Electric shocks (was: 100V appliance on 110v power supply)

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

When I said "I've got a Japanese Akai S1000 sampler", I actually meant "I'm
selling a Japanese Akai S1000 sampler for someone else". As a result, I
didn't know much about the unit and its condition.

But I asked the owner what she used to do with regards to power supply and
she gave me the transformer that she had been running it off for the past 7
years or so. Surprise surprise - it's a 240V to 115V transformer, and she
said the Akai always worked fine despite being labelled 100V. In other
words, she'd been using an incorrect transformer for years, but it worked
anyway.

A buyer emailed me today from eBay asking if the screen was still bright or
if it had gone dim with age, so I plugged in the sampler using
aforementioned 115V transformer and promptly got an electric shock from an
area on the sampler's case where a bit of the paint had been scratched off,
leaving bare metal. It is worth bearing in mind that I was barefoot and
standing on a concrete garage floor, but nevertheless, this shouldn't
happen. I plugged it in again and the same thing happened. However, when
turned on, the sampler worked fine - it just gave me a shock whenever I
touched the case (a sizeable electric shock, not like static). The owner
said that she'd never experienced this before despite using the sampler with
the same transformer on a UK mains supply.

One thing I noticed about the unit was that it used a 2-pin power lead with
apparently no earth. As in, the socket on the machine only had 2 pins, so
there was no option to use an earthed cable (even though the transformer had
earthed sockets). What's the deal with this? Can anything be done? Obviously
I can't sell a unit on eBay in Very Good Condition if it shocks you when you
plug it in, even if it works fine otherwise.

Is my only option to sell it as-seen with a buyer warning?

Thanks,

--
tj hertz

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Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

"TJ Hertz" wrote ...
> When I said "I've got a Japanese Akai S1000 sampler",
> I actually meant "I'm selling a Japanese Akai S1000 sampler
> for someone else". As a result, I didn't know much about
> the unit and its condition.
>
> But I asked the owner what she used to do with regards to
> power supply and she gave me the transformer that she had
> been running it off for the past 7 years or so. Surprise surprise
> - it's a 240V to 115V transformer, and she said the Akai
> always worked fine despite being labelled 100V. In other
> words, she'd been using an incorrect transformer for years,
> but it worked anyway.

Generously-designed equipment can likely take a 15% over-
voltage although it may run warmer (and may reduce its expected
lifespan.) But lots of modern equipment is designed on the very
edge of acceptable ranges, so I wouldn't try it as a rule.

> A buyer emailed me today from eBay asking if the screen was
> still bright or if it had gone dim with age, so I plugged in the
> sampler using aforementioned 115V transformer and promptly
> got an electric shock from an area on the sampler's case where
> a bit of the paint had been scratched off, leaving bare metal. It
> is worth bearing in mind that I was barefoot and standing on a
> concrete garage floor, but nevertheless, this shouldn't happen.
> I plugged it in again and the same thing happened. However,
> when turned on, the sampler worked fine - it just gave me a
> shock whenever I touched the case (a sizeable electric shock,
> not like static). The owner said that she'd never experienced
> this before despite using the sampler with the same transformer
> on a UK mains supply.

PLEASE DON'T do that experiment again. We would miss you
if you electrocuted yourself! Seriously! There are SAFE ways
of testing for this that don't put your life or limb at risk.

> One thing I noticed about the unit was that it used a 2-pin power
> lead with apparently no earth. As in, the socket on the machine
> only had 2 pins, so there was no option to use an earthed cable
> (even though the transformer had earthed sockets). What's the
> deal with this? Can anything be done? Obviously I can't sell a unit
> on eBay in Very Good Condition if it shocks you when you plug
> it in, even if it works fine otherwise.
> Is my only option to sell it as-seen with a buyer warning?

Now that you know about it, and especially now that you have
revealed it in public, you really have no ethical choice but to
disclose it to any potential buyer. If somebody bought it and
electrocuted themselves full disclosure would be your minimum
defense.

If it were me, I would be tempted to fit an IEC power connector
on it (like the kind used for computers), with the green-wire
ground securely bonded to the metal chassis. But mains wiring
is not a project for amateurs. I would think that most consumer
equipment service shops ("TV Repair", etc.) would be equipped
for and experienced with testing and fixing this kind of problem.

Ironically, it may be working just as it was designed back
when it was first sold. But you can't get away without telling
bidders about the hazard today IMHO.

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

>One thing I noticed about the unit was that it used a 2-pin power lead with
>apparently no earth. As in, the socket on the machine only had 2 pins, so
>there was no option to use an earthed cable (even though the transformer had
>earthed sockets). What's the deal with this? Can anything be done? Obviously
>I can't sell a unit on eBay in Very Good Condition if it shocks you when you
>plug it in, even if it works fine otherwise.
>
>Is my only option to sell it as-seen with a buyer warning?
>

If you sell this product, even with a warning, you are opening up
yourself to servere liability issues.

An electric shock can be painful under the best conditions and
potentially deadly under the worst conditons.

It's likely that the transformer that the person you bought this from
was providing isolation and hence their claim of no shocks may have
valid.

Beachcomber

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

"Richard Crowley" <richard.n.crowley@intel.com> wrote in message
news7i2jd$u3a$1@news01.intel.com...
> "TJ Hertz" wrote ...

> > One thing I noticed about the unit was that it used a 2-pin power
> > lead with apparently no earth. As in, the socket on the machine
> > only had 2 pins, so there was no option to use an earthed cable
> > (even though the transformer had earthed sockets). What's the
> > deal with this? Can anything be done? Obviously I can't sell a unit
> > on eBay in Very Good Condition if it shocks you when you plug
> > it in, even if it works fine otherwise.
> > Is my only option to sell it as-seen with a buyer warning?

Someone pointed out the online manual. It has specific mention of earthing
in certain regions. You might want to take a look. Maybe something there
will be worth knowing.

j

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

Richard Crowley wrote:
> "TJ Hertz" wrote ...
>> When I said "I've got a Japanese Akai S1000 sampler",
>> I actually meant "I'm selling a Japanese Akai S1000 sampler
>> for someone else". As a result, I didn't know much about
>> the unit and its condition.
>>
>> But I asked the owner what she used to do with regards to
>> power supply and she gave me the transformer that she had
>> been running it off for the past 7 years or so. Surprise surprise
>> - it's a 240V to 115V transformer, and she said the Akai
>> always worked fine despite being labelled 100V. In other
>> words, she'd been using an incorrect transformer for years,
>> but it worked anyway.
>
> Generously-designed equipment can likely take a 15% over-
> voltage although it may run warmer (and may reduce its expected
> lifespan.) But lots of modern equipment is designed on the very
> edge of acceptable ranges, so I wouldn't try it as a rule.
>
>> A buyer emailed me today from eBay asking if the screen was
>> still bright or if it had gone dim with age, so I plugged in the
>> sampler using aforementioned 115V transformer and promptly
>> got an electric shock from an area on the sampler's case where
>> a bit of the paint had been scratched off, leaving bare metal. It
>> is worth bearing in mind that I was barefoot and standing on a
>> concrete garage floor, but nevertheless, this shouldn't happen.
>> I plugged it in again and the same thing happened. However,
>> when turned on, the sampler worked fine - it just gave me a
>> shock whenever I touched the case (a sizeable electric shock,
>> not like static). The owner said that she'd never experienced
>> this before despite using the sampler with the same transformer
>> on a UK mains supply.
>
> PLEASE DON'T do that experiment again. We would miss you
> if you electrocuted yourself! Seriously! There are SAFE ways
> of testing for this that don't put your life or limb at risk.
>
>> One thing I noticed about the unit was that it used a 2-pin power
>> lead with apparently no earth. As in, the socket on the machine
>> only had 2 pins, so there was no option to use an earthed cable
>> (even though the transformer had earthed sockets). What's the
>> deal with this? Can anything be done? Obviously I can't sell a unit
>> on eBay in Very Good Condition if it shocks you when you plug
>> it in, even if it works fine otherwise.
>> Is my only option to sell it as-seen with a buyer warning?
>
> Now that you know about it, and especially now that you have
> revealed it in public, you really have no ethical choice but to
> disclose it to any potential buyer. If somebody bought it and
> electrocuted themselves full disclosure would be your minimum
> defense.

Yeah, I know, and that's probably what I'll do - I was just asking if there
were any ways of fixing it. Obviously if the problem remains I will warn any
buyer.

>
> If it were me, I would be tempted to fit an IEC power connector
> on it (like the kind used for computers), with the green-wire
> ground securely bonded to the metal chassis. But mains wiring
> is not a project for amateurs. I would think that most consumer
> equipment service shops ("TV Repair", etc.) would be equipped
> for and experienced with testing and fixing this kind of problem.
>
> Ironically, it may be working just as it was designed back
> when it was first sold. But you can't get away without telling
> bidders about the hazard today IMHO.

I'll take it into a repair shop methinks. Thanks for the help.

TJ

--
tj hertz

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

"TJ Hertz" <tjhertz@gmail-HOLDTHESPAM.com> wrote in message
news:EL_me.25086$Li.12476@fe1.news.blueyonder.co.uk...
> When I said "I've got a Japanese Akai S1000 sampler", I actually meant
"I'm
> selling a Japanese Akai S1000 sampler for someone else". As a result, I
> didn't know much about the unit and its condition.
>
> But I asked the owner what she used to do with regards to power supply and
> she gave me the transformer that she had been running it off for the past
7
> years or so. Surprise surprise - it's a 240V to 115V transformer, and she
> said the Akai always worked fine despite being labelled 100V. In other
> words, she'd been using an incorrect transformer for years, but it worked
> anyway.
>
> A buyer emailed me today from eBay asking if the screen was still bright
or
> if it had gone dim with age, so I plugged in the sampler using
> aforementioned 115V transformer and promptly got an electric shock from an
> area on the sampler's case where a bit of the paint had been scratched
off,
> leaving bare metal. It is worth bearing in mind that I was barefoot and
> standing on a concrete garage floor, but nevertheless, this shouldn't
> happen. I plugged it in again and the same thing happened. However, when
> turned on, the sampler worked fine - it just gave me a shock whenever I
> touched the case (a sizeable electric shock, not like static). The owner
> said that she'd never experienced this before despite using the sampler
with
> the same transformer on a UK mains supply.
>
> One thing I noticed about the unit was that it used a 2-pin power lead
with
> apparently no earth. As in, the socket on the machine only had 2 pins, so
> there was no option to use an earthed cable (even though the transformer
had
> earthed sockets). What's the deal with this? Can anything be done?
Obviously
> I can't sell a unit on eBay in Very Good Condition if it shocks you when
you
> plug it in, even if it works fine otherwise.
>
> Is my only option to sell it as-seen with a buyer warning?
>
> Thanks,
>
> --
> tj hertz
>
It appears that the original usage was 240V to ground and the transformer is
an autotransformer. Using this transformer with a North American 240/120V
system could put the case at 120V with respect to ground.
If this unit is to be used with a transformer, it will require an isolating
(2 winding) 240/120V transformer and then the case can be grounded.

However, why use the transformer?

Why not connect directly to the 120V outlet. It will be necessary to
determine which lead is the neutral. You will need a voltmeter. If the case
is at 120 or so Volts to ground- reverse the wires to the plug. Check
again-you want a small or negligable voltage between case and ground. Then
set up the plug and leads accordingly (replacing the cord and plug to a 3
prong (hot, neutral and ground) is the best way.
If you have any doubts, a competent electrician can sort it out for you in a
short time- or you warn the potential buyer that it appears that the case is
tied to the neutral and you don't know which wire is neutral and leave the
correction to him/her. You don't want to be responsible for avoidable
injuries.
--
Don Kelly
dhky@peeshaw.ca
remove the urine to answer

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

Don Kelly wrote:
> "TJ Hertz" <tjhertz@gmail-HOLDTHESPAM.com> wrote in message
> news:EL_me.25086$Li.12476@fe1.news.blueyonder.co.uk...
>> When I said "I've got a Japanese Akai S1000 sampler", I actually
>> meant "I'm selling a Japanese Akai S1000 sampler for someone else".
>> As a result, I didn't know much about the unit and its condition.
>>
>> But I asked the owner what she used to do with regards to power
>> supply and she gave me the transformer that she had been running it
>> off for the past 7 years or so. Surprise surprise - it's a 240V to
>> 115V transformer, and she said the Akai always worked fine despite
>> being labelled 100V. In other words, she'd been using an incorrect
>> transformer for years, but it worked anyway.
>>
>> A buyer emailed me today from eBay asking if the screen was still
>> bright or if it had gone dim with age, so I plugged in the sampler
>> using aforementioned 115V transformer and promptly got an electric
>> shock from an area on the sampler's case where a bit of the paint
>> had been scratched off, leaving bare metal. It is worth bearing in
>> mind that I was barefoot and standing on a concrete garage floor,
>> but nevertheless, this shouldn't happen. I plugged it in again and
>> the same thing happened. However, when turned on, the sampler worked
>> fine - it just gave me a shock whenever I touched the case (a
>> sizeable electric shock, not like static). The owner said that she'd
>> never experienced this before despite using the sampler with the
>> same transformer on a UK mains supply.
>>
>> One thing I noticed about the unit was that it used a 2-pin power
>> lead with apparently no earth. As in, the socket on the machine only
>> had 2 pins, so there was no option to use an earthed cable (even
>> though the transformer had earthed sockets). What's the deal with
>> this? Can anything be done? Obviously I can't sell a unit on eBay in
>> Very Good Condition if it shocks you when you plug it in, even if it
>> works fine otherwise.
>>
>> Is my only option to sell it as-seen with a buyer warning?
>>
>> Thanks,
>>
>> --
>> tj hertz
>>
> It appears that the original usage was 240V to ground and the
> transformer is an autotransformer. Using this transformer with a
> North American 240/120V system could put the case at 120V with
> respect to ground.
> If this unit is to be used with a transformer, it will require an
> isolating (2 winding) 240/120V transformer and then the case can be
> grounded.
>
> However, why use the transformer?
>
> Why not connect directly to the 120V outlet. It will be necessary to
> determine which lead is the neutral. You will need a voltmeter. If
> the case is at 120 or so Volts to ground- reverse the wires to the
> plug. Check again-you want a small or negligable voltage between case
> and ground. Then set up the plug and leads accordingly (replacing
> the cord and plug to a 3 prong (hot, neutral and ground) is the best
> way.
> If you have any doubts, a competent electrician can sort it out for
> you in a short time- or you warn the potential buyer that it appears
> that the case is tied to the neutral and you don't know which wire is
> neutral and leave the correction to him/her. You don't want to be
> responsible for avoidable injuries.

So basically, you're saying find out which way the thing should be connected
in order to let the case be neutral, replace the mains end of the cable with
a 3-pin plug so that it can't be connected the wrong way, and glue/fix the
sampler end of the cable into the sampler so it can't be reversed (or label
which way it should go)? And this would fix the electric shock problem, but
still leave the unit unearthed?

I'll let an electrician deal with it because I have neither a
volt/multimeter nor any spare 3-pin plugs (you don't see many in the UK),
but I'd like to know what's going on anyway.

Thanks

--
tj hertz

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

"Don Kelly" wrote ...
> However, why use the transformer?
>
> Why not connect directly to the 120V outlet.

Are those common in England? I've never seen any.

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

On Tue, 31 May 2005 18:29:35 -0700, "Richard Crowley"
<rcrowley7@xprt.net> wrote:

>"Don Kelly" wrote ...
>> However, why use the transformer?
>>
>> Why not connect directly to the 120V outlet.
>
>Are those common in England? I've never seen any.
On the shaving mirror in hotels <G>. I just would not plug good
electronics into it

, _
, | \ MKA: Steve Urbach
, | )erek No JUNK in my email please
, ____|_/ragonsclaw dragonsclawJUNK@JUNKmindspring.com
, / / / Running United Devices "Cure For Cancer" Project 24/7 Have you helped? http://www.grid.org

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.engineering.electrical (More info?)

In article <jc4q91h50rjfgih4hmaqata1qu6h88okjn@4ax.com>,
Steve Urbach <dragonsclaw@NOTmindspring.com> writes:
>On Tue, 31 May 2005 18:29:35 -0700, "Richard Crowley"
><rcrowley7@xprt.net> wrote:
>
>>"Don Kelly" wrote ...
>>> However, why use the transformer?
>>>
>>> Why not connect directly to the 120V outlet.
>>
>>Are those common in England? I've never seen any.
>On the shaving mirror in hotels <G>. I just would not plug good
>electronics into it

Should be no problem, except they are limited to 25W with
a slow acting thermal cutout. The output is isolated via
an isolating transformer (floating).

--
Andrew Gabriel

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

Ioslation transformer must still have the secondary (the 120
volt side) connected back to the building safety ground. If
not, then the appliance will 'float' - can become electrically
hot. If the transformer is properly designed, then either it
has such a connection OR it has a dedicated grounding wire
terminal to make that necessary connection.

TJ Hertz wrote:
> Yeah, I know, and that's probably what I'll do - I was just asking
> if there were any ways of fixing it. Obviously if the problem
> remains I will warn any buyer.
> ...

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

"w_tom"
>
> Ioslation transformer must still have the secondary (the 120
> volt side) connected back to the building safety ground.

** Making it no longer an "isolation " transformer.

> If not, then the appliance will 'float' - can become electrically
> hot.

** The appliance's AC supply wiring will float - but nothing else since
it is all insulated from that wiring.

> If the transformer is properly designed, then either it
> has such a connection OR it has a dedicated grounding wire
> terminal to make that necessary connection.

** A step-down / isolation transformer ought to have a ground terminal on
the outlet that connects to the METALWORK of the appliance via the third pin
of the plug.

........... Phil

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

In article <429D32C0.7FFE45ED@hotmail.com>, w_tom <w_tom1@hotmail.com> wrote:
> Ioslation transformer must still have the secondary (the 120
>volt side) connected back to the building safety ground. If
>not, then the appliance will 'float' - can become electrically
>hot. If the transformer is properly designed, then either it
>has such a connection OR it has a dedicated grounding wire
>terminal to make that necessary connection.

No, that's the point of isolation. Because the appliance floats, it can
become "hot" but the leakage current has no reference to the building
ground so if you touch the hot case, no current will flow through you.

Not that a safety ground isn't _still_ a good idea, mind you.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Reply to Anonymous

Archived from groups: rec.audio.pro (More info?)

In article <429D32C0.7FFE45ED@hotmail.com> w_tom1@hotmail.com writes:

> Ioslation transformer must still have the secondary (the 120
> volt side) connected back to the building safety ground.

Duh? Then it wouldn't be an isolation transformer.

> If
> not, then the appliance will 'float' - can become electrically
> hot. If the transformer is properly designed, then either it
> has such a connection OR it has a dedicated grounding wire
> terminal to make that necessary connection.

The appliance is supposed to float. If there's a safety ground contact
on the power connector of an isolation box, it's to carry the
safety ground through the box. It's not connected to the transformer,
primary or secondary.

To the person who started the discussion about getting a shock from
something powered by a transformer, the transformer (module) must have
been defective and it should be replaced.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

Yes, that's why in all around the world the neutral of LV distribution
transformers is earthed (so I learned in my studies) so that you get
schocked and know that electricity is dangerous (no joke) AND because in a
neighborhood e.g. someone would be touching a live phase and someone else
another, so that both would be exposed to the line to line voltage which is
380 V in Europe (220 V in USA).However this happens only in LV, in MV, HV
and EHV there's no need for a reference to ground, because the windings of
the substation transformer are in delta, ungrounded.This doesn't make the
voltage not dangerous, I was told some horror stories back in Kozani.

--
Tzortzakakis Dimitrios
major in electrical engineering, freelance electrician
FH von Iraklion-Kreta, freiberuflicher Elektriker
dimtzort AT otenet DOT gr
Ï "Scott Dorsey" <kludge@panix.com> Ýãñáøå óôï ìÞíõìá
news7k9da$83a$1@panix2.panix.com...
> In article <429D32C0.7FFE45ED@hotmail.com>, w_tom <w_tom1@hotmail.com>
wrote:
> > Ioslation transformer must still have the secondary (the 120
> >volt side) connected back to the building safety ground. If
> >not, then the appliance will 'float' - can become electrically
> >hot. If the transformer is properly designed, then either it
> >has such a connection OR it has a dedicated grounding wire
> >terminal to make that necessary connection.
>
> No, that's the point of isolation. Because the appliance floats, it can
> become "hot" but the leakage current has no reference to the building
> ground so if you touch the hot case, no current will flow through you.
>
> Not that a safety ground isn't _still_ a good idea, mind you.
> --scott
>
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.engineering.electrical (More info?)

In article <d7kca3$ai4$1@usenet.otenet.gr>,
"Dimitrios Tzortzakakis" <use@address.below> writes:
>Yes, that's why in all around the world the neutral of LV distribution
>transformers is earthed (so I learned in my studies) so that you get
>schocked and know that electricity is dangerous (no joke) AND because in a
>neighborhood e.g. someone would be touching a live phase and someone else
>another, so that both would be exposed to the line to line voltage which is
>380 V in Europe (220 V in USA).However this happens only in LV, in MV, HV
>and EHV there's no need for a reference to ground, because the windings of
>the substation transformer are in delta, ungrounded.

They are often grounded even so, sometimes through a resistor
and current measuring equipment to monitor leakage in the line.
Also to prevent a transformer leak letting the lower voltage
windings float up to the voltage of the HV windings relative to
ground, which would exceed the insulation rating of the line and
downstream gear.

--
Andrew Gabriel

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.engineering.electrical (More info?)

In alt.engineering.electrical Scott Dorsey <kludge@panix.com> wrote:
| In article <429D32C0.7FFE45ED@hotmail.com>, w_tom <w_tom1@hotmail.com> wrote:
|> Ioslation transformer must still have the secondary (the 120
|>volt side) connected back to the building safety ground. If
|>not, then the appliance will 'float' - can become electrically
|>hot. If the transformer is properly designed, then either it
|>has such a connection OR it has a dedicated grounding wire
|>terminal to make that necessary connection.
|
| No, that's the point of isolation. Because the appliance floats, it can
| become "hot" but the leakage current has no reference to the building
| ground so if you touch the hot case, no current will flow through you.
|
| Not that a safety ground isn't _still_ a good idea, mind you.

Except for low voltage lighting, according to NEC article 411.

--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

"Dimitrios Tzortzakakis" <use@address.below> wrote in message
news7kca3$ai4$1@usenet.otenet.gr...
> Yes, that's why in all around the world the neutral of LV distribution
> transformers is earthed (so I learned in my studies) so that you get
> schocked and know that electricity is dangerous (no joke) AND because in a
> neighborhood e.g. someone would be touching a live phase and someone else
> another, so that both would be exposed to the line to line voltage which
is
> 380 V in Europe (220 V in USA).However this happens only in LV, in MV, HV
> and EHV there's no need for a reference to ground, because the windings of
> the substation transformer are in delta, ungrounded.This doesn't make the
> voltage not dangerous, I was told some horror stories back in Kozani.
>
> --
> Tzortzakakis Dimitrios
> major in electrical engineering, freelance electrician
> FH von Iraklion-Kreta, freiberuflicher Elektriker
> dimtzort AT otenet DOT gr
---------------
In LV, MV , HV and RHV. the transformer windings can be and often are in Y.-
.. The most common connection is Delta Wye with the HV side in Wye with
direct or impedance grounding. There are good technical and economic reasons
for that. The next most common connection is probably Y-Y -delta for
supplying EHV lines . Note that even at 4160V distribution the supply
transformer is Y on the 4160V side.
Ground faults are the most common faults on transmission lines. This means
that the unfaulted phases will see overvoltages- not good. In addition,
protective relaying problems are increased and arcing faults which are not
detected and often undetectable can occur because of capacitive coupling.
The grounding eliminates these problems as well as problems due to the line
floating up and down due to atmospheric effects (thus stressing the
insulation). The use of a Y system makes life a lot easier.

--
Don Kelly
dhky@peeshaw.ca
remove the urine to answer

> Ï "Scott Dorsey" <kludge@panix.com> Ýãñáøå óôï ìÞíõìá
> news7k9da$83a$1@panix2.panix.com...
> > In article <429D32C0.7FFE45ED@hotmail.com>, w_tom <w_tom1@hotmail.com>
> wrote:
> > > Ioslation transformer must still have the secondary (the 120
> > >volt side) connected back to the building safety ground. If
> > >not, then the appliance will 'float' - can become electrically
> > >hot. If the transformer is properly designed, then either it
> > >has such a connection OR it has a dedicated grounding wire
> > >terminal to make that necessary connection.
> >
> > No, that's the point of isolation. Because the appliance floats, it can
> > become "hot" but the leakage current has no reference to the building
> > ground so if you touch the hot case, no current will flow through you.
> >
> > Not that a safety ground isn't _still_ a good idea, mind you.
> > --scott
> >
> >
> > --
> > "C'est un Nagra. C'est suisse, et tres, tres precis."
>
>

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

Sorry, given that it was e-bay, I didn't cjheck the origin. The solution
that I suggested was for North American usage.
The key in the UK case is to pitch the original transformer and get an
isolation transformer (2 winding 120/240V)

--
Don Kelly
dhky@peeshaw.ca
remove the urine to answer

"Steve Urbach" <dragonsclaw@NOTmindspring.com> wrote in message
news:jc4q91h50rjfgih4hmaqata1qu6h88okjn@4ax.com...
> On Tue, 31 May 2005 18:29:35 -0700, "Richard Crowley"
> <rcrowley7@xprt.net> wrote:
>
> >"Don Kelly" wrote ...
> >> However, why use the transformer?
> >>
> >> Why not connect directly to the 120V outlet.
> >
> >Are those common in England? I've never seen any.
> On the shaving mirror in hotels <G>. I just would not plug good
> electronics into it
>
>
> , _
> , | \ MKA: Steve Urbach
> , | )erek No JUNK in my email please
> , ____|_/ragonsclaw dragonsclawJUNK@JUNKmindspring.com
> , / / / Running United Devices "Cure For Cancer" Project 24/7
Have you helped? http://www.grid.org

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

On Tue, 31 May 2005 14:44:52 +0000, TJ Hertz wrote:

>... promptly got an electric shock from an
> area on the sampler's case where a bit of the paint had been scratched off,
> leaving bare metal. It is worth bearing in mind that I was barefoot and
> standing on a concrete garage floor, but nevertheless, this shouldn't
> happen.

This is correct. Standing barefoot on a concrete garage floor while
dicking around with anything plugged into mains should never happen.

Good Luck - you'll need it.
Rich

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

On Tue, 31 May 2005 09:15:40 -0700, Richard Crowley wrote:

> "TJ Hertz" wrote ...

>> shock whenever I touched the case (a sizeable electric shock,
>> not like static). The owner said that she'd never experienced
>> this before despite using the sampler with the same transformer
>> on a UK mains supply.
>
> PLEASE DON'T do that experiment again. We would miss you
> if you electrocuted yourself! Seriously! There are SAFE ways
> of testing for this that don't put your life or limb at risk.

Nah - we'll just nominate him for this year's Darwin award.

Cheers!
Rich

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

On Fri, 03 Jun 2005 15:24:55 GMT, Rich Grise wrote:

> This is correct. Standing barefoot on a concrete garage floor while
> dicking around with anything plugged into mains should never happen.

Word up.

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

"Rich Grise" <richgrise@example.net> wrote in message
newsan.2005.06.03.15.26.11.282935@example.net...
> On Tue, 31 May 2005 14:44:52 +0000, TJ Hertz wrote:
>
> >... promptly got an electric shock from an
> > area on the sampler's case where a bit of the paint had been scratched
off,
> > leaving bare metal. It is worth bearing in mind that I was barefoot and
> > standing on a concrete garage floor, but nevertheless, this shouldn't
> > happen.
>
> This is correct. Standing barefoot on a concrete garage floor while
> dicking around with anything plugged into mains should never happen.
>
> Good Luck - you'll need it.
> Rich
NOTE: this experience happened in the U.S.A. and other countries may differ

a friend of mine had a phonograph player in his basement. the unit operated
fine, but if you touched a metal part of the player, and a metal support
post in the basement, you would get a mild shock (about half of what I've
gotten from touching 110v mains by accident)

Later on in life, I found out that if you attempt to bypass the safety
feature of polarized p,ugs for non-grounded equipment, or if the electrical
outlet was wired incorrectly, this happens.

as you are on a foriegn system, I cannot be sure, but I'd advise to switch
the live and neutral lines. and also put an earth line in there also.

--
Tater
President of MARS Club (NAR #660)
www.mars-rocketry.com
KC9ESF
NAR #79654 L1
EAA #703312
remove spam spelled backwards to reply

Reply to Anonymous

Archived from groups: rec.audio.pro,alt.electronics,alt.engineering.electrical (More info?)

tater schuld <taters1@maps.charter.net> wrote:
>NOTE: this experience happened in the U.S.A. and other countries may differ
>
>a friend of mine had a phonograph player in his basement. the unit operated
>fine, but if you touched a metal part of the player, and a metal support
>post in the basement, you would get a mild shock (about half of what I've
>gotten from touching 110v mains by accident)

This is because it was a hot chassis player. That is no longer acceptable
in the US, but it was very popular for many years for cheap consumer electronics
to operate without a power transformer and use a hot chassis. For almost
any cheap table radio, record player, or TV set made before 1970 this was
the case, and for a lot of TV sets well into the eighties it remained the
case.

>Later on in life, I found out that if you attempt to bypass the safety
>feature of polarized p,ugs for non-grounded equipment, or if the electrical
>outlet was wired incorrectly, this happens.

That just makes the problem worse, yes.

>as you are on a foriegn system, I cannot be sure, but I'd advise to switch
>the live and neutral lines. and also put an earth line in there also.

Grounding is a good idea, but if there is chassis leakage, that is bad and
it should be fixed if possible.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Reply to Anonymous

Forum Audio : Pro Audio - Electric shocks (was: 100V appliance on 110v power supply)

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Electric shocks (was: 100V appliance on 110v power supply)

Forum Audio : Pro Audio - Electric shocks (was: 100V appliance on 110v power supply)

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