Are mains surge protectors needed in the UK?

Assumed is that lightning confronted everything inside the
house equally. Just not true. Based upon your description,
the circuit from cloud to earth borne charges found a good
path via those TVs. Therefore only TVs suffered a direct
lightning strike incoming and outgoing. Incoming and outgoing
are essential requirements for surge damage. If the computer
only had an incoming path and no outgoing path, then lightning
currents did not pass through nor damage computers. That
complete electrical path to earth ground is the essential
requirement for surge damage. Clearly other household
appliances did not make that same "complete electrical
circuit" connection; therefore were not damaged.

No adjacent protector that will stop, block, or absorb the
transient. An effective protection must shunt (divert,
connect, short circuit) the direct strike to earth so that the
direct strike does not find a better path via TVs. In your
case, that solution was a lightning rod (and not plug-in
protectors that cost tens of times more money per protected
appliance).

But again, first identify why lightning took that path to
earth ground through TVs and not through computers to learn
why damage occurs. First lightning passes through everything
in a circuit from cloud to earth. Only then does something
inside the TVs get damaged - even though other parts also
carries the electrical transient.

Concepts such as 'whole house' protectors and lightning rods
are long ago proven to be superior protection. Why? They
(unlike the ineffective plug-in protector) make a superior
connection to earth ground so that lightning does not find
earthing via TVs or computer.

AK wrote:
My house (in England) was struck by lightening - great big sodding hole in
the roof, and of course it was raining (doh!). My computer and everything
attached to it was safe as I had a surge protector incly telephone sockets.
Unfortunatelky I didn't have surge protectors on my 2 widescreen TV that
each had a DVD player attached to and my stereo so they all got
fried..........literally there was black scorth marks!!

They say lightening doesn't strike twice, but I have everything
on surge protectors now - Worth every penny imho

The frequency of destructive surges is about once every
eight years. What is that frequency in your neighborhood?
That is a question that only you (and your long term
neighbors) can answer. Surge damage is a function of
underlying geology, frequency of CG lightning, and a properly
wired building. Properly wired means all incoming utilities
enter at same location and use the same single point earth
ground.

What can affect your frequency of surges? How and what kind
of trees are nearby (that might act as lightning rods)?
Underground utilities such as transcontinental pipeline?
Monolithic earth means better equipotential geology and
therefore less probability of transients. Again, time to
discuss history with the neighbors.

Effective 'whole house' protectors cost about £1 per
protected appliance. Is it necessary? Only you can provide
the other numbers.

In the meantime, plug-in protectors are not effective, cost
tens of times more money per protected appliance, and are
typically undersized. No sense wasting good money on
ineffective protectors that don't even claim to protect from
the typically destructive transient. A protector is only as
effective as its earth ground - which plug-in power strip and
UPS manufacturers fear you might learn.

Lem wrote:
I don't want to take stupid risks. But I don't stupidly want to
spend money to prevent almost non-existent risks.

I don't have a surge protector on my TV or my stereo. So, do I
need one on my PC?

AK wrote:

My house (in England) was struck by lightening - great big sodding hole in
the roof, and of course it was raining (doh!). My computer and everything
attached to it was safe as I had a surge protector incly telephone sockets.
Unfortunatelky I didn't have surge protectors on my 2 widescreen TV that
each had a DVD player attached to and my stereo so they all got
fried..........literally there was black scorth marks!!

Hint: could you possibly have had the TVs connected to some wiring on
the roof?

On Thu, 08 Jul 2004 16:27:15 +0100, Harry wrote:

I do have surge protectors on my PC equipment. For an extra few quid
it seemed a good safety measure.

me too; I repair/change internal fuses in my surge protectors at least
once a year; the last time was 2weeks ago. it was so damn close
lightening hit, that my PC wake up from suspend, alarm sounded from
PCprobe, all voltages were screwed & protection shut down the machine
(even if was on surge protector!); TV shut off (recently mounted a
surge protector on it) ; real BigBANG ...

Computer first did not wanted to start few minutes & also TV few times
....later !!!! (but survived). not connected outside TV antenna preAmp
survived, but not its PSU even it was on surge protector-it got a hit
thru coax cable & practically blown inside some soldered stuff (was
some repairing next morning!)

my surge protectors payed off many many times . ..

12y ago I encountered a close lighting hit from a CLEAR sky (hardly to
believe if you do not experience that, I know). no surge protectors at
that time & had 100$ material costs to repair things in my home,
mainly TV set ! ....
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Bagpuss wrote:

On Thu, 08 Jul 2004 16:58:57 +0100, Lem wrote:


Am I being too complacent?

I've never used one. I've never had a surge blow anything
either. My next door neigbour as one for her PC, but makes SFA
difference. Of course in our house the fuse box has one of
those quick trip over fueses where even if a light bulb blows
you have to reset the trip switch, but even then its only ever
the light bulb circuit that trips.


Harry wrote:

I do have surge protectors on my PC equipment. For an extra
few quid it seemed a good safety measure.

Chances of a power surge are probably 5000 to 1. But wouldnt
you feel silly if you were that 5000th person?

At then end of the day its your call. Do you feel lucky? Just
how many thunderstorms are we having compared with last year,
and the year before?


I don't want to take stupid risks. But I don't stupidly want to
spend money to prevent almost non-existent risks.

I don't have a surge protector on my TV or my stereo. So, do I
need one on my PC?


The only time I know of a lighting strike potentially affecting
equipment round here was where I used to work. But then the lighting
hit a cable outsite, passed down into the network switch then fanned
out from there blowing several PCs and melting the switch unit and the
wall mounted box it was located in. Of course a mains surge protector
would have done nothing for that.

If you have a quick trip fuse box in the house its probably not worth
it.

Circuit breakers and fuses, quick trip or not, will not prevent equipment
faults. They are there to prevent fires after the equipment fault.

If you don't then OK your PC is saved, but your TV, HiFi, Fridge
e.t.c is screwed :-)

half_pint wrote:

How about using a plug with the correct sized fuse in it?

The proper fuse is always a good idea but fuses do not protect from power
line faults. They blow after your 'protected' device is fried and pulling
too much current as a result of it.


Probably a lot cheaper?

Probably a waste of money.

You probably have a greater chance of deing struck by
lightnening.

Lem wrote:

Stormsinger wrote:
=20
=20
modems are different. If the strike hits a telephone pole then
the resulting surge down the phone line can easily take out a
modem, and if you're unlucky your mobo as well. Usually though
your modem will act as a very expensive fuse.=20

Buy a surge protection device that also protects modems and
you should be okay. IMHO Belkin are the best, but others may
have a different view.=20

Look at it this way. A couple of years ago we had a massive
storm in our area - apparently there were 30,000 odd
lightening strikes over the county. (according to the
electricity people). Over a two week period, I replaced
several dozen modems for people who "suddenly couldn't get
online". My supplier ran out of stock! Even the local PCWorld
ran out (someone from there even phoned my business to see if
we had any modems left in stock that they could buy!!).

You can save =A330 or so and take the risk - its up to you in
the end.=20

=20
=20
=20
See this posting to a second thread started with the same posting=20
as this one.
=20
It says the following.

The article below is misleading. They talk of earthing "all incoming=20
utilities" but fail to recognize that any incoming 'utility' is not simpl=
y=20
a single wire, as evidenced by their stating "even the CATV wire drops do=
wn=20
to earth ground." It's a coax cable folks, not a 'wire', and the wire in =

the middle is not 'earthed' or else there's be no signal. It IS however, =

'protected', to some degree, by the shield, which is what's earthed.

Power lines are more problematic. True, the incoming power line 'earth'=20
should be 'earthed', as they describe, but the others are not, or else yo=
ur=20
incoming power would be a direct short to each other through this common =

'earth' point.

The 'protection' for power and signal lines is an arc gap suppressor to=20
that common earth ground which, hopefully, arcs a lightning strike to ear=
th=20
at that point rather than having it find earth through the devices, or yo=
u,=20
in the home so lucky you end up with only a few hundreds, or thousands, o=
f=20
volts transients dancing around on the home wiring and your home equipmen=
t=20
with the brunt going through the arc gap suppressors.

Now you, as a human being, are probably safe from those remaining=20
transients, unless you have your finger stuck in a socket, but electronic=
=20
devices are not as they ARE plugged into the socket. And it is those=20
transients that an in-house transient/surge suppressor is meant to deal=20
with, not 'lightning strikes' per see.

It is true that small in-house 'protectors' are essentially useless if th=
e=20
home utilities AREN'T properly protected (earthed) but the implication=20
derived from the small snippet that if the home has 'proper' incoming sur=
ge=20
suppression that it's then 'safe' for electronic devices (I.E. they're=20
sufficiently 'protected') is simply hogwash.

It should also be obvious that if the surge protector has no path to eart=
h=20
then it's function is lost, which means the outlet(s) it's plugged into=20
must have the proper earth, or it's own wired earth. I.E. Using a '3 wire=
=20
to 2 wire adapter' on a surge suppressor disables the majority of it's=20
protection.

'Protection' is a multistage process. You have the 'protection' on the=20
utilities themselves, meaning the power company equipment/line outside th=
e=20
home, which absorb the brunt of most faults. Then there is the protection=
=20
going into the home, which depends on the incoming line impedance to limi=
t=20
the surge. And then you have protection (or lack thereof) from the=20
'remnants' left on the interior wiring.



=3D=3D=3D=3D=3D=3D QUOTE =3D=3D=3D=3D=3D=3D=3D
=20
A plug-in surge protector is on the order of tens of times
more money per protected appliance. Furthermore it does not
even claim to protect from the typically destructive
transient. Protectors do not stop, block, filter, or absorb
destructive transients. Ineffective protector manufacturers
get one to wish that is how they work. In reality, the
protector is not protection. Protector and protection are two
separate components of a surge protection system. Effective
systems must include the protection. And the connection to
protection is either a hardwire (less than 3 meters) or a
protector (also part of a less than 3 meter connection).
=20
In short, the protection is called single point earth
ground. Destructive surges may enter the building seeking
earth ground. If not earthed (either by hardwire connection
or by surge protector), then the destructive surge may find a
path to earth ground via computer. One classic example is due
to a direct strike to lines highest on utility poles - AC
electric. Incoming on AC electric, through computer and its
modem, then outgoing to earth ground via phone line. Many
then *assume* the surge entered on phone line, damaged modem,
then stopped - a violation of even primary school science.
=20
Effective protection means all incoming utilities are
earthed before entering the building. All must be earthed to
the same single point earth ground. That means even the CATV
wire drops down to earth ground, connects ground block 'less
than 3 meters' to that earth ground, and only then rises back
up to enter building. Again, no surge protector required
because earthing is accomplished by a direct and short
hardwire connection.
=20
These concepts are explained further including some examples
of 'whole house' protectors for AC mains at:
"RJ-11 line protection?" on 30 Dec 2003 through 12 Jan 2004 in
pdx.computing at
http://tinyurl.com/2hl53 and
"strange problem after power surge/thunderstorm" in
comp.dcom.modems on 31 Mar 2003 at=20
http://tinyurl.com/2gumt .
=20
Additional information on how surge protectors work, how
they are rated, installed, etc was posted in:
"Opinions on Surge Protectors?" on 7 Jul 2003 in the
newsgroup alt.certification.a-plus at=20
http://tinyurl.com/l3m9 and
"Power Surge" on 29 Sept 2003 in the newsgroup
alt.comp.hardware at
http://tinyurl.com/p1rk
=20
One industry professional demonstrates how two structures
are protected. Notice every wire entering each structure
(building and tower) must first connect to single point
ground. Even the buried phone wire carries a potentially
destructive transient which is why even buried wires must
enter building at the service entrance with the 'less than 3
meter' connection to earth ground:
=20
http://www.erico.com/public/library/...es/tncr002.pdf
=20
How do we identify ineffective protectors? 1) No dedicated
connection to earth ground AND 2) manufacturer avoids all
discussion about earthing. A surge protector is only as
effective as its earth ground - the protection.
=20
Those ineffective protector manufacturers fear you might
learn about the essential earth ground AND discover that
plug-in protectors cost tens of times more money per protected
appliance.
=20
=20

On Thu, 8 Jul 2004 23:16:17 UTC, "AK" wrote:

My house (in England) was struck by lightening

Did it change colour - say from beige to white? :-)

--
Bob Eager
begin a new life...dump Windows!

On Thu, 8 Jul 2004 23:41:08 UTC, w_tom wrote:

The frequency of destructive surges is about once every
eight years. What is that frequency in your neighborhood?

Lightning isn't the only cause of surges. I've seen excessive voltage
several times over the last few years. Switching transients, etc.
--
Bob Eager
begin a new life...dump Windows!

On Thu, 08 Jul 2004 21:44:41 GMT, "JULIAN HALES"
wrote:

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Please post in the group to reply.

I had a house electrical check a few weeks back from the local council, 2
guys, well one guy and his chimp, while doing it i said i do not want any
testing or surges as i run a large lan, although pre powerd down, they said
it was a good job i told them as at the end its normal to do something and
shove a surge? of some kind around the system.

yep they usualty shove 20,000 volts around IIRC as a surge test. They
do it once in a while at work and we have to unplug all the kit from
the mains.

They said, and i knew before hand even tho switched off at the wall but
still plugged in it could have blown the lot, how true this is i dont know

Potentially yes, espesh if one of the sockets was suspect.

Never had a surge pretector in years, always thought about it but never got
round to it, ok the LAN i have is cheap old junk, but the data should i lose
it would be a proble