"Well-designed and well-built plug-in protectors will actually
>>withstand the 10,000 A (8x20 s) surge current, and that is
>>rating required by NFPA 780-2004 for plug-in protectors.
>>However, the UL 1449 Standard only requires plug-in protectors
>>to withstand, without damage, ~20 500 A surges. Inexpensive
>>protectors using the 6C type of circuit are designed to respond
>>to overload by opening the protective fusing shown in Figure 6C,
>>sometimes at surge currents barely over the 500 A limit. Because
>>the UL 500 A surge withstand requirements are relatively weak, it
>>is important to have both a hard-wired protector at the service
>>entrance and a plug-in protector at the critical loads."
>
>
> That right. It's important to have hard-wired protector at the
> service entrance that has that short connection to earth ground.

According to the IEEE guide you cited, it is important to
have *both* a hard-wired protector at the service entrance
and a plug-in protector at the critical loads.

<snip>

>
> We engineers also knew that protectors do not work by absorbing all
> the surge energy - as ehsjr repeatedly claimed seven years ago.
>

LIAR. You know damn well I have never said that.
Cease and desist from lying about what I have
said.

If you think the energy absorbed in the MOV is *all*
the surge energy, you're no engineer.

Ed

On Aug 29, 5:00 pm, ehsjr <eh...@bellatlantic.net> wrote:
w_tom wrote:
>> We engineers also knew that protectors do not work by absorbing all
>> the surge energy - as ehsjr repeatedly claimed seven years ago.
>
> LIAR. You know damn well I have never said that. Cease and desist
> from lying about what I have said.
>
> If you think the energy absorbed in the MOV is *all* the surge energy
>, you're no engineer.

I did not say *all* the surge energy is absorbed in the MOV. But Ed
did.

In the newsgroup alt.engineering.electrical in a thread entitled
"cut off power to computer" on 16 Dec 1999, Ed posted:
> Wrong. Surge protectors of the type you mention - MOV's
> absorb both differential and common mode surges.

Then on 17 Dec 1999, Ed claims the MOV absorbs all of a surge:
> In the MOV surge protector, the MOV **is** the load. More
> energy is dissipated in it than in the #14 or #12 house wiring
> to which it is connected. Where do *you* think the energy
> that you say is passed through the MOV is dissipated? Ed

Where is energy absorbed after being *shunted* by an MOV? Earth
ground. Demonstrated in that thread was a 39 joule protector
dissipating a little energy while shunting significantly more energy
via that MOV. Massive more energy is shunted through MOV terminals to
be absorbed (dissipated) elsewhere. Where is that elsewhere? What
provides protection? Earth ground.

But Ed claimed on both 16 Dec and 17 Dec 1999 that the MOV protects
by absorbing *all* surge energy. Ed said I lied? How does ehsjr
explain his posts at:
http://tinyurl.com/32p3b2

Ed, you were making this claim that MOVs protect by absorbing the
entire surge for many years. Accurately posted was:
> Shunt mode protectors do not to suppress, absorb, dissipate,
> or arrest energy as ehsjr repeatedly claims over so many years.

You deny your own 1999 claims? Ed, you claimed the MOV was the
entire load; that it absorbs the entire surge.

Where is most of a surge absorbed when using an effective
protector? Earth ground. Shunt mode protector with short (less than
10 foot) dedicated connection to earth ground is effective. What kind
of protector has that dedicated earthing wire? A 'whole house'
protector as sold by responsible manufacturers such as Square D,
Siemens, Leviton, Cutler-Hammer, Intermatic, and GE. Where does a
protector dissipate a surge if not properly earthed? Page 42 Figure 8
shows one example: 8000 volts destructively via an adjacent TV.

Ed used to claim a 100 joule protector absorbed 100 joules and would
fail is the surge is larger. But a 100 joule protector shunts maybe
tens of times more energy into earth. Why are effective protectors
for lightning protection so small? Their function is not to absorb
surges. Their function is to shunt (divert, connect, clamp) that
surge to earth. No earth ground connection means no effective
protection.

Meanwhile, who is lying? Ed claimed for years that the MOV protects
by absorbing the entire surge. Ed also denied then and denies today
the importance of earth ground.

What happens if a plug-in protector has no earth ground to earth
to? One possibility is demonstrated on Page 42 Figure 8 where 8000
volts gets earthed destructively via an adjacent TV. Another
possibility are these scary pictures:
http://www.hanford.gov/rl/?page=556&parent=554
http://www.westwhitelandfire.com/Articl ... ectors.pdf
http://www.ddxg.net/old/surge_protectors.htm
http://www.zerosurge.com/HTML/movs.html
http://tinyurl.com/3x73ol

After all, if a protector does not shunt (divert) that energy into
earth, then that energy must be dissipated somewhere. Essential to
protection is a short ('less than 10 foot', no sharp bends, no
splices, etc) earthing connection so that a most of a surge entering
an MOV will be dissipated in earth.

And so again, the protector is only as effective as its earth
ground. Why did Ed repeatedly deny the need for earthing? Ed once
insisted the entire surge is absorbed (dissipated) by the MOV. But
effective protectors have the dedicated earthing wire to shunt
massively more energy into earth.

grizdog and others: the most critical component of any surge
protection system - where the surge is dissipated - is earth ground.
No earth ground means no effective protection. A surge must be
shunted to earth either by a wire or by a shunt mode protector (such
as MOVs). That is what MOVs do - shunt - become as conductive as
possible to divert a surge to earth. How does a protector become more
conductive? More joules.

w_tom <w_tom1@usa.net> wrote:

> Where is energy absorbed after being *shunted* by an MOV?

It's not shunted by the MOV, it's absorbed elsewhere.

It's been explained to w_tom a dozen times. The function is simple
enough for anyone with a basic understanding of electricity (like me).

The Metal Oxide Varistor (MOV) clamps the terminals of the circuit so
that they are the same voltage. When two points are at the same
voltage, there is no current flow and nothing gets destroyed, no
matter what the voltage. All that's left is for the surge to subside.






--
w_tom's obsession is a result of being connected to a surge suppressor
is a small child (and it didn't work)

On Aug 29, 7:12 pm, John Doe <j...@usenetlove.invalid> wrote:
> The Metal Oxide Varistor (MOV) clamps the terminals of the circuit so
> that they are the same voltage. When two points are at the same
> voltage, there is no current flow and nothing gets destroyed, no
> matter what the voltage. All that's left is for the surge to subside.

A surge is a current source. That means current must have a path to
dissipate energy. Clamp everything to nothing. Page 42 Figure 8 is
what happens. A surge then created a path destructively through
adjacent appliances. A current source will increase voltages as
necessary to create a conductive path. That energy must be dissipated
somewhere. Clamping without an earthing connection accomplishes
nothing useful AND may give that current more paths to find earth
ground ... destructively through the adjacent TV. Or that energy may
simply create 'scary pictures' - a potential house fire created by a
plug-in protector.

If that surge current is not shunted (clamped) to earth before
entering a building; if there is no place to dissipate energy; then a
surge will create potentially destructive paths to earth. Page 42
Figure 8 with all wires shunted (clamped) - that surge then created an
8000 volts path destructively through adjacent TV. Energy must be
dissipate somewhere. If not dissipated in earth, then clamping to
nothing means surge damage inside a building is either in adjacent
applai9nces or those 'scary pictures'.

Funny John Doe. You still believe a protector will somehow stop or
absorb what three miles of sky could not - by clamping to nothing? If
current is not shunted to earth ground, then voltages will increase as
necessary so that less conductive materials conduct that surge inside
the building. That surge will be as destructive as necessary to find
earth ground. No protector will stop that by 'clamping to nothing'.

What is standard for protection in Air Force bases, radio and TV
stations, and even Orange County's emergency response center?
http://www.psihq.com/AllCopper.htm
John Doe says they all waste time and money. He knows plug-in
protectors are sufficient. But then he learned using retail store
science - admits he has no electrical training. Meanwhile plug-in
protectors are often banned from reliable locations. Plug-in
protectors have even contributed to damage of adjacent and powered off
computers in a network. John Doe who admits to no engineering
training *knows* that cannot be true.

John did not know the telco installs a protector on all subscriber
lines - for free. According to John Doe, the telco need not earth
that protector. But the telco knows earthing is so critiical as to
earth your phone line protector AND make that wire short. Shorter
connection to earth means that protector is better. Why does the
telco waste time and money earthing that protector when it can clamp
to nothing - and provide protection? Clearly the telcos are also
stupid - John Doe knows better.

Page 42 Figure 8 - adjacent TV damaged because the surge was earthed
8000 volts destructively via the TV. Surge was clamped to nothing; so
surge was shunted to earth 8000 volts destructively through that TV.
But that protector was expensive. It must do something.. It clamps
to nothing - expensively and destructively. It does not even claim to
provide protection. Oh. Did John Doe also forget that the
manufacture also does not list surges and protection from those surges
in spec sheets. How curious. Manufacturer spec sheets also don't
support John Doe's assumption. Clamping to nothing provides
ineffective protection. A protector is only as effective as its earth
ground - when it has something to clamp (shunt) to.

John Doe wrote:

> w_tom <w_tom1@usa.net> wrote:
>
>> Where is energy absorbed after being *shunted* by an MOV?
>
> It's not shunted by the MOV, it's absorbed elsewhere.
>
> It's been explained to w_tom a dozen times. The function is simple
> enough for anyone with a basic understanding of electricity (like me).
>
> The Metal Oxide Varistor (MOV) clamps the terminals of the circuit so
> that they are the same voltage. When two points are at the same
> voltage, there is no current flow and nothing gets destroyed, no
> matter what the voltage. All that's left is for the surge to subside.
>
>
>

The MOV does not clamp to 0 volts. Perhaps you should review some MOV specs.

Here are some.
http://www.nteinc.com/Web_pgs/MOV.html

Note the column called Maximum Clamping Voltage. How does this fit with
your "clamps the terminals of the circuit so that they are the same
voltage" statement?

Also note the Continuous voltage columns. At or below these voltages the MOV
also does basically nothing.

When there are zero volts across the MOV it does nothing.

And, what do you think the transient energy column means?

When clamping the voltage in a circuit to some value, how much energy is
going into the MOV?