is third transformer hole an earth?
john downie2
from London, u.k. .
He already has in his house a lead with a japanese type mains plug on one
end and the normal type two pin femail type plug (the same as often goes
into radios, etc) that will go into the computer transformer.
But we see that the Aspire One has an additional *third* hole alongside the
usual two hole plug that goes into the computer transformer. The three holes
forming a triangle shape.
Is it alright to use our existing two hole Japanese type lead and then only
use *two* out of the three pins coming from the aspire transformer, please?
My guess is that the third hole is only an *earth* connection. although this
might be an additional safety feature, our main concern is whether it might
do any damage to use the two pin only lead?
I have emailed the technical services department and the spares department,
but neither will answer the question, only want to sell me one of their
three hole leads. Thanks for your advice.
Whiskers
> my brother wishes wishes to take an Acer Aspire One mini-notebook to japan,
> from London, u.k. .
>
> He already has in his house a lead with a japanese type mains plug on one
> end and the normal type two pin femail type plug (the same as often goes
> into radios, etc) that will go into the computer transformer.
>
> But we see that the Aspire One has an additional *third* hole alongside the
> usual two hole plug that goes into the computer transformer. The three holes
> forming a triangle shape.
>
> Is it alright to use our existing two hole Japanese type lead and then only
> use *two* out of the three pins coming from the aspire transformer, please?
No. If the power 'brick' has three pins, it has been designed to require
three connectors.
> My guess is that the third hole is only an *earth* connection. although this
> might be an additional safety feature, our main concern is whether it might
> do any damage to use the two pin only lead?
"Only" an earth? Sheesh!
> I have emailed the technical services department and the spares department,
> but neither will answer the question, only want to sell me one of their
> three hole leads. Thanks for your advice.
Assuming that your existing power brick can accomodate Japanese mains
voltage and frequency, you will need an earthed Japanese plug to fit the
Japanese mains socket. Which sounds like what the technical services
department are trying to convince you of.
I think Japan uses 100V mains at either 50 or 60 Hz depending on location.
--
-- ^^^^^^^^^^
-- Whiskers
-- ~~~~~~~~~~
ian field
"Whiskers" <catwh...@operamail.com> wrote in message
news:slrnghbb69.b...@ID-107770.user.individual.net...
If the "power brick" is a switch-mode converter (not an iron cored
transformer) some types automatically adjust to anywhere between 100 - 240V,
check the specification label as this information should be clearly marked.
Most PSUs of this type are double insulated and do not require an earth,
they only have a 3-pin plug because the regulations in the country of use
say that all wall sockets must be 3-pin (there wouldn't be much point in
supplying items with a 2-pin plug that didn't fit anything). Carefully
examine the mains lead, if its round then it contains 3 wires and must be
earthed, if the mains lead is flat so you can tell the outer covering is
over a pair of wires side by side then there is obviously no third wire for
an earth.
Whiskers
> transformer) some types automatically adjust to anywhere between 100 - 240V,
> check the specification label as this information should be clearly marked.
True enough.
> Most PSUs of this type are double insulated and do not require an earth,
> they only have a 3-pin plug because the regulations in the country of use
> say that all wall sockets must be 3-pin (there wouldn't be much point in
> supplying items with a 2-pin plug that didn't fit anything).
I took the OP to mean that the brick itself has three pins in the orifice
to which the incoming mains lead is connected. That suggests that the
makers of it expected it to be earthed.
Both the laptop power bricks in use in this room (one HP, one Toshiba) have
three metal pins for the mains lead to connect to - and /do/ require an
earthed mains lead and socket. The arrangement is sometimes described as
a 'cloverleaf' connector; more officially an IEC-320 type C5
<http://www.maplin.co.uk/images/full/qn62.jpg> and
<http://www.maplin.co.uk/Module.aspx?ModuleNo=218969>. The two-pin type
with no earth is a 'figure-of-eight' or IEC-320 type C7.
Here in the UK, double-insulated appliances can be fitted with a mains
lead that has a plastic 'earth' pin - whose functions are to open the
shutters on the other two holes in the socket, and to ensure correct
connection of the 'live' and 'neutral' pins. But mere presence of a metal
earth pin on the plug cannot be taken as evidence of an earth connection,
of course!
> Carefully
> examine the mains lead, if its round then it contains 3 wires and must be
> earthed, if the mains lead is flat so you can tell the outer covering is
> over a pair of wires side by side then there is obviously no third wire for
> an earth.
Never seen a 'flat' three-conductor lead, or a round two-conductor lead?
Peter Hucker
> On 2008-11-08, john downie2 <blue...@mail.invalid> wrote:
>> my brother wishes wishes to take an Acer Aspire One mini-notebook to japan,
>> from London, u.k. .
>>
>> He already has in his house a lead with a japanese type mains plug on one
>> end and the normal type two pin femail type plug (the same as often goes
>> into radios, etc) that will go into the computer transformer.
>>
>> But we see that the Aspire One has an additional *third* hole alongside the
>> usual two hole plug that goes into the computer transformer. The three holes
>> forming a triangle shape.
>>
>> Is it alright to use our existing two hole Japanese type lead and then only
>> use *two* out of the three pins coming from the aspire transformer, please?
>
> No. If the power 'brick' has three pins, it has been designed to require
> three connectors.
>
>> My guess is that the third hole is only an *earth* connection. although this
>> might be an additional safety feature, our main concern is whether it might
>> do any damage to use the two pin only lead?
>
> "Only" an earth? Sheesh!
Power bricks are plastic and don't need to be earthed for safety reasons. His question, which nobody has answered yet, is whether the supply NEEDS an earth to operate correctly.
--
http://www.petersparrots.com http://www.insanevideoclips.com http://www.petersphotos.com
Stupidity is the basic building block of the universe - Frank Zappa
catchme
similiar to North America (despite Japan only having 2 leads), i dont
know what the voltage is in the UK.
Japan runs 110v. on a 60a circuit, whereas Canada does 120.
Peter Hucker
SIXTY amps! Wow. I'm glad we have more volts in the UK.
"A slipping gear could let your M203 grenade launcher fire when you least expect it. That would make you quite unpopular in what's left of your unit."
- Army preventive maintenance publication
ian field
I'd still take it that if the original mains lead was only 2-core, even if
there is a 3-way connector on the power brick, then you can't have live,
neutral and an earth if there's only 2 wires in the mains lead. 3 pin
connectors do turn up every now and then with only 2 pins actually used but
they're not very common.
As long as the original mains lead is still with the power brick, its the
best indication whether its safe to use without an earth or not. Of course
with a detachable lead, if examination leaves any doubt as to whether its 2
or 3 wires its easy enough to continuity test the earth pin.
Whiskers
UK standard domestic mains runs at 240V 50 Hz and most houses have been
wired with "13 Amp ringmains" since the '60s. Our standard 13 Amp plugs
and sockets have three pins; there are no standard 2-pin plugs that fit
the 3-pin mains sockets - which require a third pin to open the shutters
in the 'live' and 'neutral' holes before anything can be inserted into
them (the earth pin being longer than the other two). Appliances which
don't need an earth connection can be fitted with plugs having a plastic
'earth pin' (which presumably saves manufacturers money).
Japan's mains apparently runs at 100V, 50 or 60 Hz, and the plugs and
sockets are only superficially similar to those used in the US. They seem
to be rated at 10 12 or 15 Amps. (60 Amps would be pretty nasty if things
went a little awry, even if a 6 KW fire might be useful). Three-pin
earthed sockets are apparently not as common as might be desired. See
<http://www.powercords.co.uk/standard.htm#JAPAN>
<http://www.powercords.co.uk/pc123.htm>
Dave Plowman (News)
catchme <som...@somewhere.net> wrote:
> yes, the 3rd hole is a ground, but while the voltage in Japan is
> similiar to North America (despite Japan only having 2 leads), i dont
> know what the voltage is in the UK.
> Japan runs 110v. on a 60a circuit, whereas Canada does 120.
The UK is 240v. Actual spec is 230 +10/-6% to fall in line with Europe,
but it hasn't changed from the old nominal 240.
--
*Am I ambivalent? Well, yes and no.
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
hr(bob) hofmann@att.net
> In article <5JkRk.106$Cn3...@newsfe20.iad>,
>
> > yes, the 3rd hole is a ground, but while the voltage in Japan is
> > similiar to North America (despite Japan only having 2 leads), i dont
> > know what the voltage is in the UK.
> > Japan runs 110v. on a 60a circuit, whereas Canada does 120.
>
> The UK is 240v. Actual spec is 230 +10/-6% to fall in line with Europe,
> but it hasn't changed from the old nominal 240.
>
> --
> *Am I ambivalent? Well, yes and no.
>
> To e-mail, change noise into sound.
The answer to the original poster is yes, if the power brick will
accept as low as 100V andat 50 or 60 Hz, then everything will be fine.
john d hamilton
"hr(bob) hof...@att.net" <hrho...@att.net> wrote in message
news:5804e16d-3706-4f8c...@a29g2000pra.googlegroups.com...
On Nov 8, 5:48 pm, "Dave Plowman (News)" <d...@davenoise.co.uk> wrote:
> In article <5JkRk.106$Cn3...@newsfe20.iad>,
> catchme <some...@somewhere.net> wrote:
>
> > yes, the 3rd hole is a ground, but while the voltage in Japan is
> > similiar to North America (despite Japan only having 2 leads), i dont
> > know what the voltage is in the UK.
> > Japan runs 110v. on a 60a circuit, whereas Canada does 120.
>
> The UK is 240v. Actual spec is 230 +10/-6% to fall in line with Europe,
> but it hasn't changed from the old nominal 240.
The answer to the original poster is yes, if the power brick will
accept as low as 100V andat 50 or 60 Hz, then everything will be fine.
Many thanks to all. The power brick will take the lower japanese voltage.
The japanese mains plug sockets only have two pins, so they dont have an
earth connection.
Arfa Daily
>> yes, the 3rd hole is a ground, but while the voltage in Japan is
>> similiar to North America (despite Japan only having 2 leads), i dont
>> know what the voltage is in the UK.
>> Japan runs 110v. on a 60a circuit, whereas Canada does 120.
Japan is 100v not 110v - see
http://www.currentsolutions.com/knowledge/country_spec_h-n.htm
Arfa
Arfa Daily
> wired with "13 Amp ringmains" since the '60s.
Ringmain circuits in the UK are nominally rated at 30A, but have *outlets*
on them rated to 13A. Bit of a 'picky' point, I know, but might be a bit
misleading to non uk posters, the way you had put it.
Arfa
Dave Plowman (News)
Arfa Daily <arfa....@ntlworld.com> wrote:
> Ringmain circuits in the UK are nominally rated at 30A, but have
> *outlets* on them rated to 13A. Bit of a 'picky' point, I know, but
> might be a bit misleading to non uk posters, the way you had put it.
Being even more picky they're actually rated at 32 amps.
--
*Why do overlook and oversee mean opposite things? *
Dave Plowman da...@davenoise.co.uk London SW
Arfa Daily
"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
news:4ffba77...@davenoise.co.uk...
> In article <v6FRk.32439$mr4....@newsfe19.ams2>,
> Arfa Daily <arfa....@ntlworld.com> wrote:
>> Ringmain circuits in the UK are nominally rated at 30A, but have
>> *outlets* on them rated to 13A. Bit of a 'picky' point, I know, but
>> might be a bit misleading to non uk posters, the way you had put it.
>
> Being even more picky they're actually rated at 32 amps.
Well, the cable itself may be rated to 32 amps, and the breaker may be
either 32 amps or 30 amps in an older installation, but never-the-less, this
type of installation has always been known generically as a '30 amp ring
main circuit' and is generally accepted as being safely rated to 30 amps to
include all ages of installation.
See
http://www.diydata.com/planning/ring_main/ring_main.php
http://www.diyfixit.co.uk/diy/electrics/power_circuit/power_circuit_1.html
Arfa
Dave Plowman (News)
Arfa Daily <arfa....@ntlworld.com> wrote:
> Well, the cable itself may be rated to 32 amps, and the breaker may be
> either 32 amps or 30 amps in an older installation, but never-the-less,
> this type of installation has always been known generically as a '30
> amp ring main circuit' and is generally accepted as being safely rated
> to 30 amps to include all ages of installation.
Dates from the days of rewirable fuses were it was a nice round figure.
But with those you could comfortably exceed 30 amps if the load was
imposed gently. MCBs react rather quicker so it's now 32 amps.
It's actually quite tricky to work out the loading in various parts of the
ring since there are so many variables - the lengths and how it is run,
ventilation wise. As well as where the load is actually taken. It's
basically a bit of a bodge - but a very satisfactory one for today's
lifestyle despite being some 60 years old in conception.
--
*I'm pretty sure that sex is better than logic, but I can't prove it.
Peter Hucker
> Peter Hucker:
>
>> Power bricks are plastic and don't need to be earthed for safety reasons.
>> His question, which nobody has answered yet,
>> is whether the supply NEEDS an earth to operate correctly.
>
> The answer is no.
Then I wonder what it's connected to? The plastic chassis? What good does that do?
While proudly showing off his new fraternity house to friends, a college student led the way into the den. "What is the big brass gong and hammer for?" one of his friends asked.
"That's the talking clock", the man replied, with a grin. "Let me show you how it works!" And with that, he gave the gong an ear-shattering pound with the hammer.
Suddenly someone screamed from the other side of the wall, "KNOCK IT OFF, YOU ARSEHOLES! IT'S 2 AM!"
Peter Hucker
And costs you money when you stand on one and snap the pin off. Even worse when it's a wall wart.
> Japan's mains apparently runs at 100V, 50 or 60 Hz, and the plugs and
> sockets are only superficially similar to those used in the US. They seem
> to be rated at 10 12 or 15 Amps. (60 Amps would be pretty nasty if things
> went a little awry, even if a 6 KW fire might be useful).
Our UK ring mains are 6kW too, why are you surprised?
Three-pin
> earthed sockets are apparently not as common as might be desired. See
> <http://www.powercords.co.uk/standard.htm#JAPAN>
> <http://www.powercords.co.uk/pc123.htm>
>
--
A woman storms into her boss's office with this complaint:
"All the other women in the office are suing you for sexual harassment.
"Since you haven't sexually harassed me, I'm suing you for discrimination."
Peter Hucker
>
> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
> news:4ffba77...@davenoise.co.uk...
>> In article <v6FRk.32439$mr4....@newsfe19.ams2>,
>> Arfa Daily <arfa....@ntlworld.com> wrote:
>>> Ringmain circuits in the UK are nominally rated at 30A, but have
>>> *outlets* on them rated to 13A. Bit of a 'picky' point, I know, but
>>> might be a bit misleading to non uk posters, the way you had put it.
>>
>> Being even more picky they're actually rated at 32 amps.
>
>
> Well, the cable itself may be rated to 32 amps,
There is no such thing as 32A cable. It depends on where you run it and at what ambient temperature.
> and the breaker may be
> either 32 amps or 30 amps in an older installation, but never-the-less, this
> type of installation has always been known generically as a '30 amp ring
> main circuit' and is generally accepted as being safely rated to 30 amps to
> include all ages of installation.
I'm not so think as you drunk I am...
Peter Hucker
> In article <EFJRk.52823$vm.2...@newsfe08.ams2>,
> Arfa Daily <arfa....@ntlworld.com> wrote:
>> Well, the cable itself may be rated to 32 amps, and the breaker may be
>> either 32 amps or 30 amps in an older installation, but never-the-less,
>> this type of installation has always been known generically as a '30
>> amp ring main circuit' and is generally accepted as being safely rated
>> to 30 amps to include all ages of installation.
>
> Dates from the days of rewirable fuses were it was a nice round figure.
> But with those you could comfortably exceed 30 amps if the load was
> imposed gently.
Some fuses are really rubbish. I know of someone who ran a kettle for 3 weeks (under normal everyday use) on a 5A fuse before it blew. The kettle element was consuming its rated 10 amps.
> MCBs react rather quicker so it's now 32 amps.
>
> It's actually quite tricky to work out the loading in various parts of the
> ring since there are so many variables - the lengths and how it is run,
> ventilation wise. As well as where the load is actually taken. It's
> basically a bit of a bodge - but a very satisfactory one for today's
> lifestyle despite being some 60 years old in conception.
60? I thought 60 years ago we had the 5A and 15A star topology?
While taxiing at London's Gatwick Airport, the crew of a U.S. Air flight departing for Ft. Lauderdale made a wrong turn and came nose to nose with a United 727.
An irate female ground controller lashed out at the U.S. Air crew, screaming:
"U.S. Air 2771, where the hell are you going? I told you to turn right onto Charlie taxiway! You turned right on Delta!
Stop right there. I know it's difficult for you to tell the difference between C and D, but get it right!"
Continuing her rage to the embarrassed crew, she was now shouting hysterically:
"god! Now you've screwed everything up! It'll take forever to sort this out! You stay right there and don't move till I tell you to!
You can expect progressive taxi instructions in about half an hour and I want you to go exactly where I tell you, when I tell you, and how I tell you! You got that, U.S. Air 2771?"
"Yes, ma'am," the humbled crew responded.
Naturally, the ground control communications frequency fell terribly silent after the verbal bashing of U.S. Air 2771.
Nobody wanted to chance engaging the irate ground controller in her current state of mind. Tension in every cockpit around Gatwick was definitely running high.
Just then an unknown pilot broke the silence and keyed his microphone, asking: "Wasn't I married to you once?"
ian field
"Peter Hucker" <no...@spam.com> wrote in message
news:op.uke2s...@fx62.mshome.net...
> On Mon, 10 Nov 2008 00:26:24 -0000, Dave Plowman (News)
> <da...@davenoise.co.uk> wrote:
>
>> In article <EFJRk.52823$vm.2...@newsfe08.ams2>,
>> Arfa Daily <arfa....@ntlworld.com> wrote:
>>> Well, the cable itself may be rated to 32 amps, and the breaker may be
>>> either 32 amps or 30 amps in an older installation, but never-the-less,
>>> this type of installation has always been known generically as a '30
>>> amp ring main circuit' and is generally accepted as being safely rated
>>> to 30 amps to include all ages of installation.
>>
>> Dates from the days of rewirable fuses were it was a nice round figure.
>> But with those you could comfortably exceed 30 amps if the load was
>> imposed gently.
>
> Some fuses are really rubbish. I know of someone who ran a kettle for 3
> weeks (under normal everyday use) on a 5A fuse before it blew. The kettle
> element was consuming its rated 10 amps.
>
Some peoples knowledge is really rubbish.
There are defined tables and graphs which accurately describe fusing
capacity of fuses, it is known that a 5A fuse will carry 10A - but not for
very long! If the kettle boils before the fuse wire works up to its melting
temperature then the fuse wire cools again before it blows so you get away
with it another day, but each time the fuse is used above its rated current
it degrades a little and sooner or later will fail within the time it takes
the kettle to boil.
Actually a 5A fuse carrying exactly 5A has a finite fife expectancy - which
actually isn't all that long, unfortunately I can't find the graphs to look
up the exact life expectancy.
Whiskers
> On Sat, 08 Nov 2008 22:16:47 -0000, Whiskers <catwh...@operamail.com> wrote:
>> On 2008-11-08, catchme <som...@somewhere.net> wrote:
>>> john downie2 wrote:
[...]
>> Japan's mains apparently runs at 100V, 50 or 60 Hz, and the plugs and
>> sockets are only superficially similar to those used in the US. They seem
>> to be rated at 10 12 or 15 Amps. (60 Amps would be pretty nasty if things
>> went a little awry, even if a 6 KW fire might be useful).
>
> Our UK ring mains are 6kW too, why are you surprised?
[...]
Our power sockets are only 3kW each - but it isn't the Watts that really
hurt, or even the Volts; it's the Amps you really need to be careful with.
60 Amps at a Japanese 100V would be a lot more dangerous than 30 Amps at a
European 230V. (Although either could kill you, so the difference could
be academic as far as the one grasping the wires is concerned).
Notice that fuses and cut-outs are rated in Amps, and that "non-lethal"
stunners for the cops are rated at tens of thousands of volts. In the
right (or wrong!) circumstances, the current that will make a torch bulb
glow can be enough to stop the human heart.
Dave Plowman (News)
Whiskers <catwh...@operamail.com> wrote:
> Our power sockets are only 3kW each - but it isn't the Watts that really
> hurt, or even the Volts; it's the Amps you really need to be careful
> with. 60 Amps at a Japanese 100V would be a lot more dangerous than 30
> Amps at a European 230V. (Although either could kill you, so the
> difference could be academic as far as the one grasping the wires is
> concerned).
Not quite sure what you mean. The current drawn by a given resistance is
proportional to the voltage - and touching a 1000 amp supply is no more
dangerous to a human than touching a 1 amp one.
And since the body resistance would be a constant 230 volts would cause
more current to flow than 100 - so more likely to kill. Indeed in the UK
110 volts is used on building sites for safety reasons. This is obtained
usually via an isolating transformer so there is no potential to ground.
--
*Hang in there, retirement is only thirty years away! *
Paul Hovnanian P.E.
>
> On Sun, 09 Nov 2008 16:51:43 -0000, lars <la...@testbox.tld> wrote:
>
> > Peter Hucker:
> >
> >> Power bricks are plastic and don't need to be earthed for safety reasons.
> >> His question, which nobody has answered yet,
> >> is whether the supply NEEDS an earth to operate correctly.
> >
> > The answer is no.
>
> Then I wonder what it's connected to? The plastic chassis? What good does that do?
Internal surge supression/EMC circuitry.
--
Paul Hovnanian mailto:Pa...@Hovnanian.com
------------------------------------------------------------------
Just say 'No' to Windows.
-- Department of Defenestration.
Whiskers
> In article <slrnghhb1o.b...@ID-107770.user.individual.net>,
> Whiskers <catwh...@operamail.com> wrote:
>> Our power sockets are only 3kW each - but it isn't the Watts that really
>> hurt, or even the Volts; it's the Amps you really need to be careful
>> with. 60 Amps at a Japanese 100V would be a lot more dangerous than 30
>> Amps at a European 230V. (Although either could kill you, so the
>> difference could be academic as far as the one grasping the wires is
>> concerned).
>
> Not quite sure what you mean. The current drawn by a given resistance is
> proportional to the voltage - and touching a 1000 amp supply is no more
> dangerous to a human than touching a 1 amp one.
Well you go right ahead and play with the 1000 Amp wires if you want to,
but wait for me to get out of sight and earshot first - I'm a bit
squeamish.
> And since the body resistance would be a constant
It isn't. There's a threshold at around 50V at which the body's internal
resistance drops considerably; after that, the resistance will depend on
the path taken through and/or over the body and the amount of tissue
damage caused - those things being dependent on the energy (ie Amps)
available rather than on the voltage. AC and DC current also have
different effects.
> 230 volts would cause
> more current to flow than 100 - so more likely to kill.
Think of water pipes. A narrow pipe can be likened to a low current cable
(few Amps) and a wide pipe is like a cable carrying a large current (many
Amps). Both can be at the same pressure (Voltage) but one will cause a lot
more damage when it bursts than the other. Even if the wide pipe is at a
lower pressure, it can still deliver a lot more water than the narrow
pipe; likewise, even at a lower voltage a cable carrying a lot of current
will deliver a lot more energy than one with less capacity but at a higer
voltage.
> Indeed in the UK
> 110 volts is used on building sites for safety reasons. This is obtained
> usually via an isolating transformer so there is no potential to ground.
I don't know what the regulations are for temporary electrical
installations on construction sites in the UK, but I suspect they aren't
much different from those relating to permanent installations. The use of
110V equipment may have more to do with avoiding such stringent inspection
and installation standards as apply to higher voltages - but the safety
measures in use will be related to the current available, not the voltage.
If there is "no potential to ground" then the system will only be safe
with "double-insulated" appliances.
To deliver a given amount of power, a low voltage supply has to carry more
current (more Amps) than a higher voltage supply, so in that respect it
can be more dangerous.
Once the current is flowing, what matters is the amount of energy (Amps)
not the 'pressure' (Volts) - and where the energy flows. A few milliamps
will stop the heart, if that current flows along a path that disrupts the
tiny nerve signals involved.
Walking across a synthetic carpet can generate a charge of thousands of
Volts - enough to create a spark when you get near another person or a
metal fixture or piece of furniture. But there is very little energy
involved.
See <http://www.pa.msu.edu/sciencet/ask_st/010892.html>.
Arfa Daily
I've got to agree with Dave on this one. Much of what you say appears to be
based on an incorrect understanding of Ohms Law, and how it applies to the
potential for causing electrocution of the human body. The water and pipes
analogy is good for some simple college explanations involving DC systems
with fixed parameters, but its validity for explaining complex dynamic
systems, is tenuous at best.
A system carrying a lot of amps to the load that's drawing it, is no more or
less dangerous than one that's only carrying a small current, except in as
much as there is a greater potential for heat failure at connection points
within that system. A high voltage system, irrespective of how many amps it
is capable of carrying above a few milliamps, is far more dangerous to a
human, than a low voltage system good for a few hundred amps. Given the
(reasonably) constant resistance of any described path through the human
body, a voltage of a hundred volts with a current availability of as little
as 50mA, may be enough to kill under the right (wrong!) circumstances. On
the other hand, a low voltage welding supply, will not have enough voltage
behind it to push enough current through that same path to kill you, even
though that supply is good for 200 amps or more.
As far as your contention that a transformer isolated supply is only safe
with double insulated equipment, that simply isn't true. The only way that
you can drive current through the body from such an isolation transformer,
is to hang yourself across both output terminals. Either terminal to ground
will present no electric shock hazard at all.
Arfa
Peter Hucker
> On 2008-11-10, Peter Hucker <no...@spam.com> wrote:
>> On Sat, 08 Nov 2008 22:16:47 -0000, Whiskers <catwh...@operamail.com> wrote:
>>> On 2008-11-08, catchme <som...@somewhere.net> wrote:
>>>> john downie2 wrote:
>
> [...]
>
>>> Japan's mains apparently runs at 100V, 50 or 60 Hz, and the plugs and
>>> sockets are only superficially similar to those used in the US. They seem
>>> to be rated at 10 12 or 15 Amps. (60 Amps would be pretty nasty if things
>>> went a little awry, even if a 6 KW fire might be useful).
>>
>> Our UK ring mains are 6kW too, why are you surprised?
>
> [...]
>
> Our power sockets are only 3kW each
I know, but the reference was to Japanese RINGS.
> - but it isn't the Watts that really
> hurt, or even the Volts; it's the Amps you really need to be careful with.
It's both. 1 billion amps at 0.5 volts definitely won't do you any harm - mainly because you have too much resistance to conduct 1 billion amps without a much bigger voltage. I'd actually go for the watts being the best measure of danger (but you have to take into account how many watts you will dissipate, not how many are available). I can draw 5kW off a decent car battery into an invertor to power mains appliances, but if I touch the two terminals, I feel nothing, and I certainly don't dissiapte 5kW!
> 60 Amps at a Japanese 100V would be a lot more dangerous than 30 Amps at a
> European 230V. (Although either could kill you, so the difference could
> be academic as far as the one grasping the wires is concerned).
>
> Notice that fuses and cut-outs are rated in Amps,
They are mainly to stop a fire from a short. The safety circuit breaker is the earth leakage one.
> and that "non-lethal"
> stunners for the cops are rated at tens of thousands of volts. In the
> right (or wrong!) circumstances, the current that will make a torch bulb
> glow can be enough to stop the human heart.
--
PNEUMONOULTRAMICROSCOPICSILICOVOLCANOCONIOSIS (45 letters, a lung disease caused by breathing in particles of siliceous volcanic dust) is the longest word in the English language, beating TETRAMETHYLDIAMINOBENZHYDRYLPHOSPHINOUS ACID, HEPATICOCHOLANGIOCHOLECYSTENTEROSTOMIES, FORMALDEHYDETETRAMETHYLAMIDOFLUORIMUM, and DIMETHYLAMIDOPHENYLDIMETHYLPYRAZOLONE.
Peter Hucker
> Peter Hucker wrote:
>>
>> On Sun, 09 Nov 2008 16:51:43 -0000, lars <la...@testbox.tld> wrote:
>>
>> > Peter Hucker:
>> >
>> >> Power bricks are plastic and don't need to be earthed for safety reasons.
>> >> His question, which nobody has answered yet,
>> >> is whether the supply NEEDS an earth to operate correctly.
>> >
>> > The answer is no.
>>
>> Then I wonder what it's connected to? The plastic chassis? What good does that do?
>
> Internal surge supression/EMC circuitry.
Ah, required to pass the tests to be able to sell it, but of no concern to the end user.
A woman goes into a sporting goods store to buy a shotgun.
"It's for my husband," she tells the clerk.
"Did he tell you what gauge to get?" asked the clerk.
"Are you kidding?" she says. "He doesn't even know that I'm going to shoot him!"
Dave Plowman (News)
Whiskers <catwh...@operamail.com> wrote:
> On 2008-11-10, Dave Plowman (News) <da...@davenoise.co.uk> wrote:
> > In article <slrnghhb1o.b...@ID-107770.user.individual.net>,
> > Whiskers <catwh...@operamail.com> wrote:
> >> Our power sockets are only 3kW each - but it isn't the Watts that really
> >> hurt, or even the Volts; it's the Amps you really need to be careful
> >> with. 60 Amps at a Japanese 100V would be a lot more dangerous than 30
> >> Amps at a European 230V. (Although either could kill you, so the
> >> difference could be academic as far as the one grasping the wires is
> >> concerned).
> >
> > Not quite sure what you mean. The current drawn by a given resistance
> > is proportional to the voltage - and touching a 1000 amp supply is no
> > more dangerous to a human than touching a 1 amp one.
> Well you go right ahead and play with the 1000 Amp wires if you want to,
> but wait for me to get out of sight and earshot first - I'm a bit
> squeamish.
Err, your car has one totally uninsulated conductor carrying many hundreds
of amps when you start it. Perhaps you need to avoid driving...
> > And since the body resistance would be a constant
> It isn't. There's a threshold at around 50V at which the body's
> internal resistance drops considerably;
Can you give a reference for this?
> after that, the resistance will
> depend on the path taken through and/or over the body and the amount of
> tissue damage caused - those things being dependent on the energy (ie
> Amps) available rather than on the voltage.
It only takes milliamps to kill you under the right conditions. That's why
RCDs are set as they are.
> AC and DC current also have different effects.
Not many homes have high voltage DC supplies.
> > 230 volts would cause more current to flow than 100 - so more likely
> > to kill.
> Think of water pipes. A narrow pipe can be likened to a low current
> cable (few Amps) and a wide pipe is like a cable carrying a large
> current (many Amps). Both can be at the same pressure (Voltage) but
> one will cause a lot more damage when it bursts than the other.
Electricity doesn't spill out when a cable breaks. ;-)
> Even if the wide pipe is at a lower pressure, it can still deliver a lot
> more water than the narrow pipe; likewise, even at a lower voltage a
> cable carrying a lot of current will deliver a lot more energy than one
> with less capacity but at a higer voltage.
All of which is irrelevant when considering potentially lethal current.
> > Indeed in the UK
> > 110 volts is used on building sites for safety reasons. This is obtained
> > usually via an isolating transformer so there is no potential to ground.
> I don't know what the regulations are for temporary electrical
> installations on construction sites in the UK, but I suspect they aren't
> much different from those relating to permanent installations.
They are very different.
> The use of 110V equipment may have more to do with avoiding such
> stringent inspection and installation standards as apply to higher
> voltages - but the safety measures in use will be related to the current
> available, not the voltage.
You're talking nonsense.
> If there is "no potential to ground" then the system will only be safe
> with "double-insulated" appliances.
More nonsense.
> To deliver a given amount of power, a low voltage supply has to carry
> more current (more Amps) than a higher voltage supply, so in that
> respect it can be more dangerous.
Only in terms of a fire risk.
> Once the current is flowing, what matters is the amount of energy (Amps)
> not the 'pressure' (Volts) - and where the energy flows. A few
> milliamps will stop the heart, if that current flows along a path that
> disrupts the tiny nerve signals involved.
And you can't have that current flow without the voltage.
> Walking across a synthetic carpet can generate a charge of thousands of
> Volts - enough to create a spark when you get near another person or a
> metal fixture or piece of furniture. But there is very little energy
> involved.
You seem to be technical terms around without understanding their meaning.
> See <http://www.pa.msu.edu/sciencet/ask_st/010892.html>.
Have you actually read it?
--
*You never really learn to swear until you learn to drive *
Whiskers
>
> "Whiskers" <catwh...@operamail.com> wrote in message
> news:slrnghja8j.e...@ID-107770.user.individual.net...
>> On 2008-11-10, Dave Plowman (News) <da...@davenoise.co.uk> wrote:
>>> In article <slrnghhb1o.b...@ID-107770.user.individual.net>,
>>> Whiskers <catwh...@operamail.com> wrote:
[...]
> A system carrying a lot of amps to the load that's drawing it, is no more or
> less dangerous than one that's only carrying a small current, except in as
> much as there is a greater potential for heat failure at connection points
> within that system. A high voltage system, irrespective of how many amps it
> is capable of carrying above a few milliamps, is far more dangerous to a
> human, than a low voltage system good for a few hundred amps. Given the
> (reasonably) constant resistance of any described path through the human
> body, a voltage of a hundred volts with a current availability of as little
> as 50mA, may be enough to kill under the right (wrong!) circumstances.
So a charge of 10kV from walking across a carpet (DC) , or a "non-lethal"
50kV "Tazer" (AC), are more dangerous than a 1kV power line? The danger
from 'High Voltage' power lines comes from the vast amount of current they
can deliver.
> On
> the other hand, a low voltage welding supply, will not have enough voltage
> behind it to push enough current through that same path to kill you, even
> though that supply is good for 200 amps or more.
What voltage does a 'low voltage' welder operate at? Don't they use
capacitors to raise the supply voltage to at least 40kV? Or can welding
really happen at 12V?
> As far as your contention that a transformer isolated supply is only safe
> with double insulated equipment, that simply isn't true. The only way that
> you can drive current through the body from such an isolation transformer,
> is to hang yourself across both output terminals. Either terminal to ground
> will present no electric shock hazard at all.
>
> Arfa
Sounds too good to be true.
Whiskers
> On Mon, 10 Nov 2008 21:48:40 -0000, Whiskers <catwh...@operamail.com> wrote:
>
>> On 2008-11-10, Peter Hucker <no...@spam.com> wrote:
>>> On Sat, 08 Nov 2008 22:16:47 -0000, Whiskers <catwh...@operamail.com> wrote:
>>>> On 2008-11-08, catchme <som...@somewhere.net> wrote:
>>>>> john downie2 wrote:
[...]
>> - but it isn't the Watts that really
>> hurt, or even the Volts; it's the Amps you really need to be careful with.
>
> It's both. 1 billion amps at 0.5 volts definitely won't do you any harm
> - mainly because you have too much resistance to conduct 1 billion amps
> without a much bigger voltage. I'd actually go for the watts being the
> best measure of danger (but you have to take into account how many watts
> you will dissipate, not how many are available). I can draw 5kW off a
> decent car battery into an invertor to power mains appliances, but if I
> touch the two terminals, I feel nothing, and I certainly don't dissiapte
> 5kW!
[...]
You can touch the 12V battery terminals reasonably safely, but don't try
it with the 240V terminals. That voltage is well in excess of the body's
50V limit for being a non-conductor, and the battery can deliver plenty of
Amps to be lethal. It isn't the 240V that kill, it's the 21A.
Turning fresh meat into smoke and ash can dissipate a great many Watts.
Peter Hucker
But if we compare 110 volts and 240 volts, 240 volts will dissipate far more power in you. Both supplies have enough amps to give your body what it will conduct.
Women, you're in good shape as long as you can still touch your toes.
Just remember, using your boobs doesn't count.
Peter Hucker
> In article <slrnghhb1o.b...@ID-107770.user.individual.net>,
> Whiskers <catwh...@operamail.com> wrote:
>> Our power sockets are only 3kW each - but it isn't the Watts that really
>> hurt, or even the Volts; it's the Amps you really need to be careful
>> with. 60 Amps at a Japanese 100V would be a lot more dangerous than 30
>> Amps at a European 230V. (Although either could kill you, so the
>> difference could be academic as far as the one grasping the wires is
>> concerned).
>
> Not quite sure what you mean. The current drawn by a given resistance is
> proportional to the voltage - and touching a 1000 amp supply is no more
> dangerous to a human than touching a 1 amp one.
>
> And since the body resistance would be a constant 230 volts would cause
> more current to flow than 100 - so more likely to kill. Indeed in the UK
> 110 volts is used on building sites for safety reasons. This is obtained
> usually via an isolating transformer so there is no potential to ground.
Makes you wonder why they have neutral in households as ground potential.
_
/ /\
/ /\ \
/ /||\ \
/ / || \ \
/ / || \ \
/ / || \ \
/ / |_ \ \
/ / /\ \ \ \
/ / / /\ \ \ \
/ / / /||\ \ \ \
/ / / / || \ \ \ \
/ / / / || \ \ \ \
/ / / / _| \ \ \ \
/ / / / / /\ \ \ \ \
/ / / / / /\ \ \ \ \ \
/ / / / / /||\ \ \ \ \ \
/ / / / / / |_ \ \ \ \ \ \
/_/ /_/ /_/ /\_\ \_\ \_\ \_\
\ \ \ \ \ \ \/_/ / / / / / /
\ \ \ \ \ \ || / / / / / /
\ \ \ \ \ \||/ / / / / /
\ \ \ \ \ \/ / / / / /
\ \ \ \ \_\/ / / / /
\ \ \ \ || / / / /
\ \ \ \ || / / / /
\ \ \ \ || / / / /
\ \ \ \||/ / / /
\ \ \ \/ / / /
\ \ \/_/ / /
\ \ || / /
\ \ || / /
\ \ || / /
\ \ || / /
\ \||/ /
\ \/ /
\_\/
||
_..--=='||'==--.._
( '' )
'==--..______..--=='
Dave Plowman (News)
Whiskers <catwh...@operamail.com> wrote:
> So a charge of 10kV from walking across a carpet (DC) , or a
> "non-lethal" 50kV "Tazer" (AC), are more dangerous than a 1kV power
> line? The danger from 'High Voltage' power lines comes from the vast
> amount of current they can deliver.
Sigh. You don't need 'vast amounts of current to kill'. That's why RCDs
are set at 30 mA. Less than that is *generally* safe.
--
*Money isn't everything, but it sure keeps the kids in touch *
Peter Hucker
> On 2008-11-11, Arfa Daily <arfa....@ntlworld.com> wrote:
>>
>> "Whiskers" <catwh...@operamail.com> wrote in message
>> news:slrnghja8j.e...@ID-107770.user.individual.net...
>>> On 2008-11-10, Dave Plowman (News) <da...@davenoise.co.uk> wrote:
>>>> In article <slrnghhb1o.b...@ID-107770.user.individual.net>,
>>>> Whiskers <catwh...@operamail.com> wrote:
>
> [...]
>
>> A system carrying a lot of amps to the load that's drawing it, is no more or
>> less dangerous than one that's only carrying a small current, except in as
>> much as there is a greater potential for heat failure at connection points
>> within that system. A high voltage system, irrespective of how many amps it
>> is capable of carrying above a few milliamps, is far more dangerous to a
>> human, than a low voltage system good for a few hundred amps. Given the
>> (reasonably) constant resistance of any described path through the human
>> body, a voltage of a hundred volts with a current availability of as little
>> as 50mA, may be enough to kill under the right (wrong!) circumstances.
>
> So a charge of 10kV from walking across a carpet (DC) , or a "non-lethal"
> 50kV "Tazer" (AC), are more dangerous than a 1kV power line? The danger
> from 'High Voltage' power lines comes from the vast amount of current they
> can deliver.
A tazer limits the current to a lot less than your body could conduct at that voltage. A 110 volt power line and a 1000 volt power line both have more currrent than your body will draw, so the limit is your resistance. And 1000 volts will give you more current for the same resistance.
>> On
>> the other hand, a low voltage welding supply, will not have enough voltage
>> behind it to push enough current through that same path to kill you, even
>> though that supply is good for 200 amps or more.
>
> What voltage does a 'low voltage' welder operate at? Don't they use
> capacitors to raise the supply voltage to at least 40kV? Or can welding
> really happen at 12V?
I think it's a pretty low voltage, hence the very thick cables! From memory it's something like 12 volts at 500 amps. And no it's not dangerous to touch, from an electrical point of view - the heating when welding is in progress might be a tad sore though.
>> As far as your contention that a transformer isolated supply is only safe
>> with double insulated equipment, that simply isn't true. The only way that
>> you can drive current through the body from such an isolation transformer,
>> is to hang yourself across both output terminals. Either terminal to ground
>> will present no electric shock hazard at all.
>
> Sounds too good to be true.
Why?
What's the difference between a church and a cinema?
In a church they say "Pray in the name of Jesus!"
In a cinema they say "Shut up for christ's sake!"
Peter Hucker
> In article <slrnghja8j.e...@ID-107770.user.individual.net>,
> Whiskers <catwh...@operamail.com> wrote:
>> On 2008-11-10, Dave Plowman (News) <da...@davenoise.co.uk> wrote:
>> > 230 volts would cause more current to flow than 100 - so more likely
>> > to kill.
>
>> Think of water pipes. A narrow pipe can be likened to a low current
>> cable (few Amps) and a wide pipe is like a cable carrying a large
>> current (many Amps). Both can be at the same pressure (Voltage) but
>> one will cause a lot more damage when it bursts than the other.
>
> Electricity doesn't spill out when a cable breaks. ;-)
Which is why I suck at plumbing.
Do you know what a Jewish dilemma is?
Free ham.
ian field
See:
http://en.wikipedia.org/wiki/Electric_shock
and scroll down to "Lethality of a shock".
From the table there it is apparent that passing a current anything over
about 0.1A is quite likely to be fatal, so it makes little difference
whether the voltage source is capable of supplying 1A or 1000A.
The lethality of any voltage source that can supply more than about 100mA
will depend on there being sufficient voltage to pass lethal current through
the body according to Ohms law (V/R=I).
Typical estimates for human body resistance:
Unbroken dry skin = about 100,000 - 500,000 Ohms
Unbroken wet skin= About 1000 Ohms
Broken skin= As low as 100 Ohms
The higher the voltage, the greater the likelihood that localised burning
will break the skin resulting in a rapid drop in resistance with consequent
increase in current flow.
Arfa Daily
You see, there you go getting your apples and oranges mixed up again. A
static charge from a carpet is not lethal to you because it is an extremely
high resistance source. That is the nature of a static charge. No matter
whether it is 1kV, 10kV or 40kV, the source resistance will ensure that only
uA will flow for decimals of a uS. Enough to give you a nasty little crack,
yes, but not enough to come within several orders of magnitude of being
lethal. The same applies to the taser. It is designed to not be able to
supply enough current (theoretically) to be lethal. However, its aim is to
incapacitate by disrupting nerve activity and causing extreme pain. To do
this, the charge is applied to the receiving body in multiple short-duration
pulses. In some cases, this has proven to be fatal, I believe, due to the
length of time that the pulses are delivered for. On the other hand, a high
voltage power line, or even a fairly low voltage household supply, *is*
potentially lethal not because it can deliver huge amounts of amps, but
because the voltage that is present, is sufficient to drive *enough* (mili)
amps from that low resistance source through the conduction path within the
body.
>
>> On
>> the other hand, a low voltage welding supply, will not have enough
>> voltage
>> behind it to push enough current through that same path to kill you, even
>> though that supply is good for 200 amps or more.
>
> What voltage does a 'low voltage' welder operate at? Don't they use
> capacitors to raise the supply voltage to at least 40kV? Or can welding
> really happen at 12V?
Yes, arc welding can occur at 12v and, in fact, at lower voltages than this,
although there are many different methods these days of generating and
controlling the welding arc, though none that operate by charging caps to
the sorts of voltages that you are talking about, as far as I am aware. In
general, arc welding is a high current rather than high voltage system. Spot
welders sometimes work by charging very large capacitors to low voltages.
The reason that the low voltage arc welder is not capable of killing you,
any more than a car battery can, is because although both are extremely low
internal resistance sources, and hence capable of supplying large amounts of
current to a low resistance load, the human body is a much higher resistance
load, so the 12v is not capable of pushing enough miliamps through that
path, to cause electrocution - or even electric shock.
>
>> As far as your contention that a transformer isolated supply is only safe
>> with double insulated equipment, that simply isn't true. The only way
>> that
>> you can drive current through the body from such an isolation
>> transformer,
>> is to hang yourself across both output terminals. Either terminal to
>> ground
>> will present no electric shock hazard at all.
>>
>> Arfa
>
> Sounds too good to be true.
Well, if you understood the principles of isolation transformers, which as
well as being used on building sites for obvious reasons, are also to be
found in every professional electronics workshop, to render safe, the need
to work on live equipment employing such potentially lethal nasties, as
switch mode power supplies, then you would know that it isn't too good to be
true - it simply *is* true. Sketch it down on a piece of paper then have a
good think about it.
Arfa
Arfa Daily
This is unmitigated nonsense. You clearly have little understanding of how
the terms that you are bandying about, relate to one another, and more
importantly, to current flow within the human body. I don't mean to be
offensive, but there's a good old phrase which goes something like -
"When the hole that you're digging gets too deep to climb out of, stop ... "
'Nuff said, I think.
Arfa
Whiskers
Precisely; it isn't the voltage that's lethal, it's the current. If the
current isn't available, the voltage is pretty harmless. High-voltage
mains power lines carry a /lot/ of current, whereas high-voltage 'Tazers'
don't.
>>> On
>>> the other hand, a low voltage welding supply, will not have enough
>>> voltage
>>> behind it to push enough current through that same path to kill you, even
>>> though that supply is good for 200 amps or more.
>>
>> What voltage does a 'low voltage' welder operate at? Don't they use
>> capacitors to raise the supply voltage to at least 40kV? Or can welding
>> really happen at 12V?
>
> Yes, arc welding can occur at 12v and, in fact, at lower voltages than this,
> although there are many different methods these days of generating and
> controlling the welding arc, though none that operate by charging caps to
> the sorts of voltages that you are talking about, as far as I am aware. In
> general, arc welding is a high current rather than high voltage system. Spot
> welders sometimes work by charging very large capacitors to low voltages.
> The reason that the low voltage arc welder is not capable of killing you,
> any more than a car battery can, is because although both are extremely low
> internal resistance sources, and hence capable of supplying large amounts of
> current to a low resistance load, the human body is a much higher resistance
> load, so the 12v is not capable of pushing enough miliamps through that
> path, to cause electrocution - or even electric shock.
OK, I'm not familiar with arc welding, and I'm surprised that 12V is
enough to strike an arc. But your comment that it is the high current
that matters for creating a weld, rather supports my contention that
current is more dangerous than voltage.
Electron beam welding (which you probaby won't find happening in a garden
shed or on a building site) requires many thousand volts, but only a small
current (less than 1A).
The only welding I've ever done myself, involved a coke-burning forge and
a heavy hammer.
>>> As far as your contention that a transformer isolated supply is only safe
>>> with double insulated equipment, that simply isn't true. The only way
>>> that
>>> you can drive current through the body from such an isolation
>>> transformer,
>>> is to hang yourself across both output terminals. Either terminal to
>>> ground
>>> will present no electric shock hazard at all.
>>>
>>> Arfa
>>
>> Sounds too good to be true.
>
> Well, if you understood the principles of isolation transformers, which as
> well as being used on building sites for obvious reasons, are also to be
> found in every professional electronics workshop, to render safe, the need
> to work on live equipment employing such potentially lethal nasties, as
> switch mode power supplies, then you would know that it isn't too good to be
> true - it simply *is* true. Sketch it down on a piece of paper then have a
> good think about it.
>
> Arfa
The only 'isolation transformers' I've come across, are earthed - and
either have an output restricted to 50V or less (that threshold at which
the human body's resistance drops substantially) or provide a good earth
connection for the appliance. An isolation transformer /does/ disconnect
the connection that exists between the power station and the ground and is
carried by the 'live' or 'hot' cable, but that is /not/ the same as the
safety 'earth' connection which is meant to provide a relatively safe
return path in case exposed metal parts of the appliance accidentally
become connected to the power supply.
The 'earth' connection provided by an 'isolation transformer' to the
appliances running off it, may be arranged to effectively create a
'short-circuit' on the output windings of the transformer if any current
flows through it, and that should trigger the safety cut-off (probably a
'residual current device'). Or the 'earth' connection will pass straight
through to the same 'earth' as the mains supply provides.
A double-insulated appliance has no exposed metal parts that can become
connected to the power supply, and that's why they are permitted to be
used with no 'earth'.
Arfa Daily
Neutral and ground are bonded together at the substation
>
> The 'earth' connection provided by an 'isolation transformer' to the
> appliances running off it, may be arranged to effectively create a
> 'short-circuit' on the output windings of the transformer if any current
> flows through it, and that should trigger the safety cut-off (probably a
> 'residual current device'). Or the 'earth' connection will pass straight
> through to the same 'earth' as the mains supply provides.
>
> A double-insulated appliance has no exposed metal parts that can become
> connected to the power supply, and that's why they are permitted to be
> used with no 'earth'.
>
> --
> -- ^^^^^^^^^^
> -- Whiskers
> -- ~~~~~~~~~~
Hmmmm. Your understanding of the principles of ground isolation by use of a
transformer seem very flawed I'm afraid, as also is your knowledge of
electricity distribution schemes, and earth / neutral commonality.
Arfa
Peter Hucker
"Current kills" is a vast oversimplification, as Arfa has explained.
To confirm the discontinuation of stopping the startup, click cancel.
ian field
In that case you shouldn't have any problem grabbing the high voltage
terminal of a 2kV microwave oven transformer - its only rated for 500mA.
On the bright side, we wouldn't have to put up with you talking complete and
utter bollox.
ian field
"Meat Plow" <me...@petitmorte.net> wrote in message
news:2bc3rq....@news.alt.net...
> On Wed, 12 Nov 2008 14:50:28 -0000, "Arfa Daily"
> Probably got trolled here by the Hucker idiot.
PHucker usually hangs out on alt.binaries.chatter , I can't recall seeing
whiskers there. PHucker sometimes trolls on the sci.electronics groups -
usually asking stupid questions then criticizing the answers he's given.
ian field
> On Wed, 12 Nov 2008 21:23:05 -0000, "ian field"
> <gangprob...@ntlworld.com>wrote:
> enough to engage in some useful conversations should he choose to do
> so.
He claims to have a degree in physics, yet according to him he found physics
too boring so he settled for a tech support job in a computer dept - funny
how he visits this group yet never seems to contribute in any meaningful
way.
David Nebenzahl
> On 2008-11-10, Dave Plowman (News) <da...@davenoise.co.uk> wrote:
>
>> In article <slrnghhb1o.b...@ID-107770.user.individual.net>,
>> Whiskers <catwh...@operamail.com> wrote:
>>
>>> Our power sockets are only 3kW each - but it isn't the Watts that really
>>> hurt, or even the Volts; it's the Amps you really need to be careful
>>> with. 60 Amps at a Japanese 100V would be a lot more dangerous than 30
>>> Amps at a European 230V. (Although either could kill you, so the
>>> difference could be academic as far as the one grasping the wires is
>>> concerned).
>>
>> Not quite sure what you mean. The current drawn by a given resistance is
>> proportional to the voltage - and touching a 1000 amp supply is no more
>> dangerous to a human than touching a 1 amp one.
>
> Well you go right ahead and play with the 1000 Amp wires if you want to,
> but wait for me to get out of sight and earshot first - I'm a bit
> squeamish.
He (Dave P.) is right. Once you're about the amount of current
sufficient to be lethal (which is measured in milliamps, not amperes),
the ampacity of a circuit you're touching--whether 15, 20 or 200
amps--matters not.
No reason to be overly impressed by a 60-amp circuit. No more deadly
than a 1-amp circuit.
--
I am a Canadian who was born and raised in The Netherlands. I live on
Planet Earth on a spot of land called Canada. We have noisy neighbours.
- harvested from Usenet
VanguardLH
> He (Dave P.) is right. Once you're about the amount of current
> sufficient to be lethal (which is measured in milliamps, not amperes),
> the ampacity of a circuit you're touching--whether 15, 20 or 200
> amps--matters not.
>
> No reason to be overly impressed by a 60-amp circuit. No more deadly
> than a 1-amp circuit.
Google Groups copy of old thread: http://preview.tinyurl.com/ylf7uo8
You thought any participant in that *OVER 1-YEAR OLD* thread was still
waiting for a response?
David Nebenzahl
You were reading an *OVER 1-YEAR-OLD* thread? and commenting on it? (And
look--I *did* get a response!)
In my defense, I neglected to look at the year; thought it was about a
month old.
nobody >
> On 11/11/2008 7:47 AM Whiskers spake thus:
>
>> On 2008-11-10, Dave Plowman (News) <da...@davenoise.co.uk> wrote:
> >
>>> In article <slrnghhb1o.b...@ID-107770.user.individual.net>,
>>> Whiskers <catwh...@operamail.com> wrote:
> >>
>>>> Our power sockets are only 3kW each - but it isn't the Watts that
>>>> really
>>>> hurt, or even the Volts; it's the Amps you really need to be careful
>>>> with. 60 Amps at a Japanese 100V would be a lot more dangerous than 30
>>>> Amps at a European 230V. (Although either could kill you, so the
>>>> difference could be academic as far as the one grasping the wires is
>>>> concerned).
>>>
>>> Not quite sure what you mean. The current drawn by a given resistance is
>>> proportional to the voltage - and touching a 1000 amp supply is no more
>>> dangerous to a human than touching a 1 amp one.
>>
>> Well you go right ahead and play with the 1000 Amp wires if you want to,
>> but wait for me to get out of sight and earshot first - I'm a bit
>> squeamish.
>
> He (Dave P.) is right. Once you're about the amount of current
> sufficient to be lethal (which is measured in milliamps, not amperes),
> the ampacity of a circuit you're touching--whether 15, 20 or 200
> amps--matters not.
>
> No reason to be overly impressed by a 60-amp circuit. No more deadly
> than a 1-amp circuit.
>
That's true if you are just worried about contact shock hazard.
Arc flash/blast is a whole 'nother ball game.
http://www.easypower.com/arc_flash/arc_flash_videos.php