Are mains surge protectors needed in the UK?

Conor wrote:

In article , David Maynard says...
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.

Or don't blow at all. Sister in Law is running a washing machine and
tumble drier off an extension. THe tumble drier developed a fault this
week. THe extension cable got red hot - too hot to touch. To get that
hot it had to have exceeded the plug fuse rating. Neither the fuse in
the extension chord or the fuse in the tumble drier mains plug blew.


The "fuse" isn't an M5x25 bolt is it? ;-)

Parish

Bob Eager wrote:

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.

Ignore w_tom, his pontification has run before at lentht. He doesn't
understand the UK wiring system.

On Fri, 09 Jul 2004 12:07:50 +0100, Parish wrote:

Conor wrote:

In article , David Maynard says...
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.

Or don't blow at all. Sister in Law is running a washing machine and
tumble drier off an extension. THe tumble drier developed a fault this
week. THe extension cable got red hot - too hot to touch. To get that
hot it had to have exceeded the plug fuse rating. Neither the fuse in
the extension chord or the fuse in the tumble drier mains plug blew.


The "fuse" isn't an M5x25 bolt is it? ;-)

Thats the Commodore 64 internal fuse replacement isn't it?

Conor wrote:

In article , David Maynard says...

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.


Or don't blow at all. Sister in Law is running a washing machine and
tumble drier off an extension. THe tumble drier developed a fault this
week. THe extension cable got red hot - too hot to touch. To get that
hot it had to have exceeded the plug fuse rating. Neither the fuse in
the extension chord or the fuse in the tumble drier mains plug blew.



Yeah. That can happen. Obviously, since it did If it's not sized right
the wire resistance of the extension can act as a current limiter
'protecting' the fuse.

Graham W wrote:

"Mike Tomlinson" wrote in message
...
=20
In article , w_tom
writes

[more crap from w_tom]


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

Really? Care to tell me how a lightning strike is going to discriminat=
e
between a roof-mounted lightning rod and a TV aerial? (hint: in the
UK, most houses have a roof-mounted TV aerial.)
=20
=20
I'm never one to jump to the defence of w_tom's American based
opinions

As an American myself I can testify that w-toms's opinions are unrelated =
to=20
nationality.

but I think his 'lightning rod' =3D our 'earth-spike' and thus he
is talking about the effective ground rather than the place where
the strike enters the system. AICBW 8=AC)

A lightning rod is simply an earthed conductive pole mounted atop the=20
building to provide a more attractive target for lightning and shunt the =

energy to ground.

So the question was valid and the answer would be that the lightning rod =

should be configured so it provides a lower impedance path to earth than =

the 'aerial-thru-tv-set' path and located higher than the aerial. While=20
debatable, one rule of thumb for the 'zone of protection' is a 45 degree =

cone extending downward from the rod. The antenna should also be earthed =

and equipped with a lightning arrester.



--
Graham W http://www.gcw.org.uk/ PGM-FI page updated, Graphics Tutoria=
l
WIMBORNE http://www.wessex-astro-society.freeserve.co.uk/ Wessex
Dorset UK Astro Society's Web pages, Info, Meeting Dates, Sites & Maps=

Change 'news' to 'sewn' in my Reply address to avoid my spam filter.
=20

"Parish" wrote in message
...
Strange Lad wrote:


a friend of mine has had a machine totalled by a surge following a
nearby lightning strike that shot up his phone line, in through the
modem and spaltted his mobo to hell and gone.



I thought BT master sockets, NTE5s, have a built in lightning arrestor?
Maybe they don't, or he has an old type?

Parish

Dunno. It is an old Victorian house but I don't know how old the sockets
were. All I saw was his knackered computer.

Strange lad

--
I do not consider it an insult, but rather a
compliment to be called an agnostic.
I do not pretend to know where
many ignorant men are sure --
that is all that agnosticism means.
Clarence Darrow

Yes, utility switching does cause transients. But nothing
that should overwhelm internal protection in household
appliances. If switching transients were so destructive, then
we all would be replacing RCDs, dimmer switches, and clock
radios weekly. Once numbers are applied to those switching
transients, then those transients become irrelevant.

Bob Eager wrote:
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.

Please find the manufacturer datasheet that claims surge
protectors "absorb the energy they're dealing with". Surge
protector components absorb energy just like a wire absorbs
energy. Does a wire also stop, block, or absorb surges? They
are called shunt mode devices for very good reason. The
protector does not stop, block, filter, or absorb surges - as
so often promoted by myth purveyors.

Furthermore, if a component vaporizes, then the surge
protector was defective by design - grossly undersized. MOV
manufacturers even provide charts on life expectancy. The
number and size of transients determined when the MOV has
degraded. Not vaporized. There is no part on the chart for
vaporization because that is a failure beyond what MOVs are
designed for. Surge protectors shunt every surge without
human knowledge. Eventually, MOVs degrade - and do not
vaporize.

This assumes the protector is properly sized. Since they
are not selling effective protectors, then many plug-in
protectors are so grossly undersized as to be vaporized. Then
the naive consumer recommends these ineffective and grossly
overpriced products to friends. It is how a product gets
promoted by myth purveyors. Effective (properly sized)
protectors shunt transients to earth ground without damage.
That is the difference between real world protectors and the
junk sold as plug-in protectors.

In the big city, electronics for TV and FM stations atop the
Empire State Building is struck about 25 times per year
without damage. In the WTC, that was 40 times per year. Why
no damage? Incoming lightning is earthed - and is not stopped
or absorbed by protectors or UPSes. So what is the difference
between the big city and atop a mountain? The big city
suffers more strikes in the same location. (BTW, a valley
between two mountains is just as likely to be struck. Geology
and not height more determines frequency of strike.)

That plug-in UPS offers the same protection circuit found in
power strip protectors. A plug-in UPS for surge protection
is also mythical. Notice a fundamental difference between
plug-in UPSes and building wide UPS systems. The building
wide system has the short connection to earth ground;
therefore can provide effective protection. The plug-in UPS
does not even claim (see its numerical specifications) to
provide protection from the destructive type of transient.

Michael Salem wrote:
Surge protectors (be they capacitors, varistors, or anything
else) must absorb the energy they're dealing with. Anything
physically small will vaporise and give little protection
against a direct lightning strike on the building, though
they may protect against surges from further away.

I would expect a suitable Uninterruptible Power Supply to
provide reasonable lightning protection -- some APC units
guarantee this, though you'd have to ensure that all
computers, monitors, etc. on a network are powered through
the UPC for safest results (or use fibre optic cabling
or wireless networking).

Surge protectors are probably of some use. A lightning rod
for the building is important. Personally I unplug computer
equipment from mains and phone during electrical storms
if possible, But, in a city environment, I haven't come
across lightning damage, though I've heard of it.

Obviously there are differences between a building in the
middle of a city and a house on a lone mountaintop!

Best wishes,
--
Michael Salem

A wall receptacle safety ground is not earth ground. Yes,
safety ground and earth ground do connect. But when
discussing the earthing of destructive transients, then wall
receptacle ground is just too far away from earth ground.

Wire has impedance. 18 meters of 2.5 mm copper wire may be
less than 0.2 ohms resistance. But same wire would be maybe
130 ohms impedance to a surge. Wire impedance is why a
protector must connect less than 3 meters to earth ground. If
the plug-in protector attempts to earth a trivial 100 amp
transient down that 18 meter safety ground wire, then wall
receptacle would be at something less than 13,000 volts.
Where is the protection? Does not exist because wall
receptacle safety ground is not an effective earth ground.

Ineffective plug-in protectors such as Belkin fear you
might learn these facts. Belkin and others avoid all
discussion about earthing to make their sales. No earth
ground connection (using two wire or three wire plugs) means
they don't provide effective protection.

We install surge protector to earth direct lightning
strikes. Done routinely since before WWII. Your telco does
not shut down for every thunderstorm to protect their
multi-million dollar computer. 'Whole house' type protectors
with the less than 10 foot connection to earth ground have
been proven that effective for too many generations. And yet
today, still some recommend those ineffective plug-in
protectors such as the Belkin.

Every single wire (that is all AC wires and both phone
wires) must make a connection to earth ground. Some wires are
connected directly (ie AC neutral wire). Other wires must
make that earthing connection via a surge protector. But that
connection must be less than 3 meters and must be all wires to
same earth ground.

Defined is protection from direct lightning strikes because
lightning seeks earth ground. No earth ground (or earthing
wire too long) means no effective protection. What plug-in
protectors fear you might learn: a surge protector is only as
effective as its earth ground.

Properly noted is that protection is layered. That is not
layers of protectors. That is layers of earthing. Earthing
(not the protectors) is protection. Primary protection is
provided by the utility (see pictures cited below).
Secondary protection is the building's (service entrance)
'whole house' protector. So what is a plug-in protector?
Where is that plug-in protector's nearest earth ground?
Adjacent to 'whole house' protector. So where is the
layering by a plug-in protector? No layering exists because,
at best, it can only connect to same earth ground as the
'whole house' protector. Layering for protection - the earth
ground at pole and then the earth ground at building.

Again, protection is the earth ground - not inside a
protector. Layering is defined by the earth ground; and not
by protectors. Important pictures demonstrate why the
'Primary' protector can be compromised:
http://www.tvtower.com/fpl.html

Again, every incoming utility wires must be earthed to a
single point earth ground before entering the building.
Earthed directly or earthed via a 'whole house' protector.
Protection from direct lightning strikes is about earthing.

David Maynard wrote:
The article below is misleading. They talk of earthing "all
incoming utilities" but fail to recognize that any incoming
'utility' is not simply a single wire, as evidenced by their
stating "even the CATV wire drops down 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' should be 'earthed', as they describe, but the
others are not, or else your 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 that common earth ground which, hopefully,
arcs a lightning strike to earth at that point rather than
having it find earth through the devices, or you, in the
home so lucky you end up with only a few hundreds, or
thousands, of volts transients dancing around on the home
wiring and your home equipment
with the brunt going through the arc gap suppressors.

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

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

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

'Protection' is a multistage process. You have the
'protection' on the utilities themselves, meaning the power
company equipment/line outside the home, which absorb the
brunt of most faults. Then there is the protection going
into the home, which depends on the incoming line impedance
to limit the surge. And then you have protection (or lack
thereof) from the 'remnants' left on the interior wiring.

Wall receptacle is safety ground; not earth ground - as
explained in another post in this thread. However let's
assume the plug-in protector does earth a destructive
transient via wall receptacle. Now that transient is on a
wire bundled with other wires. Induced transient is now
created by that plug-in protector. By earthing on safety
ground wire, we have now induced transients on all other
adjacent wires. What kind of protection is that?
Ineffective.

Same problem applies to the service entrance and single
point earth ground. All earthing wires must be installed from
each utility wire to earth ground separated from all other
wires. Too many installers want to be neat. They make clean
sharp bends and nylon ty-wrap all wires together. IOW they
compromise the protection 'system'. Even sharp wire bends
increase wire impedance. Earthing wires must be shorter (less
than 3 meters), no splices (which wall receptacle safety
ground wires violate), not inside metallic conduit, and
separated from all other wires.

Just more reasons why plug-in protectors are so
ineffective. Therefore plug-in protectors avoid all
discussion about earthing. They fear you might learn about
the less than 3 meter necessity. So they avoid all discussion
about earthing. They would even encourage the consumer to be
confused about safety ground verse earth ground.

Mike Tomlinson wrote:
In article , w_tom writes
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.

And in Europe, the "earth ground" on mains wiring is good,
hence plug-in surge protectors do the job they were designed
to do, shunting the surge to earth.

In the States, not all power outlets can be assumed to have
an earth connection, so plug-in surge protectors have to
shunt surges to the other phase line, which makes them vastl
less effective.

--
A. Bottom posters
Q. What's the most annoying thing on Usenet because they
complain too much and make their posts harder to read?