On Tue, 25 Feb 2014 18:48:16 -0000, wrote:

On Tuesday, February 25, 2014 6:02:45 PM UTC, Uncle Peter wrote:
On Tue, 25 Feb 2014 17:54:32 -0000, wrote:
On Tuesday, February 25, 2014 5:21:05 PM UTC, Uncle Peter wrote:
On Tue, 25 Feb 2014 17:14:55 -0000, 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 **** 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 ****.

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.

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.

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.


--

On Wed, 26 Feb 2014 04:44:01 -0000, westom 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.

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

On Wed, 26 Feb 2014 13:17:55 -0000, "Uncle Peter" wrote:

On Wed, 26 Feb 2014 04:44:01 -0000, westom 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

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.


--

westom wrote:
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.



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

On Wed, 26 Feb 2014 14:56:46 -0000, 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."

On Wed, 26 Feb 2014 16:52:17 -0000, Johny B Good wrote:

On Wed, 26 Feb 2014 13:17:55 -0000, "Uncle Peter" wrote:

On Wed, 26 Feb 2014 04:44:01 -0000, westom 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.

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.

On Wed, 26 Feb 2014 18:44:02 -0000, westom wrote:

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.

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 ****ed 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."

On Wed, 26 Feb 2014 18:58:57 -0000, Capitol wrote:

westom wrote:
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.



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

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

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

Uncle Peter wrote:
On Wed, 26 Feb 2014 18:58:57 -0000, Capitol wrote:

westom wrote:
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.



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

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

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.

On Wed, 26 Feb 2014 22:15:23 -0000, Capitol wrote:

Uncle Peter wrote:
On Wed, 26 Feb 2014 18:58:57 -0000, Capitol wrote:

westom wrote:
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.



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

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

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.

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.

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

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.

--

Uncle Peter wrote:
On Wed, 26 Feb 2014 22:15:23 -0000, Capitol wrote:

Uncle Peter wrote:
On Wed, 26 Feb 2014 18:58:57 -0000, Capitol wrote:

westom wrote:
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.



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

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

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.

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?


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

On Tuesday, February 25, 2014 7:09:54 PM UTC, Uncle Peter wrote:
On Tue, 25 Feb 2014 18:48:16 -0000, wrote:
On Tuesday, February 25, 2014 6:02:45 PM UTC, Uncle Peter wrote:
On Tue, 25 Feb 2014 17:54:32 -0000, wrote:
On Tuesday, February 25, 2014 5:21:05 PM UTC, Uncle Peter wrote:
On Tue, 25 Feb 2014 17:14:55 -0000, 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 **** 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 ****.
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

On Wednesday, 26 February 2014 21:10:33 UTC, Uncle Peter wrote:
On Wed, 26 Feb 2014 14:56:46 -0000, 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

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.

--

On Wed, 26 Feb 2014 22:44:01 -0000, 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. 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."

On Wed, 26 Feb 2014 22:45:00 -0000, Capitol wrote:

Uncle Peter wrote:
On Wed, 26 Feb 2014 22:15:23 -0000, Capitol wrote:

Uncle Peter wrote:
On Wed, 26 Feb 2014 18:58:57 -0000, Capitol wrote:

westom wrote:


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

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

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.

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?


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

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

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

On Wed, 26 Feb 2014 23:02:57 -0000, wrote:

On Tuesday, February 25, 2014 7:09:54 PM UTC, Uncle Peter wrote:
On Tue, 25 Feb 2014 18:48:16 -0000, wrote:
On Tuesday, February 25, 2014 6:02:45 PM UTC, Uncle Peter wrote:
On Tue, 25 Feb 2014 17:54:32 -0000, wrote:
On Tuesday, February 25, 2014 5:21:05 PM UTC, Uncle Peter wrote:
On Tue, 25 Feb 2014 17:14:55 -0000, 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 ****.
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.

wrote in message
...
On Tuesday, February 25, 2014 7:09:54 PM UTC, Uncle Peter wrote:
On Tue, 25 Feb 2014 18:48:16 -0000, wrote:
On Tuesday, February 25, 2014 6:02:45 PM UTC, Uncle Peter wrote:
On Tue, 25 Feb 2014 17:54:32 -0000, wrote:
On Tuesday, February 25, 2014 5:21:05 PM UTC, Uncle Peter wrote:
On Tue, 25 Feb 2014 17:14:55 -0000, 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 **** 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 ****.
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.

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

On Wed, 26 Feb 2014 23:38:41 -0000, wrote:

On Wednesday, 26 February 2014 21:10:33 UTC, Uncle Peter wrote:
On Wed, 26 Feb 2014 14:56:46 -0000, 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.

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."

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: 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.


--

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

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

In article , Peter
Crosland 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

On 27/02/2014 12:48, tony sayer wrote:
In article , Peter
Crosland 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.

tony sayer wrote:
In articlePPidnW5aTOHycJPOnZ2dnUVZ8mWdnZ2d@brightvie w.co.uk, Peter
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;!!..



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

On Thu, 27 Feb 2014 13:22:40 -0000, John Williamson wrote:

On 27/02/2014 12:48, tony sayer wrote:
In article , Peter
Crosland 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.

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.

On 27/02/2014 12:48, tony sayer wrote:
In article , Peter
Crosland 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

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

On Thu, 27 Feb 2014 21:47:33 -0000, Vir Campestris wrote:

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.

He designed computer power supplies.

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

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

On Thu, 27 Feb 2014 21:55:18 -0000, wrote:

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.

The peak equivalent obviously.

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

In article , Vir
Campestris scribeth thus
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

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

On Thu, 27 Feb 2014 22:10:55 -0000, tony sayer wrote:

In article , Vir
Campestris scribeth thus
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

No, they do sometimes dissipate a charge before it builds up to form a
much bigger discharge...

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.

"Uncle Peter" wrote in message
news
On Mon, 24 Feb 2014 14:15:06 -0000, Graham. wrote:

On Mon, 24 Feb 2014 13:48:25 -0000, "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.

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 **** 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

"Uncle Peter" wrote in message
news
On Mon, 24 Feb 2014 14:15:06 -0000, Graham. wrote:

On Mon, 24 Feb 2014 13:48:25 -0000, "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.

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 **** 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?

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

"Uncle Peter" wrote in message
news
On Tue, 25 Feb 2014 17:14:55 -0000, 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.