T
Tim Auton
w_tom said:
Because there are and were millions of them. Next!
Come back when you've learnt some statistics. Or run for office.
Tim
Because there are and were millions of them. Next!
Come back when you've learnt some statistics. Or run for office.
Tim
H
half_pint
David Maynard said:
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.
K
kony
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.
D
David Maynard
Mike said:I do, yes.
This is the distinction made in the wiring code between the "grounded"
and the "grounding" terminal... which causes confusion all of its own
Hehe. true. But 'neutral' and 'ground' are separate wires in 3 prong plugs
even though 'neutral' is earthed at the entry, as is the 'ground' wire. The
'ground' is really 'protective (as in human safety) ground'. Aside from the
voltage and U.S. wall outlets being one phase of 230/240 (for 115/120), the
U.S. and U.K grounding scheme is essentially the same. FUSING and ring vs
star wiring is another matter.
I don't know where you're getting you're information on 'U.S.' surge
protectors but I have the advantage of possessing more than one of them and
that description is inaccurate. The typical surge protector is 100% 3
prong, sockets and plug, with 3 MOVs: one from each 'power' wire to
protective ground (what you call earth) and one between the two with,
usually, a cap in parallel plus, on the premium models, additional noise
suppression (LC).
I may have missed one but I am not aware of any 'U.S.' surge protectors
that are 'designed' for a 2 prong outlet, or come with a 2 prong plug, nor,
for that matter, any PCs that come with 2 prong plugs.
D
David Maynard
Mike said:
Here, here. I second that.
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.
One of these days you need to take off the 'U.S. bigot' blinders.
J
Johannes H Andersen
half_pint said:
I am sorry you're wrong flap_paint. Semi conductor devices are blown by
excess Voltage. A fuse only senses the current.
Rubbish half_faint!
As said before, voltages also kills semiconductor devices. Why do you
think there are such things as electrostatic bags?
T
Tim Auton
half_pint said:
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
T
Tim Auton
w_tom said:
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
V
VWWall
Just a small correction. U.S. wall outlets are on opposite "sides" of aDavid said:
230/420 volt circuit, with respect to their neutral. They are both on
the same phase. There are very few U. S. domestic units supplied with
more than single phase power. Two different sets of outlets can, and
often do, share the same neutral wire. This can lead to a "wild
neutral", if an open in the neutral circuit back to the entry
distribution point leads to two, (sets), of outlets becoming in series
across the entire 230/240 power. They will split the voltage between
them in accordance with the loads connected to each side. If one is
lightly loaded, and the other side is heavily loaded, the light load
side can have much higher than its normal 115/120 volts. I've seen
cases where "surge protectors" prevented damage. I suspect it was the
low amperage circuit breaker in the outlet strip that protected the
equipment, perhaps aided by the protector's MOVs drawing a high current
because of the over-voltage. The MOVs in a local protector can't stand
an overvoltage for more than a few milliseconds.
A single computer power supply is a small load if, the other "side" is
connected to a refrigerator starting up. I recall a microwave oven
which had its own internal MOV destroyed in this way. Most new U.S.
codes require things like refrigerators to be on "home run" individual
circuits, but many homes still have them on common kitchen outlets.
This is a problem UK protectors would not have to contend with.
Virg Wall
M
Michael Salem
Mike said:
Of course. I phrased this badly: the protective devices must be able to
divert the energy of the strike to earth before failing due to overload;
varistors must absorb the energy due to the very high current through
their residual resistance (integrated over the duration of the strike).
Their mode of operation is not to absorb all the energy of a strike.
If you mean that "surge protection" is a more inclusive term, covering
surges due to lightning, and also to any other cause, I'll not argue.
UPSs are usually bought to cover power failures; it's worth remembering
that they additionally protect from damage due to surges.
This is a point of practical importance to anyone involved in protecting
equipment, so I'll quote what manufacturers say. Some types of UPSs
isolate equipment from the mains more than others (it's quite a complex
subject), but you need to look at more than just theoretical
considerations -- lightning is a great jumper of gaps, even if other
surges are more manageable.
APS are very confident:
"The new Back-UPS ES 350 and Back-UPS ES 500 from American Power
Conversion (APC) ...
So confident is APC that these new home and home office UPSs provide the
level of protection demanded by today's home PC users, they now offer a
"Lifetime Equipment Protection Policy" (EPP) which guarantees up to
100,000 Euros/ GBP 50,000 in compensation should properly connected
equipment be damaged by lightning strikes "for as long as a customer
owns the product" (valid in EU countries only)."
Other UPS manufacturers offer similar guarantees in Europe and the US.
I suppose you could be cynical and say that the publicity value of this
guarantee far outweighs the cost of replacing a few home computers every
year even if the unit offered no protection.
Buy a few Back-UPS ES 500 units -- at least you'll be able to afford to
replace your equipment.
Best wishes,
D
David Maynard
half_pint said:
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
That is certainly the myth. It is not, however, reality.
D
David Maynard
VWWall said:
If it's not wired according to code I suppose they could. But code has
separate runs back to the entry panel.
I really don't know *what* problems a UK protector would have to contend
with if someone broke code and ran wire just any old way they felt like.
D
David Maynard
w_tom said:
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>
D
David Maynard
w_tom said:
Must be some odd problem of yours as I've never had one fail.
Just below you said they weren't. Make up your mind.
Couldn't say as mine all work.
Then why did you say they weren't?
For one who critiques a 'lack of numbers' they are notably missing from you.
Now you're back to saying they don't matter. Do you always talk in babble
circles or is this a special occasion?
No one said routine 'daily' switching was necessarily a problem.
Now show me there can NEVER be ANY kind of utility, or industry, or
construction, or by any thing else, generated destructive power surge.
I've never had any of the above mentioned devices fail from a lightning
surge either so, using your (il)logic of 'colloquial non failure
observation', I guess I don't need your stuff either.
You just tried to claim they don't.
Speak for yourself, paleface.
Except most reputable 'whole house' protection manufacturers recommend
'plug in' surge protectors on sensitive electronic equipment, such as
computers, in addition to their 'whole house' devices.
W
w_tom
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:
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?
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:
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?
W
w_tom
One can convert a plug-in protector into a 'whole house'
protector. First cut down that 'too long' power cord. Then
increase the joules rating significantly to be equivalent to a
'whole house' protector. Then attach that plug-in protector
at the service entrance. Of course for the same money, one
gets a protector that has longer life expectancy (on the order
of up to 100 times longer because it is properly sized), is
designed for that location, is easier to install, and is
actually safety rated for that location - all for about the
same money as one or two overrated plug-in protectors.
protector. First cut down that 'too long' power cord. Then
increase the joules rating significantly to be equivalent to a
'whole house' protector. Then attach that plug-in protector
at the service entrance. Of course for the same money, one
gets a protector that has longer life expectancy (on the order
of up to 100 times longer because it is properly sized), is
designed for that location, is easier to install, and is
actually safety rated for that location - all for about the
same money as one or two overrated plug-in protectors.
W
w_tom
David Maynard did not have an LED clock fail because
utility switching does generate typically destructive
transients. Why do we need surge protectors? Because the
destructive transients are from truly destructive events such
as lightning. Plug-in protectors don't even claim to protect
from such transients. For protection from destructive
transients, we require properly earthed 'whole house'
protectors. Protectors that would also and even protect from
insignificant or extremely rare transients such as those due
to utility switching.
Which then returns to the original question. Do we need
surge protectors in the UK? That depends, in part, on the
frequency of CG lightning in that neighborhood, and how much
inside the building requires protection. 'Whole house'
protectors and earth ground are quite inexpensive as well as
more effective. If the house has computers, RCDs, kitchen
appliances, touch on-off lights, alarm system, smoke
detectors, digital timer switches, etc; then by all means the
'whole house' protector protects so much for so little money.
In the meantime if anything else should strangely cause a
destructive transient, then still everything remains protected
by same 'whole house' protector. So much more protection for
less money per protected appliance.
What is the alternative? Plug-in protectors on each and
every appliance? Rather foolish for too many reasons. Costs
are so excessive many times over. Product is typically
undersized. Product does not even claim to provide effective
protection.
The costs and advantages of 'whole house' protectors and
single point earth ground make a mains surge protector quite
reasonable protection even for the UK where lightning is not
as frequent.
utility switching does generate typically destructive
transients. Why do we need surge protectors? Because the
destructive transients are from truly destructive events such
as lightning. Plug-in protectors don't even claim to protect
from such transients. For protection from destructive
transients, we require properly earthed 'whole house'
protectors. Protectors that would also and even protect from
insignificant or extremely rare transients such as those due
to utility switching.
Which then returns to the original question. Do we need
surge protectors in the UK? That depends, in part, on the
frequency of CG lightning in that neighborhood, and how much
inside the building requires protection. 'Whole house'
protectors and earth ground are quite inexpensive as well as
more effective. If the house has computers, RCDs, kitchen
appliances, touch on-off lights, alarm system, smoke
detectors, digital timer switches, etc; then by all means the
'whole house' protector protects so much for so little money.
In the meantime if anything else should strangely cause a
destructive transient, then still everything remains protected
by same 'whole house' protector. So much more protection for
less money per protected appliance.
What is the alternative? Plug-in protectors on each and
every appliance? Rather foolish for too many reasons. Costs
are so excessive many times over. Product is typically
undersized. Product does not even claim to provide effective
protection.
The costs and advantages of 'whole house' protectors and
single point earth ground make a mains surge protector quite
reasonable protection even for the UK where lightning is not
as frequent.
M
Mike Tomlinson
David Maynard said:
I apologise for the comment, which was inappropriate. Having had a few
glasses of wine did not help.
I'm not a "US bigot" and in fact visit the States two or three times a
year. I still feel that the quality of electrical appliances in the
US, such as you'd buy in your local WalMart, is extremely poor compared
to their European equivalents. Perhaps it's a sign of the 'throwaway
society', where appliances are replaced rather than repaired (see
sci.electronics.repair)
D
David Maynard
w_tom said:
I understand them just fine and apparently better than you who can't follow
a simple surge path.
Just as it would go somewhere when there is no device to protect.
No, the dufuss would be you who didn't plug the modem into the protector
even though I clearly said "all conductive paths in/out."
Won't be 'the same money'.
Except responsible manufacturers of 'whole house' protectors recommend a
'plug in' protector for sensitive equipment in addition to their own device.
And why should they believe someone who reverts to absurdities like that
statement?
No, your fantasy numbers, which I showed are impossible.
Of course it does. Or else your 'whole house' protectors wouldn't work.
The 'whole house' protector must have a short earth path because it is
located upstream and downstream equipment inside the home will be earth
referenced through the wall outlet. If the 'whole house' protector had a
high impedance path to ground it would leave a high voltage spike on the
power lines to be propagated on in to the earth referenced device. The
surge across the interior equipment would then be the let through clamp
voltage of the 'whole house' device plus the rise above earth caused by the
high impedance path to earth.
The 'plug in' unit has no such problem because it clamps all wires to a
common potential AT the device so what that potential is, relative to
earth, is irrelevant to the protected device: It sees nothing across any
wires in excess of it's rating regardless of where 'earth' is.
Which you apparently don't understand.
My 'wishing' has nothing to do with it. It's called ohms law.
Which is arc gap shunted to earth at the entry panel.
The power lines at the input panel are voltage clamped and that let through
voltage (surge) is then presented through the wiring resistance to the
interior devices.
Maybe you should take year 2 where they cover arc gap suppressors and
voltage clamps.
Except you got everything about them wrong.
No, the input panel arc gap suppressors voltage clamp the power lines and
shunt the current to earth so what the interior wiring sees is a voltage
source surge.
<snip of w_tom babble>
D
David Maynard
w_tom said:
Except that responsible 'whole house' protector manufacturers recommend
'plug in' protectors for sensitive equipment in addition to their protector.