Clamping voltage on surge protector?

[Uncle Peter]

I've got a few cheap micromark surge protectors, and noticed they have a clamping voltage of 650V.
Anyone know where I can get a much lower one? I've heard of protectors as low as 270V, but I can't find any to buy.

--
You know you've spent too much time on the computer when you spill milk and the first thing you think is, 'Edit, Undo.'

[Graham.]

On Mon, 24 Feb 2014 13:48:25 -0000, "Uncle Peter" <n...@spam.com> wrote:

>I've got a few cheap micromark surge protectors, and noticed they have a clamping voltage of 650V.
>Anyone know where I can get a much lower one? I've heard of protectors as low as 270V, but I can't find any to buy.

For 230V RMS?

650 is the peal to peak equivalent, but I think it's just the peak
voltage that's relevant here, so anything less than 325v is no good,
and you are going to need some margin above that.

Don't know what micromark offer, but if it's just a few twopenny MOVs
I shouldn't bother.

[Uncle Peter]

On Mon, 24 Feb 2014 14:15:06 -0000, Graham. <m...@privicy.net> wrote:

> On Mon, 24 Feb 2014 13:48:25 -0000, "Uncle Peter" <n...@spam.com> wrote:
>
>> I've got a few cheap micromark surge protectors, and noticed they have a clamping voltage of 650V.
>> Anyone know where I can get a much lower one? I've heard of protectors as low as 270V, but I can't find any to buy.
>
> For 230V RMS?

Yes.

> 650 is the peal to peak equivalent, but I think it's just the peak
> voltage that's relevant here, so anything less than 325v is no good,
> and you are going to need some margin above that.
>
> Don't know what micromark offer, but if it's just a few twopenny MOVs
> I shouldn't bother.

This: http://petersphotos.com/temp/surge.jpg

It's to protect computers. Looking at other surge protectors up to 100 quid (this one was 4 quid), nothing is lower than 650V. And some of the 100 quid ones are 750V!

Am I right in thinking 650V is rubbish? I mean the surge could double the peak supply voltage without the protector doing anything, and if the surge was more, it would clamp it down to double, which is enough to fuck up a computer. Mind you if it's just the power supply caps that go bang, I suppose it doesn't matter. Does a PC power supply stop surges getting past it?

Or.... does 650V mean peak to peak as opposed to zero to peak?

--
Nagry: the state of emotion a woman is in when yelling at her husband

[Steve]

Uncle Peter presented the following explanation :

Absolutely not! I've just done a partial rebuild of a gaming machine
for someone that has cost United Utilities (their electricity supplier)
over £1,500 after it was hit by a voltage surge - same house also had
two TVs and a microwave oven blow up too. And about twelve other houses
were affected so not a happy time for UU.

[Andrew Gabriel]

In article <uJWdnVNAzdt1wJbO...@bt.com>,

This sounds like a loss of neutral fault, and a MOV is useless for
protecting against such a sustained fault - it will just burst into
flames if the fault goes over the clamping voltage (and they have
been known to start fires).

Consequently, the MOV must have a clamping voltage above the 3-phase
peak of 570V. Secondly, each time it takes a significant spike, its
clamping voltage drops a bit, and it must still remain over 570V after
this.

The device is used up a bit by each spike (unless the spike is tiny).

Finally, a MOV (or any surge supression) just across live and neutral
is remarkably ineffective for protecting against lightning, where the
spike tends to be between different services, such as the phone line
and mains, or mains and ground, etc. and not between live and neutral.
It won't generally protect against broken neutral (which sees the mains
voltage rise to up to 400V). Just what is it you are trying to protect
against?

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

[Capitol]

Computers are designed to withstand about 2.5KV spikes and survive
minor lightning strikes. A 650V surge protector is quite adeaquate, but
might not last long as my local supply frquently gets 1500V fast
transients (microseconds), zero to peak. The surge protector is
bidirectional, ie it doesn't care which way round the volts are. The
current flowing is purely determined by the source impedance, which for
lightning strikes is close to zero if local. For interference spikes,
surge protectors work OK, but if your supply is cables in the air, then
they may well fail quite soon. My worst experiences have been "brown
outs", where the supply suddenly reverses phase or skips cycles, which
causes transformer saturation and doubles the peak supply volts(up to
700V zero to peak) for a cycle, which then takes a few cycles to settle
down. This also buggers up switched mode PSUs, which don't like having
their dc supply briefly doubled. If this happens, no surge protector
will operate correctly and survive. IME, unless you have a transformer
fed supply with a good UPS you are going to lose a few PSUs with the
current state of our electricity supply. I lost a couple last year. Just
be thankful you are not in the US, where lightning strikes are common
and the supply is frequently crap as well.

[Uncle Peter]

I've seen that. At my 2nd last place of work, an electrician mixed up the wiring as they had some old colours and some new, causing L1 and L2 to be connected to a ring of 13A sockets instead of L1 and neutral. A surge protected plug on a digital projector melted, and the bulk capacitors in all 20 computers in the room burst (they had no surge protectors), giving off some stinky smoke. All this tripped the circuit breaker for the room, which presumably stopped any further damage or a fire. After I replaced all the capacitors, the computers were fine.

> Consequently, the MOV must have a clamping voltage above the 3-phase
> peak of 570V.

Why? If I get a momentary spike or surge between single phase peak and three phase peak, I want it removed. Also one above the 3-phase peak I want clamped down to the 1-phase peak, not the 3-phase peak!

> Secondly, each time it takes a significant spike, its
> clamping voltage drops a bit, and it must still remain over 570V after
> this.
>
> The device is used up a bit by each spike (unless the spike is tiny).
>
> Finally, a MOV (or any surge supression) just across live and neutral
> is remarkably ineffective for protecting against lightning, where the
> spike tends to be between different services, such as the phone line
> and mains, or mains and ground, etc. and not between live and neutral.

This one claims to be across any pair of pins. I thought they all were.

> It won't generally protect against broken neutral (which sees the mains
> voltage rise to up to 400V).

Why does it rise? If there was no neutral, and the load on all three phases was equal, nobody would notice. You'd get a rise (or fall) if your phase was not the same as the other two.

> Just what is it you are trying to protect against?

A spike or surge. I don't want it just trimmed to 650V! The spike is still there!!

--
I'm not so think as you drunk I am...

[Uncle Peter]

Maybe it depends how long the surge was. See my other post (reply to a reply to yours) where a room full of computers was fine when connected to two phases by mistake. Just the bulk capacitors in the PSUs blew. I've also accidentally connected a printer and a computer to 240V instead of 110V when the switch was incorrectly set at the back. Also I've seen about 10 computers with the switch set wrongly on purpose by kids. Just a bang and a new capacitor required. I would have expected the fuse or breaker to blow before the voltage got through to the equipment in your case though - the bulk capacitors go short circuit?

--
The world's largest fruit are giant pumpkins. The world record is 1061lbs (481.3 kg).

[Uncle Peter]

They're cheap, I don't care, and they have an LED to indicate they're still running.

> My worst experiences have been "brown
> outs", where the supply suddenly reverses phase or skips cycles, which
> causes transformer saturation and doubles the peak supply volts(up to
> 700V zero to peak) for a cycle, which then takes a few cycles to settle
> down. This also buggers up switched mode PSUs, which don't like having
> their dc supply briefly doubled. If this happens, no surge protector
> will operate correctly and survive.

Explain how the phase can get reversed?

And why not have a surge protector that absorbs anything over 340V? Yes it wouldn't protect an extended double voltage, but it would remove more of the spikes.

> IME, unless you have a transformer
> fed supply with a good UPS you are going to lose a few PSUs with the
> current state of our electricity supply. I lost a couple last year. Just
> be thankful you are not in the US, where lightning strikes are common
> and the supply is frequently crap as well.

I've got a good UPS on the only computer with data on it, but that was mainly to stop it going off if there was a short powercut for a second or two, which I get a lot of in bad weather. I've never known a power supply break here.

--
Father walks into his son's room and starts talking.
"Son, masturbating will cause you to go blind."
"But dad, I'm over here!"

[Dave Liquorice]

On Mon, 24 Feb 2014 14:15:06 +0000, Graham. wrote:

> 650 is the peal to peak equivalent, but I think it's just the peak
> voltage that's relevant here, so anything less than 325v is no good,
> and you are going to need some margin above that.

Aye mains voltage spec is 230 V -6% +10% or 216 to 253 V. The peak
for 253 is 358 V.

--
Cheers
Dave.

[Harry Bloomfield]

Dave Liquorice was thinking very hard :

> Aye mains voltage spec is 230 V -6% +10% or 216 to 253 V. The peak
> for 253 is 358 V.

All they are intended to do is temporarily short out a brief surge,
maybe even long enough to pop the fuse, after which they (the MOV) need
to be replaced. In many cases, without having the means to none
destructively test them, you will not even know the MOV has failed.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

[Fredxxx]

On 24/02/2014 13:48, Uncle Peter wrote:
> I've got a few cheap micromark surge protectors, and noticed they have a
> clamping voltage of 650V.
> Anyone know where I can get a much lower one? I've heard of protectors
> as low as 270V, but I can't find any to buy.

I feel you are on a loser here. Most power supplies can withstand modest
surges in their own right.

Surge protectors offer minimal protection, though I guess any is better
than none.

The voltages you quote are way of the mark. 650V is chosen for perfectly
good reasons.

If you want true protections then you should be looking at an Online UPS.

http://en.wikipedia.org/wiki/Uninterruptible_power_supply#Online.2Fdouble-conversion


At least if that goes down, your equipment will still be working, and
furthermore will offer protection against power outages.

[Uncle Peter]

On Mon, 24 Feb 2014 16:59:24 -0000, Fredxxx <fre...@nospam.com> wrote:

> On 24/02/2014 13:48, Uncle Peter wrote:
>> I've got a few cheap micromark surge protectors, and noticed they have a
>> clamping voltage of 650V.
>> Anyone know where I can get a much lower one? I've heard of protectors
>> as low as 270V, but I can't find any to buy.
>
> I feel you are on a loser here. Most power supplies can withstand modest
> surges in their own right.
>
> Surge protectors offer minimal protection, though I guess any is better
> than none.
>
> The voltages you quote are way of the mark. 650V is chosen for perfectly
> good reasons.

What are the reasons? I can't find any details about clamping voltage online, just a brief description of what it is.

--
Cetus: What were you doing in the flooded sections of the city?
O'Neill: The backstroke
Talus: What are you planning?
O'Neill: I was planning to retire.

[Capitol]

Uncle Peter wrote:
> On Mon, 24 Feb 2014 16:59:24 -0000, Fredxxx <fre...@nospam.com> wrote:
>
>> On 24/02/2014 13:48, Uncle Peter wrote:
>>> I've got a few cheap micromark surge protectors, and noticed they have a
>>> clamping voltage of 650V.
>>> Anyone know where I can get a much lower one? I've heard of protectors
>>> as low as 270V, but I can't find any to buy.
>>
>> I feel you are on a loser here. Most power supplies can withstand modest
>> surges in their own right.
>>
>> Surge protectors offer minimal protection, though I guess any is better
>> than none.
>>
>> The voltages you quote are way of the mark. 650V is chosen for perfectly
>> good reasons.
>
> What are the reasons? I can't find any details about clamping voltage
> online, just a brief description of what it is.
>

Because under fault conditions the mains peak can reach 700V. This is
very rare, so 650V is a reasonable compromise. I suggest you look up
varistor characteristics for more information.

[Andrew Gabriel]

In article <op.xbsmw...@red.lan>,

"Uncle Peter" <n...@spam.com> writes:
>> Just what is it you are trying to protect against?
>

> A spike or surge. I don't want it just trimmed to 650V! The spike is s=
> till there!!

Then you need an online UPS.
Not cheap, but this isn't a level of protection most things need.

[Uncle Peter]

On Mon, 24 Feb 2014 17:23:54 -0000, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:

> In article <op.xbsmw...@red.lan>,
> "Uncle Peter" <n...@spam.com> writes:
>>> Just what is it you are trying to protect against?
>>
>> A spike or surge. I don't want it just trimmed to 650V! The spike is s=
>> till there!!
>
> Then you need an online UPS.
> Not cheap, but this isn't a level of protection most things need.

I would have thought doubling the voltage was bad for a lot of things.

--
Is it just a coincidence that Christianity and insanity end with the same letters?

[Uncle Peter]

Exactly, "fault conditions". Surely the point of a surge protector is to remove faults? Maybe it won't last long, but even if it sacrifices itself, and trips the breaker, you've save the more expensive equipment. What I seem to have here should be called a spike protector.

--
Peter is listening to "Who's the best - DJ Mad Dog feat. Tommyknocker"

[Fredxxx]

Mains impedance is very low with a short circuit current measured in kA,
so a MOV has to dissipate a lot of energy if it should start to conduct.

How big an MOV do you want to use, or how many?

Unless you have a crowbar type of protection no breaker is ever going to
open under a fault condition before it's all too late.

A surge protector does not remove faults. It merely reduces the symptoms
of a fault. A bit like closing a stable door whilst the horse is escaping.

[Uncle Peter]

Oh, I assumed that the surge protector could handle a huge current for long enough for the breaker to open.
http://petersphotos.com/temp/surge.jpg
It says 9000A, 240J. Could that trip a breaker?

> A surge protector does not remove faults. It merely reduces the symptoms
> of a fault. A bit like closing a stable door whilst the horse is escaping.

Can you get a crowbar surge protector that would blow the 13A plug fuse or the 30A breaker?

--
A boomerang that doesn't come back is a stick.

[Harry Bloomfield]

Capitol submitted this idea :

That is a much better description of what they can effectively deal
short spikes with very little current behind the spikes.

[Uncle Peter]

But the short spikes will only be reduced to 650V will they not? I'd much rather they were reduced to 340V and lose a surge protector now and again.

--
In the beginning the Universe was created. This has made a lot of people very angry and been widely regarded as a bad move.

[Uncle Peter]

On Mon, 24 Feb 2014 18:09:48 -0000, Harry Bloomfield <harry...@nospam.tiscali.co.uk> wrote:

http://en.wikipedia.org/wiki/Surge_protector#Clamping_voltage
"The theoretical lowest possible let-through voltage for 120 V power lines was 180 V. New technology, high quality surge suppressors can now clamp voltage at 130 V."

[Andrew Gabriel]

In article <op.xbsqz...@red.lan>,

"Uncle Peter" <n...@spam.com> writes:
> On Mon, 24 Feb 2014 17:23:54 -0000, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:
>
>> In article <op.xbsmw...@red.lan>,
>> "Uncle Peter" <n...@spam.com> writes:
>>>> Just what is it you are trying to protect against?
>>>
>>> A spike or surge. I don't want it just trimmed to 650V! The spike is s=
>>> till there!!
>>
>> Then you need an online UPS.
>> Not cheap, but this isn't a level of protection most things need.
>
> I would have thought doubling the voltage was bad for a lot of things.

Not a short spike. It won't get past the SMPSU storage capacitor.
(Power factor correction circuit might be slightly more vulnerable.)

A MOV won't handle anything longer than a short spike, without risk
of failing in an unsafe mode.

[Uncle Peter]

On Mon, 24 Feb 2014 18:54:43 -0000, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:

> In article <op.xbsqz...@red.lan>,
> "Uncle Peter" <n...@spam.com> writes:
>> On Mon, 24 Feb 2014 17:23:54 -0000, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:
>>
>>> In article <op.xbsmw...@red.lan>,
>>> "Uncle Peter" <n...@spam.com> writes:
>>>>> Just what is it you are trying to protect against?
>>>>
>>>> A spike or surge. I don't want it just trimmed to 650V! The spike is s=
>>>> till there!!
>>>
>>> Then you need an online UPS.
>>> Not cheap, but this isn't a level of protection most things need.
>>
>> I would have thought doubling the voltage was bad for a lot of things.
>
> Not a short spike. It won't get past the SMPSU storage capacitor.
> (Power factor correction circuit might be slightly more vulnerable.)

Ok, I'll assume I've protected the computers well enough then. I've got a spike arrestor on the phoneline too.

> A MOV won't handle anything longer than a short spike, without risk
> of failing in an unsafe mode.

Oh. I assumed if it shorted it'd blow a fuse or breaker before it melted. I mean if you short a wire in a mains plug, the fuse blows before any hint of a fire.

--
Bad or missing mouse. Spank the cat [Y/N]?

[Capitol]

Yes, but it may well be too slow to protect the circuitry. Protection
is a risk reduction process, not a risk removal process.

[Uncle Peter]

I guess it would need to be use in conjunction with other devices. What about a crowbar along with a MOV set to 350V?

--
Japanese scientists have created a camera with a shutter speed so fast, they can now photograph a woman with her mouth shut.

[Capitol]

If the source impedance is low enough. Also, for many units 130V is the
level at which clamping starts, the let through voltage can be much
higher if it is a varistor system. Large Zener diodes have a lower
series resistance, but the clamping current can destroy the device if
large enough. Also, Zener diodes do not like RF energy, so lightning
strikes can destroy them at quite low levels of energy (punch through
occurs).

[Capitol]

Correction If the source impedance id high enough.
Crowbars only protect to an extent, if the fuses arc through, the
crowbar will self destruct. That's why fuses have a breaking capacity
rating.

[Andrew Gabriel]

In article <UqGdnbR62cgvBpbO...@brightview.co.uk>,

Capitol <sp...@wher.eva.co.uk> writes:
>> If the source impedance is low enough. Also, for many units 130V is the
>> level at which clamping starts, the let through voltage can be much
>> higher if it is a varistor system. Large Zener diodes have a lower
>> series resistance, but the clamping current can destroy the device if
>> large enough. Also, Zener diodes do not like RF energy, so lightning
>> strikes can destroy them at quite low levels of energy (punch through
>> occurs).
>
> Correction If the source impedance id high enough.
> Crowbars only protect to an extent, if the fuses arc through, the
> crowbar will self destruct. That's why fuses have a breaking capacity
> rating.

The first minicomputers I worked on were switched off by crowbarring
the DC supplies. The original systems supported core store which is
non-volatile, but you don't want it to get scribbled on by the
computer collapsing in an uncontrolled way as the various voltage
rails decay. So, once the supply controller had decided the computer
was powering off (which lots of events could trigger), it told the
CPU so it could save the current registers to memory, and then it
crowbarred the supplies by shorting them out with large SCRs in a
controlled sequence, designed to protect the core store contents.

When you powered it up, if it was fitted with core store, it would
carry on running from where it stopped.

[Mike Tomlinson]

In article <mn.c3e47de2cb...@NOSPAM.tiscali.co.uk>, Harry
Bloomfield <harry...@NOSPAM.tiscali.co.uk> writes

>All they are intended to do is temporarily short out a brief surge,
>maybe even long enough to pop the fuse, after which they (the MOV) need
>to be replaced. In many cases, without having the means to none
>destructively test them, you will not even know the MOV has failed.

Time to trot this out again :-)

This is a photo of two failed 13A power strips. Each has two neons, one
to show 'power on' and another to show 'surge protection working'.

The 'SP working' neons were still lit despite the MOVs having vaporised
:-)

http://jasper.org.uk/pics/Boom.jpg

--
(\_/)
(='.'=)
(")_(")

[Andrew Gabriel]

In article <lyMBLhA0...@jasper.org.uk>,

They've been responsible for some fires in the US, and I believe UL
are cracking down hard on MOV devices.

I know we had to stop using them in computer systems we manufactured
sometime around 1980, due to regulatory changes due to fire risk.

In power strips, they are a gimmick. Power strips are produced for
under £1. The MOV devices cost in the order of 10p in bulk, but
the addition of this 10p device enables you to market the power
strip for at least £5 more. Hence you can ship a higher margin
product, even though the added value pretty much useless.

I generally make a point of making sure power strips that I buy do
*not* have any MOV devices in them.

[westom]

replying to Uncle Peter , westom wrote:

> no wrote:
> "The theoretical lowest possible let-through voltage for 120 V power lines
was 180 V. New technology, high quality surge suppressors can now clamp
voltage at 130 V."
> --

--

Learn what those numbers are actually report. Normal minimum let-through
voltage for 120 volt protectors is 330 volts. Normal let-through voltage
for 230 volts would be almost double that. 180 volts is reporting
something completely different.

Also appreciate what a protector does and does not do. For example,
excessive voltage by an electrician miswire would only destroy a protector
- do no protection. And if the protector's thermal fuse (not to be
confused with a 13 amp line fuse) does not trip fast enough, then a fire
may occur.

That protector only claims to protect from one type of anomaly that
typically causes no electronics damage. Due to robust protection already
inside appliances. Robust protection that even says why 650 volts during
a surge does not damage electronics.

The many who did not know 650 volts is a standard should cause you
pause. Since so many made recommendations without even knowing basics.

Finally, typically destructive surges can be hundreds of thousands of
joules. A protector adjacent to an appliance can only stop that current
or absorb that energy. How many joules does that protector claim to
absorb? Compare that number to hundreds of thousands of joules. Then ask
yourself, "What does it claim to do?" That should also give you pause.

You may want to learn of a completely different device (also called a
protector) that would address your concerns.


--

[Graham.]

Its reassuring to know that my view on these things is shared by
someone as knowledgeable as you.

Here are my pictures
http://flic.kr/s/aHsjTjtS2A
What I was trying to illustrate here is how the L & N use the MOV PCB
as a junction block, relying on two blobs of best lead free solder.

If you were designing such a thing wouldn't you ferrule and spot weld
the incoming mains *directly* to the bus bars, and hang the PCB on the
bus bars separately?

[Uncle Peter]

On Tue, 25 Feb 2014 14:44:01 -0000, westom <caedfaa9ed1216d60e...@example.com> wrote:

> replying to Uncle Peter , westom wrote:
> no wrote:
> "The theoretical lowest possible let-through voltage for 120 V power lines
> was 180 V. New technology, high quality surge suppressors can now clamp
> voltage at 130 V."

Learn what those numbers are actually report. Normal minimum let-through
voltage for 120 volt protectors is 330 volts. Normal let-through voltage
for 230 volts would be almost double that. 180 volts is reporting
something completely different.

Also appreciate what a protector does and does not do. For example,
excessive voltage by an electrician miswire would only destroy a protector
- do no protection. And if the protector's thermal fuse (not to be
confused with a 13 amp line fuse) does not trip fast enough, then a fire
may occur.

That protector only claims to protect from one type of anomaly that
typically causes no electronics damage. Due to robust protection already
inside appliances. Robust protection that even says why 650 volts during
a surge does not damage electronics.

The many who did not know 650 volts is a standard should cause you
pause. Since so many made recommendations without even knowing basics.

Finally, typically destructive surges can be hundreds of thousands of
joules. A protector adjacent to an appliance can only stop that current
or absorb that energy. How many joules does that protector claim to
absorb? Compare that number to hundreds of thousands of joules. Then ask
yourself, "What does it claim to do?" That should also give you pause.

You may want to learn of a completely different device (also called a
protector) that would address your concerns.

---

Surely if the surge protector could just short the line to anything that was over the 240V RMS, it would blow a fuse or breaker, and not cause a fire?

-- 

The Artist Formerly Known As Prince has a new album out.
It's called "The Songs Formerly Known As Hits."

[meow...@care2.com]

On Monday, February 24, 2014 6:59:34 PM UTC, Uncle Peter wrote:


> Ok, I'll assume I've protected the computers well enough then.

The designer & manufacturer of the PC PSU has done that.

> I've got a spike arrestor on the phoneline too.

Overhead phone services already have those built in.

Youre buying into marketing bs and wasting your time.


NT

[Uncle Peter]

On Tue, 25 Feb 2014 17:14:55 -0000, <meow...@care2.com> wrote:

> On Monday, February 24, 2014 6:59:34 PM UTC, Uncle Peter wrote:
>
>
>> Ok, I'll assume I've protected the computers well enough then.
>
> The designer & manufacturer of the PC PSU has done that.

Then I guess the 4 quid surge protector is protecting several 40 quid PSUs.

>> I've got a spike arrestor on the phoneline too.
>
> Overhead phone services already have those built in.
>
> Youre buying into marketing bs and wasting your time.

Then why did my dad's network card burn out when he got lightning through his phone line, through the router, and into the ethernet port?

--
Does the Little Mermaid wear an algebra?

[meow...@care2.com]

On Tuesday, February 25, 2014 5:21:05 PM UTC, Uncle Peter wrote:
> On Tue, 25 Feb 2014 17:14:55 -0000, <meow...@care2.com> wrote:
> > On Monday, February 24, 2014 6:59:34 PM UTC, Uncle Peter wrote:
> >
> >
> >> Ok, I'll assume I've protected the computers well enough then.
> >
> > The designer & manufacturer of the PC PSU has done that.

> Then I guess the 4 quid surge protector is protecting several 40 quid PSUs.

they dont protect anything, other than someone's profits

> >> I've got a spike arrestor on the phoneline too.
> >
> > Overhead phone services already have those built in.
> >
> > Youre buying into marketing bs and wasting your time.

> Then why did my dad's network card burn out when he got lightning through his phone line, through the router, and into the ethernet port?

Presumably because it was hit by lightning. No tiny surge arrestor can do anything about that.


NT

[Uncle Peter]

On Tue, 25 Feb 2014 17:54:32 -0000, <meow...@care2.com> wrote:

> On Tuesday, February 25, 2014 5:21:05 PM UTC, Uncle Peter wrote:
>> On Tue, 25 Feb 2014 17:14:55 -0000, <meow...@care2.com> wrote:
>> > On Monday, February 24, 2014 6:59:34 PM UTC, Uncle Peter wrote:
>> >
>> >
>> >> Ok, I'll assume I've protected the computers well enough then.
>> >
>> > The designer & manufacturer of the PC PSU has done that.
>
>> Then I guess the 4 quid surge protector is protecting several 40 quid PSUs.
>
> they dont protect anything, other than someone's profits

At 4 quid I very much doubt there is much profit. That includes postage and packing and packaging and Ebay fees.

>> >> I've got a spike arrestor on the phoneline too.
>> >
>> > Overhead phone services already have those built in.
>> >
>> > Youre buying into marketing bs and wasting your time.
>
>> Then why did my dad's network card burn out when he got lightning through his phone line, through the router, and into the ethernet port?
>
> Presumably because it was hit by lightning. No tiny surge arrestor can do anything about that.

It might do enough to reduce the effect.

So, why did the plug in surge protector melt when at my 2nd last place of work an electrician put 2 phases onto a circuit instead of one? If they do nothing below 650V, it should have just sat there.

--
Do you know what a Jewish dilemma is?
Free ham.

[jrwal...@gmail.com]

Computer equipment sold in Europe needs to comply with EN55024 (Information technology equipment - Immunity characteristics - Limits and methods of measurement) to obtain CE marking.

This requires the following immunity on the mains input:
Surges: 1kV peak L to N, 2kV peak L or N to E
Fast transients: 1kV peak at 5kHz repetition rate.

Surges and transients are applied with both polarities and random phase relative to the mains waveform, so some of the surges are on top of the peak mains voltage.

Immunity in this case means that the equipment continues operating correctly after the test and that stored data has not been corrupted during the test.

Therefore, there is no point in clamping just above the mains voltage. A 650V clamping device is good enough. However, I agree with the other posters who make a point of avoiding TVS "protected" mains adapters which don't do anything useful but which can explode under extreme conditions. There are some very substantial DIN-rail protectors which protect the whole property and might be useful, but they are very expensive.

John

[meow...@care2.com]

On Tuesday, February 25, 2014 6:02:45 PM UTC, Uncle Peter wrote:
> On Tue, 25 Feb 2014 17:54:32 -0000, <meow...@care2.com> wrote:
> > On Tuesday, February 25, 2014 5:21:05 PM UTC, Uncle Peter wrote:
> >> On Tue, 25 Feb 2014 17:14:55 -0000, <meow...@care2.com> wrote:
> >> > On Monday, February 24, 2014 6:59:34 PM UTC, Uncle Peter wrote:

> >> Then I guess the 4 quid surge protector is protecting several 40 quid PSUs.
> >
> > they dont protect anything, other than someone's profits

> At 4 quid I very much doubt there is much profit. That includes postage and packing and packaging and Ebay fees.

Of course there is, or they wouldnt be sold. Its basic capitalism principles. You can get them in retail quantities for 50p last time I looked.

> >> >> I've got a spike arrestor on the phoneline too.
> >> >
> >> > Overhead phone services already have those built in.
> >> >
> >> > Youre buying into marketing bs and wasting your time.
> >
> >> Then why did my dad's network card burn out when he got lightning through his phone line, through the router, and into the ethernet port?
> >
> > Presumably because it was hit by lightning. No tiny surge arrestor can do anything about that.

> It might do enough to reduce the effect.

You've got sometimes a billion plus volts crossing over a mile of air. You've got maybe 300,000 amps. You've got a discharge path exceeding 50,000 degrees C. Do you seriously think a 1cm disc of any material on earth is going to make the slightest difference?

> So, why did the plug in surge protector melt when at my 2nd last place of work an electrician put 2 phases onto a circuit instead of one? If they do nothing below 650V, it should have just sat there.

who cares? All you get for your money is a fire risk. Even the insurance that often comes with them is too often worthless, and at best worth very little. Its just a game, a profitable game.


NT

[Uncle Peter]

On Tue, 25 Feb 2014 18:48:16 -0000, <meow...@care2.com> wrote:

> On Tuesday, February 25, 2014 6:02:45 PM UTC, Uncle Peter wrote:
>> On Tue, 25 Feb 2014 17:54:32 -0000, <meow...@care2.com> wrote:
>> > On Tuesday, February 25, 2014 5:21:05 PM UTC, Uncle Peter wrote:
>> >> On Tue, 25 Feb 2014 17:14:55 -0000, <meow...@care2.com> wrote:
>> >> > On Monday, February 24, 2014 6:59:34 PM UTC, Uncle Peter wrote:
>
>> >> Then I guess the 4 quid surge protector is protecting several 40 quid PSUs.
>> >
>> > they dont protect anything, other than someone's profits
>
>> At 4 quid I very much doubt there is much profit. That includes postage and packing and packaging and Ebay fees.
>
> Of course there is, or they wouldnt be sold. Its basic capitalism principles. You can get them in retail quantities for 50p last time I looked.

It's not very much profit though is it?

>> >> >> I've got a spike arrestor on the phoneline too.
>> >> >
>> >> > Overhead phone services already have those built in.
>> >> >
>> >> > Youre buying into marketing bs and wasting your time.
>> >
>> >> Then why did my dad's network card burn out when he got lightning through his phone line, through the router, and into the ethernet port?
>> >
>> > Presumably because it was hit by lightning. No tiny surge arrestor can do anything about that.
>
>> It might do enough to reduce the effect.
>
> You've got sometimes a billion plus volts crossing over a mile of air. You've got maybe 300,000 amps. You've got a discharge path exceeding 50,000 degrees C. Do you seriously think a 1cm disc of any material on earth is going to make the slightest difference?

So lightning protectors are a con? And they are legally sold? I don't think so. Otherwise I could make up any old shit and stick it in a plastic box and sell it.

>> So, why did the plug in surge protector melt when at my 2nd last place of work an electrician put 2 phases onto a circuit instead of one? If they do nothing below 650V, it should have just sat there.
>
> who cares?

It disproves the 650V shit.

> All you get for your money is a fire risk.

It probably helped trip the breaker by causing a short.

--
I don't care what they say, I don't think "phone sex" is any fun at all, unless you happen to be in the same booth with her.

[westom]

A 5000 volt surge is approaching on any or all wires. A protector
shorts maybe a hot wire surge to other AC wires. Now 5000 volts are on all
wires and still hunting for earth destrutively via nearby appliances.
Learn about many types of currents. One you are thinking about is not the
typically destructive type of current.

Fuses blow to disconnect AFTER damage has occured. Furse are mostly for
human safety. So that resulting damage does not cause a fire.

A surge does damage in microseconds. A fuse may take milliseconds or
longer to open. Numbers describe what a fuse really does.

Destructive surges increase voltage as neceassary to flow through
anything that might stop it. A voltage number is printed on each fuse.
If 250 volts, then a surge simply increases voltage above 250 volts to
continue flowing through that blown fuse.

Protection is only about connecting a surge to earth on a path that does
not flow through and near to any appliances. Protection is always about
where hundreds of thousands of joules dissopate. That means a low
impedance current path is installed / defined by a homeowner. Otherwise a
surge hunts for earth destructively via appliances.

Fuses do not do surge protection. Fuses avert a resulting fire.


--

[Uncle Peter]

On Wed, 26 Feb 2014 04:44:01 -0000, westom <caedfaa9ed1216d60e...@example.com> wrote:

> replying to Uncle Peter , westom wrote:
>> no wrote:
>> Surely if the surge protector could just short the line to anything
>> that was over the 240V RMS, it would blow a fuse or breaker, and
>> not cause a fire?
>
> A 5000 volt surge is approaching on any or all wires. A protector
> shorts maybe a hot wire surge to other AC wires. Now 5000 volts are on all
> wires and still hunting for earth destrutively via nearby appliances.
> Learn about many types of currents. One you are thinking about is not the
> typically destructive type of current.

Surely the surge would not be present on the earth wire, as that is earthed via a stake at the premises or the substation.

> Fuses blow to disconnect AFTER damage has occured. Furse are mostly for
> human safety. So that resulting damage does not cause a fire.

But the surge protector would short the surge to earth, the surge protector would be destroyed, and the fuse would prevent the surge protector catching fire.

> A surge does damage in microseconds. A fuse may take milliseconds or
> longer to open. Numbers describe what a fuse really does.

The surge protector blocks the surge during the time taken for the fuse to blow.

> Destructive surges increase voltage as neceassary to flow through
> anything that might stop it. A voltage number is printed on each fuse.
> If 250 volts, then a surge simply increases voltage above 250 volts to
> continue flowing through that blown fuse.
>
> Protection is only about connecting a surge to earth on a path that does
> not flow through and near to any appliances. Protection is always about
> where hundreds of thousands of joules dissopate. That means a low
> impedance current path is installed / defined by a homeowner. Otherwise a
> surge hunts for earth destructively via appliances.
>
> Fuses do not do surge protection. Fuses avert a resulting fire.

--

Experience is what you got by not having it when you need it.

[jrwal...@gmail.com]

On Wednesday, February 26, 2014 1:17:55 PM UTC, Uncle Peter wrote:

> Surely the surge would not be present on the earth wire, as that is earthed via a stake at the premises or the substation.

The manufacturers of your Micromark surge protector don't think so, because they claim to protect L,N and E.

> But the surge protector would short the surge to earth, the surge protector would be destroyed, and the fuse would prevent the surge protector catching fire.
> > A surge does damage in microseconds. A fuse may take milliseconds or
> > longer to open. Numbers describe what a fuse really does.
> The surge protector blocks the surge during the time taken for the fuse to blow.
>

Would the fuse really prevent the "surge protector" from catching fire?

Numbers do define what a fuse does - here are some to think about:

According to data from Bussmann who make 13A fuse cartridges, a 13A cartridge is allowed to pass a current of up to 4 times the rated capacity for 0.8s or 2.6 times rated capacity for 10s.

Lets assume the surge protector is triggered by a large transient and starts to fail by dropping in resistance. If it is protected by a 13A fuse, then a current of 260A could flow for 10s before the fuse blows. At 240V it will have let through an energy of about 81000 Joules. The Micromark protector claims to be able to absorb up to 240Joules. So where do the other 80760 Joules go?

This isn't a very realistic example though, because by now there would be a ball of plasma inside the housing which is a very good electrical conductor. Under these more extreme conditions, the fuse is rated to blow in 0.02s at a current of 20 times the rated current. (There is nothing in the specification which requires it to blow faster than this.)

The energy let through would be 240 x 13 x 20 x 0.02 Joules. This is 1248 Joules. So, even under the most optimistic conditions of fast fuse blowing, there are still over 1000 Joules unaccounted for after the proteector has absorbed its quota of 240 Joules.

These numbers are just for normal mains voltage. Now suppose there has been a more realistic surge of 415V, perhaps caused by a lost neutral. Then, if the protector fails slowly, the energy will be about 140000 Joules. If it fails quickly, the energy will "only" be 2158 Joules.

You wonder why many posters here avoid using these devices?

John

[Johny B Good]

On Wed, 26 Feb 2014 13:17:55 -0000, "Uncle Peter" <n...@spam.com> wrote:

>On Wed, 26 Feb 2014 04:44:01 -0000, westom <caedfaa9ed1216d60e...@example.com> wrote:
>
>> replying to Uncle Peter , westom wrote:
>>> no wrote:
>>> Surely if the surge protector could just short the line to anything
>>> that was over the 240V RMS, it would blow a fuse or breaker, and
>>> not cause a fire?
>>
>> A 5000 volt surge is approaching on any or all wires. A protector
>> shorts maybe a hot wire surge to other AC wires. Now 5000 volts are on all
>> wires and still hunting for earth destrutively via nearby appliances.
>> Learn about many types of currents. One you are thinking about is not the
>> typically destructive type of current.
>
>Surely the surge would not be present on the earth wire, as that is earthed via a stake at the premises or the substation.
>

You over-estimate the conductance of protective earthing and
under-estimate the strength of the current in a lightning bolt.

It's quite a 'neat trick' to get earth resistance down to a tenth of
an ohm (even the pile of 'copper mongery' buried in the foundations of
a large telephone exchange may not approach such a laudibly low
resistance figure of merit).

The current in a ground seeking lightning bolt can easily be 50,000
amperes or more with rise times measured in nano to micro seconds. If
the local exchange building recieves a direct hit by a modest strength
lightning bolt of 50,000 amperes, the exchange earth potential will be
raised by 5KV with an earthing resistance of just 0.1 ohms (and this
ignores the effect of inductance in the earth cable runs to the
exchange earth bonding point which will likely raise this by another
order of magnitude or so).

Such a strike at (or even just very close to[1]) the exchange will
send kilvolt pulses along every telephone line as a 'common mode'
surge. This isn't normally a problem for most line powered telephones
but can wreak havoc with any equipment that relies upon an external
mains connected PSU.

[1] A close ground strike is anything within about a hundred metres.
This will raise the local earth potential by several thousand volts
varying not only according to the strength of the lightning bolt
itself but also according to the nature of topsoil and underlying
bedrock.

This also applies to direct/close strikes at the customer end of such
galvanically connected lines (telephone and Public Supply Utilites).
You can turn the whole house into a faraday cage but the benefit is
easily negated by the need to have a galvanic connection to external
remote services such as phone lines and mains electricity supply.

It is possible to 'filter' such external sources of destructive
surges but the 'filters' tend to require well buried convoluted runs
of cabling designed to short circuit any such surges to earth (and, if
necessary fail destructively in a final act of sacrifice to protect
the connected equipment) along with more conventional (if rather heavy
duty) EMC filtering to remove the 'final sting' from the residual
voltage spikes that the special sacrificial cable runs let through.

When it comes to lighting strikes, this type of wild and unruly
example of electrical discharge is no respector of "Keep Off The
Grass" signs (insulation) normally obeyed by mains voltage levels. It
will tend to vaguely follow the path of the conductors but quite
happily, so to speak, take any shortcuts it can.
--
Regards, J B Good

[westom]

replying to Uncle Peter , westom wrote:
> no wrote:
> Surely the surge would not be present on the earth wire, as that is earthed
via a stake at the premises or the substation.

Those assumptions about how electricity works are incorrect. Electricity
is never same on both ends of a wire. How different. Again, every answer
must always include numbers.

To demonstrate. Connect a 200 watt transmitter to a long wire antenna.
Touch one part of that antenna to feel no voltage. Touch another part to
be shocked by over 100 volts. How does zero volts and 100 volts both
exist at different points of the same wire? That is how electricity works.

For same reasons, safety ground wire in a receptacle is not earth
ground. Another critically important number exists due to how electricity
works. "Less than 10 feet". If a surge does not make a connection low
impedance (ie 'no sharp wire bends') to earth, then the connection is
compromised.

For effective protection, a surge is connected low impedance (ie 'less
than 10 feet') to single point earth ground. That power strip protector
(what should be obvious) has no earth ground. And does not even claim to
protect from destructive surges. A protector is only as effective as its
earth ground.


--

[Capitol]

I have seen 10KV standing waves on 415V lines. The results are very
destructive.

[Uncle Peter]

On Wed, 26 Feb 2014 14:56:46 -0000, <jrwal...@gmail.com> wrote:

> On Wednesday, February 26, 2014 1:17:55 PM UTC, Uncle Peter wrote:
>
>> Surely the surge would not be present on the earth wire, as that is earthed via a stake at the premises or the substation.
>
> The manufacturers of your Micromark surge protector don't think so, because they claim to protect L,N and E.
>
>> But the surge protector would short the surge to earth, the surge protector would be destroyed, and the fuse would prevent the surge protector catching fire.
>> > A surge does damage in microseconds. A fuse may take milliseconds or
>> > longer to open. Numbers describe what a fuse really does.
>> The surge protector blocks the surge during the time taken for the fuse to blow.
>>
>
> Would the fuse really prevent the "surge protector" from catching fire?
>
> Numbers do define what a fuse does - here are some to think about:
>
> According to data from Bussmann who make 13A fuse cartridges, a 13A cartridge is allowed to pass a current of up to 4 times the rated capacity for 0.8s or 2.6 times rated capacity for 10s.
>
> Lets assume the surge protector is triggered by a large transient and starts to fail by dropping in resistance. If it is protected by a 13A fuse, then a current of 260A could flow for 10s before the fuse blows. At 240V it will have let through an energy of about 81000 Joules. The Micromark protector claims to be able to absorb up to 240Joules. So where do the other 80760 Joules go?

You've got your figures wrong. 2.6 times rated capacity = 33.8A, not 260A could low for 10s before the fuse blows.

> This isn't a very realistic example though, because by now there would be a ball of plasma inside the housing which is a very good electrical conductor. Under these more extreme conditions, the fuse is rated to blow in 0.02s at a current of 20 times the rated current. (There is nothing in the specification which requires it to blow faster than this.)
>
> The energy let through would be 240 x 13 x 20 x 0.02 Joules. This is 1248 Joules. So, even under the most optimistic conditions of fast fuse blowing, there are still over 1000 Joules unaccounted for after the proteector has absorbed its quota of 240 Joules.

Its quota of 240 Joules probably leaves it looking brand spanking new, but with the operating LED off. 5 times that might leave it brown or melted a little, but I doubt it would burst into flames.

> These numbers are just for normal mains voltage. Now suppose there has been a more realistic surge of 415V, perhaps caused by a lost neutral. Then, if the protector fails slowly, the energy will be about 140000 Joules. If it fails quickly, the energy will "only" be 2158 Joules.
>
> You wonder why many posters here avoid using these devices?

I've stated three times before in this thread that I've seen a surge protector get L1-L2 across it. It was deformed, but did not catch fire or emit significant smoke before the 32A circuit breaker tripped.

Also, a loss of neutral would cause 415V? Explain! That is the absolute worst case scenario with completely imbalanced phases.

--
Have you heard the slogan for Trojan's new "Stealth" Condom?
"They'll never see you coming."

[Uncle Peter]

Agreed. Although the surge protector would still help to reduce the potential difference between each of the three wires going into the equipment. Depending where the appliance is situated, I guess the lightning might want to go through it - eg a washing machine sat on the ground floor.

--
What do you call an Amish man with his arm up a horse's ass?
A mechanic.

[Uncle Peter]

I guess the one I've got is only designed to (and it does say things like that on the packet) protect against little surges from motors, arc welders, etc on the same or a nearby circuit. Or perhaps a little spike on the power lines from a fucked up switch over by the electricity board.

--
"His idea of safe sex is an `X' spray-painted on the rump of animals that are known to kick."

[Uncle Peter]

Sounds interesting. What was the source of the 10kV?

--
Drugs lead nowhere, but it's the scenic route.

[Capitol]

Reflections on the transmission lines which just happened to have the
correct length for the results to be additive. It's a very common
effect on Radar transmitter systems, fortunately rare on 50Hz systems.
Took a bit of head scratching to realise what the problem was and look
for it.

[Uncle Peter]

I guess the wavelength of 50Hz electricity is exceedingly long (I make it about 6000km), so not likely to cause a standing wave. However a SATA3 cable I believe operates at 3GHz, which has a wavelength of 10cm if my calculations are correct. I wonder if they have to consider reflections causing interference?

--
Those who jump off a bridge in Paris are in Seine.

[westom]

> spam wrote:
> I have seen 10KV standing waves on 415V lines. The results are very
> destructive.

A protector adjacent to appliances would not even claim to protect from
them. A completely different device (that unfortunately shares a same
name) is for such anomalies. And would be necessary to protect an
expensive power strip and UPS from that anomaly.

People have undersized protectors behind TVs and under desks only because
advertising says so. Most also do not know of a fire threat these create
due to being undersized and located where fire risk is greatest. Why does
advertising forget to discuss this fire hazard and relocating protectors
in safer locations? Are they being honest or simply manipulating the
naive for higher profits? The so called 'high quality' protectors are
little different from $10 ones. They operate similar. And only from
anomalies that typically cause no damage.

Monster also sells them. Monster has a long history of identifying
scams. Then selling an equivlent product at even higher prices. Because
so many know a higher price and more expensive paint means it must be
better quality. Those who know without learning numbers are so easily
manipulated as to even recommend these ineffective devices.

Voltage spikes between wires are rarely destructive due to how
appliances are designed. That transient is easy to avert. Destructive
surges seek earth ground. For over 100 years, the solution has always
been earthing at the service entrance of every incoming wire.

How often does your telco not provide phone service for four days while
they replacen that $multi-million computer? Never? Exactly. Because
telcos use this same and proven protection solution - with an even better
earth ground. Their CO, connected to wires all over town, suffers about
100 surges per storm ... without damage.

Homeonwers need to worry about one surge maybe every seven years. A
number that also says why so many do not even know if their surge
protector did anything.

Suppose a nearby strike raises voltage beneath the house by 10,000 volts.
No proboem. Everything at 10,000 volts means zero volts across any
appliance. This well understood concept is even described by a Faraday
cage. Unfortunately those myths about ground resitance and high earth
voltage live on when a simple physics concept - Faraday cage - is not
understood.

Lightning strikes a church steeple because wood is an electrical
conductor. That maybe 20,000 amps through a poor electrical conductor to
earth means a high voltage across the church steeple. 20,000 amps times a
high voltage means high energy and damaged church steeple.

Franklin mounted a lightning rod. Do lighting rods do protection? Of
course not. A lightning rod is effective when connected to earth on a
separate wire. 20,000 amps on a conductive wire means near zero voltage.
20,000 amps times near zero voltage is near zero energy. No steeple
damage.

Same applies here. Lightning permitted inside a building means a high
current to earth via appliances and conductive house materials (ie wood).
A high voltage is created. A high current times a high voltage is high
energy. Appliances damaged.

For over 100 years, the informed earthed incoming wires directly or via
a 'whole house' protector. Do protectors do protection? Of course not. A
protector means a near zero voltage when connected low impoedance (ie
'less than 10 feet') to earth on a dedicated earthing electrode. High
current times a near zero voltage is near zero energy. Protection already
inside every appliance is not overwhelmed. And all appliances are also
protected from lesser anomalies. This is the well proven solution used
even 100 years ago.

Protection is always about where hundreds of thousands of joules

dissipate. Anyone who does not discuss energy and relevant numbers is
probably reciting advertising myths and other forms of propaganda. Many
denials here are devoid of basic electrical concepts. And half truths
promoted by hearsay.

Best solution, without doubt, that costs less money is earthing a 'whole
house' protector. Otherwise next best protection is that already inside
all appliances. Fewer who did this stuff as engineers would know that. A
majority only informed by advertising would not. And forget to include
numbers in their recommendations. Forget to answer this - "Where do
hundreds of thousands of joules dissipate?"

A protector is only as effective as its earth ground. Numbers are
provided to show why. And to show why other 'so called' high quality
protectors (better called profit centers) do not even claim that
protection.

Of course, soundbytes dispute this. Reality always takes longer.

--

[Capitol]

The termination impedance is critical. Early PC 100MHz+ boards found
reflections to be a problem and there was a bit of a learning curve.

[meow...@care2.com]

On Tuesday, February 25, 2014 7:09:54 PM UTC, Uncle Peter wrote:
> On Tue, 25 Feb 2014 18:48:16 -0000, <meow...@care2.com> wrote:
> > On Tuesday, February 25, 2014 6:02:45 PM UTC, Uncle Peter wrote:
> >> On Tue, 25 Feb 2014 17:54:32 -0000, <meow...@care2.com> wrote:
> >> > On Tuesday, February 25, 2014 5:21:05 PM UTC, Uncle Peter wrote:
> >> >> On Tue, 25 Feb 2014 17:14:55 -0000, <meow...@care2.com> wrote:
> >> >> > On Monday, February 24, 2014 6:59:34 PM UTC, Uncle Peter wrote:


> >> >> Then I guess the 4 quid surge protector is protecting several 40 quid PSUs.
> >> >
> >> > they dont protect anything, other than someone's profits
> >
> >> At 4 quid I very much doubt there is much profit. That includes postage and packing and packaging and Ebay fees.

> > Of course there is, or they wouldnt be sold. Its basic capitalism principles. You can get them in retail quantities for 50p last time I looked.

> It's not very much profit though is it?

£1 postage, 5p envelope, 27p ebay fee makes 2.67. Less 50p uk retail cost, or more likely 10p chinese wholesale cost, makes 2.57 profit, or 2500% markup. Sell a million of those and you're laughing.

> > You've got sometimes a billion plus volts crossing over a mile of air. You've got maybe 300,000 amps. You've got a discharge path exceeding 50,000 degrees C. Do you seriously think a 1cm disc of any material on earth is going to make the slightest difference?

> So lightning protectors are a con?

What exactly do you mean by lightning protectors?
How do you define a con?
Which claims about them constitute the con?

> And they are legally sold? I don't think so.

You've not bothered to get your facts right. Selling junk products is all about giving people an unrealistic impression of what they can do. There's no lack of such products in the marketplace.

> Otherwise I could make up any old shit and stick it in a plastic box and sell it.

Almost, but too simplistic. There's no shortage of bs on products.

> >> So, why did the plug in surge protector melt when at my 2nd last place of work an electrician put 2 phases onto a circuit instead of one? If they do nothing below 650V, it should have just sat there.
> >
> > who cares?
> It disproves the 650V shit.
> > All you get for your money is a fire risk.
> It probably helped trip the breaker by causing a short.

No.

Surge protectors have some use for specific types of surge in very restricted circumstances. The idea that that translates to them being of any realistic use hooked across normal mains supplies is simply cobblers - but it sure does sell. With those sort of markups its a marketers dream.


NT

[jrwal...@gmail.com]

On Wednesday, 26 February 2014 21:10:33 UTC, Uncle Peter wrote:
> On Wed, 26 Feb 2014 14:56:46 -0000, <jrwal...@gmail.com> wrote:

> > Lets assume the surge protector is triggered by a large transient and starts to fail by dropping in resistance. If it is protected by a 13A fuse, then a current of 260A could flow for 10s before the fuse blows. At 240V it will have let through an energy of about 81000 Joules. The Micromark protector claims to be able to absorb up to 240Joules. So where do the other 80760 Joules go?
>
> You've got your figures wrong. 2.6 times rated capacity = 33.8A, not 260A could low for 10s before the fuse blows.
>

Oops! Sorry about that. I mistyped the current, but the result is correct.

13 * 2.6 * 240 * 10 = 81120 Joules

> Also, a loss of neutral would cause 415V? Explain! That is the absolute worst case scenario with completely imbalanced phases.
>

Yes. It is perfectly possible under fault conditions.

John

[westom]

replying to westom, westom wrote:

> westom wrote:
> Suppose a nearby strike raises voltage beneath the house by 10,000 volts.
> No proboem. Everything at 10,000 volts means zero volts across any
appliance.

--
I should probably also add something rarely known. Other incoming utility
wires (ie cable TV, telephone) already have this 'whole house' solution.
As required by code, industry standards, and for other reasons. Many do
not even know it exists.

--

[Uncle Peter]

On Wed, 26 Feb 2014 22:44:01 -0000, westom <caedfaa9ed1216d60e...@example.com> wrote:

> Suppose a nearby strike raises voltage beneath the house by 10,000 volts.
> No proboem. Everything at 10,000 volts means zero volts across any
> appliance. This well understood concept is even described by a Faraday
> cage. Unfortunately those myths about ground resitance and high earth
> voltage live on when a simple physics concept - Faraday cage - is not
> understood.
>
> Lightning strikes a church steeple because wood is an electrical
> conductor. That maybe 20,000 amps through a poor electrical conductor to
> earth means a high voltage across the church steeple. 20,000 amps times a
> high voltage means high energy and damaged church steeple.
>
> Franklin mounted a lightning rod. Do lighting rods do protection? Of
> course not. A lightning rod is effective when connected to earth on a
> separate wire. 20,000 amps on a conductive wire means near zero voltage.
> 20,000 amps times near zero voltage is near zero energy. No steeple
> damage.

Someone once told me that lightning rods actually do not conduct lightning, they conduct the charge previous to lightning, discouraging the main bolt from taking that path.

--
"Flashlights are tubular metal containers kept in a flight bag for the purpose of storing dead batteries."

[Uncle Peter]

Ah, like with the old coax ethernet and SCSI systems.

--
Only 55% of Americans know that the sun is a star.

[Uncle Peter]

On Wed, 26 Feb 2014 23:02:57 -0000, <meow...@care2.com> wrote:

> On Tuesday, February 25, 2014 7:09:54 PM UTC, Uncle Peter wrote:
>> On Tue, 25 Feb 2014 18:48:16 -0000, <meow...@care2.com> wrote:
>> > On Tuesday, February 25, 2014 6:02:45 PM UTC, Uncle Peter wrote:
>> >> On Tue, 25 Feb 2014 17:54:32 -0000, <meow...@care2.com> wrote:
>> >> > On Tuesday, February 25, 2014 5:21:05 PM UTC, Uncle Peter wrote:
>> >> >> On Tue, 25 Feb 2014 17:14:55 -0000, <meow...@care2.com> wrote:
>> >> >> > On Monday, February 24, 2014 6:59:34 PM UTC, Uncle Peter wrote:
>
>
>> >> >> Then I guess the 4 quid surge protector is protecting several 40 quid PSUs.
>> >> >
>> >> > they dont protect anything, other than someone's profits
>> >
>> >> At 4 quid I very much doubt there is much profit. That includes postage and packing and packaging and Ebay fees.
>
>> > Of course there is, or they wouldnt be sold. Its basic capitalism principles. You can get them in retail quantities for 50p last time I looked.
>
>> It's not very much profit though is it?
>
> £1 postage, 5p envelope, 27p ebay fee makes 2.67. Less 50p uk retail cost, or more likely 10p chinese wholesale cost, makes 2.57 profit, or 2500% markup. Sell a million of those and you're laughing.

Last time I checked, it cost 3 quid to post something if it was fatter than 2.5cm. It cost me a pound to post a CD to someone, and 3 pounds for 2 CDs in jewel cases.

>> > You've got sometimes a billion plus volts crossing over a mile of air. You've got maybe 300,000 amps. You've got a discharge path exceeding 50,000 degrees C. Do you seriously think a 1cm disc of any material on earth is going to make the slightest difference?
>
>> So lightning protectors are a con?
>
> What exactly do you mean by lightning protectors?

http://www.ebay.co.uk/itm/260971329731

> How do you define a con?

Something which doesn't do anything.

> Which claims about them constitute the con?

The name.

>> And they are legally sold? I don't think so.
>
> You've not bothered to get your facts right. Selling junk products is all about giving people an unrealistic impression of what they can do. There's no lack of such products in the marketplace.

If it's called a lightning protector, it should protect against lighting, or it isn't a lightning protector.

>> >> So, why did the plug in surge protector melt when at my 2nd last place of work an electrician put 2 phases onto a circuit instead of one? If they do nothing below 650V, it should have just sat there.
>> >
>> > who cares?
>> It disproves the 650V shit.
>> > All you get for your money is a fire risk.
>> It probably helped trip the breaker by causing a short.
>
> No.
>
> Surge protectors have some use for specific types of surge in very restricted circumstances. The idea that that translates to them being of any realistic use hooked across normal mains supplies is simply cobblers - but it sure does sell. With those sort of markups its a marketers dream.

Why do you dispute that a shorted out surge protector tripped the breaker?

--
Computers are like air conditioners: They stop working when you open Windows.

[bm]

<meow...@care2.com> wrote in message
news:a0178174-7acd-423e...@googlegroups.com...

Don't forget, it's PHucker (spelt troll) that you're typing to. He has a
degree, you know.

[Uncle Peter]

How? Neutral is only required to stabilise uneven phases, and is often a thinner conductor.

--
A man was sunbathing naked at the beach.
For the sake of decency and civility, and to keep it from getting sunburnt, he had a hat over his private parts.
A woman walks past and says, snickering, "If you were a gentleman you'd lift your hat."
He raised an eyebrow and replied, "If you were better looking it would lift itself."

[westom]

replying to Uncle Peter , westom wrote:
> no wrote:

> Someone once told me that lightning rods actually do not conduct lightning,
they conduct the charge previous to lightning, discouraging the main bolt
from taking that path.


--

It demostrates the point. Many only know what hearsay and urban myths
tell them. Many do not do what was taught in junior high science; how to
know a fact.

Described was an ESE device. This myth claims that pointy conductors will
discharge air (miles up to the cloud) so that a lightning bolt will be
discharged before it can strike. These were submitted to the NFPA in 1999
to become part of the National Electrical Code. And was rejected by that
non-profit organization. So Heary Bros sued the NFPA with intent of
bankrupting it. Blackmail. So the question was put to an indenpendent
study group (Bryan Panel). Who then said, in essense, the ESE industry
has spend massive money to promote their product and never spent any money
on research that justified their product.

A research paper by Hartono and Robiah states this bluntly: [quote]The
failure of the ESE air terminals to intercept nearby lightning strikes
poses an unacceptable risk to public safety.[/quote]

Numerous IEEE papers describe ESE myth. In one experiment, an ESE device
was mounted on an FAA control tower. Next day, a direct lightning strike
blasted it off the building.

Where is a responsible source to justify ESE devices? How many promote it
with zero basis in science? And yet so many still believe that myth.
Getting people to beleive lies based only in hearsay is easy. Again, a
simple rule. Honesty also requires perspective - ie numbers.


--

[Peter Crosland]

On 24/02/2014 13:48, Uncle Peter wrote:
> I've got a few cheap micromark surge protectors, and noticed they have a
> clamping voltage of 650V.
> Anyone know where I can get a much lower one? I've heard of protectors
> as low as 270V, but I can't find any to buy.

The reality is that these surge protectors offer very little, if any,
protection against lightning strikes. A lightning strike close by can
kill your electronic equipment regardless of what protection you have. I
regard them in the same league as expensive hi-fi interconnects or snake
oil.


--
Peter Crosland

[jrwal...@gmail.com]

On Thursday, 27 February 2014 00:17:24 UTC, Uncle Peter wrote:

> >> Also, a loss of neutral would cause 415V? Explain! That is the absolute worst case scenario with completely imbalanced phases.

> > Yes. It is perfectly possible under fault conditions.

> How? Neutral is only required to stabilise uneven phases, and is often a thinner conductor.

Incoming neutral goes open circuit. If one phase happens to be heavily loaded and the other two very lightly loaded then the voltage on those approaches 415V.

Or, of course, the example you already gave of incorrect wiring.

John

[tony sayer]

In article <PPidnW5aTOHycJPO...@brightview.co.uk>, Peter
Crosland <g6...@yahoo.co.uk> scribeth thus

>On 24/02/2014 13:48, Uncle Peter wrote:
>> I've got a few cheap micromark surge protectors, and noticed they have a
>> clamping voltage of 650V.
>> Anyone know where I can get a much lower one? I've heard of protectors
>> as low as 270V, but I can't find any to buy.
>
>The reality is that these surge protectors offer very little, if any,
>protection against lightning strikes. A lightning strike close by can
>kill your electronic equipment regardless of what protection you have.

Except that equipment at comms sites and Radio and TV transmitting
stations does survive year in year out;!...

>I
>regard them in the same league as expensive hi-fi interconnects or snake
>oil.

The Ross Andrews lightning conductor!! allows you to use your audio
system in any weather!, made of some unknown to science metal a snip at
£3,000 a yard;!!..
>
>

--
Tony Sayer

[John Williamson]

On 27/02/2014 12:48, tony sayer wrote:
> In article <PPidnW5aTOHycJPO...@brightview.co.uk>, Peter
> Crosland <g6...@yahoo.co.uk> scribeth thus
>> On 24/02/2014 13:48, Uncle Peter wrote:
>>> I've got a few cheap micromark surge protectors, and noticed they have a
>>> clamping voltage of 650V.
>>> Anyone know where I can get a much lower one? I've heard of protectors
>>> as low as 270V, but I can't find any to buy.
>>
>> The reality is that these surge protectors offer very little, if any,
>> protection against lightning strikes. A lightning strike close by can
>> kill your electronic equipment regardless of what protection you have.
>
>
> Except that equipment at comms sites and Radio and TV transmitting
> stations does survive year in year out;!...
>

That's as may be, but they tend to have rather better quality protection
on all their connections than a cheapie "surge protected" 13A strip with
a tuppenny MOV in it.


--
Tciao for Now!

John.

[Capitol]

Perhaps I can interest you all in a new magnetic water softener!

[Uncle Peter]

I once had a surge protected 13A plug, with a 13A fuse, powering an extension cord. Into that extension cord was plugged a UPS (among other things). Into the UPS was plugged a computer and a monitor, which I was using. I didn't notice anything had happened until the UPS bleeped to inform me the battery was almost empty (3 hours later - it had an extended battery). I then checked the surge plug, which had a brown indicator on it instead of white, to indicate it was expired. The 13A fuse had blown. No appliances were damaged, and I was drawing nowhere near 13A on that extension cord, so I can only guess the plug removed a surge, blew the fuse, and prevented the surge hitting any equipment. The plug was undamaged, didn't smell bad, just had a brown indicator.

--
What do you call it when a blonde drives down the street with her head out the window?
Refueling.

[Peter Crosland]

On 27/02/2014 12:48, tony sayer wrote:

> In article <PPidnW5aTOHycJPO...@brightview.co.uk>, Peter
> Crosland <g6...@yahoo.co.uk> scribeth thus
>> On 24/02/2014 13:48, Uncle Peter wrote:
>>> I've got a few cheap micromark surge protectors, and noticed they have a
>>> clamping voltage of 650V.
>>> Anyone know where I can get a much lower one? I've heard of protectors
>>> as low as 270V, but I can't find any to buy.
>>
>> The reality is that these surge protectors offer very little, if any,
>> protection against lightning strikes. A lightning strike close by can
>> kill your electronic equipment regardless of what protection you have.
>
>
> Except that equipment at comms sites and Radio and TV transmitting
> stations does survive year in year out;!...

Those have considerably better design against damage from electrical
storms. Nevertheless they are not immune to damage. Likewise aeroplanes.
In a domestic situation it is quite common for large amounts of
electronic equipment to be damaged by nearby lightnings strikes without
there being any evidence of a direct strike on the equipment.


--
Peter Crosland

[Vir Campestris]

On 26/02/2014 23:49, Uncle Peter wrote:
> Someone once told me that lightning rods actually do not conduct
> lightning, they conduct the charge previous to lightning, discouraging
> the main bolt from taking that path.

Someone was wrong.

Andy

[Uncle Peter]

He designed computer power supplies.

--
"Sex is one of the most beautiful, wholesome, and natural things that money can buy." -- Steve Martin

[meow...@care2.com]

On Monday, February 24, 2014 1:48:25 PM UTC, Uncle Peter wrote:

> I've got a few cheap micromark surge protectors, and noticed they have a clamping voltage of 650V.
>
> Anyone know where I can get a much lower one? I've heard of protectors as low as 270V, but I can't find any to buy.

They will of course go into conduction every half cycle, and quickly have a melt down or fire. But hey you know what you're doing.... apparently.


NT

[Uncle Peter]

The peak equivalent obviously.

--
Two fish are in a tank. One says to the other, "I'll man the guns, you drive".

[tony sayer]

In article <8PydnaFGbrjpL5LO...@brightview.co.uk>, Vir
Campestris <vir.cam...@invalid.invalid> scribeth thus

No, they do sometimes dissipate a charge before it builds up to form a
much bigger discharge;)...
--
Tony Sayer

[Uncle Peter]

Can we have a vote on this, or even better a link to the correct answer?

--
Gardening Rule:
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it.
If it comes out of theground easily, it is a valuable plant.

[harryagain]

"Uncle Peter" <n...@spam.com> wrote in message
news:op.xbsi5...@red.lan...
> On Mon, 24 Feb 2014 14:15:06 -0000, Graham. <m...@privicy.net> wrote:

>
>> On Mon, 24 Feb 2014 13:48:25 -0000, "Uncle Peter" <n...@spam.com> wrote:
>>
>>> I've got a few cheap micromark surge protectors, and noticed they have a
>>> clamping voltage of 650V.
>>> Anyone know where I can get a much lower one? I've heard of protectors
>>> as low as 270V, but I can't find any to buy.
>>

>> For 230V RMS?
>
> Yes.
>
>> 650 is the peal to peak equivalent, but I think it's just the peak
>> voltage that's relevant here, so anything less than 325v is no good,
>> and you are going to need some margin above that.
>>
>> Don't know what micromark offer, but if it's just a few twopenny MOVs
>> I shouldn't bother.
>
> This: http://petersphotos.com/temp/surge.jpg
>
> It's to protect computers. Looking at other surge protectors up to 100
> quid (this one was 4 quid), nothing is lower than 650V. And some of the
> 100 quid ones are 750V!
>
> Am I right in thinking 650V is rubbish? I mean the surge could double the
> peak supply voltage without the protector doing anything, and if the surge
> was more, it would clamp it down to double, which is enough to fuck up a
> computer. Mind you if it's just the power supply caps that go bang, I
> suppose it doesn't matter. Does a PC power supply stop surges getting
> past it?
>
> Or.... does 650V mean peak to peak as opposed to zero to peak?


RMS=Root of the Mean Squared.
It gives the equivalent of the DC for the purpose of calculating power usage
etc.

It is the peak voltage x 0.707 = RMS voltage (but only for sine waves).

So if you have 650Vpeak, the RMS value will be 460V

Mains power 230 volts (RMS) peak value is 325 volts.

So the cable insulation has to stand 325 volts.

For square waves the factor is 0.5

[harryagain]

Voltages in AC are normally referenced to zero unless otherwise specified.

[harryagain]

"Uncle Peter" <n...@spam.com> wrote in message

news:op.xbuk5...@red.lan...
> On Tue, 25 Feb 2014 17:14:55 -0000, <meow...@care2.com> wrote:
>
>> On Monday, February 24, 2014 6:59:34 PM UTC, Uncle Peter wrote:
>>
>>
>>> Ok, I'll assume I've protected the computers well enough then.
>>
>> The designer & manufacturer of the PC PSU has done that.

>
> Then I guess the 4 quid surge protector is protecting several 40 quid
> PSUs.
>

>>> I've got a spike arrestor on the phoneline too.
>>
>> Overhead phone services already have those built in.
>>
>> Youre buying into marketing bs and wasting your time.
>
> Then why did my dad's network card burn out when he got lightning through
> his phone line, through the router, and into the ethernet port?

No little bit of electronic bollix will resist a nearby lighning strike.

[harryagain]

"Uncle Peter" <n...@spam.com> wrote in message

news:op.xbup6...@red.lan...

> On Tue, 25 Feb 2014 18:48:16 -0000, <meow...@care2.com> wrote:
>
>> On Tuesday, February 25, 2014 6:02:45 PM UTC, Uncle Peter wrote:
>>> On Tue, 25 Feb 2014 17:54:32 -0000, <meow...@care2.com> wrote:

>>> > On Tuesday, February 25, 2014 5:21:05 PM UTC, Uncle Peter wrote:
>>> >> On Tue, 25 Feb 2014 17:14:55 -0000, <meow...@care2.com> wrote:
>>> >> > On Monday, February 24, 2014 6:59:34 PM UTC, Uncle Peter wrote:
>>
>>> >> Then I guess the 4 quid surge protector is protecting several 40 quid
>>> >> PSUs.
>>> >

>>> > they dont protect anything, other than someone's profits
>>
>>> At 4 quid I very much doubt there is much profit. That includes postage
>>> and packing and packaging and Ebay fees.
>>
>> Of course there is, or they wouldnt be sold. Its basic capitalism
>> principles. You can get them in retail quantities for 50p last time I
>> looked.
>
> It's not very much profit though is it?
>

>>> >> >> I've got a spike arrestor on the phoneline too.
>>> >> >
>>> >> > Overhead phone services already have those built in.
>>> >> >
>>> >> > Youre buying into marketing bs and wasting your time.
>>> >
>>> >> Then why did my dad's network card burn out when he got lightning
>>> >> through his phone line, through the router, and into the ethernet
>>> >> port?
>>> >

>>> > Presumably because it was hit by lightning. No tiny surge arrestor can
>>> > do anything about that.
>>
>>> It might do enough to reduce the effect.

>>
>> You've got sometimes a billion plus volts crossing over a mile of air.
>> You've got maybe 300,000 amps. You've got a discharge path exceeding
>> 50,000 degrees C. Do you seriously think a 1cm disc of any material on
>> earth is going to make the slightest difference?
>

> So lightning protectors are a con? And they are legally sold? I don't
> think so. Otherwise I could make up any old shit and stick it in a

> plastic box and sell it.
>

All depends on how close the strike is. If you think some bit of electronic
crap is going to divert the Megawatts of power in a near strike, you want
your head looking.
Buildings can be protected with lightning conductors, maybe 250mm squ
conductor.
Your litte fartbox is worthless in such a situation.

The only real protection is disconnection in these situations. ie pull the
plugs (all of them) if you see lightning nearby.

[harryagain]

"Uncle Peter" <n...@spam.com> wrote in message

news:op.xbsm0...@red.lan...
On Mon, 24 Feb 2014 14:57:45 -0000, Steve <no...@needed.com> wrote:

> Uncle Peter presented the following explanation :

> Absolutely not! I've just done a partial rebuild of a gaming machine
> for someone that has cost United Utilities (their electricity supplier)
> over £1,500 after it was hit by a voltage surge - same house also had
> two TVs and a microwave oven blow up too. And about twelve other houses
> were affected so not a happy time for UU.

Maybe it depends how long the surge was. See my other post (reply to a
reply to yours) where a room full of computers was fine when connected to
two phases by mistake. Just the bulk capacitors in the PSUs blew. I've
also accidentally connected a printer and a computer to 240V instead of 110V
when the switch was incorrectly set at the back. Also I've seen about 10
computers with the switch set wrongly on purpose by kids. Just a bang and a
new capacitor required. I would have expected the fuse or breaker to blow
before the voltage got through to the equipment in your case though - the
bulk capacitors go short circuit?

A fuse can carry four times it's rated current for an hour before it melts.
MCBs are a bit better.

They are clumsy overcurrent devices, voltage makes no difference.
In no way will they protect electronic devices.
They are not anti-surge protectors.

[charles]

In article <lepo2i$tqn$1...@dont-email.me>, harryagain

and - if it strikes your house when you are in the act of pulling them?

--
From KT24

Using a RISC OS computer running v5.18

[westom]

replying to Peter Crosland , westom wrote:

> johnwilliamson wrote:
> That's as may be, but they tend to have rather better quality protection
> on all their connections than a cheapie "surge protected" 13A strip with
> a tuppenny MOV in it.

Described was a simple and well proven solution used in radio stations,
telco switching centers, and even munitions dumps so that surges
(including direct lightning strikes) do not cause damage. Quite a few
here are posting denials based in feelings; not justified by any
professional source, personal experience, or basic electrical concepts.

For example, an average lightning strike is about 20,000 amps. And is
routinely made irrelevant by a properly connection to earth. Lightning can
be as high as 100,000 amps. So rare that most here have probably never
seen one. Meanwhile an IEEE paper in the late 1970s says what happens
when a rare 100,000 amp lightning strike hits incoming AC wires. 40,000
typically goes to earth via the 'primary' protection system (including the
earth ground for each transformer). Another 20,000 amps may go off to
other connections. And 40,000 amps may be incoming to the nearby
building. Why do professionals recommend at least 50,000 amps protector
for 'secondary' protection? Numbers published by professionals define the
problem.

> tony wrote:
> No, they do sometimes dissipate a charge before it builds up to form a
> much bigger discharge;)...

Good luck finding even one responsible source (ie IEEE, NFPA, FAA, BS,
ISO, etc) that makes that claim. ESE devices have long been cited by
professional sources as, at best, unproven.

Nothing stops lightning. And yet that is what adjacent protectors or ESE
devices must do.

In any facility that cannot have damage, protection has always been about
connecting surges (such as lightning) harmlessly to earth. Lightning rods
do that to protect structures. Dedicated ground wires or 'whole house'
protector to utility wires does that to protect interio appliances. In
every case, protection is always about making a more conductive and lower
impedance connection to earth. Earth is where hundreds of thousands of
joules harmlessly dissipate.

Devices that claim to block, absorb, or avert surges such as lightning
(ie series mode filter, plug-in protectors, ESE devices, magic boxes that
claim to convert tiny surges into useful energy) are bogus. As indicated
by claims even contradicted or not supported by manufacturer
specifications. Voting is useless. since an only useful recommendation
says why with numbers. As found in professional papers and manufacturer
specifications.

Telco switching centers all over the world use properly earthed 'whole
house' protectors. Since that less expensive and superior solution is
also proven by over 100 years os science and experience. Similar solutions
also implemented in muntions dumps since explosions are unacceptable. No
other device (not even ESE) have that credibility. Protection is and has
been always about the quality of and connection to earth.

Should you want more, well, ask and be buried in professional citations
and case studies. But then only a fewest here actually did this stuff.
And have describes in siginifcant detail and numbers how and why those
proven solutoins work.

The protector at 650 volts means it starts doing protection at 650
volts. If a surge current is larger, voltage on that protector increases
to over 1000 volts (current, not voltage, is the relevant parameter).
Eventually that voltage becomes so high that a protector fails
catastrophically. How high might voltage go? That is why the 'whole
house' protector starts at 50,000 amps. Another example of how to
separate hearsay from experience. Experiences describes concepts with
well proven numbers traceable to responsible sources.


--

[westom]

replying to Peter Crosland , westom wrote:

> g6jns wrote:
> The reality is that these surge protectors offer very little, if any,
> protection against lightning strikes. A lightning strike close by can
> kill your electronic equipment regardless of what protection you have.

--
And then an engineer who did this stuff cites experience tempered by
knowledge. A lightning strike (maybe 20,000 amps) stuck the building's
lightning rod That wire to earth was only four feet away from an IBM PC.
The PC did not even blink. Nothing inside was interrupted or damaged by
20,000 amps on a nearby wire. If nearby strikes are destructive, that PC
should have been damaged or at least only crashed. It was not for one
simple reason. Only wild speculation says nearby strikes create massive
fields that do damage.

Another example. Lightning must connect a cloud to earthborne charges
maybe 5 kilometers distant. A shortest electrical path is three km down
to a tree. And 4 km through earth to those charges. Only 10 meters from
that tree was a dead cow. Did the nearby bolt create fields that killed
the cow? Those who know from speculation assumed so. Science says
something completely different.

A shortest 4 km path from tree to distant charges was up the cow's hind
legs and down its fore legs. What others assumed was a nearby strike was
actually a direct strike to a tree and cow.

Nearby strikes are only destructive when wild speculation creates a
conclusion. Knowledge comes from first learning 100 years of well proven
science - and demanding numbers.

Any golfers? What happened to that cow should also have your attention.


--

[Johny B Good]

W_Tom, I'm not quite sure what you're trying to put across with the
tree and cow example. From the details you gave, cow showing post
mortem signs that the electrocuting charge had passed between the fore
and hindlegs whilst a mere 33 feet away from the ground strike point
(the hapless tree), suggest the cow was either facing towards or away
from the tree at the time and was killed by the potential gradient
created by the lightning strike in the ground it was standing on[1].

There is video evidence[2] of this effect exemplified by half the
players on a sodden football pitch being stunned by a direct hit to
the metalwork of the grandstand creating perhaps a kilovolt or more
per metre voltage gradient on the pitch.

Any players who happened to have both feet in contact with the ground
would have suffered an electric shock varying in intensity which
depended not only how far they were from the (effective) entry point
of the lightning strike but also their orientation and the seperation
distance of their feet.

Those lucky enough to have both feet out of contact at the critical
moment would have felt nothing, others who happened to have just one
foot in ground contact would have experienced a lesser electric shock
through that foot which would have also varied according to
orientation and distance from the strike point.

[1] Possibly a 'ground leader' but most likely due to Ground Current
or "Step Potential" as quoted from the wiki article here (second
paragraph):

<http://en.wikipedia.org/wiki/Lightning_strike>

[2] Surprisingly, I can't track this video down. It seems to have been
'pulled' despite there being no fatalities in this case. My memory of
the video suggests it was the second non-fatal incident reported here:

<http://news.bbc.co.uk/1/hi/world/africa/203137.stm>

--
Regards, J B Good

[westom]

replying to Johny B Good , westom wrote:

> johnny-b-good wrote:
> I'm not quite sure what you're trying to put across with the
> tree and cow example. From the details you gave, cow showing post
> mortem signs that the electrocuting charge had passed between the fore
> and hindlegs whilst a mere 33 feet away from the ground strike point
> (the hapless tree), suggest the cow was either facing towards or away
> from the tree at the time and was killed by the potential gradient
> created by the lightning strike in the ground

No harmful gradient from a field existed as many assume with a term
'induced surge'. Had a cow been on the other side of that tree, then
current would not have flowed up its hind legs and down its fore legs.

Destructive current had to be incoming on one path and outgoing on
another. Induced transients (E-M gradients) do not cause damage or death.
Actual current from a lightning strike must pass through (with an
incoming and outgoing path) to cause damage. Damage is defijned by where
current flows.

Another example. A nearby lightning strike hit l0 meters from a long
wire antenna. Thousands of volts appear on that antenna's lead. Connect
a NE-2 glow lamp (a milliamp lamp) to that antenna lead. The resulting
current is so tiny as to barely cause that light to glow. And voltage
drops from thousands to tens of volts.

Many see thousands of volts to assume a nearby surge is destrutive.
Conduct a millimap or less to make that induced surge completely
irrelevant. Induces surges are that easily eliminated. Simplest
protection in all electronics means no damage from nearby strikes. To
have damage means the item is part of that surge current path. That
defines both an incoming and outgoing current path.

Farmers encircle barns with a buried ground loop. So that current from
a lightning strike passes around the barn; not destructively through
animals inside. Protection is always about where current flows; or does
not flow.

Your wikipedia citation is discussing a lightning bolt - the plasma
'wire'. We are discussing what actually does damage - an electrical
current. Simultaneous current is same in the 'direct' lightning bolt and
'indirect' bolt. Relevent here is that actual electrical current. Either
current is created by a nearby, induced or indirect surge (generated by
electromagnetic fields). Or a current is what flows directly from cloud
to distant charnges. Latter is the current that causes hardware damage.

Earth a protector so that the current does not flow incoming and outgoing
through any appliance. Then nearby strikes (with massive E-M fields)
cause no damage.


--

[PeterC]

On Sat, 01 Mar 2014 01:52:41 +0000, Johny B Good wrote:

> W_Tom, I'm not quite sure what you're trying to put across with the
> tree and cow example. From the details you gave, cow showing post
> mortem signs that the electrocuting charge had passed between the fore
> and hindlegs whilst a mere 33 feet away from the ground strike point
> (the hapless tree), suggest the cow was either facing towards or away
> from the tree at the time and was killed by the potential gradient
> created by the lightning strike in the ground it was standing on

I wonder if cattle are as susceptible as horses. Quite recently there was a
case of a racehorse killed by a mains leak underground. That would have been
a much lower voltage gradient than a lightning strike, but apparently horses
are far more sensitive to this than are human beings.
--
Peter.
The gods will stay away
whilst religions hold sway

[tony sayer]

>
> Farmers encircle barns with a buried ground loop. So that current from
>a lightning strike passes around the barn; not destructively through
>animals inside. Protection is always about where current flows; or does
>not flow.
>

We _must_ have W_Tom back again as no farmer in England would do
anything to protect their cows like that!..

All in its just a very simple shunt job to shunt the lightning discharge
around what it is you need to protect. Use a low resistance and as low
INDUCTANCE a path as possible and thats more or less that..

That bit re lightning charge dissipation came from a handbook provided
by Messers Furse of Nottingham who have been making lightning protection
systems for use world-wide for some 120 odd years now!..


--
Tony Sayer

[Graham.]

That would be a low *impeadence* path then.

[Uncle Peter]

Yes, so I'm only preventing something that's more than double the standard voltage getting through.

--
Prostration - the act of exposing your genitalia to your god.

[Uncle Peter]

It must have been a very small part of the strike, as only the network card died. Now if the network card can save the motherboard, why can't a surge protector?

--
Gary's weather forecasting stone:
Stone is wet Rain
Stone is dry Not raining
Shadow on ground Sunny
White on top Snowing
Can't see stone Foggy
Swinging stone Windy
Stone jumping up and down Earthquake
Stone gone Tornado

[Uncle Peter]

Well every single time I've seen a PSU's bulk caps explode because of double voltage input, the 5A fuse in the IEC lead has blown.

--
Everybody is ignorant, only on different subjects.

[Uncle Peter]

Do a rave dance.

--
An expert is someone who takes a subject you understand and makes it sound confusing.

[Uncle Peter]

It'll protect the smaller ones. You might as well say why wear a seatbelt? I mean it won't protect you when you slam at 70mph into an oncoming lorry.

[meow...@care2.com]

funny


NT

[Uncle Peter]

Well my dad's network card protected his computer from a smaller one. You do understand that there isn't just one main lightning bolt don't you?

--
What's soft and warm when you go to bed, but hard and stiff when you wake up?
Vomit.

[tony sayer]

In article <5ec13cba-d974-4ed0...@googlegroups.com>,
Graham. <i.need.a.us...@gmail.com> scribeth thus

>That would be a low *impeadence* path then.

To be sure soir!! it would indeed;)...
--
Tony Sayer