belkin power conditioner for my Samsung LCD - is it worth it???

w_tom wrote:
On Aug 8, 1:15 pm, bud-- wrote:
But that doesn't matter. As I have said more than once, the IEEE guide
explains that plug-in suppressors work by clamping the voltage on all
wires (power and signal) to the common ground at the suppressor.
They do NOT work primarily by earthing the surge. The guide
explains that the NEC does not intend for surges to be earthed on
the ground wire of a branch circuit. In the IEEE guide example
starting pdf page 40, almost all the earthing of the surge coming in
on the CATV drop is through the 'ground' wire from the CATV entr
block to the power service.

Notice how Bud routinely forgets to
mention that earthing - not the protector - is protection.

The statement of religious belief in earthing.

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


So what happens when it does not have earth ground to clamp to? Page
42 Figure 8. The protector had no earthing wire because that wire was
too long, many sharp bends, bundled with other wires, etc. So the
protector, instead, earths that surge destructively through an
adjacent TV.

The lie repeated 4 times in w_’s post. The plug-in suppressor at TV1
lowers the voltage at TV2 although the point of the illustration is "to
protect TV2, a second multiport protector located at TV2 is required."

And w_ has never explained how a service panel suppressor would provide
any protection. The problem is lack of a “single point ground”.


Same drivel from w_.

Still no link to another lunatic that agrees that plug-in suppressors do
NOT work.

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

Still never answered:
- Why do the only 2 examples of protection in the IEEE guide use plug-in
suppressors?
- Why does the NIST guide says plug-in suppressors are "the easiest
solution"?
- How would a service panel suppressor provide any protection in the
IEEE example, pdf page 42?
- Why does the IEEE Emerald book include plug-in suppressors as an
effective surge protection device.


Bizarre claim - plug-in surge suppressors don't work
Never any sources that say plug-in suppressors are NOT effective.
Twists opposing sources to say the opposite of what they really say -
IEEE guide.
Attempts to discredit opponents.
w_ is a purveyor of junk science.

--
bud--

wrote:
On Wed, 08 Aug 2007 12:15:39 -0500 bud-- wrote:

| The N-G bond at US services turns common mode surges on the power line
| into differential mode surges.

To the extent that it diverts current on the neutral line. That assumes
the hit came in the service drop. It will never be 100% because the
grounding wire and electrode impedance are not zero. But in most cases
a well installed system can reduce most of the neutral current and leave
things in mostly differential mode.

The neutral and system ‘ground’ are solidly bonded at US services. With
an incoming common mode surge, the neutral will be held to the same
potential as the system ‘ground’ by the N–G bond. That produces a
current to earth. The system “grounds’ (both power and signal) will be
lifted from ‘absolute’ ground by the surge earth current through the
resistance to earth. It only makes sense to talk about common mode with
respect to the system ‘ground’.


But consider if an outdoor lighting fixture is what takes the hit. That
can be a common mode current on L+N+G.

I would consider that a direct hit, since it is not practical to control
where the lightning travels (short of lightning rods).

If the circuit travels directly to the service panel, the common mode
surge becomes a differential mode surge at the panel as above.



| But that doesn't matter. As I have said more than once, the IEEE guide
| explains that plug-in suppressors work by clamping the voltage on all
| wires (power and signal) to the common ground at the suppressor. They do
| NOT work primarily by earthing the surge. The guide explains that the
| NEC does not intend for surges to be earthed on the ground wire of a
| branch circuit. In the IEEE guide example starting pdf page 40, almost
| all the earthing of the surge coming in on the CATV drop is through the
| ?ground? wire from the CATV entry block to the power service.
|
| Plug-in suppressors do NOT work primarily by diverting lightning. You
| have not figured out how they do work.

I know exactly how they work. It's still diversion ... just backwards
along the grounding conductor of the circuit. And that's if the surge
is not also coming up along that line (which it can).

A good illustration is IEEE guide starting pdf page 40. A surge comes in
on a cable drop. Because the ‘ground’ wire from the cable entry block to
the power service is too long, 10,000V develops between the cable wires
and the power wires.

A plug-in suppressor is installed for a TV, and both cable and power
wires go through it. The cable shield connects to the branch circuit
ground wire at the suppressor. There is current through the shield -
branch circuit ground wire path. But the guide says that “in most cases,
the impedance of the signal wire to the equipment, plus the impedance of
the AC wiring, is much greater” than the ‘ground’ wire from cable entry
block to power service. “So the vast majority of the incoming lightning
surge current flows through” the cable entry block ‘ground’ wire. And
the guide says that is “as the NEC/CEC writers intended.”

The guide also says “it is important to realize that multiport
protectors usually do not significantly reduce the” voltage between the
cable ground block and the power service ‘ground’. That is because the
suppressor is not “diverting” much of the surge.

The surge is ‘diverted’ almost entirely through the cable entry ‘ground
wire. The purpose of the plug-in suppressor is not primarily to provide
an earth path “diversion” for the surge.

The suppressor clamps the voltage on the hot, neutral and coax center
conductor to the common ground at the suppressor. The voltages to the TV
are at levels safe for the TV.

The ground potential of the suppressor is raised above the ground
potential at the power service, just as the ground potential of the
power service is raised above ‘absolute’ ground potential by the surge
earth current.

--------------------------------
Take your favorite common mode surge to a TV with no other connections
but power.
With a plug-in suppressor, the voltages from both H-G and N-G are
clamped. In addition, the voltage from H-N is clamped. The voltages
between the power wires is safe for the TV. Because of the impedance of
the branch circuit there is a relatively low current on the branch
circuit ground wire, and there is very little “diverting” of the surge.

So where does the surge go? The surge on the neutral is directly earthed
at the service by the N-G bond. The surge on the hot (for a strong
surge) results in arc-over at the service panel at about 6kV which dumps
most the energy to earth. That is why the 2nd Martzloff paper had a
spark gap at the source. The ground potential at the service (and phone,
cable, ... protectors) rises above ‘absolute’ earth potential. The
ground potential of the plug-in suppressor rises above the potential of
the service ‘ground’.

-----------------------------
If a plug-in suppressor is very near the service panel it may provide
significant “diversion”. But that is not how they usually work.



| Protection is always a trade-off of - degree of risk - value of what you
| are protecting - cost of protection.

Right. No protection is 100%. But you can get reasonably close to that
by making sure things are installed right, and not just the protection
gear ... everything needs to be installed right (for example a common
entrance point).


| If I lived in central Florida I would make sure I had:
| a good earth connection
| a good 'single point ground'
| a high rating service panel suppressor
| a high rating plug-in suppressors on high value equipment
| (primarily 2-link) like HDTV and computer (not so much because of
| computer value as value of the date).
|
| If I lived in Nevada, I would probably concentrate on the plug-in
| suppressors.

To each his own. In my design-in-progress next house, there will be a
master entrance point protection for everything.

Always a trade off. How likely is lightning? How likely are power
system switching transients? How high a rating should service panel
suppressor be? What rating for plug-in suppressors? Lightning rods?
Suppressor at pad mounted A/C evaporator (IEEE guide details ground
potential rise from a lightning strike can lift the earth away from the
power wiring)? Surge protectors on amplifier audio outputs? At your
speakers? Nuclear EMP protection?



| What I have read, including the guides and the 2 Martzloff papers,
| indicates even without service panel suppressors, plug-in suppressors
| with high ratings connected properly are very likely to protect against
| all but very near strikes.

So what will you be doing for the very near strikes and the direct hits?
Buying all new appliances for your new house?

The only way I know to protect from direct hits is to use lightning rods.

My reading of the 2 Martzloff papers is that even very close strikes are
likely survivable. But it is still a trade-off. Do you protect from a
200,000A lightning strike on the power service drop to your house
(extremely unlikely)?




| As I said above, plug-in suppressors work for any mode surge. It doesn?t
| matter.

Not for full common mode. Where is the energy going to go?

See the explanation above.



| I expect ?common? overvoltage sources would be an open neutral on a
| service (or multiwire branch circuit) and a high voltage distribution
| wire dropping onto 120V secondary wires.

Would that be from the classic loose neutral connection, or from a neutral
blown open by a lightning strike?

Loose neutral.
I have not heard of burning a neutral open from lightning, and if it did
the open neutral would probably be the least of your problems.



| The 330V rating is a peak voltage. 240V RMS is equivalent to 340V peak.
| As a MOV starts to fail, conduction starts at a progressively lower voltage.

So we need higher MOVs for 240 volts.

Yes for MOVs designed to work on a 240V circuit.

My comment was aimed at a MOV on a 120V L-N system with an open
neutral, which can be hit with up to 240V depending on loading on each leg.

--
bud--

"bud--" wrote in message
.. .
w_tom wrote:

Posting to the thread, not you personally. This seems to be a better read on
the subject than this thread.

http://www.powerchx.com/Fundamentals.htm

Don't kill the messenger!

w_tom wrote:
On Aug 7, 10:52 pm, wrote:
As for TVs working at 95 volts, a lot of the older ones, especially tube
models, will "work" as in attempt to do something, usually underscanning
a fading picture. Because a switching power supply, as most TVs
have today, will use _more_ current when the voltage drops, a low voltage
can actually damage them. So they usually have some kind of overcurrent
cutoff circuit or component. I have heard of under utilized computer
power supplies going to rather low voltages and continuing to operate.

Electronics even 30+ years ago were required to operate on voltages
that low. The industry standard even states in block letters "No
Damage" when AC electric voltage is that low.

What industry standard?

It has been that
standard that long for computers to not be damaged by voltage drop.
Meanwhile Intel specs says that computers must even start with a full
load and operate perfectly normal when voltages go even lower - 90 VAC
or 180 VAC on 240 VAC power.

That is computers. The thread is about HDTVs.



TVs will work just fine when bulbs are even at 40% intensity. Other
electronics such as computers must work (and even start) when line
voltages are lower - 90 VAC;

Computers again. Provide a source that says HDTVs must operate at 95V.



(Bud does not have this kind of design experience - he is
a promoter.)

Ho hum, repeating again:
"To quote w_ 'It is an old political trick. When facts cannot be
challenged technically, then attack the messenger.' "


As usual, no links that verify w_'s claim - *which is about HDTVs*.

--
bud--

w_tom wrote:
On Aug 8, 11:56 am, "Peter H. Coffin" wrote:
No, the question is not whether plug-in suppressors are effective (at
diverting surges) but whether such suppressors extend the life of
televisions 5-10 years, under real-world condiitions.

Bud promotes for plug-in protector manufacturers.

Ho-ho-hum, repeating again:
"To quote w_ 'It is an old political trick. When facts cannot be
challenged technically, then attack the messenger.' "

He follows me
everywhere (a troll) to promote those grossly profitable protectors.

w_ uses groups to troll for "surge" so he can spread his wisdom.
Unfortunately his wisdom about plug-in suppressors is wrong - read the
IEEE and/or NIST guides.

He 'cut and pastes' the same responses in maybe 300 discussions.

w_ 'cuts and pastes' the same nonsense wherever his trolling discovers
"surge".

Bud
is promoting a product line.

Ho-ho-ho-hum, repeating again:
"To quote w_ 'It is an old political trick. When facts cannot be
challenged technically, then attack the messenger.' "


Bud does not care to
discuss voltage variations.

w_ is not able to provide a source that verifies his claim - which is
about *HDTVs*.

Bud is here to promote myths for plug-in
protectors.

w_ is here to promote his religious beliefs about plug-in suppressors.

For reality read the IEEE and/or NIST guides.

--
bud--

bud-- wrote:


My comment was aimed at a MOV on a 120V L-N system with an open
neutral, which can be hit with up to 240V depending on loading on each leg.


Trying to teach poor old phil is as much a waste of time as trying to
teach w_tom, but for different reasons. Poor old phil has no interest in
learning and treats this ng as write only, w_tom has a religious belief.

Matthew

--
I'm a consultant. If you want an opinion I'll sell you one.
Which one do you want?

--
Posted via a free Usenet account from http://www.teranews.com

On Aug 9, 12:26 pm, "Captain Midnight" wrote:
Posting to the thread, not you personally. This seems to be a better
read on the subject than this thread.
http://www.powerchx.com/Fundamentals.htm

That article discusses power problems - and only some. Problems are
harmonics, noise, blackouts, brownouts, and surges. Article forgets
to mention that most all power problems are made irrelevant by the
power supply - numerous functions inside a power supply.

For example, harmonics and noise are made irrelevant by filters and
other circuits in a supply's front end. This was even standard in
1950s televisions. Manufacturer specs define those functions and
other standards that a supply must meet. If noise or harmonics are
too massive for a power supply, then your utility is both a problem
and the solution. Electronics are so robust as to make those problems
irrelevant even in factories. Residential power must be even
'cleaner'.

Brownouts and blackouts are also made irrelevant by a power supply.
Electronics must work just fine even when incandescent bulbs dim to
40% intensity. Computers (as defined by Intel specs even 10+ years
ago) must both startup and work when line voltage drops even lower.
If line voltage drops even lower, then no hardware damage must occur.
Again a standard from even more than 30 years ago. Another functions
found inside a power supply.

What constitutes power conditioning includes "isolation
transformers, ferroresonant transformers, and combination of TVSS or
filter components and isolation transformers." These also exist in a
supply. For a power conditioner to improve on that function, its
costs is typically hundreds of dollars more money. How often does
unconditioned power destroy electronics in dimmer switches,
dishwasher, bathroom GFCIs, and smoke detectors? Why are these hourly
or daily problems not destructive? Therein lies a problem with power
conditioners. What is sufficient for residential service is already
inside electronic appliances - another function of the power supply.

Appliance internal protection may be overwhelmed by something that
occurs typically once every seven years. A number that varies
significantly with region, geology, and sometimes even within a
town. That destructive surge, that may overwhelm appliance internal
protection, seeks earth ground. Therefore responsible facilities do
as is demonstrated in an application note from an industry
professional:
http://www.erico.com/public/library/...es/tncr002.pdf

Every wire in every cable first connects to single point earth
ground before entering the building. Look closer. Not just any earth
ground. All utilities connect to the *same* earth ground. Even
underground wires must make that connection. This is not difficult.
After all, it is based on what we were taught about Ben Franklin's
1752 invention in primary school science.

That connection to earth is short to make protection better. For
residential protection, each earthing wire should be 'less than 10
feet'. Other recommendations are detailed in comp.sys.mac.comm on 4
Jul 2007 entitled "DSL speed" at
http://tinyurl.com/2gbgef
Earthing connection is made either directly (using hardwire) or via
a protector (since a protector's job is to shunt / connect / clamp /
bond to earth).

Each structure has its own single point earth ground. Any wire that
connects between two structures (in this case building and tower) must
connect to earth ground for both structures before entering each
structure. So that protection is even better, those separate earthing
electrodes are connected via a buried ground wire. What defines
protection? Something so often forgotten because it is out of sight -
buried. Its all there in that above figure from www.erico.com.

Noise, harmonics, blackouts, and brownouts are solved elsewhere -
mostly inside appliances. Surges are the electrical event that may
overwhelm protection already inside all appliances. Each layer of
protection is defined by its single point earthing electrode. As that
app note figure demonstrates, building earth ground is located at the
service entrance - secondary protection.

Utilities provide your primary protection. Inspect that protection
layer as in pictures at:
http://www.tvtower.com/fpl.htm

Nothing here disagrees with the www.powerchx.com article. However
this post puts that discussion into perspective by adding the missing
information. Blackouts, brownouts, noise, and harmonics typically do
not harm household appliances. Appliances are quite robust (when
properly designed. Appliances contain surge protection and power
conditioning. So that the rare and so destructive surge does not
overwhelm existing proetction, we install one protector AND the short
earthing connection to that protector. The most critical protector
device that every building must have is that earthing electrode). The
electrode is required for human protection. The we connect utilities
to it via hardwire or protectors also for transistor protection.

How effective is a properly earthed protector? So effective and so
inexpensive that every incoming phone line has one installed by the
telco - for free. Did you know that telco protector exists? A
protector that may be compromised if YOU did not provide proper
earthing.

What did Franklin do so that lightning did not find earth ground,
destructively, via church steeples? He did the exact same thing.
Earthing. Is a lightning rod protection? Of course not. Lightning
rod does same thing as a protector - a connecting device to earth
ground. How effective is that lightning rod? Only as effective as
its earth ground.

No protector defines a protection system. Each protection layer is
what an effective protector shunts (connects, diverts, clamps) surges
to: earth ground. No earth ground? Then nothing to shunt (clamp) to
- no effective protection. Those numeric specs say same thing by
omission. Why is the TV on Page 42 Figure 8 destroyed when the
protector earths a surge through that TV? Where is the 'less than 10
foot' dedicated connection to earthing? No earth ground means no
effective protection. Other four other power problems made irrelevant
by circuits inside power supplies.

Notice the difference between this and www.powerchx.com. This
discusses all five power problems AND details where and how a solution
is installed.

Protection is only as good as its earth ground. In at least one
case, that missing earth ground resulting in a house explosion - no
human protection. For transistor protection, we exceed post 1990
National Electrical Code earthing requirements. A protector will only
be as effective as its earth ground. Put that www.powerchx.com
article in perspective. What typically harms appliances when
protection already exists in all appliances? Even that www.powerchx.com
article did not provide simple solutions you can implement for so
little money - such as inspect your primary protection system and
upgrade the secondary protection system to meet and exceed post 1990
NEC requirements. Did you even know your phone line already has a
protector - installed for free? Did you know why that protector needs
the earthing connection? A protector is only as effective as its
earth ground. Standard procedure where effective protection means
many surges, less money, and no damage.

Appreciate how many know this must not be true because of propaganda
and half truths in retail stores by 'expert' salesman. Did they learn
this generations ago by learning the science AND by building this
stuff? Of course not. I did. Others who post in denial don't even
have engineering design experience and prove their knowledge using
insults. Who do you believe? The posters who insults with one
paragraph or who promotes for plug-in protectors manufacturers? Or
the engineer who has done so much testing as to even have who
protectors completely vaporized (only left was two wires) AND who has
earthed direct lightning strikes that created no appliance damage but
damaged the electric meter? Notice so many more words are needed to
describe one who actually learned what creates protection. No earth
ground means no effective protection - which is the rule in telephone
switching stations, commerical broadcasting stations, military bases,
FCC airport facilities, and even Franklin lightning rods. Anyplace
that actually installs protection - earthing is the only component
that is always required.

Defined were all five power problems and solutions for each.

Why did Piggy's cable company not recommend the protector? They had
already earthed the cable - that grossly overpriced $90 protector did
nothing useful and may even degrade cable signal. A $3.50 power strip
with some ten cent parts selling for $90? No wonder the store expert
- a salesman without even a science degree - so strongly recommended
it. Others also 'feel' it must doing something useful because is was
so expensive OR because it is called a "protector". After all,
anything called a "protector" must be "protection". Right? Wrong.
The protector is simply a connecting device to protection. Protection
is earth ground. Piggy's cable guy told her the truth - cable was
already properly earthed without any protector.

"w_tom" wrote in message
oups.com...
On Aug 9, 12:26 pm, "Captain Midnight" wrote:
Posting to the thread, not you personally. This seems to be a better
read on the subject than this thread.
http://www.powerchx.com/Fundamentals.htm

That article discusses power problems - and only some. Problems are
harmonics, noise, blackouts, brownouts, and surges. Article forgets
to mention that most all power problems are made irrelevant by the
power supply - numerous functions inside a power supply.

For example, harmonics and noise are made irrelevant by filters and
other circuits in a supply's front end. This was even standard in
1950s televisions. Manufacturer specs define those functions and
other standards that a supply must meet. If noise or harmonics are
too massive for a power supply, then your utility is both a problem
and the solution. Electronics are so robust as to make those problems
irrelevant even in factories. Residential power must be even
'cleaner'.

Brownouts and blackouts are also made irrelevant by a power supply.
Electronics must work just fine even when incandescent bulbs dim to
40% intensity. Computers (as defined by Intel specs even 10+ years
ago) must both startup and work when line voltage drops even lower.
If line voltage drops even lower, then no hardware damage must occur.

Well both my microwave and VCR got killed during a brownout a few years ago.
So much for that requirement.

On Thu, 09 Aug 2007 11:26:18 -0500 bud-- wrote:
| wrote:
| On Wed, 08 Aug 2007 12:15:39 -0500 bud-- wrote:
|
| | The N-G bond at US services turns common mode surges on the power line
| | into differential mode surges.
|
| To the extent that it diverts current on the neutral line. That assumes
| the hit came in the service drop. It will never be 100% because the
| grounding wire and electrode impedance are not zero. But in most cases
| a well installed system can reduce most of the neutral current and leave
| things in mostly differential mode.
|
| The neutral and system ?ground? are solidly bonded at US services. With
| an incoming common mode surge, the neutral will be held to the same
| potential as the system ?ground? by the N?G bond. That produces a
| current to earth. The system ?grounds? (both power and signal) will be
| lifted from ?absolute? ground by the surge earth current through the
| resistance to earth. It only makes sense to talk about common mode with
| respect to the system ?ground?.

This is only relevant to a surge passing by the bonding point. Take a
look inside a typical service panel and you will see that most have
separate busses for neutral and ground, and are bonded with a strap
between them. That's quite sufficient for the grounding needs of the
electrical service itself. But that does not mean a zero impedance
path to ground. So not all of the surge will go to ground (especially
the leading edge when the inductance of the path is high).


| But consider if an outdoor lighting fixture is what takes the hit. That
| can be a common mode current on L+N+G.
|
| I would consider that a direct hit, since it is not practical to control
| where the lightning travels (short of lightning rods).
|
| If the circuit travels directly to the service panel, the common mode
| surge becomes a differential mode surge at the panel as above.

Partially.

If the hit is strictly on the line wire only, it will basically start as
a common mode, but create its own differential mode by mutual inductance
to the neutral/ground (and the opposing phase or phases). At the point
of bonding, some of that current is taken off to earth. But unless there
is also an arc point, the line surge will rise at that point.

If the hit is on all conductors, it stays common mode, but gets damped a
lot by the higher effective self-inductance. The current on the neutral
will mostly go to ground (depending on the ground path impadance) but not
all. The current on the line wire won't.

The difference in these cases isn't much. It basically determines the
direction of the current in the grounded neutral.


| | But that doesn't matter. As I have said more than once, the IEEE guide
| | explains that plug-in suppressors work by clamping the voltage on all
| | wires (power and signal) to the common ground at the suppressor. They do
| | NOT work primarily by earthing the surge. The guide explains that the
| | NEC does not intend for surges to be earthed on the ground wire of a
| | branch circuit. In the IEEE guide example starting pdf page 40, almost
| | all the earthing of the surge coming in on the CATV drop is through the
| | ?ground? wire from the CATV entry block to the power service.
| |
| | Plug-in suppressors do NOT work primarily by diverting lightning. You
| | have not figured out how they do work.
|
| I know exactly how they work. It's still diversion ... just backwards
| along the grounding conductor of the circuit. And that's if the surge
| is not also coming up along that line (which it can).
|
| A good illustration is IEEE guide starting pdf page 40. A surge comes in
| on a cable drop. Because the ?ground? wire from the cable entry block to
| the power service is too long, 10,000V develops between the cable wires
| and the power wires.

And this is exactly why merely having a grounding bond will NOT completely
remove the surge, nor will it completely transform a common mode to a
differential mode.



| A plug-in suppressor is installed for a TV, and both cable and power
| wires go through it. The cable shield connects to the branch circuit
| ground wire at the suppressor. There is current through the shield -
| branch circuit ground wire path. But the guide says that ?in most cases,
| the impedance of the signal wire to the equipment, plus the impedance of
| the AC wiring, is much greater? than the ?ground? wire from cable entry
| block to power service. ?So the vast majority of the incoming lightning
| surge current flows through? the cable entry block ?ground? wire. And
| the guide says that is ?as the NEC/CEC writers intended.?

Usually the vast majority will. But a lot won't.

No _one_ of these protection methods is 100%. A combination is better
but still not 100%.


| Take your favorite common mode surge to a TV with no other connections
| but power.

I don't have a favorite surge of any mode.


| To each his own. In my design-in-progress next house, there will be a
| master entrance point protection for everything.
|
| Always a trade off. How likely is lightning? How likely are power
| system switching transients? How high a rating should service panel
| suppressor be? What rating for plug-in suppressors? Lightning rods?
| Suppressor at pad mounted A/C evaporator (IEEE guide details ground
| potential rise from a lightning strike can lift the earth away from the
| power wiring)? Surge protectors on amplifier audio outputs? At your
| speakers? Nuclear EMP protection?

Lightning can be very likely. I saw 3 direct hits to the US Steel
building in Pittsburgh yesterday, and 1 to the AT&T building. The
house I live in now has taken a direct hit to a drain vent on the
roof and went to ground in the crawl space underneath, with damage
to a phone near the path, and burn holes in the plastic covering
over the crawl space ground cover. Probably the most spectacular
one I saw came in on the power lines at my grandfather's house and
destroyed his electric stove (wiring melted and the wall behind it
all blackened). The branch circuit wiring even had to be replaced.


| | What I have read, including the guides and the 2 Martzloff papers,
| | indicates even without service panel suppressors, plug-in suppressors
| | with high ratings connected properly are very likely to protect against
| | all but very near strikes.
|
| So what will you be doing for the very near strikes and the direct hits?
| Buying all new appliances for your new house?
|
| The only way I know to protect from direct hits is to use lightning rods.

Even that's not 100% protection. But every little bit (usually) helps.
If you reduce the number of hits, or the chance of a hit, you are better
off for it.


| My reading of the 2 Martzloff papers is that even very close strikes are
| likely survivable. But it is still a trade-off. Do you protect from a
| 200,000A lightning strike on the power service drop to your house
| (extremely unlikely)?

I have seen a directly lightning strike to a power service drop that
melted the point and brought down the line (with the supply side doing
a continuous arc until the power got cut off). I never found out how
much damage was done inside that house, if any, but the fire crews
were in there doing something (maybe just checking).


| | As I said above, plug-in suppressors work for any mode surge. It doesn?t
| | matter.
|
| Not for full common mode. Where is the energy going to go?
|
| See the explanation above.

I wanted you to answer the question to ponder the issue. If it is
common mode, then going back along any of the wires in the branch
circuit is not an option since it is coming to the device over all
three wire in parallel. It will have to jump as the high impedance
of the end of the circuit raises the voltage substantially.


| So we need higher MOVs for 240 volts.
|
| Yes for MOVs designed to work on a 240V circuit.
|
| My comment was aimed at a MOV on a 120V L-N system with an open
| neutral, which can be hit with up to 240V depending on loading on each leg.

If you are constructor a MOV based protector designed for a USA style 240
volt circuit (e.g. NEMA 6-XX or 14-XX) you will need a mix of MOV voltages
since L-N and L-G are 120 and L-L is 240 (or 208 depending on system type).
The 480/277 volt circuits are another beast (but Square-D and Cutler-Hammer
do have protectors for them, as I am sure some others do as well).

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / |
|------------------------------------/-------------------------------------|

On Thu, 09 Aug 2007 19:44:05 -0400 Matthew L. Martin wrote:
| bud-- wrote:
|
|
| My comment was aimed at a MOV on a 120V L-N system with an open
| neutral, which can be hit with up to 240V depending on loading on each leg.
|
|
| Trying to teach poor old phil is as much a waste of time as trying to
| teach w_tom, but for different reasons. Poor old phil has no interest in
| learning and treats this ng as write only, w_tom has a religious belief.

Look in the mirror.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / |
|------------------------------------/-------------------------------------|