Hello,

We've had two thunderstorms inn the last three days. I realise I am
not sure what are sensible precautions to take and what are old wives'
tales: unplug the tv and don't use the phone seem plausible but keep
away from radiators, windows, and don't have a bath? Are they good
ideas or just mad?

Our tv equipment is plugged into one of those Belkin surge protector
extension leads, as is the computer but they look untidy on the floor.
I was thinking about getting more sockets put on the ring main to tidy
up these cables. Are there any cheap surge protector sockets, or are
the extention leads the cheapest way? I see that CPC sell some sockets
but IIRC they are £14 each for the surge protection and even more for
ones that filter RFI. By the way, is the RFI filtering worth having?
Do you know of any cheaper ones? I would have thought there would be a
demand for these protecting equipment in offices and industry?

What about telephone and tv protection? Other than the extension
leads, are protected sockets available?

I was thinking about the aerial cable. If lightning strikes, the
current will have to travel down the cable to the suppressor in the
extension lead. Won't it have melted the coax by the time it gets
downstairs? Shouldn't the suppressor be as soon as the cable enters
the loft?

To complicate things even further, we live in a dip, so we have to
have the aerial on a 16' pole and even then we need a masthead
pre-amp. That amp requires a power supply, so would I be right to
think the suppressor has to be after the power supply? Would it block
the power otherwise?

Is there anything I can do to prevent the 16' pole attracting
lightning? Whilst I realise the odds of a lightning strike are 1 in
3,500,000, there was report on the news about an unexposed house in
Derby being destroyed after lighting hit their aerial.

I guess these precautions only protect against small charges from
distant lightning? I guess a direct hit would be so powerful it would
melt whatever earthing or suppressors you had connected?

One last question: is there some sort of surge protector you can fit
at the CU to protect the whole house?

Thanks,
Stephen.

We've had two thunderstorms inn the last three days. I realise I am
not sure what are sensible precautions to take and what are old wives'
tales: unplug the tv and don't use the phone seem plausible but keep
away from radiators, windows, and don't have a bath? Are they good
ideas or just mad?

Our tv equipment is plugged into one of those Belkin surge protector
extension leads, as is the computer but they look untidy on the floor.
I was thinking about getting more sockets put on the ring main to tidy
up these cables. Are there any cheap surge protector sockets, or are
the extention leads the cheapest way? I see that CPC sell some sockets
but IIRC they are £14 each for the surge protection and even more for
ones that filter RFI. By the way, is the RFI filtering worth having?
Do you know of any cheaper ones? I would have thought there would be a
demand for these protecting equipment in offices and industry?

What about telephone and tv protection? Other than the extension
leads, are protected sockets available?

I was thinking about the aerial cable. If lightning strikes, the
current will have to travel down the cable to the suppressor in the
extension lead. Won't it have melted the coax by the time it gets
downstairs? Shouldn't the suppressor be as soon as the cable enters
the loft?

To complicate things even further, we live in a dip, so we have to
have the aerial on a 16' pole and even then we need a masthead
pre-amp. That amp requires a power supply, so would I be right to
think the suppressor has to be after the power supply? Would it block
the power otherwise?

Is there anything I can do to prevent the 16' pole attracting
lightning? Whilst I realise the odds of a lightning strike are 1 in
3,500,000, there was report on the news about an unexposed house in
Derby being destroyed after lighting hit their aerial.

I guess these precautions only protect against small charges from
distant lightning? I guess a direct hit would be so powerful it would
melt whatever earthing or suppressors you had connected?

One last question: is there some sort of surge protector you can fit
at the CU to protect the whole house?


Nothing is going to stop the effects of a realy close or direct strike. Many
so called surge protectors don't actully provide much real protection anyway
because a lot of damage can, and is, caused by the currents induced in
internal wiring or even directly in the equipment.

Peter Crosland

On Jul 3, 9:54*am, Stephen wrote:
Hello,

We've had two thunderstorms inn the last three days. I realise I am
not sure what are sensible precautions to take and what are old wives'
tales: unplug the tv and don't use the phone seem plausible but keep
away from radiators, windows, and don't have a bath? Are they good
ideas or just mad?
Our tv equipment is plugged into one of those Belkin surge protector
extension leads, as is the computer but they look untidy on the floor.
I was thinking about getting more sockets put on the ring main to tidy
up these cables. Are there any cheap surge protector sockets, or are
the extention leads the cheapest way? I see that CPC sell some sockets
but IIRC they are £14 each for the surge protection and even more for
ones that filter RFI. By the way, is the RFI filtering worth having?
Do you know of any cheaper ones? I would have thought there would be a
demand for these protecting equipment in offices and industry?

What about telephone and tv protection? Other than the extension
leads, are protected sockets available?

I was thinking about the aerial cable. If lightning strikes, the
current will have to travel down the cable to the suppressor in the
extension lead. Won't it have melted the coax by the time it gets
downstairs? Shouldn't the suppressor be as soon as the cable enters
the loft?

To complicate things even further, we live in a dip, so we have to
have the aerial on a 16' pole and even then we need a masthead
pre-amp. That amp requires a power supply, so would I be right to
think the suppressor has to be after the power supply? Would it block
the power otherwise?

Is there anything I can do to prevent the 16' pole attracting
lightning? Whilst I realise the odds of a lightning strike are 1 in
3,500,000, there was report on the news about an unexposed house in
Derby being destroyed after lighting hit their aerial.

I guess these precautions only protect against small charges from
distant lightning? I guess a direct hit would be so powerful it would
melt whatever earthing or suppressors you had connected?

One last question: is there some sort of surge protector you can fit
at the CU to protect the whole house?

Thanks,
Stephen.


The idea that a surge protector csn protect againt a lightning strike
is one of those misunderstandings the manufactureres only encourage.
What they really do is introduce a fire risk and take your money.

TVs, PCs etc already have filtering built in that are orders of
magnitude more effective than a surge supporessor, but even those are
completely unprotected against a strike.


NT

In article ,
Stephen writes:
Hello,

We've had two thunderstorms inn the last three days. I realise I am
not sure what are sensible precautions to take and what are old wives'
tales: unplug the tv and don't use the phone seem plausible but keep
away from radiators, windows, and don't have a bath? Are they good
ideas or just mad?

There are two different events to protect against.
A direct hit, which is very rare.
High voltage pulses delivered via your services, due to a
nearby hit, which is more common.
(Local situation can adjust the relative importance of these.)

There are two different things to protect.
Injury and death.
Your property (both home and electronic devices).

These two orthognal sets create 4 cases, and handling each of
these should be done as a separate risk assessment.

However, in most cases, the output of a risk assessment in a
domestic situation is likely to be "change nothing".
I might only add on top of that, avoid using a landline phone
or handling the TV and aerial whilst there's a lightning storm
overhead.

See if your insurance covers damage due to lightning.
In domestic situations, that's about the only protection of
property which is generally of any use. Nothing much

Our tv equipment is plugged into one of those Belkin surge protector
extension leads, as is the computer but they look untidy on the floor.
I was thinking about getting more sockets put on the ring main to tidy
up these cables. Are there any cheap surge protector sockets, or are
the extention leads the cheapest way? I see that CPC sell some sockets
but IIRC they are £14 each for the surge protection and even more for
ones that filter RFI. By the way, is the RFI filtering worth having?
Do you know of any cheaper ones? I would have thought there would be a
demand for these protecting equipment in offices and industry?

If you do the maths, it's cheaper for the manufacturer to actually
put nothing in domestic surge protectors and then just pay out for
equipment which gets damaged.

If you want effective surge protection, that's something which has
to be designed into an installation when the wiring is laid out and
when the services are initially connected up to the house. It's not
something you can do effectively by buying a few surge protectors
and adding plugging them in to an existing domestic system.

If you're talking commercial installation and paying commercial
prices for protection, then full protection against even direct hits
is standardly provided. It would cost you many times the replacement
cost of all your domestic equipment and wiring though, which is why
it's not viable in a domestic setting.

What about telephone and tv protection? Other than the extension
leads, are protected sockets available?

Yes. It's done by having the phone cable enter the house as near as
possible to the main earthing terminal, and routed (in steel conduit
if it's any distance or unavoidably near any other wiring) to that
terminal where a surge protector is fitted (usually with gas
flashovers) and a short fat connection to the main earth terminal.

I was thinking about the aerial cable. If lightning strikes, the
current will have to travel down the cable to the suppressor in the
extension lead. Won't it have melted the coax by the time it gets
downstairs? Shouldn't the suppressor be as soon as the cable enters
the loft?

In a commercial setting where protection was required, the aerial
pole would be earthed as part of a the lightning conductor system.

To complicate things even further, we live in a dip, so we have to
have the aerial on a 16' pole and even then we need a masthead
pre-amp. That amp requires a power supply, so would I be right to
think the suppressor has to be after the power supply? Would it block
the power otherwise?

The aerial wire in an incoming service, and handled like the phone
connection above, if you really want to do this properly.

Is there anything I can do to prevent the 16' pole attracting
lightning?

No, but you can make sure a strike on it is harmless, if you want
to throw lots of money at the problem.

Whilst I realise the odds of a lightning strike are 1 in
3,500,000, there was report on the news about an unexposed house in
Derby being destroyed after lighting hit their aerial.

I guess these precautions only protect against small charges from
distant lightning? I guess a direct hit would be so powerful it would
melt whatever earthing or suppressors you had connected?

This goes back to what I said at the beginning. You have to decide
which type of event you are trying to protect against. You can do
both, but unless you have several million quid of electronics, such
as a local area phone exchange in your home, it's unlikely to be
worthwhile.

BTW, BT equipment takes about 600 lightning strikes a day, across
the UK.

One last question: is there some sort of surge protector you can fit
at the CU to protect the whole house?

Depends on how all your services are routed.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Stephen wrote:
Hello,

We've had two thunderstorms inn the last three days. I realise I am
not sure what are sensible precautions to take and what are old wives'
tales: unplug the tv and don't use the phone seem plausible but keep
away from radiators, windows, and don't have a bath? Are they good
ideas or just mad?

Our tv equipment is plugged into one of those Belkin surge protector
extension leads, as is the computer but they look untidy on the floor.

I don't believe these surge protectors do much except for con people out of
a few extra quid for a 4-gang extention lead. I bet if you took one apart
there would be little more than a couple of capacitors and an inductor or
two to act as dampers, which would cost pence.

They're a bit like the revolutionary "soft eject" of tape decks twenty years
or so ago which consisted of a gob of rocol snotty grease on the mechanism
to load it and has been used on tuning inductors since the 60's Everyone
thought they were really innovative!

The switched mode PSU found in PC's will smooth out any voltage surges
anyway, so the surge protecting sockets are moot! I've never heard of
anyone's PC from crashing because of a voltage spike.

Davey wrote:
The switched mode PSU found in PC's will smooth out any voltage surges
anyway, so the surge protecting sockets are moot! I've never heard of
anyone's PC from crashing because of a voltage spike.

Depends how crap the power supply is and how the intensity of the last
and final noise it made before its caps spewed the guts. A spike will
trigger that, and the customer will make the journey back to PC World
for the surge protector for their next attempt at IT.

--
Adrian C

Davey wibbled:

Stephen wrote:
Hello,

We've had two thunderstorms inn the last three days. I realise I am
not sure what are sensible precautions to take and what are old wives'
tales: unplug the tv and don't use the phone seem plausible but keep
away from radiators, windows, and don't have a bath? Are they good
ideas or just mad?

Our tv equipment is plugged into one of those Belkin surge protector
extension leads, as is the computer but they look untidy on the floor.

I don't believe these surge protectors do much except for con people out
of a few extra quid for a 4-gang extention lead. I bet if you took one
apart there would be little more than a couple of capacitors and an
inductor or two to act as dampers, which would cost pence.


Agree. Back in 1986, when I was at York Uni, they used to have terrible
problems with induction from nearby lightening on the bundles of overhead
RS232 cabling in the walkway roofs.

The RS surge protectors were useless.

So I got a summer job designing some new ones. IIRC the RS product certainly
contained a gas tube and a varistor of some sort but not much else.

I set up a test rig using a van de Graff in the physics dept and a test
board with sacrifical 232 driver chips (cheaper than blowing up a Wyse
terminal).

The RS ones blew the line driver chip after one strike.

By the time I'd finished I had a fairly cheap circuit based on the same gas
tube and similar varistor, but augmented with resistors, capacitors and a
high power zener, the zener being the component that made the difference.

After some tweaking I could present more than a dozen direct strikes from
the van de Graaf before the chips showed any signs of suffering, so it was
deem a success. I dare say, it took the RS232 out of spec, but it could
still run at 19200 which was good enough for the job.

Guess what next summer's job was

They're a bit like the revolutionary "soft eject" of tape decks twenty
years or so ago which consisted of a gob of rocol snotty grease on the
mechanism to load it and has been used on tuning inductors since the 60's
Everyone thought they were really innovative!

Tim S wrote:


Guess what next summer's job was


A "soft eject" tape mechanism?

Lightning rod holder?

Adrian C wrote:
Davey wrote:
The switched mode PSU found in PC's will smooth out any voltage
surges anyway, so the surge protecting sockets are moot! I've never
heard of anyone's PC from crashing because of a voltage spike.

Depends how crap the power supply is and how the intensity of the last
and final noise it made before its caps spewed the guts. A spike will
trigger that, and the customer will make the journey back to PC World
for the surge protector for their next attempt at IT.

Kerching

Tim S wrote:

Guess what next summer's job was

Designing a "soft eject" tape mechanism?

Lightning rod holder?

Davey wrote:

The switched mode PSU found in PC's will smooth out any voltage surges
anyway, so the surge protecting sockets are moot! I've never heard of
anyone's PC from crashing because of a voltage spike.

I have rebuilt a few for people following damage from non direct
lightening strikes. The main vector for damage usually being internal
dial up modems rather than the mains supply. Usually its just the line
interface side of the modem that goes tits up, but on a few occasions
has done more damage.

One took out the internal modem plus 4 of the five phones in the house.

Another one where half the PC was killed... that seemed to be a surge
that killed the PSU (so probably mains carried this time) in such a a
way that it failed with a high voltage output. That took out the mobo,
ram, and optical drives, plus an attached USB scanner. The hard drive
survived however. We put that one back with a line interactive UPS on
the supply and then realised that the quality of the mains supply always
had been appalling. The UPS was intervening many times a day to correct
all sorts of problems including under and over voltages. (place was out
in the sticks with a few adjacent industrial/farming operations)


--
Cheers,

John.

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

"Stephen" wrote in message
...
....
To complicate things even further, we live in a dip, so we have to
have the aerial on a 16' pole and even then we need a masthead
pre-amp. That amp requires a power supply, so would I be right to
think the suppressor has to be after the power supply? Would it block
the power otherwise?

Is there anything I can do to prevent the 16' pole attracting
lightning? ...

Put taller metal poles with sharp spikes on top on the hills around the dip.

Colin Bignell

On Fri, 3 Jul 2009 14:36:58 +0100, "nightjar" cpb@insert my surname
here.me.uk had this to say:


"Stephen" wrote in message
.. .
...
To complicate things even further, we live in a dip, so we have to
have the aerial on a 16' pole and even then we need a masthead
pre-amp. That amp requires a power supply, so would I be right to
think the suppressor has to be after the power supply? Would it block
the power otherwise?

Is there anything I can do to prevent the 16' pole attracting
lightning? ...

Put taller metal poles with sharp spikes on top on the hills around the dip.

The Furse website quotes some US study which reckons that blunt air
terminals are more effective than sharp ones.

--
Frank Erskine

Davey wibbled:

Tim S wrote:

Guess what next summer's job was

Designing a "soft eject" tape mechanism?

Lightning rod holder?



No - making 100+ of the bloody things (having made quite a few the previous
year and they'd been in service without incident).

Now that was a boring, but well paid 3 months

On Jul 3, 4:54 am, Stephen wrote:
We've had two thunderstorms inn the last three days. I realise I am
not sure what are sensible precautions to take and what are old wives'
tales: unplug the tv and don't use the phone seem plausible but keep
away from radiators, windows, and don't have a bath? Are they good
ideas or just mad?

Appreciate what useful protectors do. From the NIST:
You cannot really suppress a surge altogether, nor
"arrest" it. What these protective devices do is
neither suppress nor arrest a surge, but simply
divert it to ground, where it can do no harm.

How does that Belkin 'divert' without a short connection to earth?
It doesn't. Which is why its manufacturer's numeric specs also do not
claim protection.

When damage cannot happen, the protectors are located as close to
earth as possible. A surge diverted to earth before entering the
building does not go hunting for earth, destructively, through
household appliances. Your telco suffers about 100 surges with every
thunderstorm. They also do not waste money on protectors adjacent to
electronics. Effective protection means every incoming wire in every
cable gets connected to earth either directly or through a protector.

Will a protector stop or absorb what three miles of sky could not?
That is how the Belkin gets recommended. That is also why your telco
does not waste money on those solutions.

Ben Franklin demonstrated the concept in 1752. Lightning seeks
earth ground. Since a wooden church steeple is an electrical
conductor, then lightning strikes the church. Unfortunately, wood is
not a perfect conductor. Therefore voltage exists. Voltage times
current defined the energy destructively dissipated in that steeple.
Franklin simply diverted lightning to earth - lightning rod. A
conductive lightning rod means near zero voltage - energy not
dissipated. Therefore energy gets dissipated harmlessly in earth.

Your solutions even to the antenna are same. You must divert the
current. Energy must is dissipated harmlessly in earth. If the surge
enters a building, it may find destructive paths via appliances.
Protection means that current does not enter the building. Protection
means energy is dissipated harmlessly in earth.

Your solution is a 'whole house' protector and earthing that both
meets and exceeds post 1990 National Electrical Code. Your phone
line already has that protector installed for free. Same concept also
used by the telco in their every CO to have no damage. Your cable
needs no protector - must be earthed directly before entering the
building. Same concept. A surge that finds earth before entering a
building need not enter the building.

Every incoming surge path must connect to single point ground before
entering the building. For example, the antenna lead must route over
and connect to that same ground before entering a building.

Fundamental to making this work is repeated by the NIST:
A very important point to keep in mind is that your
surge protector will work by diverting the surges to
ground. The best surge protection in the world can
be useless if grounding is not done properly.

How good is your protector? Only as effective as its earth ground.
How to make any protector better? Upgrade earthing and connections to
that earthing. A protector is only as effective as its earth
ground. Some solutions need no protector. But every protection
solution always requires the one critical component - single point
earth ground.

The idea that a surge protector csn protect againt a lightning strike
is one of those misunderstandings the manufactureres only encourage.
What they really do is introduce a fire risk and take your money.
Agreed, and it's not just catastrophic faliure of the sacrafisial MOVs

Case in point; look at this Belkin branded power-strip that failed after
a short time

http://myweb.tiscali.co.uk/infoweb/belkinout.jpg
http://myweb.tiscali.co.uk/infoweb/belkinin.jpg

This is rated for the full 13A continuous load and note how the
connections to the bus-bars are properly ferruled and spot-welded,
but, oh dear, look at the intervianing surge protection board,
4 blobs of finest lead-free!!
These solder blobs are supposed to pass 13A continually?
I_don't_think_so.
Fortunately the resulting dry-joint went
totally open-circuit without too much arcing and sparking.

Who agrees that a better arrangement would for the incoming
cable to be ferruled and spot welded onto the bus-bar and
the PCB to be connected to the bus-bars at a different
point?


--
Graham.

%Profound_observation%

"Frank Erskine" wrote in message
...
On Fri, 3 Jul 2009 14:36:58 +0100, "nightjar" cpb@insert my surname
here.me.uk had this to say:


"Stephen" wrote in message
. ..
...
To complicate things even further, we live in a dip, so we have to
have the aerial on a 16' pole and even then we need a masthead
pre-amp. That amp requires a power supply, so would I be right to
think the suppressor has to be after the power supply? Would it block
the power otherwise?

Is there anything I can do to prevent the 16' pole attracting
lightning? ...

Put taller metal poles with sharp spikes on top on the hills around the
dip.

The Furse website quotes some US study which reckons that blunt air
terminals are more effective than sharp ones.

In which case, I'd use both.

Colin Bignell

Frank Erskine wrote:
On Fri, 3 Jul 2009 14:36:58 +0100, "nightjar" cpb@insert my surname
here.me.uk had this to say:

"Stephen" wrote in message
...
...
To complicate things even further, we live in a dip, so we have to
have the aerial on a 16' pole and even then we need a masthead
pre-amp. That amp requires a power supply, so would I be right to
think the suppressor has to be after the power supply? Would it block
the power otherwise?

Is there anything I can do to prevent the 16' pole attracting
lightning? ...
Put taller metal poles with sharp spikes on top on the hills around the dip.

The Furse website quotes some US study which reckons that blunt air
terminals are more effective than sharp ones.

Probably depends on if you are attempting to prevent the strike in the
first place, or control its location. The pointy type are good for
spraying out charged particles to help lower the voltage gradient -
reducing the likelihood of a strike IIUC, and the rounded ones make a
better strike target.

(you know this thread is wandering into territory that might summon you
know who...)

--
Cheers,

John.

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

On Fri, 3 Jul 2009 14:28:38 UTC, westom wrote:

Oh dear. It's w_tom. He's back...

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
http://www.diybanter.com

On Fri, 3 Jul 2009 16:25:46 UTC, John Rumm
wrote:

Frank Erskine wrote:
On Fri, 3 Jul 2009 14:36:58 +0100, "nightjar" cpb@insert my surname
here.me.uk had this to say:

"Stephen" wrote in message
...
...
To complicate things even further, we live in a dip, so we have to
have the aerial on a 16' pole and even then we need a masthead
pre-amp. That amp requires a power supply, so would I be right to
think the suppressor has to be after the power supply? Would it block
the power otherwise?

Is there anything I can do to prevent the 16' pole attracting
lightning? ...
Put taller metal poles with sharp spikes on top on the hills around the dip.

The Furse website quotes some US study which reckons that blunt air
terminals are more effective than sharp ones.

Probably depends on if you are attempting to prevent the strike in the
first place, or control its location. The pointy type are good for
spraying out charged particles to help lower the voltage gradient -
reducing the likelihood of a strike IIUC, and the rounded ones make a
better strike target.

(you know this thread is wandering into territory that might summon you
know who...)

Too late...although he's on gmail now...

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
http://www.diybanter.com

On 03 Jul 2009 10:54:14 GMT, Andrew Gabriel wrote:

However, in most cases, the output of a risk assessment in a
domestic situation is likely to be "change nothing".

Not quite.

See if your insurance covers damage due to lightning.

That is what you should do and change such the lightening damage is
covered. It might be worth checking if cover is only for a direct hit
on your property or includes nearby strikes as well.

A direct hit will be knocking holes in roofs or demolishing the
chimeny along with blowing the sockets out of the walls and it's not
unknown for the cabling to "unchase" itself as well...

As far as electronics is concerned it's rarely damage via the mains.
It's induction into any connected wires that zap the relatively
unprotected and delicate input/output stages. I've got an IP camera
and network card that got fried when there was a strike about 200yds
away. They were connected by about 15' of CAT5. The camera still
works but not its ethernet port.

--
Cheers
Dave.

In article , Bob Eager
writes
On Fri, 3 Jul 2009 14:28:38 UTC, westom wrote:

Oh dear. It's w_tom. He's back...

He never went away. Just subtly morphs occasionally to make sure he
escapes killfiles. And he's still a one-eyed idiot.

--
(\__/)
(='.'=) Bunny says Windows 7 is Vi$ta reloaded.
(")_(") http://imgs.xkcd.com/comics/windows_7.png

Andrew Gabriel wrote:


There are two different events to protect against.
A direct hit, which is very rare.
High voltage pulses delivered via your services, due to a
nearby hit, which is more common.
(Local situation can adjust the relative importance of these.)

There are two different things to protect.
Injury and death.
Your property (both home and electronic devices).

These two orthognal sets create 4 cases, and handling each of
these should be done as a separate risk assessment.

This is accurate IME.

However, in most cases, the output of a risk assessment in a
domestic situation is likely to be "change nothing".
I might only add on top of that, avoid using a landline phone
or handling the TV and aerial whilst there's a lightning storm
overhead.

See if your insurance covers damage due to lightning.
In domestic situations, that's about the only protection of
property which is generally of any use. Nothing much


Yes.

If you want effective surge protection, that's something which has
to be designed into an installation when the wiring is laid out and
when the services are initially connected up to the house. It's not
something you can do effectively by buying a few surge protectors
and adding plugging them in to an existing domestic system.

Yes.

If you're talking commercial installation and paying commercial
prices for protection, then full protection against even direct hits
is standardly provided. It would cost you many times the replacement
cost of all your domestic equipment and wiring though, which is why
it's not viable in a domestic setting.

Yes.

What about telephone and tv protection? Other than the extension
leads, are protected sockets available?

Yes. It's done by having the phone cable enter the house as near as
possible to the main earthing terminal, and routed (in steel conduit
if it's any distance or unavoidably near any other wiring) to that
terminal where a surge protector is fitted (usually with gas
flashovers) and a short fat connection to the main earth terminal.

I was thinking about the aerial cable. If lightning strikes, the
current will have to travel down the cable to the suppressor in the
extension lead. Won't it have melted the coax by the time it gets
downstairs? Shouldn't the suppressor be as soon as the cable enters
the loft?

In a commercial setting where protection was required, the aerial
pole would be earthed as part of a the lightning conductor system.

To complicate things even further, we live in a dip, so we have to
have the aerial on a 16' pole and even then we need a masthead
pre-amp. That amp requires a power supply, so would I be right to
think the suppressor has to be after the power supply? Would it block
the power otherwise?

The aerial wire in an incoming service, and handled like the phone
connection above, if you really want to do this properly.

Is there anything I can do to prevent the 16' pole attracting
lightning?

No, but you can make sure a strike on it is harmless, if you want
to throw lots of money at the problem.


My experience of a _DIRECT_ strike is simply that what gets fried and
what does not is almost totally random. A few mm of spacing difference
means the arc jumps one way rather than another.

By and large I was surprised at how much kit did survive.

Most of what did not, was associated with the actual phone line that was
struck and stuff adjacent to it.

Namely the modem, the serial parallel card into which it was plugged,
the laser printer also in the parallel port which fried its input and
its power supply.

The only other items of note were two 'digital electronics' bits of kit
that were on at the time - a Revox record deck and a TV on standby. The
Revox needed a new chip, the TV I scrapped. Its possible that surge
arrestors would have protected those, as the discharge ripped round the
mains wiring and arced over in many places, needing a complete rewire. I
surmise it found the mains via the laser printer.

From personal experience here and in S Africa, the frequency of 'near'
strikes to 'real' strikes is about 20:1. With a 'real' strike all bets
are off, and the tendency is to either spend a fortune, if
uninterruptibility is what you want, or simply pay insurance.

With a close strike, you do well if you have isolated balanced inputs on
phones and antennae: This is normally the case anyway..such things
usually end up at a balun - and some sort of clamping device to limit
overvoltage as well.

Or simply regard the input devices as sacrificial, and replace as
necessary. Field engineers with loads of input cards running round in
small white vans were the S African experience.

Mains surge arrestors do no harm, but probably do no good either. The
actual energy in a close strike is not high, and is easily absorbed by
an SMPS and its RF filtering, anyway

Really the manufacturers have seen to the 'average' level of pulse
energy in most bits of kit. There's no need to duplicate their efforts,
and if its a really bad hit, frankly house fires and most of the wiring
being made unsafe are far more a problem than the odd bit of electronics
going down.

Insurance as the man says, is the answer.

As far as what to do..well shut computers down, so any power cuts don't
trash their disks.

Apart from that, don't do anything. A major direct strike will hop feet,
not inches. Its really no point in worrying about it.

In article
..com, westom writes

Your solution is a 'whole house' protector and earthing that both
meets and exceeds post 1990 National Electrical Code.

What do you think the uk in uk.d-i-y means, you complete waste of skin?

--
(\__/)
(='.'=) Bunny says Windows 7 is Vi$ta reloaded.
(")_(") http://imgs.xkcd.com/comics/windows_7.png

"Bob Eager" wrote in message
...
On Fri, 3 Jul 2009 14:28:38 UTC, westom wrote:

Hi Group

I live halfway up a hill and suffered either a direct strike or very close -
how can you tell the difference? The video recorder was first in line and
got the full treatment. The insides were melted and the digital display
blown right across the room. The video recorder was a hire one and the TV
was still OK We are now on cable which functions OK except for when their
station got hit.

Alan

Roberts wrote:

I live halfway up a hill and suffered either a direct strike or very close -
how can you tell the difference?

Please do not engage w_tom in conversation. Thanks.

--
Adrian C

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember westom saying
something like:

When damage cannot happen, the protectors are located as close to
earth as possible.
snip

Oh, do **** off. It's tedious.

Tim S wrote:

Agree. Back in 1986, when I was at York Uni, they used to have terrible
problems with induction from nearby lightening on the bundles of overhead
RS232 cabling in the walkway roofs.


Odd. A few years before all that stuff was running on current loop, and
all seemed to be fine!

Andy (Goodricke!)

Mike Tomlinson wrote:

What do you think the uk in uk.d-i-y means, you complete waste of skin?

University of Kentucky.

Andy Champ coughed up some electrons that declared:

Tim S wrote:

Agree. Back in 1986, when I was at York Uni, they used to have terrible
problems with induction from nearby lightening on the bundles of overhead
RS232 cabling in the walkway roofs.


Odd. A few years before all that stuff was running on current loop, and
all seemed to be fine!

Andy (Goodricke!)

There you go - reverse progress



They were installing fibre during my time, but I think they were running X25
or some such over it to the PADs. Hmm. Proper computers...

Tim (Wentworth, Prison Block C)

In article , Graham.
writes

This is rated for the full 13A continuous load and note how the
connections to the bus-bars are properly ferruled and spot-welded,
but, oh dear, look at the intervianing surge protection board,
4 blobs of finest lead-free!!
These solder blobs are supposed to pass 13A continually?
I_don't_think_so.

Me neither. That is extremely poor quality.

Another thing: there're only MOVs across phase and neutral. A quality
strip would have MOVs between phase/earth and neutral/earth too.

The cable restraint is crap. This is totally shoddy Chinese made junk.
Either it's fake or Belkin has allowed their quality standards to slide
alarmingly.

Fortunately the resulting dry-joint went
totally open-circuit without too much arcing and sparking.

A definite fire hazard. I think that should be taken up with trading
standards. What if someone had plugged a heater into it? The boys at
your local fire station may also be interested or be able to tell you
how to get it escalated.

Who agrees that a better arrangement would for the incoming
cable to be ferruled and spot welded onto the bus-bar and
the PCB to be connected to the bus-bars at a different
point?

It would be better, yes, but quality is so lacking elsewhere in the
construction of that strip that the only place it's fit for is the bin.

--
(\__/)
(='.'=) Bunny says Windows 7 is Vi$ta reloaded.
(")_(") http://imgs.xkcd.com/comics/windows_7.png

wibbled:

On 3 Jul,
Tim S wrote:


Tim (Wentworth, Prison Block C)

I was there the first year it was in use. My son was there the year before
they demolished it. A very cheap and nasty block compared with Goodricke
and others, they even forgot to plaster the walls.


You should have seen A and B blocks - they forgot to paint the corridor
walls too.

At least C had 13A sockets...

Always though Derwent seemed more gentile for some reason... In Wenty we
were too busy fiddling the arcade machines to be gentile ;-o

Stephen wrote:

Hello,

We've had two thunderstorms inn the last three days. I realise I am
not sure what are sensible precautions to take and what are old wives'
tales: unplug the tv and don't use the phone seem plausible but keep
away from radiators, windows, and don't have a bath? Are they good
ideas or just mad?

Our tv equipment is plugged into one of those Belkin surge protector
extension leads, as is the computer but they look untidy on the floor.
I was thinking about getting more sockets put on the ring main to tidy
up these cables. Are there any cheap surge protector sockets, or are
the extention leads the cheapest way? I see that CPC sell some sockets
but IIRC they are £14 each for the surge protection and even more for
ones that filter RFI. By the way, is the RFI filtering worth having?
Do you know of any cheaper ones? I would have thought there would be a
demand for these protecting equipment in offices and industry?

What about telephone and tv protection? Other than the extension
leads, are protected sockets available?

I was thinking about the aerial cable. If lightning strikes, the
current will have to travel down the cable to the suppressor in the
extension lead. Won't it have melted the coax by the time it gets
downstairs? Shouldn't the suppressor be as soon as the cable enters
the loft?

To complicate things even further, we live in a dip, so we have to
have the aerial on a 16' pole and even then we need a masthead
pre-amp. That amp requires a power supply, so would I be right to
think the suppressor has to be after the power supply? Would it block
the power otherwise?

Is there anything I can do to prevent the 16' pole attracting
lightning? Whilst I realise the odds of a lightning strike are 1 in
3,500,000, there was report on the news about an unexposed house in
Derby being destroyed after lighting hit their aerial.

I guess these precautions only protect against small charges from
distant lightning? I guess a direct hit would be so powerful it would
melt whatever earthing or suppressors you had connected?

One last question: is there some sort of surge protector you can fit
at the CU to protect the whole house?

Thanks,
Stephen.

I think more importantly is, what if your house is distroyed? What are
you going to do for the week before the insurance kicks in? Where will
you sleep - on the ground? What happens if you have only the pajamas
your standing in?

--
---
zaax
Frustration casues accidents: allow faster traffic to overtake.

In message , zaax
writes
Stephen wrote:

Hello,

We've had two thunderstorms inn the last three days. I realise I am
not sure what are sensible precautions to take and what are old wives'
tales: unplug the tv and don't use the phone seem plausible but keep
away from radiators, windows, and don't have a bath? Are they good
ideas or just mad?

Our tv equipment is plugged into one of those Belkin surge protector
extension leads, as is the computer but they look untidy on the floor.
I was thinking about getting more sockets put on the ring main to tidy
up these cables. Are there any cheap surge protector sockets, or are
the extention leads the cheapest way? I see that CPC sell some sockets
but IIRC they are £14 each for the surge protection and even more for
ones that filter RFI. By the way, is the RFI filtering worth having?
Do you know of any cheaper ones? I would have thought there would be a
demand for these protecting equipment in offices and industry?

What about telephone and tv protection? Other than the extension
leads, are protected sockets available?

I was thinking about the aerial cable. If lightning strikes, the
current will have to travel down the cable to the suppressor in the
extension lead. Won't it have melted the coax by the time it gets
downstairs? Shouldn't the suppressor be as soon as the cable enters
the loft?

To complicate things even further, we live in a dip, so we have to
have the aerial on a 16' pole and even then we need a masthead
pre-amp. That amp requires a power supply, so would I be right to
think the suppressor has to be after the power supply? Would it block
the power otherwise?

Is there anything I can do to prevent the 16' pole attracting
lightning? Whilst I realise the odds of a lightning strike are 1 in
3,500,000, there was report on the news about an unexposed house in
Derby being destroyed after lighting hit their aerial.

I guess these precautions only protect against small charges from
distant lightning? I guess a direct hit would be so powerful it would
melt whatever earthing or suppressors you had connected?

One last question: is there some sort of surge protector you can fit
at the CU to protect the whole house?

Thanks,
Stephen.

I think more importantly is, what if your house is distroyed? What are
you going to do for the week before the insurance kicks in?

Come up with a unified theory of everything

Where will
you sleep - on the ground?

Bricks for a pillow

What happens if you have only the pajamas
your standing in?


Hope that the cord doesn't snap ...

PJs are for wimps

--
geoff

Stephen wrote:

We've had two thunderstorms inn the last three days. I realise I am
not sure what are sensible precautions to take

Here in rural France I take no chances; it is common for people to get
fried computers / modems / phones during a thunderstorm.

If a thunderstorm approaches I simply unplug the power to the computer,
TV etc and disconnect the TV aerial and phone socket. If the storm gets
closer and looks like it is going to be directly overhead I also throw
the main breaker on the consumer unit and light a couple of candles
until it passes. Lo-tech solution but successful.

The power supply in very rural places like this seems more unstable than
in towns and the lights flicker a lot as storms approach - sometimes
killing (expensive) low energy bulbs; traditional tungsten filament are
more resistant to such abuse.

--
David in Normandy.
To e-mail you must include the password FROG on the
subject line, or it will be automatically deleted
by a filter and not reach my inbox.

"Bob Eager" wrote in message
...
On Fri, 3 Jul 2009 16:25:46 UTC, John Rumm
wrote:

Frank Erskine wrote:
On Fri, 3 Jul 2009 14:36:58 +0100, "nightjar" cpb@insert my surname
here.me.uk had this to say:

"Stephen" wrote in message
...
...
To complicate things even further, we live in a dip, so we have to
have the aerial on a 16' pole and even then we need a masthead
pre-amp. That amp requires a power supply, so would I be right to
think the suppressor has to be after the power supply? Would it block
the power otherwise?

Is there anything I can do to prevent the 16' pole attracting
lightning? ...
Put taller metal poles with sharp spikes on top on the hills around
the dip.

The Furse website quotes some US study which reckons that blunt air
terminals are more effective than sharp ones.

Probably depends on if you are attempting to prevent the strike in the
first place, or control its location. The pointy type are good for
spraying out charged particles to help lower the voltage gradient -
reducing the likelihood of a strike IIUC, and the rounded ones make a
better strike target.

(you know this thread is wandering into territory that might summon you
know who...)

Too late...although he's on gmail now...


I hadn't seen his posts in any UK group for ages; I thought he must have
died. I wonder if...

....no that's too cruel

--
Graham.

%Profound_observation%

On Sat, 04 Jul 2009 10:36:58 +0200, David in Normandy wrote:
If a thunderstorm approaches I simply unplug the power to the computer,
TV etc and disconnect the TV aerial and phone socket.

It's surprising how many folk forget the latter, I think - they'll
unplug stuff from the mains, but completely forget about other paths
such as the broadband connection...

On Jul 3, 2:17*pm, "Roberts" wrote:
I live halfway up a hill and suffered either a direct strike or very close -
how can you tell the difference? The video recorder was first in line and
got the full treatment. The insides were melted and the digital display
blown right across the room.

If you had that damage, it was not a nearby hit. It was the surge
or 'follow through current' due to that surge.

Nearby strikes may cause a long wire antenna to have thousands of
volts. So many believe this to be destructive. Then we simply connect
that surge via an NE-2 glow lamp. The milliamps conducted by that
tiny lamp reduced that thousands of volts to near zero. Why? Because
nearby strikes are easily make irrelevant. Notice that every car
radio and mobile is destroyed by a nearbly strike? Of course not.
Damage from nearby strikes is found in myths. Made irrelevant by
protection routine in all electronics.

Routine is to have direct lightning strikes and no damage. Some
foolishly believe disconnecting is effective. Not reliable. Not
necessary. Your damage is do to surge energy permitted inside the
building. That damage sounds too great to be lightning alone. Again,
a reference to 'follow through current'.

On Sat, 04 Jul 2009 10:36:58 +0200, David in Normandy wrote:

Stephen wrote:

We've had two thunderstorms inn the last three days. I realise I am
not sure what are sensible precautions to take

Here in rural France I take no chances; it is common for people to get
fried computers / modems / phones during a thunderstorm.

If a thunderstorm approaches I simply unplug the power to the computer,
TV etc and disconnect the TV aerial and phone socket. If the storm gets
closer and looks like it is going to be directly overhead I also throw
the main breaker on the consumer unit and light a couple of candles
until it passes. Lo-tech solution but successful.

Even here, village in England, I do that; also unplug the fridge/freezer,
as motors don't like stop-start.

There is a bit of protection he the W. Coast Main Line is 100m away,
with lobody gert gantries up on an embankment, so I guess that they'd get
it preferentially.

The power supply in very rural places like this seems more unstable than
in towns and the lights flicker a lot as storms approach - sometimes
killing (expensive) low energy bulbs; traditional tungsten filament are
more resistant to such abuse.


--
Peter.
The head of a pin will hold more angels if
it's been flattened with an angel-grinder.

On Jul 4, 10:58 am, Jules
wrote:
It's surprising how many folk forget the latter, I think - they'll
unplug stuff from the mains, but completely forget about other paths
such as the broadband connection...

Which is why your telco stops all phone service when thunderstorms
approach? Which is why all radio and TV stations disconnect from
their antenna and power lines to protector equipment?

Routine is to have direct lightning strike with no damage. But that
means installing solutions that costs less than the Belkin solution.
That means installed what was even well proven 100 years ago. That
means learning well proven technology that many today would rather
mock than learn.

Surge that need not enter a building to find earth ground does not
cause electronics (or light bulb) damage. Therefore your telco also
never has computer damage and need not disconnect during storms.