Huge wrote:
Jesus, what an arse. So, you reckon some wanky little surge protector
is going to handle a kiloampere lightning strike?

One posts well proven facts even demonstrated in Westinghouse and GE
papers in the 1930s. Another proves knowledge using insults and words
such as 'arse'. Clearly insults demonstrate grasp of technology.

A lurker can cry "woe is me" as Huge does. Or a lurker can learn
even from BT who must not suffer damage even though connected to
overhead wires everywhere in town. Huge speculates numbers for
lightning and then knows BT must disconnect service during
thunderstorms. Clearly no protector can provide protection. Huge
says so.

Meanwhile earthed protectors are rated for many thousands of amps and
higher. If Huge was correct, then BT disconnects all phone service
during thunderstorms because those little protectors could not work.

w_tom wrote:
Huge wrote:
Jesus, what an arse. So, you reckon some wanky little surge protector
is going to handle a kiloampere lightning strike?

One posts well proven facts even demonstrated in Westinghouse and GE
papers in the 1930s. Another proves knowledge using insults and words
such as 'arse'. Clearly insults demonstrate grasp of technology.

A lurker can cry "woe is me" as Huge does. Or a lurker can learn
even from BT who must not suffer damage even though connected to
overhead wires everywhere in town. Huge speculates numbers for
lightning and then knows BT must disconnect service during
thunderstorms. Clearly no protector can provide protection. Huge
says so.

Meanwhile earthed protectors are rated for many thousands of amps and
higher. If Huge was correct, then BT disconnects all phone service
during thunderstorms because those little protectors could not work.

The reality is that BT protects its own networks, not customer equipment

The reality is that most cables are underground these days, and poles
are only the last 100 meters.

The reality is that most lightning strikes are not direct, and only
induce a few KV at fairly high impedance into the wires. These are
easily coped with by most equipment which IS fitted with surge
suppression..and earthed.

The reality is that nothing will protect against a direct strike. In my
case it burnt out 10 meters of overhead cable completely.

However it is instructive to look at what was subsequently damaged.

- the modem died completely.
- the serial parallel card it was plugged into died completely.
- the input board and the power supply board of a computer connected by
a parallel cable to it does completely. The rest of the computer survived.
- an aerial socket connected to a bit of coax going nowhere except near
the phone line, blew out the wall.
- so did a mains socket that proved to have never had an earth,
- I had scorch marks in some carpert where a twin mains flex light cable
running to a light by the bed ran underneath it and a cable cobnnceted
to a vacuume cleaner rand above it. It jumped from commons mode mains to
the earth burning a 2mm hole in all the insulations and the carpet.

- The RCD tripped.
- The TV on standby failed - it wasn't worth fixing so I replaced it.
- My priceless revox parallel tracking deck stopped working. I got it
fixed - IC gone.

My total spend was £75 for repairs and £75 for a new telly.

The phones - POTS - survived IIRC. I am not sure whether the asnwering
machine did or not.


The printer and the modem were fixed under warranty actually. The US
robotics modems had lifetime guarantees, and tehy wer happy to send me
a new one. The HP laserjet did not, but the service engineer was a kind man.

I had no insurance.

My landlord did, and the insurance company insisted on a rewire. I
didn't complain about that. ;-)

The final reality is that most manufactires of kit that is connected too
telephone lines have a vested interest in making sure that it works
through the average thunderstorm. Yes, a proportion of kit always fails
after a bad one, but never high enough to give them bad press. And if
they take the US Robotics view, they will replace it FOC anyway.

I know because I worked in South Africa, what persistent intense
thunderstorms can do..but by bit we redesigned kit to take it till the
returns and service calls got down to an acceptable level.

All I will say is that switching stuff OFF completely during a very very
bad storm is wise..if the mains gets a strong surge, that will in
general protect that kit..the surge will go where stuff IS switched on..
probably the fridges and freezers etc..and in general it will flip the
RCD..a good reason to have an overall one as well as individuals.

As far as ADSL kit goes..well maybe you will blow it, but its got its
own stuff in there anyway, and if you get a direct strike you can kiss
it, most of your phones and a lot of other random stuff good bye. That
is why you have insurance on house contents..

On 22 Jan 2007 02:31:29 -0800, w_tom wrote:

Where is the confusion?

In your pointy little head.

Huge wrote:
On 2007-01-22, The Natural Philosopher wrote:
w_tom wrote:
Huge wrote:
Jesus, what an arse. So, you reckon some wanky little surge protector
is going to handle a kiloampere lightning strike?
One posts well proven facts even demonstrated in Westinghouse and GE
papers in the 1930s. Another proves knowledge using insults and words
such as 'arse'. Clearly insults demonstrate grasp of technology.

A lurker can cry "woe is me" as Huge does.

I'm not a lurker. You're patently a ****wit, though. And a persistent
one, judging by the comments made by others here.


Hang on a minute. *I* didn't say that - HE said it.

Or a lurker can learn
even from BT who must not suffer damage even though connected to
overhead wires everywhere in town. Huge speculates numbers for
lightning

Err, no. They're from the relevant British Standard, which has
a graph of the current flow during a strike. The vertical axis
is in units of kiloamperes, the horizontal in units of milliseconds.

The reality is that nothing will protect against a direct strike.

Quite so.

Direct strikes to overhead cabling will result in you sweeping up the
remains of your cables in the form of congealed droplets of copper.

As far as ADSL kit goes..well maybe you will blow it, but its got its
own stuff in there anyway, and if you get a direct strike you can kiss
it, most of your phones and a lot of other random stuff good bye. That
is why you have insurance on house contents..

Quite so.


See..when you respond to ME we agree!

The Natural Philosopher wrote:
The reality is that BT protects its own networks, not customer equipment

Exactly what was posted previously AND in direct contradiction to
what Natural Philosopher had posted previously. Direct lightning
strikes to BTs network (above or underground) and still BT equipment is
not damaged. Protection from direct lightning strikes is routine. How
often is phone service down for five days as BT replaces their
switching computer due to lightning damage? Never. Surge protector
does earth direct lightning strikes. Protection from direct lightning
strike is not just possible. Protection is routine.

Same solution must be earthed at the subscriber's end of that
network. Protection from direct lightning strikes - performed
routinely in BT COs, where operator wear headsets while thunderstorms
occur, commercial and cell phone transmitter sites, etc - it is about
earthing every wire that enters a building. Proper earthing means
direct lightning strikes without damage. That same protection is now
required in residences that contain transistors (ie DSL modems).

Earthed protection from direct lightning was even demonstrated in a
1950s Bodle and Gresh study from the Bell System Technical Journal
citing 100 strikes to each cable over 5 month period. Effective
protection even when using 1959 protection technology. No damage from
numerous direct lightning strikes is that common Protection is
defined by what? Earthing. Damage may occur when the protector does
not make that short connection to earthing. Damage from direct
lightning strikes means the protection 'system' was not installed - a
human failure.

Huge wrote:
I know. The indents make that clear, but I apologise if you thought
it was directed at you - you're not the FW, he is. I was replying
to both of you - he's killfiled now, so I don't see his stuff
directly.

Huge demonstrates those who will post without first learning facts.
He knows surge protectors are not effective only because he knows.
That emotion is sufficient. How emotional? Notice his proof is
provided in profanity and killfiles. As if we don't have enough
extremists who just know - Huge also wants to join that list.

Meanwhile protection is routine if properly installed and as defined
by solutions proven by generations of experience. A protector is not
protection. The protector will only be as effective as protection it
connects to. Protection is earth ground. Improperly earthing is one
typically reason for electronics damage. Effective protector makes
that short connection to earth. Single point earthing. Ineffective
protectors will not discuss earthing for obvious reasons. If informed,
then a consumer would not buy their product - that does not have a
necessary and dedicated earthing wire. Reality expressed with
technical facts, previously provided numbers, a long history of
examples, the underlying concepts, and with no profanity.

w_tom wrote:

Furthermore, POTS phone equipment does not generate 10 Khz noise (of
millivolt levels).

You often find that if you attempt to run phone and modem on the same
line they will work fine (assuming you have some DSL noise marhin
headroom) until you take the phone on or off hook. That *does* create a
burst of higher frequency noise due to the DC switching. That will often
cause a loss of DSL sync.

Andrew Gabriel has accurately described the only releveant purpose of
that filter:

Actually, it's so the phone doesn't attenuate the higher
frequency broadband data.

A small proportion of handsets (especially the older non DECT cordless
models) will also manage to demodulate some of the ADSL signal as hiss
into the audio band of the phone. I have only heard this on about three
installs (of hundreds) so far however.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

w_tom wrote:

Huge wrote:

On 2007-01-21, JohnDW wrote:

I find it better to at least try to use a single faceplate
splitter to get the signals separated as soon as possible.

..
Hear, hear. Much easier to use a faceplate splitter and go ethernet
ASAP.


1) Using a faceplate splitter lets all other phone line in the house
act as antennas for more DSL noise.

Not really, they are all connected to the filtered side of it.

2) Faceplate splitter is not as soon as possible. It is as late as
possible.

It is as soon as is legally allowed - where the line enters the
consumers master socket. All wiring prior to that belongs to the
telecoms provider and in theory should not be altered by the consumer.
(not that many of us take much notice of that restriction of course!)

3) Using 'faceplate splitters' at every phone reduces but does not
eliminate each POTS phone 'eating' a DSL signal. Each filter still

You don't use faceplate splitters at every phone. You have one and one
only at the master socket. The terminology we use for the type of
splitter one installs at each socket is a "plug in splitter" or "plug in
microfilter")

'leaks' DSL signal to a POTS phone. Each filter 'slightly reduces'
signal to the DSL modem (otherwise phone would massively reduce that
signal). Using one filter for all POTS devices means more DSL signal
from CO goes to the modem; less leaked through other filters.

Indeed. In fact the recommendation (if using more than one splitter) is
to have no more than four[1] in total (although you can have as many
POTS devices on each splitter as you want)

4) And finally, 'faceplate splitters' means many 'stubs'. Each stub

No, different terminology here...

snip stuff all are in agreement with

[1] For filters built to ITU-T Recommendation G.992.1, See BT Document
SIN 346 - http://www.sinet.bt.com/346v2p6.pdf


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Mon, 22 Jan 2007 11:26:05 +0000 someone who may be The Natural
Philosopher wrote this:-

The reality is that most cables are underground these days, and poles
are only the last 100 meters.

Indeed. My house is a few hundred metres from the telephone
exchange, but the only overhead wiring is less than 20 metres to the
pole which all the houses are connected to. From there a cable runs
down the pole to underground cables.

That is a relatively old installation, newer ones are underground
all the way.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

"David Hansen" wrote in message
...
On Mon, 22 Jan 2007 11:26:05 +0000 someone who may be The Natural
Philosopher wrote this:-

The reality is that most cables are underground these days, and poles
are only the last 100 meters.

Indeed. My house is a few hundred metres from the telephone
exchange, but the only overhead wiring is less than 20 metres to the
pole which all the houses are connected to. From there a cable runs
down the pole to underground cables.

That is a relatively old installation, newer ones are underground
all the way.


--
David Hansen, Edinburgh

This must vary by location ... perhaps country?
From my locale I can see two 'installation'. BT have placed a new pole in a
street and connected existing houses to it. The poles are inter-connected by
a cable at their tops leading to a connector box, then cables off to each
house served. Down the ways ... an-old-bungalow-with-large-garden was
renovated as a fourteen-dwelling estate with a 'posh name'; in this case a
large pole was erected by BT in a corner of the 'estate'; connected with an
overhead cable to an existing street pole then each dwelling is fed with
individual cables. It all looks quite ghastly!
Particularly as way-back the entire area was laid for cable with a, then ,
obligation for the franchisee to lay a duct ~ passing every dwelling ~ .
The developed 'estate' doesn't seem to have such connectivity , to a casual
glance. I suspect that the developer had an 'arrangement with a certain
comms supplier to make it easy for purchasers to get connected from a
certain supplier.

--

Brian

Brian Sharrock wrote:
"David Hansen" wrote in message
...
On Mon, 22 Jan 2007 11:26:05 +0000 someone who may be The Natural
Philosopher wrote this:-

The reality is that most cables are underground these days, and poles
are only the last 100 meters.
Indeed. My house is a few hundred metres from the telephone
exchange, but the only overhead wiring is less than 20 metres to the
pole which all the houses are connected to. From there a cable runs
down the pole to underground cables.

That is a relatively old installation, newer ones are underground
all the way.


--
David Hansen, Edinburgh

This must vary by location ... perhaps country?
From my locale I can see two 'installation'. BT have placed a new pole in a
street and connected existing houses to it. The poles are inter-connected by
a cable at their tops leading to a connector box, then cables off to each
house served. Down the ways ... an-old-bungalow-with-large-garden was
renovated as a fourteen-dwelling estate with a 'posh name'; in this case a
large pole was erected by BT in a corner of the 'estate'; connected with an
overhead cable to an existing street pole then each dwelling is fed with
individual cables. It all looks quite ghastly!
Particularly as way-back the entire area was laid for cable with a, then ,
obligation for the franchisee to lay a duct ~ passing every dwelling ~ .
The developed 'estate' doesn't seem to have such connectivity , to a casual
glance. I suspect that the developer had an 'arrangement with a certain
comms supplier to make it easy for purchasers to get connected from a
certain supplier.


My supply comes underground..on the far side of the road.

I have my very own pole to take it across the road.

I COULD have got he road dug up and underground put in..at my own expense...

There is some overhead trunk in the village..but most of it is
undergrounded.

BT and the power people say they are not putting in any more overhead
trunks, but they do definitely add to what they have sometimes.

In article .com,
w_tom writes
The Natural Philosopher wrote:
The reality is that BT protects its own networks, not customer equipment

Exactly what was posted previously AND in direct contradiction to
what Natural Philosopher had posted previously. Direct lightning
strikes to BTs network (above or underground) and still BT equipment is
not damaged. Protection from direct lightning strikes is routine. How
often is phone service down for five days as BT replaces their
switching computer due to lightning damage? Never. Surge protector
does earth direct lightning strikes. Protection from direct lightning
strike is not just possible. Protection is routine.

Same solution must be earthed at the subscriber's end of that
network. Protection from direct lightning strikes - performed
routinely in BT COs, where operator wear headsets while thunderstorms
occur, commercial and cell phone transmitter sites, etc - it is about
earthing every wire that enters a building. Proper earthing means
direct lightning strikes without damage. That same protection is now
required in residences that contain transistors (ie DSL modems).

Earthed protection from direct lightning was even demonstrated in a
1950s Bodle and Gresh study from the Bell System Technical Journal
citing 100 strikes to each cable over 5 month period. Effective
protection even when using 1959 protection technology. No damage from
numerous direct lightning strikes is that common Protection is
defined by what? Earthing. Damage may occur when the protector does
not make that short connection to earthing. Damage from direct
lightning strikes means the protection 'system' was not installed - a
human failure.


I think that the illustrate this argument better it isn't the "earthing"
as such, but the "shunting" and "bonding" that is inherent in lightning
protection systems so that no damaging potential differences exist that
actually do the harm!...

--
Tony Sayer

John Rumm, in article 45b5a9c7$0$8712$ed2619ec@ptn-nntp-
reader02.plus.net, says...
w_tom wrote:

....
On 2007-01-21, JohnDW wrote:

I find it better to at least try to use a single faceplate
splitter to get the signals separated as soon as possible.
....

1) Using a faceplate splitter lets all other phone line in the house
act as antennas for more DSL noise.

Not really, they are all connected to the filtered side of it.


John, I was also going to reply to w_tom's post since he
appeared to negate all my experience. I then realised he was
coming from a US wiring background so his comments were not
correct for our UK wiring practise.

For the benefit of the OP and others in the UK, some of the
comments of w_tom are not correct for the UK. We use the term
"faceplate splitter" to refer only to the type of splitter we
can install to replace the lower part of the BT master socket
faceplate. This is the first place we can (contractually)
install a filter to separate the telephone from the DSL
signals.

In the US, faceplate splitters are simply replacements for any
phone socket faceplate. They have inbuilt filters so all
standard phone sockets faceplates can be replaced by ones with
an inbuilt phone filter for a standard phone-type device. This
type of installation provides little electrical improvement
over the use of plug-in splitters. (OK, there is one less BT
plug and socket used so that is an improvement)

If you use UK style pre-filtered telephone sockets, similar to
http://www.adslnation.com/products/xtf.php, then you cannot
fit them in place of the BT master socket. They can be used in
place of user-installed secondary sockets instead of plug-in
filters, if you want a neater installation. However, this is
not the best solution, since you are still distributing the
DSL signal around your house, where it can pick-up RF noise
from the house, from switches, thermostats, and the like.

If you have an old BT master socket without the removable half
front-plate, then you could install ONE of these pre-filtered
telephone sockets next to it with a single wire pair from the
old BT master to the new splitter socket (no pin-3 ring is
needed). All your in-house wires would then be wired to the
connectors in this new socket, instead of those in the old BT
master. This will give an installation that is electrically
similar to that using the faceplate splitter.

--
JohnW.
Replace nospam with the first 3 letters of the current month
to mail me.

tony sayer wrote:
In article .com,
w_tom writes
The Natural Philosopher wrote:
The reality is that BT protects its own networks, not customer equipment
Exactly what was posted previously AND in direct contradiction to
what Natural Philosopher had posted previously. Direct lightning
strikes to BTs network (above or underground) and still BT equipment is
not damaged. Protection from direct lightning strikes is routine. How
often is phone service down for five days as BT replaces their
switching computer due to lightning damage? Never. Surge protector
does earth direct lightning strikes. Protection from direct lightning
strike is not just possible. Protection is routine.

Same solution must be earthed at the subscriber's end of that
network. Protection from direct lightning strikes - performed
routinely in BT COs, where operator wear headsets while thunderstorms
occur, commercial and cell phone transmitter sites, etc - it is about
earthing every wire that enters a building. Proper earthing means
direct lightning strikes without damage. That same protection is now
required in residences that contain transistors (ie DSL modems).

Earthed protection from direct lightning was even demonstrated in a
1950s Bodle and Gresh study from the Bell System Technical Journal
citing 100 strikes to each cable over 5 month period. Effective
protection even when using 1959 protection technology. No damage from
numerous direct lightning strikes is that common Protection is
defined by what? Earthing. Damage may occur when the protector does
not make that short connection to earthing. Damage from direct
lightning strikes means the protection 'system' was not installed - a
human failure.


I think that the illustrate this argument better it isn't the "earthing"
as such, but the "shunting" and "bonding" that is inherent in lightning
protection systems so that no damaging potential differences exist that
actually do the harm!...


I think that what constitutes a 'direct srike' is at issue.

I have seen power cables take a direct strike and survive..never a 50
pair overhead.

Most so called 'direct strikes are not to the actual wires, but to
places very near by. Yes you can get several tens of KV, and a few
hundred milliamperes..but its not the same as a Mv at 5 amperes!

There is enough impedance in the overhead line for it NOT to be the
preferred path back to earth at the exchange of course..the exchange
equipment will survive.

Its another reason BT likes to bury its cables of course..the last
couple of hundred meters of overhead, even with a direct strike, won't
do them any harm at all.

It will destroy anything and everything at the customer end of course.

Fortunately such *direct* strikes are rare. Mine is the only one in this
country I have direct knowledge of. And that was 20 years ago.
OTOH overhead power lines get struck many times in every storm..mostly
they just trip and reset. Sometimes they get burned out, or insulators
arc over and fail.

In Africa where serious thunderstorms happened every other day, and much
wiring was above ground, it was not unusual for whole swathes of phones
to be out for a day or two. They would always ring in a storm anyway.

In short indirect strikes that put a few KV on the line at a few mA are
routine, and protected against by the stuff that BT puts on its own kit
at their end, and what is built in at the customer end.

Direct strikes in this country are very very rare, and equipment
survivability is more or less a function of how far the kit is from the
strike. Mostly the strike will simply use a short section of cable which
burns out to an arc, on its way to wherever it can find ground.

JohnDW wrote:

1) Using a faceplate splitter lets all other phone line in the house
act as antennas for more DSL noise.

Not really, they are all connected to the filtered side of it.



John, I was also going to reply to w_tom's post since he
appeared to negate all my experience. I then realised he was
coming from a US wiring background so his comments were not
correct for our UK wiring practise.

I realised he was talking at crossed purposes, so thought it worth
commenting...

(he does have a bit of a "history" in this group for giving forceful
presentation of "facts" that seem to loose a bit in translation!)

If you have an old BT master socket without the removable half
front-plate, then you could install ONE of these pre-filtered
telephone sockets next to it with a single wire pair from the
old BT master to the new splitter socket (no pin-3 ring is
needed). All your in-house wires would then be wired to the
connectors in this new socket, instead of those in the old BT
master. This will give an installation that is electrically
similar to that using the faceplate splitter.

Failing that, just replace the BT master with a NTE/5 and use a
faceplate on it. Note the compatible faceplates are usually better than
the ones BT usually fit, since they often have a wired output for the
unfiltered signal as well.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

JohnDW wrote:
For the benefit of the OP and others in the UK, some of the
comments of w_tom are not correct for the UK. We use the term
"faceplate splitter" to refer only to the type of splitter we
can install to replace the lower part of the BT master socket
faceplate. This is the first place we can (contractually)
install a filter to separate the telephone from the DSL
signals.
...
If you use UK style pre-filtered telephone sockets, similar to
http://www.adslnation.com/products/xtf.php, then you cannot
fit them in place of the BT master socket. They can be used in
place of user-installed secondary sockets instead of plug-in
filters, if you want a neater installation. However, this is
not the best solution, since you are still distributing the
DSL signal around your house, where it can pick-up RF noise
from the house, from switches, thermostats, and the like.

My comments were based upon what was observed in the UK where a
'faceplate splitter' was in the room; not on a master socket.

JohnDW defines faceplate splitters, instead, only located one on the
master socket. JohnDW's post apparently clarifies that confusion.

In addition to the XTF sockets shown in
http://www.adslnation.com/products/xtf.php are other devices used in
UK that does same filter function and called a microfilter. In North
America, same devices are just called filters; come in a wide variety
of configurations from dongle like microfilter to faceplate replacement
types. Most American installations put the filter adjacent to a POTS
phone since additional losses due to 'stubs' and 'antenna noise' on
twisted par wire is typically trivial; in most situations.

Described was how I had changed some American installations to
duplicate the 'faceplate splitter on master socket' electrical circuit
- to learn from experience. Yes, it will reduce noise and distortion.
But in most every case, those advantages were not quantifiable. For
example, twist pair wire made DSL frequency noise irrelevant.

Puting the faceplate splitter on Master Socket is an electrically
superior soution.

On Tue, 23 Jan 2007 09:42:45 GMT someone who may be "Brian Sharrock"
wrote this:-

Indeed. My house is a few hundred metres from the telephone
exchange, but the only overhead wiring is less than 20 metres to the
pole which all the houses are connected to. From there a cable runs
down the pole to underground cables.

This must vary by location ... perhaps country?

My installation is in Scotland and is typical of what the Post
Office did in the 1960s.

Another house in the family in a different country, England, has an
underground telephone connection all the way to a little box inside
the front door. It is typical of 1980s installations. Other houses
in the family in the same village have overhead or underground
telephone connections, depending on when they were built.

I doubt if new estates will be built with overhead telephone
connections, but where there are new houses in an older area, or a
house in an older area is getting a new telephone line, these will
come off the existing poles rather then a new cable being laid.
Seems sensible to me.

One can spot similar eras in other connections to houses.



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Jan 23, 8:10 am, The Natural Philosopher wrote:
I think that what constitutes a 'direct srike' is at issue.:

I have seen power cables take a direct strike and survive..never a 50
pair overhead.

Most so called 'direct strikes are not to the actual wires, but to
places very near by. Yes you can get several tens of KV, and a few
hundred milliamperes..but its not the same as a Mv at 5 amperes!
...

Two golfers sought shelter during a thunderstorm when lightning
struck a nearby tree. Golfers suffered a direct strike when lightning
went down tree, up one golfer's leg, down other, and then on through
earth to distant charges. Golfers suffered severe direct strike due to
a concept called GPR. Golfers are encouraged to keep feet together
during storms; to create a single point connection to earth.

Same problem is why cattle and other four legged creatures are killed
by a direct strike when lightning strikes a nearby tree. A direct
strike conducts that current through the animal or object.

Polyphaser, a legendary company for protection, also describes a
direct lightning strike to communication equipment in a nearby
building:
http://www.polyphaser.com/ppc_TD1026.aspx
Lightning strikes somewhere across the street close
to the below grade West cable vault. ... The first line
of defense is the telco protection panel, but the panel
must be connected to a low resistance / inductance
ground. There was no adequate ground available in
the telephone room.

More than 95% of trees that suffer direct strikes do not suffer
appreciable damage as even a US Forestry Service study determined.
Direct strikes are not just the 'so rare ones' that permenantly scar a
tree. Numerous direct strikes need not leave obvious indications.

All are examples of direct strikes. Average direct strike
distributes about 20,000 amps. To protect from lightning, a minimally
sized 'whole house' protector for AC electric is 50,000 amps. That
protector and other earthing paths (other dwellings, ground wire on
pole, transformer earthing, etc) earth that transient which is why a
direct strike to one building may average less than 20,000 amps.

Telcos bury wires before those wires get to COs for many reasons
including a connection to the underground vault of 'whole house' type
protectors. That cable must first enter the underground vault so that
all wires can be earthed via protectors. Only then the cable emerges
into the building; well separated from switching computer.

But as demonstrated in a 1950s Bodle and Gresh study published in the
Bell System Technical Journal, some 100 strikes were recorded to each
cable (underground and overhead) over 5 month period.

The typical homeowner should expect maybe one serious direct strike
every seven years. This number will vary significantly and is
typically much less in UK. However the number also varies
significantly even within same town due to underground conditions such
as a nearby pipeline, conductive rock formations, etc. Being atop a
hill or in a valley makes little difference. In fact, sides of a
mountain may be more often struck then its top. More important are
geological conditions.

How important would be even better earthing or a longer lasting
(higher joule) protector? Neighborhood history is one factor to
consider.

Point is that direct strikes to household electronics can even occur
when different utilities share different earthing electrodes. Like
cattle and those golfers, a nearby strike to a tree would then be a
direct strike to equipment inside the dwelling. Down tree, up one
ground electrode, across house destructively via household appliances,
down other electrode, then onward through earth. Human saw a direct
strike to a tree. He learned later it was also a direct strike through
his appliances because dwelling was not constructed using a single
point earthing electrode.

Just another example of a direct strike.

w_tom wrote:
On Jan 23, 8:10 am, The Natural Philosopher wrote:
I think that what constitutes a 'direct srike' is at issue.:

I have seen power cables take a direct strike and survive..never a 50
pair overhead.

Most so called 'direct strikes are not to the actual wires, but to
places very near by. Yes you can get several tens of KV, and a few
hundred milliamperes..but its not the same as a Mv at 5 amperes!
...

Two golfers sought shelter during a thunderstorm when lightning
struck a nearby tree. Golfers suffered a direct strike when lightning
went down tree, up one golfer's leg, down other, and then on through
earth to distant charges. Golfers suffered severe direct strike due to
a concept called GPR. Golfers are encouraged to keep feet together
during storms; to create a single point connection to earth.

Same problem is why cattle and other four legged creatures are killed
by a direct strike when lightning strikes a nearby tree. A direct
strike conducts that current through the animal or object.

Polyphaser, a legendary company for protection, also describes a
direct lightning strike to communication equipment in a nearby
building:
http://www.polyphaser.com/ppc_TD1026.aspx
Lightning strikes somewhere across the street close
to the below grade West cable vault. ... The first line
of defense is the telco protection panel, but the panel
must be connected to a low resistance / inductance
ground. There was no adequate ground available in
the telephone room.

More than 95% of trees that suffer direct strikes do not suffer
appreciable damage as even a US Forestry Service study determined.
Direct strikes are not just the 'so rare ones' that permenantly scar a
tree. Numerous direct strikes need not leave obvious indications.

All are examples of direct strikes. Average direct strike
distributes about 20,000 amps. To protect from lightning, a minimally
sized 'whole house' protector for AC electric is 50,000 amps. That
protector and other earthing paths (other dwellings, ground wire on
pole, transformer earthing, etc) earth that transient which is why a
direct strike to one building may average less than 20,000 amps.

Telcos bury wires before those wires get to COs for many reasons
including a connection to the underground vault of 'whole house' type
protectors. That cable must first enter the underground vault so that
all wires can be earthed via protectors. Only then the cable emerges
into the building; well separated from switching computer.

But as demonstrated in a 1950s Bodle and Gresh study published in the
Bell System Technical Journal, some 100 strikes were recorded to each
cable (underground and overhead) over 5 month period.

The typical homeowner should expect maybe one serious direct strike
every seven years. This number will vary significantly and is
typically much less in UK. However the number also varies
significantly even within same town due to underground conditions such
as a nearby pipeline, conductive rock formations, etc. Being atop a
hill or in a valley makes little difference. In fact, sides of a
mountain may be more often struck then its top. More important are
geological conditions.

How important would be even better earthing or a longer lasting
(higher joule) protector? Neighborhood history is one factor to
consider.

Point is that direct strikes to household electronics can even occur
when different utilities share different earthing electrodes. Like
cattle and those golfers, a nearby strike to a tree would then be a
direct strike to equipment inside the dwelling. Down tree, up one
ground electrode, across house destructively via household appliances,
down other electrode, then onward through earth. Human saw a direct
strike to a tree. He learned later it was also a direct strike through
his appliances because dwelling was not constructed using a single
point earthing electrode.

Just another example of a direct strike.

Well I have only ever heard of one direct strike,to a house...mine.

In 56 years.

If a householder expects one every 7 years, and there are say 10 million
households, that means that there are on average 1.428 million strikes -
direct strikes to houses - every year. I make that one every 22 seconds.

On average. Now since storms typically occur on only about 20 days of
the year, that means that in those days a house recieves a direct strike
every 1.3 seconds.

Wow. Thosee internal protectors in all the gear we buy must be pretty
****ing good, taking that 50000A without a murmurs every 1.3 seconds and
soldiering on through.

Not to mention the innocent public never even noticing!

Or is a more reasonable assumption that you are in fact talking out of
your arse?.

In article . com, w_tom
writes
On Jan 23, 8:10 am, The Natural Philosopher wrote:
I think that what constitutes a 'direct srike' is at issue.:

I have seen power cables take a direct strike and survive..never a 50
pair overhead.

Most so called 'direct strikes are not to the actual wires, but to
places very near by. Yes you can get several tens of KV, and a few
hundred milliamperes..but its not the same as a Mv at 5 amperes!
...

Two golfers sought shelter during a thunderstorm when lightning
struck a nearby tree. Golfers suffered a direct strike when lightning
went down tree, up one golfer's leg, down other, and then on through
earth to distant charges. Golfers suffered severe direct strike due to
a concept called GPR. Golfers are encouraged to keep feet together
during storms; to create a single point connection to earth.

Step distance its called!...


Same problem is why cattle and other four legged creatures are killed
by a direct strike when lightning strikes a nearby tree. A direct
strike conducts that current through the animal or object.

Polyphaser, a legendary company for protection, also describes a
direct lightning strike to communication equipment in a nearby
building:
http://www.polyphaser.com/ppc_TD1026.aspx
Lightning strikes somewhere across the street close
to the below grade West cable vault. ... The first line
of defense is the telco protection panel, but the panel
must be connected to a low resistance / inductance
ground. There was no adequate ground available in
the telephone room.

More than 95% of trees that suffer direct strikes do not suffer
appreciable damage as even a US Forestry Service study determined.
Direct strikes are not just the 'so rare ones' that permenantly scar a
tree. Numerous direct strikes need not leave obvious indications.

All are examples of direct strikes. Average direct strike
distributes about 20,000 amps. To protect from lightning, a minimally
sized 'whole house' protector for AC electric is 50,000 amps. That
protector and other earthing paths (other dwellings, ground wire on
pole, transformer earthing, etc) earth that transient which is why a
direct strike to one building may average less than 20,000 amps.

Telcos bury wires before those wires get to COs for many reasons
including a connection to the underground vault of 'whole house' type
protectors. That cable must first enter the underground vault so that
all wires can be earthed via protectors. Only then the cable emerges
into the building; well separated from switching computer.

But as demonstrated in a 1950s Bodle and Gresh study published in the
Bell System Technical Journal, some 100 strikes were recorded to each
cable (underground and overhead) over 5 month period.

The typical homeowner should expect maybe one serious direct strike
every seven years. This number will vary significantly and is
typically much less in UK. However the number also varies
significantly even within same town due to underground conditions such
as a nearby pipeline, conductive rock formations, etc. Being atop a
hill or in a valley makes little difference. In fact, sides of a
mountain may be more often struck then its top. More important are
geological conditions.


Yes storms seem to follow rivers according to a local yokel who knows
more about country matters than most all;!..

How important would be even better earthing or a longer lasting
(higher joule) protector? Neighborhood history is one factor to
consider.

Point is that direct strikes to household electronics can even occur
when different utilities share different earthing electrodes. Like
cattle and those golfers, a nearby strike to a tree would then be a
direct strike to equipment inside the dwelling. Down tree, up one
ground electrode, across house destructively via household appliances,
down other electrode, then onward through earth. Human saw a direct
strike to a tree. He learned later it was also a direct strike through
his appliances because dwelling was not constructed using a single
point earthing electrode.

Just another example of a direct strike.


--
Tony Sayer

Well I have only ever heard of one direct strike,to a house...mine.

In 56 years.

If a householder expects one every 7 years, and there are say 10 million
households, that means that there are on average 1.428 million strikes -
direct strikes to houses - every year. I make that one every 22 seconds.

On average. Now since storms typically occur on only about 20 days of
the year, that means that in those days a house recieves a direct strike
every 1.3 seconds.

Wow. Thosee internal protectors in all the gear we buy must be pretty
****ing good, taking that 50000A without a murmurs every 1.3 seconds and
soldiering on through.

Not to mention the innocent public never even noticing!

Or is a more reasonable assumption that you are in fact talking out of
your arse?.





Beg to differ about the number of direct hits NP. Years ago I used to
work in a TV shop and part of that was fixing TV aerials reckon about 2
to 3 direct hits per storm. Aerial bent due to the heat current aerial
cable vaporised bricks blown out of walls other cables rendered U/S
etc....

--
Tony Sayer

tony sayer wrote:
Well I have only ever heard of one direct strike,to a house...mine.

In 56 years.

If a householder expects one every 7 years, and there are say 10 million
households, that means that there are on average 1.428 million strikes -
direct strikes to houses - every year. I make that one every 22 seconds.

On average. Now since storms typically occur on only about 20 days of
the year, that means that in those days a house recieves a direct strike
every 1.3 seconds.

Wow. Thosee internal protectors in all the gear we buy must be pretty
****ing good, taking that 50000A without a murmurs every 1.3 seconds and
soldiering on through.

Not to mention the innocent public never even noticing!

Or is a more reasonable assumption that you are in fact talking out of
your arse?.





Beg to differ about the number of direct hits NP. Years ago I used to
work in a TV shop and part of that was fixing TV aerials reckon about 2
to 3 direct hits per storm. Aerial bent due to the heat current aerial
cable vaporised bricks blown out of walls other cables rendered U/S
etc....

that isn't as high as yer man indicated tho.

Anyway the point is that mostly it jumps off somewhere else after
killing the cable.

In article , The Natural
Philosopher writes
tony sayer wrote:
Well I have only ever heard of one direct strike,to a house...mine.

In 56 years.

If a householder expects one every 7 years, and there are say 10 million
households, that means that there are on average 1.428 million strikes -
direct strikes to houses - every year. I make that one every 22 seconds.

On average. Now since storms typically occur on only about 20 days of
the year, that means that in those days a house recieves a direct strike
every 1.3 seconds.

Wow. Thosee internal protectors in all the gear we buy must be pretty
****ing good, taking that 50000A without a murmurs every 1.3 seconds and
soldiering on through.

Not to mention the innocent public never even noticing!

Or is a more reasonable assumption that you are in fact talking out of
your arse?.





Beg to differ about the number of direct hits NP. Years ago I used to
work in a TV shop and part of that was fixing TV aerials reckon about 2
to 3 direct hits per storm. Aerial bent due to the heat current aerial
cable vaporised bricks blown out of walls other cables rendered U/S
etc....

that isn't as high as yer man indicated tho.

Anyway the point is that mostly it jumps off somewhere else after
killing the cable.


One across the way from here the other year.. took the chimney down and
set fire to the loft was a direct .. saw it myself;!..

There is some software for calculating strike risk from the Furze
company. Interesting reading all the same....
--
Tony Sayer