Are mains surge protectors needed in the UK?

Lem wrote:

Are surge protectors on the main power supply actually needed in
the UK?

w_tom is currently debating this on sci.electronics.basics and another
4 or so crossposted groups. You may all wish to go to and read that
thread too, particularly the exchanges between w_tom and Charles
Perry.

http://groups.google.com/groups?q=gr...suppressors%22


Tim
--
My last .sig was rubbish too.

"David Maynard" wrote in message
...
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.

I am sorry but you are wrong. a correct sized fuse will always protect you.

Your protected device will never be 'fried' if you use the correct fuse.
It is *impossible* unless the fuse is faulty.

The blow before the device draws enough current to be damaged, that is
how they are designed.





Probably a lot cheaper?

Probably a waste of money.

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

On Sat, 10 Jul 2004 00:42:25 +0100, "half_pint"
wrote:


"David Maynard" wrote in message
...
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.

I am sorry but you are wrong. a correct sized fuse will always protect you.

Your protected device will never be 'fried' if you use the correct fuse.
It is *impossible* unless the fuse is faulty.

The blow before the device draws enough current to be damaged, that is
how they are designed.


Another GUESS, eh?

Did you forget to consider that all computer power supplies have
a fuse, yet they can (are) still damaged? Suppose you 'd now
claim the engineers designing them don't know as well as you how
to select a fuse?

A fuse is a failsafe for damaged or otherwise compromised
equipment, not a preventative measure.

Mike Tomlinson wrote:

In article , w_tom
drooled:

Your reputation would be much enhanced and your posts would be far more
legible if you stopped top-posting and replied to each point raised,
quoting context, instead of rambling in a long, top-posted, hand-waving
rant.

Here, here. I second that.



Furthermore, many plug-in manufacturers
grossly undersized internal components. How would you know?


Many good quality European surge protectors illuminate a warning lamp to
indicate when the protective devices have degraded such that they are no
longer effective and that the protector should be replaced. Some,
including Belkin devices, also illuminate a lamp to indicate that the
protector has been connected to an outlet with a good earth.

Just like the strip outlet surge protector in my 'U.S.' bedroom.

Also just like the 'wall brick' one I have in my 'U.S.' dinette.

What w-tom fails to mention in his 'whole house' tirade is that the 'whole
house' protectors use essentially the same protective devices as the 'plug
in' protectors he so derides, albeit of larger capacity. The reason
'plug-ins' use smaller devices is because of the wiring, which all 'surge
protectors' depend on to limit the current surge. And because the
'plug-ins' are located at the computer end of the wiring, there is more
wiring resistance and, hence, a lower surge current for them to deal with.

His claim that the devices in the 'plug-ins' degrades applies equally to
his own preferred protection scheme.


Given that you in the USA tend to use for your electrical accessories
the cheapest and nastiest **** from China, it comes as no surprise that
your "surge protectors" do not carry even this basic feature.

One of these days you need to take off the 'U.S. bigot' blinders.


So again,
the plug-in protector still does not provide effective
protection.


Complete crap. As usual.

half_pint wrote:

"David Maynard" wrote in message
...
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.

I am sorry but you are wrong. a correct sized fuse will always protect you.

I am sorry you're wrong flap_paint. Semi conductor devices are blown by
excess Voltage. A fuse only senses the current.

Your protected device will never be 'fried' if you use the correct fuse.
It is *impossible* unless the fuse is faulty.

Rubbish half_faint!

The blow before the device draws enough current to be damaged, that is
how they are designed.

As said before, voltages also kills semiconductor devices. Why do you
think there are such things as electrostatic bags?

"half_pint" wrote:
"David Maynard" wrote in message
...
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.

I am sorry but you are wrong. a correct sized fuse will always protect you.

If the current is enough to melt a wire (the fuse) do you really think
it that same current can't have done any damage to your equipment?
Your electronics will be dead before the fuse is even warm.

A fuse might stop your house burning down after an electrical fault,
but it won't protect your PC from a surge.


Tim
--
My last .sig was rubbish too.

w_tom wrote:

It does not matter whether you top post or bottom post.

Yes it does. If you're going to go to the effort of writing your
massively long posts you might as well format them in a way which
makes it easy for the reader to follow the conversation.


Tim
--
My last .sig was rubbish too.

half_pint wrote:

"David Maynard" wrote in message
...

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.


I am sorry but you are wrong. a correct sized fuse will always protect you.

Your protected device will never be 'fried' if you use the correct fuse.
It is *impossible* unless the fuse is faulty.

For a robust motor, or a heating element, or other devices of that type (if
it's not actually the device itself that's at fault, as in a stalled
motor), yes. Generally because they are simple, robust, electro-mechanical
devices whose 'failure mode', that's being protected, is usually a result
of over heating and they have thermal response times slower than a fuse.
They are also relatively immune from surge remnants left over from the
entry point lightning supressors as their electrical response times are too
slow to be affected, as long as the surge does not exceed the insulation
resistance.

For electronic devices, no. And it's inherent to the nature of electronics.
By the time an electronic device is pulling excessive current whatever is
at fault inside has long since gone to the happy hunting grounds, or else
it would not be pulling excessive current. And there's nothing you can do
about it by 'sizing' the external fuse as the failed device could be a
100mw component inside a 200 watt computer where the normal operating power
fluctuations are hundreds of times larger. And even if you did have a
'constant power consumption' electronic device, for which you could
'tightly' size a fuse, electronic components can, and do, go into
catastrophic failure hundreds of times faster than a fuse can blow.

Surge -- component failure -- excessive current -- fuse blows

The blow before the device draws enough current to be damaged, that is
how they are designed.

That is certainly the myth. It is not, however, reality.

w_tom wrote:

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.

Poppycock.

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.

Setting aside your made up numbers, which are irrelevant anyway, it matters
not, from the aspect of protecting the device, what potential the 'ground'
at the protected device looks like with respect to your treasured 'earth'
as long as all conducive paths in/out of the device are clamped to it: the
device never sees any potential outside it's limits and that is all that
matters to it.

Back to your fantasy numbers, you try to invent a 13,000 volts potential
with a 100 amp transient while ignoring that the 100 amps would have to
arrive at the surge protector down one of those same 'high impedance' wires
before it begins the trip down the ground wire you use to fabricate the
13,000 volts which, of course, would mean there could not be the 100 amp
surge you pretend because the let though on the input panel lightning
suppressors is no where near 26,000 volts (or 13,000 either).

What you have inadvertently done is provide the reason why 'small devices',
as you derisively call them, are sufficient for down-stream, 'plug in',
surge protection: the wiring limits the magnitude of the current surge.


snip of w_tom babble

So the plug-in protector is at something less than 13,000
volts when attempting to earth a trivial 100 amp transient.
"Poppycock", he says so that he need not deal with numbers he
does not understand. In the meantime that less than 13,000
volts must go somewhere. How convenient - that modem and
phone line is a perfect outgoing path. And so we have modem
damage because someone foolishly spent big bucks on a plug-in
protector. Someone hoped the protector would provide
protection that even its manufacturer does not claim.

Suppose the same money was spent on a earthing a 'whole
house' protector. Now we have a protected computer (not at
thousands of volts relative to earth) AND we have protected
all other 50 appliances also.

Which should one believe. The person whose entire knowledge
of surge protection is limited to the word 'poppycock'. Or
numbers based upon basic electrical principles. Wire has
impedance which is why real world protectors manufacturers
discuss and promote protectors with the short, direct, and
independent connection to a common earth ground. Those
adjacetives having engineering significance.

David can wish that wire limits an incoming current. But
that destructive current comes from a current mode source.
Voltage will rise, as necessary, to maintain that current
flow; a first year engineering concept.

Posted are basic electrical principles such as wire
impedance and current mode sources that describe how surges
can create destructive voltages. David's lucid response
includes poppycock and some idea that wire resistance will
limit the current out of a current source. Maybe David could
cite some EE101 principles. No. Apparently David forgot to
take that course. Maybe David should just cite the
manufacturer's specification that claims such protection. No,
he cannot cite numerical specifications that do not even
exist. What can David do?

When one cannot dispute the numbers, then one just ignore
those numbers? - or instead post:
For one who critiques a 'lack of numbers' they are notably
missing from you.
What more can I do other than hold his hand? You can take a
horse to water, but....

It still remains that a surge protector is only as effective
as its earth ground which is why the excessively priced and
typically undersized plug-in protectors are so ineffective.
Which is why the 'whole house' protector remains such a
superior option. Since the 'whole house' solution is so
effective and so inexpensive, then any significant amount of
electronics means a 'whole house' protector is advisable.
What other alternative exists?

David Maynard wrote:
w_tom wrote:
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.

Poppycock.

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.

Setting aside your made up numbers, which are irrelevant
anyway, it matters not, from the aspect of protecting the
device, what potential the 'ground' at the protected device
looks like with respect to your treasured 'earth' as long as
all conducive paths in/out of the device are clamped to it:
the device never sees any potential outside it's limits and
that is all that matters to it.

Back to your fantasy numbers, you try to invent a 13,000
volts potential with a 100 amp transient while ignoring that
the 100 amps would have to arrive at the surge protector down
one of those same 'high impedance' wires before it begins the
trip down the ground wire you use to fabricate the 13,000
volts which, of course, would mean there could not be the 100
amp surge you pretend because the let though on the input
panel lightning suppressors is no where near 26,000 volts
(or 13,000 either).

What you have inadvertently done is provide the reason why
'small devices', as you derisively call them, are sufficient
for down-stream, 'plug in', surge protection: the wiring
limits the magnitude of the current surge.

snip of w_tom babble