household ground system

[James]

..

The real question is given the level of damage described in this Switchboard
how much damage do you think would have been avoided by a set of 1KJ Movs
(as recommended by the Moron w_tom) across the power Lines ???

Dunno to tell the truth, large MOV's might have helped. I suspect by
the look of it that lightning initiated the flashover, then the arcing
was sustained for a longer time by the mains. I guess at the time of
installation might have been worth spending an extra $500 on some 80kA
rated diverters, not sure what the final cost was but would have been
over $10k. They may or may not have prevented this happening, but wont
do any harm anyway.

Phone MDF was about a metre away from this switchboard and completely
untouched, phone was working when i went on site. Shows how
unpredictable lightning can be.

Snip
Where the strike is of sufficent Magnitude to cause damage then the MOV is
going to fail in roughly the first 20nS (it is all they are typically rated
for) leaving in excess of 80nS for the Lightning to cause further
destruction.

The Danger of Morons like w_tom is that he is stupid enough to claim that
his 'whole house protection' provides 100% protection from Lightning. This
is contrary to what anyone who has seen the effects of Lightning first hand
would tell you. Unfortunately People on these Newsgroups like Arpit may not
have the experience or knowledge to assess w_toms Flawed advice and realise
that w_tom is in fact full of Crap and then fail to take reasonable
precautions as a result of the Very bad advice they have received.

yeah, I agree that some of his advice seems a little sus to me as

well. Contradictory to what some R&D people from a power protection
company said at a presentation at work too. I think some of the better
diverters (the big ones) have some value but its no substitute for
unplugging stuff when a storm is comming. If you are in a tropical
area, then lightning really is a problem, we've had a few things
damaged over the years here as have most other people in teh area.

Its certainly interesting what lightning can do anyway, good to watch
from somewhere safe too I guess a big problem with surge diverters
is you never really know when/if they've prevented any damage. They
certainly blow fuses so they do operate, but whether that prevented
any damage or not is anyones guess. A bit like the elephant repelling
rock - theres no elephants around so it must work

cheers
James

 

[Richard Freeman]

"Alan Peake" <adpeake@nospam.internode.on.net> wrote in message
news:adpeake.138.001207A1@nospam.internode.on.net...

Just on the subject of grounds, a few have quoted resistance figures for
grounding systems. How are they measuring that - i.e. between where and
where? I'm on a stand-alone solar system so I can't measure the
resistance
from my earth stake to anything else except another earth stake and that's
not
particularly low - especially in the lightning prone area I live in.
Alan

The Bad news Is The Only way I know of for Measuring Ground Resistance is
with reference to ..... ground.
When I was Servicing Telex machines the method was to measure the Resistance
of the the telex line then measure the resistance to Earth from the exchange
via the Telex line (in this way the measurement was referenced to the
exchange Earth) then subtract the line resistance from that figure.
a more common way of measuring earth resistance is referencing to the MEN
earth ..... I guess both methods are out for you ;-(

This may not be however as big an issue as you suspect with a stand alone
Solar installation Think about it .
The main Purpose of Earthing the System is in order to make sure that it
remains at Same or near same Potential as the rest of the geographical area
(the House etc) so that any Strikes that do occour are common mode ( a term
w_tom spouts regularly but does not understand ).
What this means is that although the strike may cause your Solar system to
rise maybe 10's of Thousands of Volts above 'Ground' no two parts of the
System have much potential across them ( Plug in surge arrestors actually
often do this much more effectively than 'whole house protection' and this
is why a good (there are many cheap and useless ones on the market) plug in
surge arrestor can provide superior protection) so that no insulation
breakdowns occour and therefore no damage.

in summary the purpose of Earthing a stand alone installation (and there are
some proponents who say dont bother) is to keep everything at the same
potential in a strike so that Local Earth should be Fine. The real concern
for you should be does the earth between different parts of the installation
have much resistance.

Regards
Richard Freeman

 

[w_tom]

Concepts of earth ground testing and example of earth ground
network:
http://www.leminstruments.com/pdf/LEGP.pdf (page 14)
[or]

http://leminstruments.com/grounding_tutorial/html/index.shtml
[section entitled "Measuring Ground Resistance at Cellular
Sites,Microwave and Radio Towers"]

Often when surge damage occurred, then investigation starts
with the earthing system as 'reason for failure'.
Unfortunately earthing is the art of protection. Not possible
to fully test the installation until after an event. When
failure does happen, then humans return to learn why their
failure permitted the failure.

However humans have an advantage. This stuff has been
proven effective so often; protection so well proven; that we
install good protection systems and rarely suffer damage. Lem
Instruments sells equipment to increase the odds. Damage is
how we learn from our mistakes. Richard Freeman posts a "woe
is me" defeatist attitude which is why his posts are not even
worth reading. Install effective protection - and learn from
mistakes should a failure occur. Or cry "woe is me" and learn
nothing.

Alan Peake wrote:

Just on the subject of grounds, a few have quoted resistance
figures for grounding systems. How are they measuring that - i.e.
between where and where? I'm on a stand-alone solar system so I
can't measure the resistance from my earth stake to anything else
except another earth stake and that's not particularly low -
especially in the lightning prone area I live in.
Alan

 

[Richard Freeman]

"James" <j.l@octa4.net.au> wrote in message
news:9c685cb8.0402250438.4c04fea@posting.google.com...

.

The real question is given the level of damage described in this
Switchboard
how much damage do you think would have been avoided by a set of 1KJ
Movs
(as recommended by the Moron w_tom) across the power Lines ???

Dunno to tell the truth, large MOV's might have helped. I suspect by
the look of it that lightning initiated the flashover, then the arcing
was sustained for a longer time by the mains. I guess at the time of
installation might have been worth spending an extra $500 on some 80kA
rated diverters, not sure what the final cost was but would have been
over $10k. They may or may not have prevented this happening, but wont
do any harm anyway.

Yes Flashovers tend to account for a high proportion of Damage to power
distribution systems following Lightning Strikes and MOVs need to have a
fairly high clamp voltage to avoid this same effect - in addition MOVs are
actually fairly slow to start working and Spikes still get past them so the
race is on to see wether the Flashover shorts the line out first or the MOV.
There is actually an interesting Paper on Lightning supression at:
http://plaza.ufl.edu/rakov/Fernandezetal.(1999).pdf
by amongst other people Martin Uman who is one of the leading experts on
Lightning in the world this study is by the way on an un earthed power
distribution System and I note that they support the claim that a well
earthed system (ie MEN) will be less susceptible to Lightning damage as in
the conclusion the paper Says :

"In an Actual (grounded) System, Continuing currents will tend to flow into
the System as a whole, finding their way to ground throughout the System."
and further :
"Because of the much lower impedance of the system to the low frequency
coninuing currents , compared to an arrestor, very little of the continuing
current would be discharged by the arrestor" in other words what they are
saying is that in a typical well Grounded Power distribution System an
Arrestor offers little in the way of extra Protection which is really what
my claim has been.

BTW I see I have been believing the statements made by Surge protection
Manufacturers Lightning to much - Lightning lasts in the order of mS not
nano Seconds........

Phone MDF was about a metre away from this switchboard and completely
untouched, phone was working when i went on site. Shows how
unpredictable lightning can be.

ahh but Contrary to lies told by w_tom Phone lines are not earthed there is
no reason for the Lightning to head for the Phone Lines - Lightning usually
heads in the opposite Direction that is from the Phone Lines to the Mains
Earth. In the case you have mentioned the earth would have been more than
adequately provided by the MEN.

Snip
Where the strike is of sufficent Magnitude to cause damage then the MOV
is
going to fail in roughly the first 20nS (it is all they are typically
rated
for) leaving in excess of 80nS for the Lightning to cause further
destruction.

The Danger of Morons like w_tom is that he is stupid enough to claim
that
his 'whole house protection' provides 100% protection from Lightning.
This
is contrary to what anyone who has seen the effects of Lightning first
hand
would tell you. Unfortunately People on these Newsgroups like Arpit may
not
have the experience or knowledge to assess w_toms Flawed advice and
realise
that w_tom is in fact full of Crap and then fail to take reasonable
precautions as a result of the Very bad advice they have received.

yeah, I agree that some of his advice seems a little sus to me as
well. Contradictory to what some R&D people from a power protection
company said at a presentation at work too. I think some of the better
diverters (the big ones) have some value but its no substitute for
unplugging stuff when a storm is comming. If you are in a tropical
area, then lightning really is a problem, we've had a few things
damaged over the years here as have most other people in teh area.

Heh ;-) you are being too diplomatic. I have found most if not all his
Pontfications on the Subject of Lightning protection to be at best wildly
inaccurate but more often merely Blatent Lies which he has to invent in
order to explain all the times Lightning ignores his theories and obeys the
Laws of Physics

Its certainly interesting what lightning can do anyway, good to watch
from somewhere safe too

And even Interesting cleaning up after a strike to work out what the path
and sequence of events was.

I guess a big problem with surge diverters
is you never really know when/if they've prevented any damage. They
certainly blow fuses so they do operate, but whether that prevented
any damage or not is anyones guess. A bit like the elephant repelling
rock - theres no elephants around so it must work

Too true but then again when you find Surge arrestors blown to pieces and
Equipment still damaged you have to start to wonder about how effective they
were in the first place - especially when following the path of damage from
Lightning shows that Surge arrestors across AC mains protect against damage
which is at best very rare. I have seen plenty of damage From Lightning
strikes to Phone lines (even underground lines are not immune) and building
cabling (PA systems and the like) and TV/Video repair men tell me that
damage via TV/Radio aerials is as common as chips but Lightning damage via
AC mains is in my experience ( and that of many other Techs I have spoken
to) very rare and in fact at almost every site I have visited following a
Lightning strike equipment plugged into AC mains alone has usually survived
the strike.

Regards
Richard Freemna

 

[Joe Van]

"Vermin" <Vermin@nowhere.com> wrote in message
news8jb30l7jav4tqoqj9qvq7mo7e0b3n2c99@4ax.com...

On Fri, 20 Feb 2004 11:49:56 +1100, "Joe Van"
JoeVandeletethis@atps.net> slandered:


First of all w_tom how about some answers to those questions you keep
avoiding In fact just to show what a complete and utter Ignoramous w_tom
is
I think I should provide google references for these questions :

Have you found out what a thermal Fuse is ?


Actually that was me not this tosser (though from checking the header
it appears he has been conned into using bigpond broadband too,
however he is posting from another state, look up the servers).

The odd thing is you do not seem to show up at all in the thread of the
message the link was for

And if you are still missing the point of that old argument;

Well actually you have missed the point of my argument. My amusement was
derived from the fact that w_tom thinks a Thermal fuse is used to protect
against over current whereas they are really to protect against
over-temprature.

1) Thermal fusing is recommended by MOV manufacturers to prevent fire
risk due to current limited sustained over voltage faults.

IMO the MOV is generally open circuit in the first few nS of a near/Direct
strike anyway.
In Reality the Thermal fuse is there to stop fires if the MOV is partially
destroyed or short circuited and not blown completely open as a Near/Direct
Lightning strike usually does to a MOV.

Check the

literature I can't be fucked finding it for a wanker like you.

2) Thermal fuses such as the THF-184 shown here;
http://www.allelectronics.com/cgi-bin/category.cgi?category=765
fail short circuit

???????????? Is that so ??????

so NTEs Thermal Fuses are unusual ?:
http://www.nteinc.com/specs/8000to8999/pdf/TCOs.pdf
as are Hosfelts :
http://www.hosfelt.com/en-us/dept_148.html
and Thermodiscs:
http://www.inet.co.th/cyberclub/nphisal/microtemp.html
and US electronics :
http://www.us-electronics.com/datasheets/Thermalcutofffuses.pdf
It's funny that all the therma fuses I have dealt with fail open.

In fact the odd thing is I cannot find a Thermal fuse that does go short
when tripped ? perhaps you could strain yourself and find me a Reference
somewhere ?and might I suggest you change hands before you get a cramp ?

and will not go open circuit due to over
temperature after being subject to just one 3kA 8/20ľs surge.


I have tested this. I do not care if you do not believe me. as I
wouldn't piss on you if you were on fire anyway. Burn.

Get your facts straight, and don't bother replying because I wont.

Is that don't bother replying because you wont get your facts straight ???
It is a funny thing about Newgroups how often People who speak utter crap
finish with a demand not to reply as if they want to get the last word in
but do not want to be shown up as the fools they often are.

V.
Formerly Tom L, and Bender *NOT* tom_w

Are you sure? or is this some sort of contest between you and w_tom to see
who can write the biggest pile of crap and keep a straight face???

Regards
Joe Van

 

[w_tom]

How does that thermal fuse get so hot as to trip open? Too
much current - typically due to AC electric as MOV remains in
a shorted condition having operated outside of MOV
manufacturer's operating range. IOW MOV grossly undersized
for the task is damaged, then vaporized by follow-through
currents from AC mains. So much current that MOV operates
like an exploding resistor - a completely unacceptable state.
A condition that no MOV should see because effective surge
protectors are designed "properly sized" for expected
transients. A properly sized MOV protector does not operate
outside of manufacturer datasheet specs during the transient.
Damage therefore does not happen when MOVs protector is
properly design and sized.

Once a grossly undersized MOV is damaged by a transient,
then the MOV can fall victim to higher energy from AC mains.
MOV can then cause fires; why UL1449 was created. This longer
AC mains current overheats MOVs; trips thermal fuse. When
does it get too hot? When a damaged MOV conducts too much AC
electric for too long.

Again, thermal fuse (and UL1449 that makes it necessary)
exists to protect human life from fire and does not blow to
create surge protection. Thermal fuse is for human
protection; not for transistor protection.

In normal operation, an MOV will never get hot enough from
an 8/20 usec transient. But we have plug-in protectors that
are often grossly undersized. So grossly undersized as to be
damaged by surges too small to even overwhelm existing
protection in an adjacent computer or other appliance.
Damaged protectors that had created house fires before UL1449.

Obvious to anyone with basic electrical design knowledge.
Fuse does not protect from surges. Thermal fuse exists
because a grossly undersized MOV protector (designed to
operate where MOV manufacturer did not intend MOV to operate)
has failed in an unacceptable and catastrophic manner. Fuse
blows not to protect electronics. Fuse blows to protect
humans from a defective and grossly undersized surge
protector. Surge protector is conducting too much current -
typically from AC electric - which is the energy source that
creates heat and potential house fire.

Joe Van wrote:

"Vermin" <Vermin@nowhere.com> wrote in message
news8jb30l7jav4tqoqj9qvq7mo7e0b3n2c99@4ax.com...
On Fri, 20 Feb 2004 11:49:56 +1100, "Joe Van"
JoeVandeletethis@atps.net> slandered:
Well actually you have missed the point of my argument. My
amusement was derived from the fact that w_tom thinks a Thermal
fuse is used to protect against over current whereas they are
really to protect against over-temprature.

1) Thermal fusing is recommended by MOV manufacturers to prevent
fire risk due to current limited sustained over voltage faults.

IMO the MOV is generally open circuit in the first few nS of a
near/Direct strike anyway. In Reality the Thermal fuse is there
to stop fires if the MOV is partially destroyed or short circuited
and not blown completely open as a Near/Direct Lightning strike
usually does to a MOV.
...

 

[Brian Goldsmith]

"w_tom" <w_tom1@hotmail.com> wrote

How does that thermal fuse get so hot as to trip open? Too
much current -------


***** Absolute cockyshit!!!!!!!!Tripping has nothing to do with too much
current .The thermal fuse is in intimate contact with the power
consuming item and trips when the power consuming item's temperature
exceeds the thermal fuse trip point.

Brian Goldsmith.

 

[Richard Freeman]

"w_tom" <w_tom1@hotmail.com> wrote in message
news:403D52CA.BDFC9EEF@hotmail.com...

Concepts of earth ground testing and example of earth ground
network:
http://www.leminstruments.com/pdf/LEGP.pdf (page 14)
[or]

http://leminstruments.com/grounding_tutorial/html/index.shtml
[section entitled "Measuring Ground Resistance at Cellular
Sites,Microwave and Radio Towers"]

Often when surge damage occurred, then investigation starts
with the earthing system as 'reason for failure'.
Unfortunately earthing is the art of protection. Not possible
to fully test the installation until after an event. When
failure does happen, then humans return to learn why their
failure permitted the failure.

Geez and this fool says I have a woe is me attitude ?

However humans have an advantage. This stuff has been
proven effective so often; protection so well proven; that we
install good protection systems and rarely suffer damage. Lem
Instruments sells equipment to increase the odds. Damage is
how we learn from our mistakes. Richard Freeman posts a "woe
is me" defeatist attitude which is why his posts are not even
worth reading.

Well Actually Richard Freeman Posts Factual information about the
effectiveness and Limitations of Lightning Protection which (unfortunately
for w_tom) shows up w_tom's Lies and misinformation to be the pile excretia
that they are this is the real reason w_tom ignores my posts - he knows he
is to moronic and ignorant to answer them

Install ineffective protection - and learn from
mistakes when failures occur.

Or as I advocate take sensible Precautions and understand the Limitations of
practical Lightning protection and suffer No failures at all

Regards
Richard Freeman

 

[Richard Freeman]

"Alan Peake" <adpeake@nospam.internode.on.net> wrote in message
news:adpeake.141.006ED68E@nospam.internode.on.net...

ahh but Contrary to lies told by w_tom Phone lines are not earthed there
is
no reason for the Lightning to head for the Phone Lines - Lightning
usually
heads in the opposite Direction that is from the Phone Lines to the Mains
Earth.

But if you don't have a mains earth? When my phone was installed, I had to
provide an earth stake and earth the shed that the phone was in. The next
point that the phone line get s close to ground is probably the RAM
(Remote
Area Multiplexer) which is on a post on my boundary - 600M from the shed.
The line is buried 300mm but the soil conductivity is so poor that a
lightning strike nearby could do a bit of damage.
I haven't had a problem yet but a neighbour keeps getting his answering
machine blown up in electrical storms. His line is about 5km from the
exchange.

This is actually very Classic Lightning damage and clearly shows the most
common path of Lightning damage - that is Lightning Hits Phone Line and
since the Phone line is (dont believe the Lies w_tom tells about this)
unearthed The Lightning strike heads for the nearest Earth which is usually
Mains Earth via the Answering machine. Given that your neighbour is on
Standalone power the Lightning is probably just seeking any trace of an
Earth.

Many years ago Telecom decided to run a Fibre optic cable across the
nullabour plain - now Fibre Optics are glass and dont conduct at all and the
cable was Nylon which again is non conductive but in order to locate the
cable they decided to run a metal trace through the cable.
All was well for several Months until a Thunderstorm rolled across the
Nullabour.... The Lightning strikes followed a nice straight line across the
nullbour following in a surprisingly accurate line the Cable Run - causing
quite a bit of damage to the cable in the process.

Lightning does even damage underground Cables

Can you suggest a reasonable protection scheme for him? He's also on
stand-alone power.

well in reality long experience (in the real world - Not in w_toms Fantasy
Land) shows that the only real effective protection is to unplug the
Answering machine from the Phone Line during a Thunderstorm. MOVs and Gas
discharge arrestors will provide some degree of protection for induced
currents during distant Strikes but given that the typical energy in a
Lightning Strike starts at 1,000,000,000 Joules and heads up to
10,000,000,000 Joules really when Lightning comes a calling it is pretty
well all over.

Regards
Richard Freeman

 

[Joe Van]

"Brian Goldsmith" <brian.goldsmith@nospamecho1.com.au> wrote in message
news:T7t%b.77712$Wa.44374@news-server.bigpond.net.au...

"w_tom" <w_tom1@hotmail.com> wrote

How does that thermal fuse get so hot as to trip open? Too
much current -------


***** Absolute cockyshit!!!!!!!!

well actually I have to say here that statement does not really go far
enough to describe w_toms psychotic gibbering. But then I guess given that a
more accurate description of w_tom's ravings would probably offend Parents
and upset Children that will probably have to do ;-)

Tripping has nothing to do with too much
current .The thermal fuse is in intimate contact with the power
consuming item and trips when the power consuming item's temperature
exceeds the thermal fuse trip point.

I'm sorry but expecting w_tom to understand basic Electrical Theory is a bit
like expecting a whale to grow wings and Fly.

Long demonstrated is w_tom's complete lack of understanding of basic
electrical theory or Physics. W_tom is psychotic individual who likes to
pontificate on subjects (like Lightning protection) that he actually knows
nothing about.
Of course think about it: given that the little MOVs are a fire hazard what
happens when one of w_toms Larger but still undersized 1KJ MOVs goes short
...... Must be spectacular and cause a merry little Blaze ;-)


Regards
Joe

 

[w_tom]

Discuss facts logically ... without exclamation points. The
power consuming item - the failed MOV that conducts AC
electric current - gets hot only because too much AC electric
current now flows through that damaged MOV. Where does the
heat come from? Not from an 8/20 microsecond transient. Heat
comes from the follow-through current - AC electric power.
That heat - due to excessive current - opens a thermal fuse.

Please explain where all that heat comes from if not from
too much current? Is heat created by some divine spirit you
have conjured up?
"Thermal fuse is in intimate contact with the power consuming
item" - and that item is conducting too much current. How,
pray tell, do you not understand this? Too much current
creates too much heat. Too much heat opens the thermal fuse.
Ergo, too much current opens a thermal fuse.

Brian Goldsmith wrote:

"w_tom" <w_tom1@hotmail.com> wrote
How does that thermal fuse get so hot as to trip open? Too
much current -------

***** Absolute cockyshit!!!!!!!!Tripping has nothing to do with
too much current .The thermal fuse is in intimate contact with
the power consuming item and trips when the power consuming
item's temperature exceeds the thermal fuse trip point.

 

[w_tom]

Is there anyone in this newsgroup with something more than
high science education on electricity? Anyone who can post
with technical knowledge and without personal insults? When
did too much current through a damaged component not create
too much heat?

As current increases, power (heat) increases exponentially.
P = I^2 * R. Why, pray tell, do you have problem with a
most basic electrical concept? Too much current creates too
much heat. Too much heat opens the thermal fuse. IOW thermal
fuse opens due to too much current. Even a high school
education makes this relationship obvious.

Joe Van wrote:

"Brian Goldsmith" <brian.goldsmith@nospamecho1.com.au> wrote in message
news:T7t%b.77712$Wa.44374@news-server.bigpond.net.au...
"w_tom" <w_tom1@hotmail.com> wrote
How does that thermal fuse get so hot as to trip open? Too
much current -------

well actually I have to say here that statement does not really go
far enough to describe w_toms psychotic gibbering. But then I guess
given that a more accurate description of w_tom's ravings would
probably offend Parents and upset Children that will probably have
to do ;-)
...

I'm sorry but expecting w_tom to understand basic Electrical Theory
is a bit like expecting a whale to grow wings and Fly.

Long demonstrated is w_tom's complete lack of understanding of
basic electrical theory or Physics. W_tom is psychotic individual
who likes to pontificate on subjects (like Lightning protection)
that he actually knows nothing about. Of course think about it:
given that the little MOVs are a fire hazard what happens when one
of w_toms Larger but still undersized 1KJ MOVs goes short
..... Must be spectacular and cause a merry little Blaze ;-)

 

[James Fenech]

Hi,

a thermal fuse is rated in degrees, not amperes. The thermal fuse is placed
in contact with something that gets hot (like a power transformer) but
shouldn't get too hot. When the temperature gets above the rating the fuse
blows (regardless of how much current is flowing) and, just like a fuse,
never passes current again. They are used to prevent the higher temperature
causing major damage, like shorted turns in the transformer.

James.

"w_tom" <w_tom1@hotmail.com> wrote in message
news:403EBE88.1A19FB3@hotmail.com...

Is there anyone in this newsgroup with something more than
high science education on electricity? Anyone who can post
with technical knowledge and without personal insults? When
did too much current through a damaged component not create
too much heat?

As current increases, power (heat) increases exponentially.
P = I^2 * R. Why, pray tell, do you have problem with a
most basic electrical concept? Too much current creates too
much heat. Too much heat opens the thermal fuse. IOW thermal
fuse opens due to too much current. Even a high school
education makes this relationship obvious.

Joe Van wrote:
"Brian Goldsmith" <brian.goldsmith@nospamecho1.com.au> wrote in message
news:T7t%b.77712$Wa.44374@news-server.bigpond.net.au...
"w_tom" <w_tom1@hotmail.com> wrote
How does that thermal fuse get so hot as to trip open? Too
much current -------

well actually I have to say here that statement does not really go
far enough to describe w_toms psychotic gibbering. But then I guess
given that a more accurate description of w_tom's ravings would
probably offend Parents and upset Children that will probably have
to do ;-)
...

I'm sorry but expecting w_tom to understand basic Electrical Theory
is a bit like expecting a whale to grow wings and Fly.

Long demonstrated is w_tom's complete lack of understanding of
basic electrical theory or Physics. W_tom is psychotic individual
who likes to pontificate on subjects (like Lightning protection)
that he actually knows nothing about. Of course think about it:
given that the little MOVs are a fire hazard what happens when one
of w_toms Larger but still undersized 1KJ MOVs goes short
..... Must be spectacular and cause a merry little Blaze ;-)

 

[Richard Freeman]

w_tom <w_tom1@hotmail.com> wrote in message news:<403EBE88.1A19FB3@hotmail.com>...

Is there anyone in this newsgroup with something more than
high science education on electricity? Anyone who can post
with technical knowledge and without personal insults? When
did too much current through a damaged component not create
too much heat?

Well if w_tom was not completely ignorant of electrical theory he
would know many instances where a component shorts out a power supply
while not dissipating much current itself. However w_tom has no real
world Experience and in fact even has major problems with the Theory

As current increases, power (heat) increases exponentially.
P = I^2 * R. Why, pray tell, do you have problem with a
most basic electrical concept? Too much current creates too
much heat. Too much heat opens the thermal fuse. IOW thermal
fuse opens due to too much current. Even a high school
education makes this relationship obvious.

As per usual w_tom rushes to misrepresent reality he has stated all
along that a Thermal fuse trips on too much current whereas everyone
else has pointed out that Thermal fuses trip according to Heat but now
he is squirming and twisting and pretending that he knew that all
along. BTW you still havent said what happens with your 'whole house
protection' MOV.

BTW w_tom if you dont wish to be shown up as the complete ignoramous
and fool you are might I suggest you stay away from any News group I
read....

Joe Van wrote:
"Brian Goldsmith" <brian.goldsmith@nospamecho1.com.au> wrote in message
news:T7t%b.77712$Wa.44374@news-server.bigpond.net.au...
"w_tom" <w_tom1@hotmail.com> wrote
How does that thermal fuse get so hot as to trip open? Too
much current -------

well actually I have to say here that statement does not really go
far enough to describe w_toms psychotic gibbering. But then I guess
given that a more accurate description of w_tom's ravings would
probably offend Parents and upset Children that will probably have
to do ;-)
...

I'm sorry but expecting w_tom to understand basic Electrical Theory
is a bit like expecting a whale to grow wings and Fly.

Long demonstrated is w_tom's complete lack of understanding of
basic electrical theory or Physics. W_tom is psychotic individual
who likes to pontificate on subjects (like Lightning protection)
that he actually knows nothing about. Of course think about it:
given that the little MOVs are a fire hazard what happens when one
of w_toms Larger but still undersized 1KJ MOVs goes short
..... Must be spectacular and cause a merry little Blaze ;-)

 

[w_tom]

How thermal fuse operates was posted previously. Your post
only repeats what had I had said. But the circuit is not just
a thermal fuse. Circuit is a thermal fuse that can be heated
by defective MOV. Damaged MOV is conducting too much
current. Damaged MOV gets too hot. Hot MOV blows thermal
fuse. Thermal fuse opens because it is too hot. Bottom line
- fuse blows because too much current has flowed through
circuit. Why is this so difficult to understand?

Maybe you don't understand what thermal fuse is installed to
do? Thermal fuse is located so that if too much current
passes through damaged MOV, then damaged MOV gets too hot, and
blows thermal fuse. Hot MOV does not burn down house.

In normal operation - when shunting a transient to earth -
neither MOV nor thermal fuse get hot. Hot only occurs when
MOV operates outside of design criteria. This can burn the
house down. Therefore thermal fuse blows when MOV conducts
too much current - gets too hot - could kill humans. Thermal
fuse serves one purpose - protect human life.

Now if thermal fuse does not blow due to excessive MOV
temperature, then why is fuse installed? What, pray tell,
gets too hot inside a surge protector other than grossly
undersized MOVs? There is no transfomer to get hot inside a
surge protector.

James Fenech wrote:

a thermal fuse is rated in degrees, not amperes. The thermal fuse
is placed in contact with something that gets hot (like a power
transformer) but shouldn't get too hot. When the temperature gets
above the rating the fuse blows (regardless of how much current is
flowing) and, just like a fuse, never passes current again. They
are used to prevent the higher temperature causing major damage,
like shorted turns in the transformer.

 

[Richard Freeman]

adpeake@nospam.internode.on.net (Alan Peake) wrote in message news:<adpeake.142.00216346@nospam.internode.on.net>...

well in reality long experience (in the real world - Not in w_toms Fantasy
Land) shows that the only real effective protection is to unplug the
Answering machine from the Phone Line during a Thunderstorm. MOVs and Gas
discharge arrestors will provide some degree of protection for induced
currents during distant Strikes but given that the typical energy in a
Lightning Strike starts at 1,000,000,000 Joules and heads up to
10,000,000,000 Joules really when Lightning comes a calling it is pretty
well all over.

Regards
Richard Freeman

Yeah, that seems to be the only really reliable solution. Mind you, not
one that would be recommended by certain purveyors of preotection gear

Alan

Ahh but my solutions are based on real world experience and cost a
heck of a lot less - and btw are 100% Succesful if implemented
correctly - unlike w_toms where he even has the gall to state :
"Unfortunately earthing is the art of protection. Not possible to
fully test the installation until after an event. When failure does
happen, then humans return to learn why their failure permitted the
failure."

This is patently w_toms 'out' for all the many instances where his
'whole house protection' fails to protect. In fact looking at what he
has written I can also see why he keeps denying that the MEN earth is
the best earth it is possible to get as he obviously uses the earth as
an excuse when his "whole house protection" doesnt work - admitting to
the integrity of the Earth then destroys his standard out when his
installations dont work.

I claim that if sane and Informed precautions are taken you should
have no failures due to lighting also Real world information (rather
than lies and Fantasies) will enable you to make a informed Risk
assesment for those cases where it is not possible to take complete
precautions.

Regards
Richard Freeman

 

[Joe Van]

The Top posting moron "w_tom" <w_tom1@hotmail.com> wrote in message
news:403FE117.DBB1E86A@hotmail.com...

How thermal fuse operates was posted previously.

Yep but not by w_tom !

Your post
only repeats what had I had said. But the circuit is not just
a thermal fuse. Circuit is a thermal fuse that can be heated
by defective MOV.

Ahh w_tom has never until now mentioned that the heat is generated in the
faulty MOV but I am glad to see the penny has finally dropped for w_tom ! He
has finally learnt one factual piece of Information now he merely has to
learn the Difference between a surge and a Spike:

http://groups.google.com/groups?q=w_tom+belkin&hl=en&lr=&ie=UTF-8&oe=UTF-8&s
elm=3FAB0E6D.F1E51914%40hotmail.com&rnum=8

Then explain how Lightning is a low energy event.

http://groups.google.com/groups?q=g:thl2460924250d&dq=&hl=en&lr=&ie=UTF-8&oe
=UTF-8&selm=3F672099.8AF65807%40hotmail.com&rnum=26

Next he needs to identify the direct connection between AC Mains and the
Integrated
Circuits in a modern modem ?

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=dfee1359.03
04141805.6c8c0bb2%40posting.google.com

Then figure out the Path through a PC motherboard to Earth :

http://groups.google.com/groups?q=g:thl2197306145d&dq=&hl=en&lr=&ie=UTF-8&oe
=UTF-8&selm=3D6E93C3.225651F9%40usa.net

If he had half a brain he would not have come up with this Gem typical of
his complete lack of understanding- I quote direct from the demented ravings
of w_tom ;-) :

Use a multimeter in continuity mode. Check for a connection
from some motherboard IC pins to the center AC prong. Notice
a direct connection. How lightning found earth ground through
your machine is not entirely clear

Then he really has to explain how 0.28mm^2 copper wire (phone line) povides
a much lower impedance
path than 2.5mm^2 copper wire (Power cable) and hence a better path to an
earth that does not even exsist on the phone line (except through the
charred and smoking ruin of quickly open circuited MOV/GDA)

this keeps cropping up whenever w_tom talks about Lightning damaging
Modems - geez this guy is a fool ! he keeps claiming that Lightning leaves
the MEN earth alone and heads for a nonexsistant earth on a phone Line

Tell us how long his much loved 1KJ mov lasts in a Direct Lightning strike
And how much protection it fails to provide.

then tell us what does for a living? I was accused of Slandering w_tom by a
previous poster but I maintain that you cannot slander a Fictional character
and since w_tom is ever so careful to avoid identifying himself (Probably
because he would be sued by one of his clients when his 'whole house
protection failed to protect )

Damaged MOV is conducting too much
current. Damaged MOV gets too hot. Hot MOV blows thermal
fuse. Thermal fuse opens because it is too hot. Bottom line
- fuse blows because too much current has flowed through
circuit. Why is this so difficult to understand?

Maybe you don't understand what thermal fuse is installed to
do? Thermal fuse is located so that if too much current
passes through damaged MOV, then damaged MOV gets too hot, and
blows thermal fuse. Hot MOV does not burn down house.

In normal operation - when shunting a transient to earth -
neither MOV nor thermal fuse get hot. Hot only occurs when
MOV operates outside of design criteria.

Such as during a near or Direct strike - if w_tom had seen MOVs after a
Lightning strike as often as I have he would not make this ludicrous claim -
Phone lines are Low energy circuits - typically 40mA short Circuit and 50V
O/C In other words much less than 1Watt yet following a Lightning Strike
MOVs are not merely Burnt but often blown into little pieces - where does
this energy come from ? the phone line ? Nope it is obvious that the feed
bridge for the phone line does not deliver anywhere near enough power to
cause this level of damage.
The MOVs are Destroyed (usually well before they provide any degree of
protection) by the Lightning Strike.

Keep the eductaion Happening w_tom you might actually start to understand
the principles and limitations of practical Lightning protection one day.

yours with much amusement

Joe Van

 

[Richard Freeman]

"w_tom" <w_tom1@hotmail.com> wrote in message
news:403EBDAE.33634090@hotmail.com...

Discuss facts logically ... without exclamation points. The
power consuming item - the failed MOV that conducts AC
electric current - gets hot only because too much AC electric
current now flows through that damaged MOV. Where does the
heat come from? Not from an 8/20 microsecond transient.

He just has to slip these Lies in - he just cannot resist the lure of BS
even when he is correcting (for a change) a misconception that he has held
so dearly. Lightning lasts a hell of a lot longer than 20uS even assuming
that only a single stroke occours. The real joke with these Figures is that
a MOV is barely starting to conduct within the first 8uS - a Fact that
Lightning protection manufacturers carefully avoid mentioning.
A good illustration of the duration of Induced Lightning strikes (Induced
strikes tend to be smaller than Normal) and Measurements of the
effectiveness of MOVs (they managed to blow the crap out of a 25KJ MOV) can
be found in a paper at :
http://plaza.ufl.edu/rakov/Fernandezetal.(1999).pdf
Read through the conclusions they are quite interesting ;-)

Heat
comes from the follow-through current - AC electric power.
That heat - due to excessive current - opens a thermal fuse.

Please explain where all that heat comes from if not from
too much current? Is heat created by some divine spirit you
have conjured up?

This is a good illustration of why w_tom Top posts - Brian had clearly
explained the process by which the Thermal fuse is blown but by top posting
w_tom can pretend that Brian had not explained this - Whereas in fact w_tom
suddenly adopts Brians Explanation and pretends he knew this all along.

"Thermal fuse is in intimate contact with the power consuming
item" - and that item is conducting too much current. How,
pray tell, do you not understand this?

This is classic w_tom and a Further illustration of why he only ever Top
posts - this is the first time w_tom has mentioned that the Thermal fuse is
in contact with the (blown) MOV The penny has finally dropped for the twit
and he is desperately back peddling and trying to pretend that this is what
he meant all along.

Too much current
creates too much heat. Too much heat opens the thermal fuse.
Ergo, too much current opens a thermal fuse.

Of course we can still refer to Brians original explanation :

Brian Goldsmith wrote:
"w_tom" <w_tom1@hotmail.com> wrote
How does that thermal fuse get so hot as to trip open? Too
much current -------

***** Absolute cockyshit!!!!!!!!Tripping has nothing to do with
too much current .The thermal fuse is in intimate contact with
the power consuming item and trips when the power consuming
item's temperature exceeds the thermal fuse trip point.

Regards
Richard Freeman

 

[Joe Van]

"Alan Peake" <adpeake@nospam.internode.on.net> wrote in message
news:adpeake.143.0018AA71@nospam.internode.on.net...

I claim that if sane and Informed precautions are taken you should
have no failures due to lighting also Real world information (rather
than lies and Fantasies) will enable you to make a informed Risk
assesment for those cases where it is not possible to take complete
precautions.

Regards
Richard Freeman

I suspect that thingo has had his wires crossed by reading some of the
literature put out by the LEM mob that he mentioned. I've seen some bad
technical writing, but this is appalling. Ever heard of "Inductivity" ?
Have a read at
http://leminstruments.com/grounding_tutorial/html/index.shtml
and you'll get the idea.
I'm not saying that what they are doing is incorrect but their
explanations
leave much to be desired.

Well actually the references do seem a bit .... shall we say Careless but
then like all the references w_tom comes up with it is trying to sell
something.
On the whole though it does not appear too bad - on a cursory flick through
it there are no glaring errors.

Of course it does point out a small fact that w_tom keeps carefully avoiding
and that is that the resistance to earth for a single earth stake is
considered by the NEC is less than 25 Ohms - calculate the EPR on that of a
Lightning strike of say a conservative 10,000 Amps.
You see w_tom keeps raving on about Earthing and there is a strand of truth
in some of what he says but he evidently does not take the time to read his
own references, or maybe he does but his complete lack of understanding of
electricity nad basic Physics means he does not even begin to comprehend
the finer (and vitally important) points.

Alan

well Alan I see you have taken the time to consider the points raised which
means you most likely now have a firmer understanding of Lightning
protection and its ins and outs than w_tom (unfortunately this does not
count as a compliment ;-) ) This means that I have achieved my purpose of
ensuring that people do not necessarily assume w_tom is an expert on the
subject just because he claims he is - with possibly disastrous consequences

 

[w_tom]

Is earth of 25 ohms at 60 hz and some amps also 25 ohms at
thousands of amps? Of course not. Resistance is only linear
within certain limits. No resistance remains linear -
constant - once we apply extreme voltages or currents. One
important parameter that defines a complete breakdown of
linear resistance is called breakdown voltage. The NEC only
defines continuity of earth within the current and frequency
ranges used by utilities.

Measure the resistance across a fluorescent tube. A 25 watt
tube must be on the order of 2000 ohms to conduct sufficient
AC electric currents. So why is that resistance in excess of
10 megohms? Again, resistance in earth and in that
fluorescent tube, is not constant for all electrical
parameters.

10 centimeters of air has multi-megohms of resistance. Many
kilometers of megohm resistors in series clearly means that
lightning cannot pass through air. And yet those many megohm
resistors become an excellent conductor of 2kamp or 20 kamp
lightning currents. How can this be? As megohms of air
become a good conductor, then so does 25 ohms of earth become
an even better conductor.

Lightning could travel 5 kilometers diagonally over to
earthborne charges - to complete an electric circuit. But a
shorter electrical path is 3 kilometers of air down to earth
and 4 kilometers through earth because, during the current
transient, earth become far more conductive than '25 ohms'.
This even though 300,000 multi-megohm resistors in air become
perfectly good conductors.

I never avoided that 25 ohms. A responsible person never
asked about those 25 ohms. When that earth resistance at 60
hz and a few amps becomes less, then that same soil becomes
even more conductive during a CG lightning strike. 25 ohms
verses other soils is a good indication as to how conductive
soil may be also during strike. But earth is not at 25 ohms
when conducting the most common 2 Kamp or 10 Kamp lightning
strikes. Earth, like air, becomes extremely conductive which
is why lighting seeks earth ground and which is why good earth
grounds make lightning rods and 'whole house' protectors so
effective.

Rather than criticize, please cite specific reference where
citation was misrepresented. Lem Instruments was only
provided as a reference on how earth conductivity is measured
- in the electrical domain defined by NEC. It was not cited
to sell anything. In the meantime NEC does not even define
how that 25 ohms should be measured. Earthing system does not
measure 25 ohms during the CG strike just like air does not
maintain multi-megohms of resistance.

Joe Van wrote:

Well actually the references do seem a bit .... shall we say
Careless but then like all the references w_tom comes up with
it is trying to sell something. On the whole though it does not
appear too bad - on a cursory flick through it there are no
glaring errors.

Of course it does point out a small fact that w_tom keeps carefully
avoiding and that is that the resistance to earth for a single
earth stake is considered by the NEC is less than 25 Ohms -
calculate the EPR on that of a Lightning strike of say a
conservative 10,000 Amps.
...