60V DC dangerous?
pbde...@spamnuke.ludd.luthdelete.se.invalid
Should one be as respectful as with 220V AC?
Tim Wescott
> Just how dangerous is 60V DC ..?,, or 50V ?
>
> Should one be as respectful as with 220V AC?
>
Bad enough that CE wants you to keep it from your product's consumers.
I would assume that it can be fatal on a Very Bad Day.
I would answer your second question but the ghost of my Lawyer is
whispering in my ear so I won't. I _will_ say that _I_ would treat
220VAC with a great deal more respect than I would treat 60VDC, because
220VAC can kill you faster.
Surely this information is out there on Google if you can think of the
right search terms?
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Posting from Google? See http://cfaj.freeshell.org/google/
"Applied Control Theory for Embedded Systems" came out in April.
See details at http://www.wescottdesign.com/actfes/actfes.html
pbde...@spamnuke.ludd.luthdelete.se.invalid
>pbde...@spamnuke.ludd.luthdelete.se.invalid wrote:
>> Just how dangerous is 60V DC ..?,, or 50V ?
>>
>> Should one be as respectful as with 220V AC?
>>
>Bad enough that CE wants you to keep it from your product's consumers.
>I would assume that it can be fatal on a Very Bad Day.
Where's the CE "keep out" limit?
(48V dc is used in PoE apps..)
>I would answer your second question but the ghost of my Lawyer is
>whispering in my ear so I won't. I _will_ say that _I_ would treat
>220VAC with a great deal more respect than I would treat 60VDC, because
>220VAC can kill you faster.
>Surely this information is out there on Google if you can think of the
>right search terms?
Problem with google is that it will more or less act like a "yes-sayer"..
StanleyLee
pbdel...@spamnuke.ludd.luthdelete.se.invalid 写道：
I my opinion, 36V DC is dangerous enough......So keep away from it.
Jeff L
<pbde...@spamnuke.ludd.luthdelete.se.invalid> wrote in message
news:44a9460d$0$490$cc7c...@news.luth.se...
> Tim Wescott <t...@seemywebsite.com> wrote:
> >pbde...@spamnuke.ludd.luthdelete.se.invalid wrote:
>
> >> Just how dangerous is 60V DC ..?,, or 50V ?
> >>
> >> Should one be as respectful as with 220V AC?
> >>
> >Bad enough that CE wants you to keep it from your product's consumers.
> >I would assume that it can be fatal on a Very Bad Day.
>
> Where's the CE "keep out" limit?
I'm not sure about CE, but NEC says 50V DC and above is potentially fatal.
That's why 48V is used for telecom apps, and PoE would likely follow those
guidelines if a lot of power must be transferred.
Ken Smith
<pbde...@spamnuke.ludd.luthdelete.se.invalid> wrote:
>Just how dangerous is 60V DC ..?,, or 50V ?
>
>Should one be as respectful as with 220V AC?
As far as AC vs DC goes, the only real difference is whether or not you
shake before you fall on the floor.
It only takes about 50mA to kill you. Depending on how good the
connection is, it takes a lot less than 50V to cause that much current to
flow through your chest. The dry skin of your hand is where most of the
voltage drop happens when you get a shock.
Depending on where you are voltages under 48V or 24V or some other is
considered by the government to be safe. At these "safe" voltages you no
longer have to make sure that a person can't come in contact with it.
Low voltage, high current situations can cause injury if a metal object
comes in contact with it. This is why, (smart) people remove any rings or
wrist watches before working on such things.
--
--
kens...@rahul.net forging knowledge
Eeyore
pbde...@spamnuke.ludd.luthdelete.se.invalid wrote:
> Tim Wescott <t...@seemywebsite.com> wrote:
> >pbde...@spamnuke.ludd.luthdelete.se.invalid wrote:
>
> >> Just how dangerous is 60V DC ..?,, or 50V ?
> >>
> >> Should one be as respectful as with 220V AC?
> >>
> >Bad enough that CE wants you to keep it from your product's consumers.
> >I would assume that it can be fatal on a Very Bad Day.
>
> Where's the CE "keep out" limit?
42 V pk IIRC ( peak value of 30V ac ). 48V is inded a bit of an anomaly but who
cares ?
Graham
lieven 'nuts' citters
> Just how dangerous is 60V DC ..?,, or 50V ?
>
> Should one be as respectful as with 220V AC?
if you want to make something for your baby, you should stay below 24V
DC. otherwise, you need to take 48V DC
Normally, AC is more dangerous then DC.
It's not voltage that's dangerous, it is current. You can feel 2 or
4mA, 10mA gives a serious chock, 20mA will make you stick on the
conductor, 50mA will knock you onconscious and 100mA will kill you.
As a student, i tried to make an ohm-meter for persons, and i started
calculating with a current of 100mA. You need way too much voltage! :D
if you want to know more about this, read ESD regulations on
www.esda.com
greets
John Larkin
pbde...@spamnuke.ludd.luthdelete.se.invalid wrote:
>Just how dangerous is 60V DC
Not very.
..?,, or 50V ?
48 DC is usually considered safe, so 50 can't be a lot worse.
>Should one be as respectful as with 220V AC?
Not really. Aside from the magnitude difference, AC is much more
dangerous.
John
Luhan
Reminds me of the "taste great; less filling" AC vs DC debate between
Edison and Tesla. Each promoted using the other's form of power for
the electric chair!
Luhan
pbde...@spamnuke.ludd.luthdelete.se.invalid
>> dangerous.
>Reminds me of the "taste great; less filling" AC vs DC debate between
>Edison and Tesla. Each promoted using the other's form of power for
>the electric chair!
For the progress of humanity .. :-)
ian field
"StanleyLee" <lizh...@hotmail.com> wrote in message
news:1151945150.0...@m79g2000cwm.googlegroups.com...
pbdel...@spamnuke.ludd.luthdelete.se.invalid ??:
Big girls blouse!!!
Ken Smith
John Larkin <jjla...@highNOTlandTHIStechnologyPART.com> wrote:
[....]
>
> Aside from the magnitude difference, AC is much more
>dangerous.
No, DC is much more dangerous. I like Tesla better than Edison.
John Larkin
Edison used to electrocute cats in his garden to demonstrate to
visitors how dangerous AC was.
There's a graph, somewhere, of how lethal AC is as a function of
frequency. I believe it peaks at about 30 Hz.
John
mrda...@gmail.com
John Larkin wrote:
> On 3 Jul 2006 11:55:53 -0700, "Luhan" <luh...@yahoo.com> wrote:
>
> >
> >John Larkin wrote:
> >> On 03 Jul 2006 15:55:25 GMT,
> >> pbde...@spamnuke.ludd.luthdelete.se.invalid wrote:
> >>
> >> >Just how dangerous is 60V DC
> >>
> >> Not very.
> >>
> >> ..?,, or 50V ?
> >>
> >> 48 DC is usually considered safe, so 50 can't be a lot worse.
> >>
> >> >Should one be as respectful as with 220V AC?
> >>
> >> Not really. Aside from the magnitude difference, AC is much more
> >> dangerous.
> >>
> >
> >Reminds me of the "taste great; less filling" AC vs DC debate between
> >Edison and Tesla. Each promoted using the other's form of power for
> >the electric chair!
> >
> >Luhan
>
> Edison used to electrocute cats in his garden to demonstrate to
> visitors how dangerous AC was.
Wow, really? Edison and Schrodinger would have gotten along very well
together, I can see...
mrda...@gmail.com
John Larkin wrote:
> On 3 Jul 2006 11:55:53 -0700, "Luhan" <luh...@yahoo.com> wrote:
>
> >
> >John Larkin wrote:
> >> On 03 Jul 2006 15:55:25 GMT,
> >> pbde...@spamnuke.ludd.luthdelete.se.invalid wrote:
> >>
> >> >Just how dangerous is 60V DC
> >>
> >> Not very.
> >>
> >> ..?,, or 50V ?
> >>
> >> 48 DC is usually considered safe, so 50 can't be a lot worse.
> >>
> >> >Should one be as respectful as with 220V AC?
> >>
> >> Not really. Aside from the magnitude difference, AC is much more
> >> dangerous.
> >>
> >
> >Reminds me of the "taste great; less filling" AC vs DC debate between
> >Edison and Tesla. Each promoted using the other's form of power for
> >the electric chair!
> >
> >Luhan
>
> Edison used to electrocute cats in his garden to demonstrate to
> visitors how dangerous AC was.
Wow, really? Edison and Schrodinger would have gotten along very well
together, I can see...
Paul
Ken Smith wrote:
> In article <ffoia2dv56695qnnl...@4ax.com>,
> John Larkin <jjla...@highNOTlandTHIStechnologyPART.com> wrote:
> [....]
> >
> > Aside from the magnitude difference, AC is much more
> >dangerous.
>
> No, DC is much more dangerous. I like Tesla better than Edison.
>
Edison used to be my childhood idol (no, he was not a contemporary),
but then I discovered Edison's uglier side and Tesla's eccentric and
unappreciated brilliance, so now he earns my respect and interest.
As for dangers of AC and DC currents and voltages, it is true that it
is the current that causes physiological problems that can be fatal.
Current causes muscle contraction, so AC current causes characteristic
shaking, which has the advantage of allowing you (possibly) to let go.
DC current causes continuous contraction, and because the muscles for
gripping are more powerful than those for opening the hand, the
tendency is for it to be impossible to release the conductor. This is
why, if you MUST touch an energized conductor, use the back of the
hand, so the contraction will take you away from danger.
The conduction of the human body varies considerably due to skin
conditions, and I think it is nominally about 10 k Ohms from one hand
to the other, or from hand to feet (the usual paths). So 120 VAC will
cause about 12 mA, which is well above the threshold of sensation
(about 5 mA), but below that for near certain fatality (50-100 mA).
However, heavy perspiration can bring that resistance down to 2-3 kOhms
or less, where 120 VAC becomes very dangerous. Also remember that 120
VAC has peaks of 180 volts, which cause pulses of more dangerous
current.
Another big problem with AC voltage is that power line frequencies are
just about the worst (or best) for causing fibrillation, which is a
life-threatening condition that can continue after removal of the
power. Essentially the heart pacemaker becomes confused and causes
extremely rapid beats that do not pump blood. A high current DC jolt
from a defib essentially resets the pacemaker and allows a normal
restart. Dick Cheney has one of these "Watchdog Timers" in his chest.
Higher frequencies often tend to travel more on the surface of the
skin, bypassing internal organs such as the heart, and are thus a bit
safer, as well as not being as likely to cause fibrillation.
Even very low voltages can cause some interesting physiological
effects. I have heard of an experiment (or party prank), where a gold
coin or a valuable ring is placed in a tank of salt water, and a 12
volt battery is connected to electrodes passing perhaps an ampere or so
of current through the solution. You can have the coin or jewelry if
you can pick it up. However, the current causes nearly immediate
paralysis of the hand while in the water. Maybe you can cheat and cover
your hand in vaseline?
I have also heard horror stories of people who were in a boating
accident with an electric motor, where the cables fell into the water
where they were trying to stay afloat, or possibly holding onto the
aluminum boat. Rather uncomfortable!
I have not fully researched the above statements, but I believe they
are at least close to realistic. The bottom line is, almost any voltage
can be dangerous, and deserves to be treated with respect and caution.
Paul
(Re-posted via Google because of problem with Coretel.net)
Ken Smith
Paul <pst...@smart.net> wrote:
[....]
>As for dangers of AC and DC currents and voltages, it is true that it
>is the current that causes physiological problems that can be fatal.
>Current causes muscle contraction, so AC current causes characteristic
>shaking, which has the advantage of allowing you (possibly) to let go.
No-one is fast and strong enough to gain let go during the very brief time
that the current is small.
>DC current causes continuous contraction, and because the muscles for
>gripping are more powerful than those for opening the hand, the
>tendency is for it to be impossible to release the conductor. This is
>why, if you MUST touch an energized conductor, use the back of the
>hand, so the contraction will take you away from danger.
This isn't completely true. The contraction may only take you to a lower
danger or just as serious of one. Based on the one experiment of this
type I did, I know that the muscles in the human arm are designed so that
the joint where the thumb connects to the hand is brought with
considerable force directly to the eyeball on the same side.
[...]
>Higher frequencies often tend to travel more on the surface of the
>skin, bypassing internal organs such as the heart, and are thus a bit
>safer, as well as not being as likely to cause fibrillation.
Yes, but higher frequencies tend to punch holes through your flesh. I have
at least one scare from this.
John Larkin
>As for dangers of AC and DC currents and voltages, it is true that it
>is the current that causes physiological problems that can be fatal.
>Current causes muscle contraction, so AC current causes characteristic
>shaking, which has the advantage of allowing you (possibly) to let go.
>DC current causes continuous contraction, and because the muscles for
>gripping are more powerful than those for opening the hand, the
>tendency is for it to be impossible to release the conductor.
Uh, I believe that's backwards. AC produces the stronger muscle
contractions. 8 milliseconds isn't a lot of time to let go.
John
Mike Monett
them somewhere but not findable at the moment. In the meantime, someone
else has done a bit of research and reports his findings
The table found in the Bussmann handbook differs slightly from the
one available from MIT: for the DC threshold of perception (men),
the MIT table gives 5.2 mA while the Bussmann table gives a slightly
greater figure of 6.2 mA. Also, for the "unable to let go" 60 Hz AC
threshold (men), the MIT table gives 20 mA while the Bussmann table
gives a lesser figure of 16 mA. As I have yet to obtain a primary
copy of Dalziel's research, the figures cited here are conservative:
I have listed the lowest values in my table where any data sources
differ.
These differences, of course, are academic. The point here is that
relatively small magnitudes of electric current through the body can
be harmful if not lethal.
Data regarding the electrical resistance of body contact points was
taken from a safety page (document 16.1) from the Lawrence Livermore
National Laboratory (website [*]), citing Ralph H. Lee as the data
source. Lee's work was listed here in a document entitled "Human
Electrical Sheet," composed while he was an IEEE Fellow at E.I.
duPont de Nemours & Co., and also in an article entitled "Electrical
Safety in Industrial Plants" found in the June 1971 issue of IEEE
Spectrum magazine.
http://www.allaboutcircuits.com/vol_1/chpt_3/10.html
Regards,
Mike Monett
Maybe pressing the button didn't work. Sorry. Blame Bill for any dupes.
MikeS...@eehomepage.com
can get to it online at: http://www.edn.com/contents/images/6330100.pdf
Regards,
Mike Stanley
http://www.eehomepage.com
Mike Monett
> EDN magazine had an article in the May 11 issue on the subject. You
> can get to it online at: http://www.edn.com/contents/images/6330100.pdf
> Regards,
> Mike Stanley
> http://www.eehomepage.com
Piffle. Only 1A. That is nothing.
For entertainment and pleasure, some reach for a Bud.
Real men grab 16,600 Volts!
electronics baby
Don Klipstein
pbde...@spamnuke.ludd.luthdelete.se.invalid wrote:
>Just how dangerous is 60V DC ..?,, or 50V ?
Officially hazardous with some risk of shock being able to be fatal.
>Should one be as respectful as with 220V AC?
DC, at least smmoth DC, is less likely to cause death than AC of
frequency in/near the 50/60 Hz ballpark. By-and-large, DC has some
significant hazard down to about 50 volts and AC down to about 25-30.
Less if you are likely to be wet with sea water - then, 28 volts DC is
borderline (29 volts is "officially hazardous") and AC is no better down
to something lower - maybe 13-15 volts?
Keep in mind that the horror stories of DC causing bad burns in
railroad/subway workers got told by people who survived and lived to tell
the ugly tales of top degree burns extending into deep tissue and muscles
and burn damage can have a halflife of 7 years or whatever and muscles
with fibers being totalled will never be the same again and nerves grow
back at some awfully slow pace or even worse when nerve cells get
totalled. Same voltage and current with 50-60 Hz AC is more likely to
cause either ventricular fibrillation or cardiac arrest - which gives
hardly any chance of the shock victim talking about nerves being fried or
muscles or deep tissue feeling fried (and feeling burned and hurting) many
years later.
Keep in mind the Edison vs. Westinghouse stuff, especially where it
relates to the "Electric Chair"!
- Don Klipstein (d...@misty.com)
Don Klipstein
>In article <44a93ded$0$487$cc7c...@news.luth.se>,
> <pbde...@spamnuke.ludd.luthdelete.se.invalid> wrote:
>>Just how dangerous is 60V DC ..?,, or 50V ?
>>
>>Should one be as respectful as with 220V AC?
>
>
>As far as AC vs DC goes, the only real difference is whether or not you
>shake before you fall on the floor.
AC is worse for both making muscles shake and worse still for making
muscles freeze. DC shock tends to have main stimulating impact on muscles
being with application and release, with 60 Hz AC accomplishing either of
these 240 times a second! (Actual effect is largely from current change,
120 times a second with 60 Hz AC.)
>It only takes about 50mA to kill you.
Most sources say the "deadly range" is 100 mA to 1 amp - but this is the
range with higher probability of ventricular fibrillation from an
arm-to-arm shock with 50-60 Hz AC. Shocks a little outside this range
are only a little less deadly.
Neon sign transformers (with built-in magnetically-based current
limiting means) rated at 30 mA output have a slight bit of a body count!
> Depending on how good the
>connection is, it takes a lot less than 50V to cause that much current to
>flow through your chest. The dry skin of your hand is where most of the
>voltage drop happens when you get a shock.
>
>Depending on where you are voltages under 48V or 24V or some other is
>considered by the government to be safe. At these "safe" voltages you no
>longer have to make sure that a person can't come in contact with it.
>
>Low voltage, high current situations can cause injury if a metal object
>comes in contact with it. This is why, (smart) people remove any rings or
>wrist watches before working on such things.
These latter parts are true!
- Don Klipstein (d...@misty.com)
Don Klipstein
'nuts' citters wrote in part:
>if you want to make something for your baby, you should stay below 24V
>DC. otherwise, you need to take 48V DC
>Normally, AC is more dangerous then DC.
AC worse than DC is largely true.
>It's not voltage that's dangerous, it is current. You can feel 2 or
>4mA,
My experience tells me that 2 mA is almost always felt and 1 mA is
usually felt and .5 mA is felt to a significant extent. This is with
small contact area with 60 Hz AC.
> 10mA gives a serious chock,
I have been through a couple 5-6 mA shocks that were so bad that I would
rank below drinking a mixture of 2-week-old coffee, grapefruit juice and
milk even while seeing the milk curdling!
>20mA will make you stick on the
>conductor, 50mA will knock you onconscious and 100mA will kill you.
Sometimes less than 20 mA will make you latch onto a conductor, with
50/60 Hz doing this worse than DC, and occaisionally also freeze your
breathing muscles or have slight chance of causing some fatal heart
disturbance!
>As a student, i tried to make an ohm-meter for persons, and i started
>calculating with a current of 100mA. You need way too much voltage! :D
100 mA is the lower end of the "most deadly range"! I would measure
human body resistance with some small fraction of a milliamp at most, and
keep in mind that currents that have any detectable shock effect (even if
less than 1 mA) could also stimulate sweat glands and lower human skin
resistance!
<SNIP>
- Don Klipstein (d...@misty.com)
Don Klipstein
<SNIP>
>Reminds me of the "taste great; less filling" AC vs DC debate between
>Edison and Tesla. Each promoted using the other's form of power for
>the electric chair!
That's not how I remembered it, at least in terms of electrocution
ability of steady DC vs. AC of lower audio frequencies.
The main battle there was Edison vs. Westinghouse. Edison favored DC
while Westinghouse favored low frequency AC that Tesla favored and did a
lot of development work for.
Meanwhile, less-shocking forms of AC associated with Tesla had
frequencies too high (typically ultrasonic to radio frequencies) to be
practical for long distance AC power transmission to intermittent and
variable loads, and utilization by at least all too many industrial
motors.
- Don Klipstein (d...@misty.com)
Don Klipstein
>In article <ffoia2dv56695qnnl...@4ax.com>,
>John Larkin <jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>[....]
>>
>> Aside from the magnitude difference, AC is much more
>>dangerous.
>
>No, DC is much more dangerous. I like Tesla better than Edison.
How is DC more dangerous? Railroad/subway DC shock victims survive to
tell horror stories of 3rd degree burns into deep tissue and/or muscles?
- Don Klipstein (d...@misty.com)
Roy L. Fuchs
>Just how dangerous is 60V DC ..?,, or 50V ?
>
>Should one be as respectful as with 220V AC?
Even a 24V configuration can cause damage applied in just the right
circumstance.
You should study up on "skin resistance", and then how water, or
particularly salt water can make that drop a lot. Or even body
lotions. The worse off one's skin gets for ESD (very dry), the better
off they are for shock resistance. Though one could argue them to be a
better "attractor" as a dry, insulated body.
Also, if one gets shocked by DC, and an arc was involved, it goes
right to the VERY SALTY bloodstream, and you get a much stronger jolt.
There is also usually an arc at the exit point to wherever the return
was. Those two points of entry become very low resistance locations.
In our power supply shop it was common to hear that "one only gets
to make a mistake once with HVDC". Whether true or not, it is always
best to act as if it is, and follow all those old basics you thought
were so unimportant.
No wrist straps on HV PS benches... :-]
Roy L. Fuchs
Klipstein) Gave us:
> with 60 Hz AC accomplishing either of
>these 240 times a second!
120.
Don Klipstein
>
>Ken Smith wrote:
>> In article <ffoia2dv56695qnnl...@4ax.com>,
>> John Larkin <jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>> >
>> > Aside from the magnitude difference, AC is much more dangerous.
>>
>> No, DC is much more dangerous. I like Tesla better than Edison.
>
>Edison used to be my childhood idol (no, he was not a contemporary),
>but then I discovered Edison's uglier side and Tesla's eccentric and
>unappreciated brilliance, so now he earns my respect and interest.
>
>As for dangers of AC and DC currents and voltages, it is true that it
>is the current that causes physiological problems that can be fatal.
>Current causes muscle contraction, so AC current causes characteristic
>shaking, which has the advantage of allowing you (possibly) to let go.
Actually, the whole involuntary muscle contraction business is less
bad with steady DC - a steady DC shock has little ability to force a
muscle to have a sustained contraction (more than several milliseconds),
anhd pulsating DC and power-line-frequency AC are much worse than steady
DC in terms of causing involuntary sustained muscle contraction!
>DC current causes continuous contraction,
Largely not true! Unsteadiness of current is more of a muscle
stimulant, as long as it has significant spectral analysis to frequencies
within maybe 3 octaves of the low end of the audio range!
>and because the muscles for
>gripping are more powerful than those for opening the hand, the
>tendency is for it to be impossible to release the conductor. This is
>why, if you MUST touch an energized conductor, use the back of the
>hand, so the contraction will take you away from danger.
That part I could agree with!
>The conduction of the human body varies considerably due to skin
>conditions, and I think it is nominally about 10 k Ohms from one hand
>to the other, or from hand to feet (the usual paths).
My favorite riddle:
Q: What do you call a 47K-ohm 1/4 watt resistor with tolerance of
+5,000/-98 percent?
A. A live human being!
> So 120 VAC will
>cause about 12 mA, which is well above the threshold of sensation
>(about 5 mA), but below that for near certain fatality (50-100 mA).
With body count being outright high due to false sense of safety due to
low fatality rate!
<SNIP stuff with some truth>
- Donb Klipstein (d...@misty.com)
Roy L. Fuchs
pbde...@spamnuke.ludd.luthdelete.se.invalid Gave us:
And to think the stupid bastards gave Arafat a Nobel Prize.
Roy L. Fuchs
Smith) Gave us:
>In article <ffoia2dv56695qnnl...@4ax.com>,
>John Larkin <jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>[....]
>>
>> Aside from the magnitude difference, AC is much more
>>dangerous.
>
>No, DC is much more dangerous. I like Tesla better than Edison.
>
Depending on the amount of stored energy available, DC can literally
disintegrate you. However even a single pulse from say a laser pulser
supply would light your ass up REAL GOOD. S P A N K! Somebody better
go get the wall mounted defib kit that most companies have nowadays...
Take the Bonneville DC Intertie run. Place yourself between a
conductor and earth such that you establish an arc.
No one will be able to find any of you. Relatively instantly.
Roy L. Fuchs
Smith) Gave us:
> I know that the muscles in the human arm are designed so that
>the joint where the thumb connects to the hand is brought with
>considerable force directly to the eyeball on the same side.
Hahahahahahahahaha! That is funny!
Roy L. Fuchs
Smith) Gave us:
>at least one scare
* B O O ! *
APR
<pbde...@spamnuke.ludd.luthdelete.se.invalid> wrote in message
news:44a93ded$0$487$cc7c...@news.luth.se...
> Just how dangerous is 60V DC ..?,, or 50V ?
>
> Should one be as respectful as with 220V AC?
>
from www.colorado.edu
The physiological effect of different currents is as follows:
10 to 20 mA painful sensation
20 to 40 mA muscular paralysis, cannot let go
40 to 80 mA breathing is difficult
100 to 200 mA fibrillation of the heart and death
> 200 mA heart muscles are clamped. Recovery is possible with immediate
> first aid. Be sure the power is off before touching a helpless person.
The internal resistance of your body (right hand to left hand, or hand to
leg) is typically 500 ?. In series with this is the surface resistance of
your skin which varies from 1000 ? when moist to over 100 k? when dry. Thus
a voltage as low as 50 V can produce a hazardous current if your hands are
wet.
Never work with electrical equipment if you hands or clothing are wet. Dry
yourself thoroughly before you start work. Note that when you are hot the
perspiration on your hands increases the hazard.
Roy L. Fuchs
<jjla...@highNOTlandTHIStechnologyPART.com> Gave us:
A DC pulse produces a single contraction that can be huge. Muscle
tearing even. A continuous DC shock with begin to cook one's flesh
too, (as will AC). AC is less likely to punch a hole in the victim,
however, and the skin resistance therefore helps. A DC shock that
started with an arc entered the body directly (as well as the exit),
and upon entry has a MUCH MUCH lower body resistance to deal with. It
gets direct contact with your body's internals (salty blood). If it
arcs into you, you are "toast" in many cases. I of course leave out
current limited HV supplies in this, as I have made many 20uA 15 to 40
kV supplies that one can handle the arc from, but it isn't pleasant
while that current is being limited, and the voltage capped to do so.
I wouldn't try this at home.
Again, our rule was, you only get to make one mistake...
Fear can cause a heart fibrillation too ya know. Even small shocks
that do not travel through the chest can cause a weak hearted man to
spawn a little fear based heart attack.
I can be working on a stereo chassis or whatever at home, and
accidentally brush the ac line and get sent across the room by the
spasm it induces (it's mental though). I can also, however, take two
bare 6" wires, AC fed, and put them between my fingers and thumbs, and
slowly work my way up on them till my arms are curling. Knowing that
you are passing current makes a difference.
Still, you should all leave that kind of thing to us certifiable
shock jocks (screw howard).
Roy L. Fuchs
>EDN magazine had an article in the May 11 issue on the subject. You
>can get to it online at: http://www.edn.com/contents/images/6330100.pdf
It is ALL at 60 Cycles, and even the chart where the breaks for "low
voltage" etcetera are still in place.
Trust me, you would not want one of out 250Volt DC converter
supplies hitting you, even at a mere 3W output (2" x 3" brick)
We certainly call 1kV "high voltage", and yes, we make 'em all the
way up to 400kV. I never did like that power company centric naming
convention chart.
Roy L. Fuchs
us:
Have you not seen the video of that?
There are about six videos of transformers exploding, big
interrupters opening while live, etc. out there somewhere... I have
them here somewhere as well... one is that guy getting a taste of
hades early.
Roy L. Fuchs
Klipstein) Gave us:
> Keep in mind the Edison vs. Westinghouse stuff, especially where it
>relates to the "Electric Chair"!
I can hear the guards now...
"Yeah... and if he survives... (snicker)... we'll let him live!...
bwuahahahah! (they all laugh heartily)"
It has to be more painful than if they had succeeded. Far more.
nospam
>The conduction of the human body varies considerably due to skin
>conditions, and I think it is nominally about 10 k Ohms from one hand
>to the other, or from hand to feet (the usual paths).
It's pretty hot here at the moment, my hands feel slightly clammy. Taking a
firm grip of my fluke probes between thumbs and forefingers the grip has to
be so firm as to be painful before I see a reading below 300k ohms.
I thought 10k sounded way low, however, I don't know what if any breakdown
voltage is associated with that resistance.
Overcoming my instincts not to be a human resistor I tested up to 24Vdc,
0.15mA, 160k. That was gripping a couple of croc clips - maybe I was
sweating a bit more by then - lol.
--
Robert Baer
> Just how dangerous is 60V DC ..?,, or 50V ?
>
> Should one be as respectful as with 220V AC?
>
Even 6V is dangerous; numerous individuals were killed or maimed
working on their cars in the 40's to 70's when most cars had a 6V system.
All one needs is to get a ring or other metal object like a wrench
across the battery terminals.
Orange-hot metal plays no favorites, and if one had recently charged
the battery, either fire or an explosion could take place.
Then there are a few rare individuals that have extremely low skin
resistance - low enough so that sufficent current can go thru the heart
to cause serious problems.
At 60V, these problems (except maybe hydrogen-related problems) can
be magnified.
feebo
>Just how dangerous is 60V DC ..?,, or 50V ?
>
>
it all depends on the individual I guess, but I was a telephone
engineer for years (-50V DC on the line) and you didn't feel a thing
across (even wet) fingers.
Ring signal was a different affair - 90-105V AC - that stung a bit. I
remember getting that across chest & left arm while reaching through
"open spans" to get to a junction box mounted above the ring-head on a
stick. Interesting but not deadly.
Never heard of a tel-eng being "zapped" by line voltage but plenty
will attest to the ringing voltage.
Telephone switchboards (PABX) by and large use much lower voltages
until you get to some older big ones (kinsman, regent etc.)
feebo
wrote:
>
>pbdel...@spamnuke.ludd.luthdelete.se.invalid ???
>
>> Tim Wescott <t...@seemywebsite.com> wrote:
>> >pbde...@spamnuke.ludd.luthdelete.se.invalid wrote:
>>
>> >> Just how dangerous is 60V DC ..?,, or 50V ?
>> >>
>> >> Should one be as respectful as with 220V AC?
>> >>
>> >Bad enough that CE wants you to keep it from your product's consumers.
>> >I would assume that it can be fatal on a Very Bad Day.
>>
>> Where's the CE "keep out" limit?
>>
>> (48V dc is used in PoE apps..)
>>
>> >I would answer your second question but the ghost of my Lawyer is
>> >whispering in my ear so I won't. I _will_ say that _I_ would treat
>> >220VAC with a great deal more respect than I would treat 60VDC, because
>> >220VAC can kill you faster.
>>
>> >Surely this information is out there on Google if you can think of the
>> >right search terms?
>>
>> Problem with google is that it will more or less act like a "yes-sayer"..
>
>I my opinion, 36V DC is dangerous enough......So keep away from it.
poof :o)
Roy L. Fuchs
<rober...@earthlink.net> Gave us:
> Even 6V is dangerous; numerous individuals were killed or maimed
>working on their cars in the 40's to 70's when most cars had a 6V system.
By the ignition coil. 20 to 40 kV (one never knew), and one mean
amperage capacity those coils had.
Jeff L
"Eeyore" <rabbitsfriend...@REMOVETHIS.hotmail.com> wrote in
message news:44A95FE4...@REMOVETHIS.hotmail.com...
>
>
> pbde...@spamnuke.ludd.luthdelete.se.invalid wrote:
>
> > Tim Wescott <t...@seemywebsite.com> wrote:
> > >pbde...@spamnuke.ludd.luthdelete.se.invalid wrote:
> >
> > >> Just how dangerous is 60V DC ..?,, or 50V ?
> > >>
> > >> Should one be as respectful as with 220V AC?
> > >>
> > >Bad enough that CE wants you to keep it from your product's consumers.
> > >I would assume that it can be fatal on a Very Bad Day.
> >
> > Where's the CE "keep out" limit?
>
but who
> cares ?
See my other post - 50V and above is considered potentially fatal by the
NEC. 48V DC has been used for years by telecom companies likely to avoid
dealing with much increased code and safety requirements.
>
> Graham
>
lang...@ieee.org
John Larkin skrev:
> On 3 Jul 2006 11:55:53 -0700, "Luhan" <luh...@yahoo.com> wrote:
>
> >
> >John Larkin wrote:
> >> On 03 Jul 2006 15:55:25 GMT,
> >> pbde...@spamnuke.ludd.luthdelete.se.invalid wrote:
> >>
> >> >Just how dangerous is 60V DC
> >>
> >> Not very.
> >>
> >> ..?,, or 50V ?
> >>
> >> 48 DC is usually considered safe, so 50 can't be a lot worse.
> >>
> >> >Should one be as respectful as with 220V AC?
> >>
> >> Not really. Aside from the magnitude difference, AC is much more
> >> dangerous.
> >>
> >
> >Reminds me of the "taste great; less filling" AC vs DC debate between
> >Edison and Tesla. Each promoted using the other's form of power for
> >the electric chair!
> >
> >Luhan
>
> Edison used to electrocute cats in his garden to demonstrate to
> visitors how dangerous AC was.
He also did an elephant:
http://www.23nlpeople.com/media/~elephant_dead.mpg
scary guy,
-Lasse
>
> There's a graph, somewhere, of how lethal AC is as a function of
> frequency. I believe it peaks at about 30 Hz.
>
> John
pbde...@spamnuke.ludd.luthdelete.se.invalid
>On 03 Jul 2006 15:55:25 GMT,
>pbde...@spamnuke.ludd.luthdelete.se.invalid Gave us:
>>Just how dangerous is 60V DC ..?,, or 50V ?
>>
>>Should one be as respectful as with 220V AC?
> Even a 24V configuration can cause damage applied in just the right
>circumstance.
That's the rule I follow. But if there's 60V DC one got to handle it somehow.
> You should study up on "skin resistance", and then how water, or
>particularly salt water can make that drop a lot. Or even body
>lotions. The worse off one's skin gets for ESD (very dry), the better
>off they are for shock resistance. Though one could argue them to be a
>better "attractor" as a dry, insulated body.
In my book water => no electricity work.
> Also, if one gets shocked by DC, and an arc was involved, it goes
>right to the VERY SALTY bloodstream, and you get a much stronger jolt.
>There is also usually an arc at the exit point to wherever the return
>was. Those two points of entry become very low resistance locations.
Any risk of coagulation ?
> In our power supply shop it was common to hear that "one only gets
>to make a mistake once with HVDC". Whether true or not, it is always
>best to act as if it is, and follow all those old basics you thought
>were so unimportant.
The general rule is to avoid any electricity paths at all times. Only
exceptions made are for <12V circuit in dry conditions.
> No wrist straps on HV PS benches... :-]
I never wear anything metallic when doing electronics. Just plain asking for
a darwin award.. :)
pbde...@spamnuke.ludd.luthdelete.se.invalid
> Most sources say the "deadly range" is 100 mA to 1 amp - but this is the
>range with higher probability of ventricular fibrillation from an
>arm-to-arm shock with 50-60 Hz AC. Shocks a little outside this range
>are only a little less deadly.
> Neon sign transformers (with built-in magnetically-based current
>limiting means) rated at 30 mA output have a slight bit of a body count!
Maybe it's just too slow ..?
I read that many ground protection circuits (useing kirchhoffs law) will
protect equipment but not humans due too slow reaction time.
Ken Smith
Non-railroad/subway AC shock victims also survive to tell horror stories.
In both cases, the ones that don't survive don't get to tell any stories.
--
--
kens...@rahul.net forging knowledge
Roy L. Fuchs
pbde...@spamnuke.ludd.luthdelete.se.invalid Gave us:
>I never wear anything metallic when doing electronics. Just plain asking for
>a darwin award.. :)
If you do not know anything about ESD risks, you should not be
working on circuitry.
An HV Supply on a bench is a different story, but for basic analog
and digital circuits, there are plenty of fragile, ESD susceptible
components on any given assembly. Whether you believe it or not, you
can do more damage to an assembly than whatever was wrong with it when
you decided to put it on your bench if your workstation is not an ESD
safe workstation.
pbde...@spamnuke.ludd.luthdelete.se.invalid
>pbde...@spamnuke.ludd.luthdelete.se.invalid Gave us:
>>I never wear anything metallic when doing electronics. Just plain asking for
>>a darwin award.. :)
> If you do not know anything about ESD risks, you should not be
>working on circuitry.
I know about ESD risks. And this was mainly about a UPS battery pack capable
of delivering 60V 30A. I hope batteries are ESD resistent ;)
The UPS itself may ofcourse be a lot more sensitive.
John Larkin
Disagree. Neither our engineering lab nor the mini-lab in my office
are ESD stations (my furniture is Ikea) and we don't have problems. If
you know that you have an especially tender part, like a gaasfet or
some fragile opamp, just handle it properly.
John
Roy L. Fuchs
pbde...@spamnuke.ludd.luthdelete.se.invalid Gave us:
>Roy L. Fuchs <royl...@urfargingicehole.org> wrote:
>>On 04 Jul 2006 11:51:47 GMT,
>>pbde...@spamnuke.ludd.luthdelete.se.invalid Gave us:
>
>>>I never wear anything metallic when doing electronics. Just plain asking for
>>>a darwin award.. :)
>
>> If you do not know anything about ESD risks, you should not be
>>working on circuitry.
>
>I know about ESD risks.
Not from what you wrote, which you conveniently snipped.
> And this was mainly about a UPS battery pack capable
>of delivering 60V 30A. I hope batteries are ESD resistent ;)
I wrote what I wrote based on the CRAP you wrote that you snipped,
do try to pull that stupid shit with me.
>The UPS itself may ofcourse be a lot more sensitive.
I'd be willing to bet that even the most basic UPS design has
several op amps that are quite sensitive.
The point was that one DOES need to use grounding and ESD smocks and
an ESD workstation when on is working on modern electronic equipment.
You were declaring that it was "Darwin Award" territory, which is
retarded, and shows a lack of actual experience. If that isn't the
case, then the remark was what? A stab in the dark?
Roy L. Fuchs
<jjla...@highNOTlandTHIStechnologyPART.com> Gave us:
> just handle it properly.
Which is what you obviously do not know the correct method for or
you would not have said that. Next thing you'll be telling us is that
you have a carpeted floor.
Ever heard of "Static Dissipative Packaging"? It is the ONLY safe
way to transport an item with ANY ESD susceptibilities from point "A"
to point "B" (as in across a room say).
ian field
"nospam" <nos...@please.invalid> wrote in message
news:eldja2dee11pt1dba...@4ax.com...
My reading was about 160k by wetting my thumbs and pressing real hard on the
probes, but I think body resistance probably drops as soon as any real
current flows!
John Larkin
<royl...@urfargingicehole.org> wrote:
>On Tue, 04 Jul 2006 12:14:19 -0700, John Larkin
><jjla...@highNOTlandTHIStechnologyPART.com> Gave us:
>
>> just handle it properly.
>
> Which is what you obviously do not know the correct method for or
>you would not have said that. Next thing you'll be telling us is that
>you have a carpeted floor.
In my office, yes. The big lab is linoleum.
> Ever heard of "Static Dissipative Packaging"? It is the ONLY safe
>way to transport an item with ANY ESD susceptibilities from point "A"
>to point "B" (as in across a room say).
Sorry, disagree. It's easy to learn safe habits without any explicit
esd gear or packaging. Most parts are pretty esd-hard these days, and
a part can only be damaged if it becomes the discharge path between
charged objects, like my body and some other big thing. So simply
touch ground once your're seated, before you pick up or put down a
part. If you hand someone else a part or an assembly, touch them
first. Zero potential makes zero damage. My clenched fist is a mighty
fine Faraday cage, better than any silly pink bag.
I think the worst things we have around here are a couple of
fabric-covered workbench-type chairs... if you slide your butt off,
they can leave you with a hefty charge. These are banned to the
kitchen.
Our manufacturing people do follow standard esd rules, straps and all
that, because customers expect it and it does potentially affect
product quality. But I don't, and I'm not seeing parts fail for
unexplained reasons.
ESD supplies, equipment, and training are a big industry, sort of like
surge supressors and Monster cables.
John
Don Klipstein
Watch out for:
1. Skin contact area is not always that small.
2. An electric shock sometimes stimulates sweat glands. I once aplied AC
to two points on the same hand, and with steady pressure and steady
contact area the current increased with time. Current, especially DC, can
cause electrolysis effects that make skin conductivity increase during a
shock.
3. Skin resistance has a negative temperature coefficient - which could
be a big problem when getting a shock that increases skin temperature. It
gets worse when the voltage is high enough to force enough current through
a small area to carbonize it.
- Don Klipstein (d...@misty.com)
Roy L. Fuchs
<jjla...@highNOTlandTHIStechnologyPART.com> Gave us:
>, better than any silly pink bag.
Yet another fallacy.
Pink bags do not qualify in any way shape or form.
Roy L. Fuchs
<jjla...@highNOTlandTHIStechnologyPART.com> Gave us:
>
>ESD supplies, equipment, and training are a big industry, sort of like
>surge supressors and Monster cables.
You've obviously never seen the photo-micrographs of ESD damage at
the input(s) to various chips.
All it takes is the failure of ONE PN junction.
It isn't about big business, it IS about a real issue.
You can generate enough charge to destroy components quite easily by
merely lifting your arms above your head if you are isolated from a
drain/balance point (ground).
You declaring that it is just a racket, which is essentially what
you did, proves that you are not well informed about the issues.
Mike Monett
>
> Watch out for:
>
> 1. Skin contact area is not always that small.
>
> 2. An electric shock sometimes stimulates sweat glands. I once
> aplied AC to two points on the same hand, and with steady pressure and
> steady contact area the current increased with time. Current,
> especially DC, can cause electrolysis effects that make skin
> conductivity increase during a shock.
>
> 3. Skin resistance has a negative temperature coefficient - which
> could be a big problem when getting a shock that increases skin
> temperature. It gets worse when the voltage is high enough to force
> enough current through a small area to carbonize it.
> - Don Klipstein (d...@misty.com)
One problem is the involuntary muscle contraction can increase the contact
pressure and the current. Positive feedback.
There are stories of farmers who were electrocuted while working on their
12V tractor battery in the rain, and touching the terminals with their gold
wedding band. I don't know how true that is, but I'd tend to believe trying
to tighten a terminal lug with a wrench and pressing against a part of the
frame to get more leverage. That might work, especially if they cut
themself on the hand.
Lessee - the body resistance with the skin broken is about 300 to 500 ohms.
So with 12V, we could get 12 / 500 = 24 mA. That is beyond the can't let go
value, so maybe they stayed clamped and had a heart attack. Maybe...
Regards,
Mike Monett
Terry Given
> In article <1151951424....@p79g2000cwp.googlegroups.com>, lieven
> 'nuts' citters wrote in part:
>
>
>>if you want to make something for your baby, you should stay below 24V
>>DC. otherwise, you need to take 48V DC
>>Normally, AC is more dangerous then DC.
>
>
> AC worse than DC is largely true.
>
>
>>It's not voltage that's dangerous, it is current. You can feel 2 or
>>4mA,
>
>
> My experience tells me that 2 mA is almost always felt and 1 mA is
> usually felt and .5 mA is felt to a significant extent. This is with
> small contact area with 60 Hz AC.
>
>
>>10mA gives a serious chock,
>
>
> I have been through a couple 5-6 mA shocks that were so bad that I would
> rank below drinking a mixture of 2-week-old coffee, grapefruit juice and
> milk even while seeing the milk curdling!
>
>
>>20mA will make you stick on the
>>conductor, 50mA will knock you onconscious and 100mA will kill you.
>
>
> Sometimes less than 20 mA will make you latch onto a conductor, with
> 50/60 Hz doing this worse than DC, and occaisionally also freeze your
> breathing muscles or have slight chance of causing some fatal heart
> disturbance!
>
>
>>As a student, i tried to make an ohm-meter for persons, and i started
>>calculating with a current of 100mA. You need way too much voltage! :D
>
>
> 100 mA is the lower end of the "most deadly range"! I would measure
> human body resistance with some small fraction of a milliamp at most, and
> keep in mind that currents that have any detectable shock effect (even if
> less than 1 mA) could also stimulate sweat glands and lower human skin
> resistance!
>
> <SNIP>
>
> - Don Klipstein (d...@misty.com)
I was talking to a doctor friend of mine a few nights ago, and he told
me that the mechanical frequency response of human muscle tissue is not
too dis-similar from 50/60Hz, exacerbating the "gripping" problem.
Cheers
Terry
pbde...@spamnuke.ludd.luthdelete.se.invalid
>>of delivering 60V 30A. I hope batteries are ESD resistent ;)
> I wrote what I wrote based on the CRAP you wrote that you snipped,
>do try to pull that stupid shit with me.
I was concerned about the danger from accidently touching live 60V DC
circuit (mainly batteries). ESD is another matter that I didn't include in
original post. Components can be replaced, people can't.
> You were declaring that it was "Darwin Award" territory, which is
>retarded, and shows a lack of actual experience. If that isn't the
>case, then the remark was what? A stab in the dark?
There are actions that have such obvious and unnecessary high risks one just
don't do them.
John Larkin
>Just how dangerous is 60V DC ..?,, or 50V ?
>
>Should one be as respectful as with 220V AC?
Enough conjecture.
I have a nice little HP power supply. So I connected two banana leads,
ended in bare alligator clips, grabbed one firmly in each hand,
slightly sweaty, and cranked it up. No sensation to 65 volts,
increasing tingling above there, gets uncomfortable at about 85-90.
John
Mike Monett
> Enough conjecture.
> I have a nice little HP power supply. So I connected two banana leads,
> ended in bare alligator clips, grabbed one firmly in each hand,
> slightly sweaty, and cranked it up. No sensation to 65 volts,
> increasing tingling above there, gets uncomfortable at about 85-90.
> John
How many milliamperes did the little power supply show?
Now try touching your tongue. How much voltage does it take?
And how many millamperes?
Regards,
Mike Monett
John Larkin
Don't be a jerk. Nobody likes a jerk.
John
Mike Monett
> Don't be a jerk. Nobody likes a jerk.
> John
No one takes you for an idiot, John. Not intended that way at all.
Obviously you would start with a very low voltage and work your way up
until you start to feel the current. Did I have to point that out, and risk
having you complain because I implied you were sub-par?
According to the recent postings, the current should be hard to detect
below 1 mA. This should correlate with the value you detected through your
fingers.
If the thought of sticking rosin-encrusted alligator clips in your mouth is
unpalatable, you can use them to clip to coffee spoons instead.
Since the same person is taking the data in both cases, subjective bias
should be reduced. This is a competely scientific and totally harmless
experiment that should add more insight to the problem and is as worth
doing as the first part was.
Regards,
Mike Monett
John Larkin
>John Larkin <jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>
>> Don't be a jerk. Nobody likes a jerk.
>
>> John
>
>No one takes you for an idiot, John. Not intended that way at all.
>
>Obviously you would start with a very low voltage and work your way up
>until you start to feel the current. Did I have to point that out, and risk
>having you complain because I implied you were sub-par?
>
>According to the recent postings, the current should be hard to detect
>below 1 mA. This should correlate with the value you detected through your
>fingers.
>
>If the thought of sticking rosin-encrusted alligator clips in your mouth is
>unpalatable, you can use them to clip to coffee spoons instead.
Oh, did I mention that nobody likes a jerk?
>
>Since the same person is taking the data in both cases, subjective bias
>should be reduced. This is a competely scientific and totally harmless
>experiment that should add more insight to the problem and is as worth
>doing as the first part was.
>
One can test a 9-volt battery by applying it to the tongue, and it's
about as unpleasant as one would voluntarily undertake. So there's
another data point.
So much talk, so little experiment.
John
Spehro Pefhany
<jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>
>One can test a 9-volt battery by applying it to the tongue, and it's
>about as unpleasant as one would voluntarily undertake. So there's
>another data point.
>
>So much talk, so little experiment.
>
>John
>
When our kid was a toddler he was sitting on the floor by my office
chair one time and he started crying suddenly. I looked down and there
was no obvious reason. A minute or so later, the same thing. Turned
out he was putting an (energized) 2mm adapter plug into his mouth. It
was for an EPROM eraser and rated at 24VDC @ 100mA (a little over 30V
unloaded). I tried it at the time just to see how bad it was...
definitely *very* unpleasant. In contrast, licking a 9V battery is a
time tested technique for checking the condition, and just a bit
unpleasant.
So, there's another data point. Of course the distance on the tongue
is short and there's no danger of electrocution (just fried tongue),
but probably higher current than you'd get most other ways.
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
sp...@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
John Larkin
<spef...@interlogDOTyou.knowwhat> wrote:
>On Wed, 05 Jul 2006 14:50:30 -0700, the renowned John Larkin
><jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>
>>
>>One can test a 9-volt battery by applying it to the tongue, and it's
>>about as unpleasant as one would voluntarily undertake. So there's
>>another data point.
>>
>>So much talk, so little experiment.
>>
>>John
>>
>
>When our kid was a toddler he was sitting on the floor by my office
>chair one time and he started crying suddenly. I looked down and there
>was no obvious reason. A minute or so later, the same thing. Turned
>out he was putting an (energized) 2mm adapter plug into his mouth. It
>was for an EPROM eraser and rated at 24VDC @ 100mA (a little over 30V
>unloaded). I tried it at the time just to see how bad it was...
>definitely *very* unpleasant. In contrast, licking a 9V battery is a
>time tested technique for checking the condition, and just a bit
>unpleasant.
>
>So, there's another data point. Of course the distance on the tongue
>is short and there's no danger of electrocution (just fried tongue),
>but probably higher current than you'd get most other ways.
>
>
A while back I felt a burning sensation on my leg. At first I ignored
it, but it kept getting worse. It was a 9-volt alkaline battery,
shorted by coins. Thermal, of course, not electrical.
One of the cats, Ajax [1], keeps chewing through the DC power cord to
Mo's Sony Vaio laptop computer. She musn't get zapped much, because
she keeps at it.
John
[1] her sister is Comet.
Mike Monett
> One can test a 9-volt battery by applying it to the tongue, and it's
> about as unpleasant as one would voluntarily undertake. So there's
> another data point.
Not much use without knowing the current. The point was to find the minimum
detectable current level.
I make a small silver ion generator for friends. It runs off 160VDC from
the line for simplicity. There are two 220k resistors to the outside leads
to limit the current. One NE-2 bulb indicates when power is applied, and
another shows when the leads don't make proper connection to the silver
electrodes.
The short-circuit current is around 360uA. Nobody can feel it, but the
second NE-2 bulb goes out when you touch the leads with your fingers.
> So much talk, so little experiment.
A badly designed experiment is of little value. We need numbers, John. 9V
across the tongue is useless, except to tell if the battery is completely
dead.
> John
Regards,
Mike Monett
Mike Monett
> One can test a 9-volt battery by applying it to the tongue, and it's
> about as unpleasant as one would voluntarily undertake. So there's
> another data point.
> So much talk, so little experiment.
> John
A 1.5V watch battery barely tastes a bit salty.
340 microamps from another silver generator current source has a bit of a
tingly taste. Not too uncomfortable. You could do that all day without
problem.
So based on my now-calibrated tongue, a 1.5V watch battery gives perhaps
less than half the sensation of 340uA. So the resistance of a wet tongue is
approximately
R = 1.5 / (340e-6 / 2) = 8,823 ohms
and unlike skin, is independent of pressure.
This compares with data indicating megohms or more for dry skin, and
perhaps 100k for damp skin.
It is interesting to note the tongue is quite a bit more sensitive than
current applied to the fingers.
Regards,
Mike Monett
John Larkin
>John Larkin <jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>
>> One can test a 9-volt battery by applying it to the tongue, and it's
>> about as unpleasant as one would voluntarily undertake. So there's
>> another data point.
>
>Not much use without knowing the current. The point was to find the minimum
>detectable current level.
It was not. I was responding to the original post, and that was about
voltage.
John
John Larkin
>John Larkin <jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>
>> One can test a 9-volt battery by applying it to the tongue, and it's
>> about as unpleasant as one would voluntarily undertake. So there's
>> another data point.
>
>> So much talk, so little experiment.
>
>> John
>
>OK, I have bravely taken the challenge, and stuck my tongue out.
>
>A 1.5V watch battery barely tastes a bit salty.
>
1.5 volts is brave?
John
Rich Grise
Once, when I was a strapping young teenager, there was an arcade at a
local abusement[sic] park, and one of the attractions was a little
console, with two chrome knobs like doorknobs that you could grasp while
standing there. You'd put in your coin, and it would start an electric
current from one knob to the other, i.e., through both arms and the
customer's chest. There was also a meter, which increased as you cranked
the right-hand knob up, (like a "volume control") and the current _did_
increase - I remember my forearms cramping up, but wanting to beat the
record and all that (being an idiot teenager), but it got to a point where
it hurt too much.
Evidently it didn't kill me. ;-P
Cheers!
Rich
Rich Grise
> On Tue, 04 Jul 2006 19:02:43 GMT, Roy L. Fuchs
>>
>>components on any given assembly. Whether you believe it or not, you
>>can do more damage to an assembly than whatever was wrong with it when
>>you decided to put it on your bench if your workstation is not an ESD
>>safe workstation.
>
> Disagree. Neither our engineering lab nor the mini-lab in my office
> are ESD stations (my furniture is Ikea) and we don't have problems. If
> you know that you have an especially tender part, like a gaasfet or
> some fragile opamp, just handle it properly.
Yabbut. you're in San Francisco, second-humid city in the country right
after Seattle, IIUC. ;-)
Thanks,
Rich
Roy L. Fuchs
100% NON-scientific.
Roy L. Fuchs
<jjla...@highNOTlandTHIStechnologyPART.com> Gave us:
>On Wed, 05 Jul 2006 16:24:53 -0400, Mike Monett <N...@email.adr> wrote:
I suppose that means that it is too late for you.
Show of hands... How many engineers feel that ESD concerns are not a
risk to electronic circuitry?
Roy L. Fuchs
<jjla...@highNOTlandTHIStechnologyPART.com> Gave us:
>One can test a 9-volt battery by applying it to the tongue, and it's
>about as unpleasant as one would voluntarily undertake. So there's
>another data point.
>
>So much talk, so little experiment.
Examine the lead spacing on a nine volt battery.
Examine the lead spacing between a spoon in your mouth, and a clip
in one hand. No comparison.
Did somebody shit in your corn flakes today?
Roy L. Fuchs
Gave us:
>Evidently it didn't kill me. ;-P
Took your brain out though.
John Larkin
It's a lot more scientific than anything the rest of the wusses tried,
ie, nothing. I learned more in 2 minutes of experimenting then anybody
else did in hours of typing.
So be brave, or creative, or anything non-wussey and actually measure
something. Get us some comparable AC numbers, for example.
Or shut up.
John
Mike Monett
>>OK, I have bravely taken the challenge, and stuck my tongue out.
>>
>>A 1.5V watch battery barely tastes a bit salty.
> 1.5 volts is brave?
> John
Don't mind me, John. Since being exposed to high concentrations of mold
spores in Ottawa 5 years ago, I have been in a vegetative state, very ill
from the mold toxins that are around us constantly.
I am gradually learning how to process my clothing where the spores
germinate, and I am finally starting to get some control over the illness.
I am starting to get my mind back, and the paper I posted on SPICE analysis
of crystal oscillators was very encouraging to me. It told me I am
recovering and am still able to find creative solutions to problems.
But I need to increase my memory and vocabulary. You tend to lose things
after not using them for years. So I try to pick simple topics to respond
to, and hope I don't get into too much trouble. Sorry if I disturbed you.
The full recovery should occur when I am able to get a machine working that
will kill the spores. From the numerous symptoms I have experienced, it
seems possible the toxins and metabolism products of spores can be very
damaging. This may contribute to arthritus, MS, sore muscles and joints,
digestion problems, emotional problems, loss of memory and ability to
focus, and many other vague symptoms that seem to accompany old age and
currently have no cure.
My most important project right now is to learn how to destroy spores that
grow in bedding. These are activated by body heat and moisture, and you
breath a high concentration of spores for many hours each night. Over many
years, I believe these toxins degrade your immune system and ability to
heal. Then the damage process accelerates.
Nothing we have in the normal household will kill spores. I have tried
chemicals, acids, bases, enzymes, and various industrial products that are
normally used to kill spores, such as proprionic acid (used to keep mold
from growing in bread). I tried folding blankets and putting them in boxes
to heat in the microwave. This gets you up to the temperature of steam, but
the spores require 20 to 40 degrees C higher to have much effect. So all I
managed to do was to start some microwave fires in the kitchen, which are a
serious problem since the fabrics ten to burst into flame as soon as you
unwrap them and expose them to oxygen.
Part of the problem killing mold is you tend to kill off the weak portion
of the population, and the strong stuff comes back with a vengance. So I
would get sicker and sicker.
But after learning a whole new way of living to minimize spore growth in
the environment, and many small details to constantly check, I am able to
accomplish a bit more. I am trying to make an ozone machine that will
penetrate the fabric and destroy the outer wall of the spores.
However, I am going a bit slower than usual. I had to sell my lab in Ottawa
to pay the rent, and a job I was hoping to get didn't pan out. So here I am
now trying to make a 200 watt PWM switcher to generate the high voltage,
and the only instrument I have is a Wallmart 3 1/2 digit dvm. But I was
able to study the problems in SPICE, and come up with a slightly new method
of driving fets at the large offset votages needed. So hopefully, I should
have some results soon.
If the machine works, and my theories prove to be even partially correct,
it could potentially affect the health of most of the people on the planet.
Regards,
Mike Monett
Roy L. Fuchs
<jjla...@highNOTlandTHIStechnologyPART.com> Gave us:
>On Thu, 06 Jul 2006 03:16:32 GMT, Roy L. Fuchs
><royl...@urfargingicehole.org> wrote:
>
>>On Wed, 05 Jul 2006 11:14:42 -0700, John Larkin
>><jjla...@highNOTlandTHIStechnologyPART.com> Gave us:
>>
>>>On 03 Jul 2006 15:55:25 GMT,
>>>pbde...@spamnuke.ludd.luthdelete.se.invalid wrote:
>>>
>>>>Just how dangerous is 60V DC ..?,, or 50V ?
>>>>
>>>>Should one be as respectful as with 220V AC?
>>>
>>>Enough conjecture.
>>>
>>>I have a nice little HP power supply. So I connected two banana leads,
>>>ended in bare alligator clips, grabbed one firmly in each hand,
>>>slightly sweaty, and cranked it up. No sensation to 65 volts,
>>>increasing tingling above there, gets uncomfortable at about 85-90.
>>>
>>>John
>>
>> 100% NON-scientific.
>
>
>It's a lot more scientific than anything the rest of the wusses tried,
>ie, nothing. I learned more in 2 minutes of experimenting then anybody
>else did in hours of typing.
Yet you recorded nor attempted to record the surface area of
contact, which is 100% proportionate to skin resistance. Dry hands,
wet hands, lotion bathed hands??? All make a difference, and pinching
the lead between the thumb and forefinger is definitive of very
little.
>
>So be brave, or creative, or anything non-wussey and actually measure
>something. Get us some comparable AC numbers, for example.
>
>Or shut up.
Grow up.
You obviously didn't read the thread. I mentioned a 40kV event in
one response.
Roy L. Fuchs
us:
>The full recovery should occur when I am able to get a machine working that
>will kill the spores. From the numerous symptoms I have experienced, it
>seems possible the toxins and metabolism products of spores can be very
>damaging. This may contribute to arthritus, MS, sore muscles and joints,
>digestion problems, emotional problems, loss of memory and ability to
>focus, and many other vague symptoms that seem to accompany old age and
>currently have no cure.
Why no mention of respiratory illness? That is one of the most
health threatening.
APR
"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in message
news:fj1pa2pjr16edj5hc...@4ax.com...
>>>
>>>I have a nice little HP power supply. So I connected two banana leads,
>>>ended in bare alligator clips, grabbed one firmly in each hand,
>>>slightly sweaty, and cranked it up. No sensation to 65 volts,
>>>increasing tingling above there, gets uncomfortable at about 85-90.
>>>
>>>John
>>
>> 100% NON-scientific.
>
>
> It's a lot more scientific than anything the rest of the wusses tried,
> ie, nothing. I learned more in 2 minutes of experimenting then anybody
> else did in hours of typing.
>
> So be brave, or creative, or anything non-wussey and actually measure
> something. Get us some comparable AC numbers, for example.
>
> Or shut up.
>
> John
>
I would not be inclined to do any form of "testing" to determine the
physiological responses of my body to AC voltages as death is always a
possability. If you wish to experiment have a person trained in CPR with you
and a phone near by to call for medical assistance.
I have had some involvement in Voltage Reduction Devices (VRD's) as used on
electric welders (not from a design point, only to evaluate from the point
of an end user). These devices are designed to reduce the open circuit
voltage of either an AC or DC welder to a level considered safe when not
actually welding. There is a significant amount of literature around that
details fatalities as a result of current flow through the body when using
welders, what the recommended precautions are, and the results of coronial
enquiries and control authority investigations into the electrocution of
persons using welders.
Many (especially older) welders have open circuit voltage approaching, and
in some instances exceeding, 100 volts AC, and welder operators are renowned
for getting a "bite" when changing rods. More common open circuit voltage
from welding machines is 50 to 80 volts. (eg, Lincoln Idealarc DC 400, a
very common welder in fabrication shops, max open circuit voltage of 67
volts DC).
Typically, electrocution when welding has occurred as a result of current
flowing through the chest cavity when the operator is in a situation where
the environment is less then ideal (eg, inside a vessel where the vessel is
earthed to the welder return lead, the operator is sweating due to poor air
circulation and wearing protective clothing that promotes sweating). The
operator may hold the hand piece between forearm and chest to remove a glove
to allow him to pick up a rod. While doing this he may lean back against
earthed steel behind him. Current may then flow from the front of the chest
through to the material he is leaning against causing ventricular
fibrillation and possible death if assistance is not immediate.
What has been identified is that the effects of ventricular fibrillation are
not always immediate to the person, and irregularity of the heart beat can
be occurring for up to days with the person not being aware.
It is to be noted that there are no known instances of death in Australia by
electrocution from a DC welder but a significant number from AC welders. The
likelyhood of ventricular fibrillation from DC is relatively remote
evidently.
fpga...@yahoo.com
Paul wrote:
> I have also heard horror stories of people who were in a boating
> accident with an electric motor, where the cables fell into the water
> where they were trying to stay afloat, or possibly holding onto the
> aluminum boat. Rather uncomfortable!
Now consider EV's and accidents where wet.
Mike Monett
Yes, asthma is very serious, as well as allergies and a host of other
problems that might be aggravated by mold toxins and byproducts of
metabolism. There will be a tremendous amount of work to do finding
candidates, determining protocols, documenting the slightest details,
and so on.
Perhaps the strongest indication may be from individuals themselves. If
they tend to leave the program easily, it may not be helping much. However,
if they give a strong response they want to continue, maybe there is
something helping them.
A great deal will rest on the design of experiments and procedures to help
determine if there are any reactions, and how to measure these things. I
certainly don't know much about this where people are involved, and will
have a lot to learn. But where to start?
Regards,
Mike Monett
Mike Warren
> One of the cats, Ajax [1], keeps chewing through the DC power cord to
> Mo's Sony Vaio laptop computer. She musn't get zapped much, because
> she keeps at it.
A friend of mine had a pet rabbit that used to regularly bite through
live 240V Mains cables to lamps etc. and managed to survive.
-Mike
John Larkin
<royl...@urfargingicehole.org> wrote:
Oh, I knew the approximate AC voltages already. I was just checking
your wimp-factor, and it looks like I knew that pretty well, too.
John
John Larkin
What a group of "electronics designers"! Don't know how much voltage
it would take to tickle, and afraid to find out.
Mighty fine bunch of typists, though.
John
APR
"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in message
Why don't you take your own bait and see how much AC you can take from arm
to arm, John. What say you start at 85 volt AC and work up. Also ensure
maximum contact surface area for the electrodes and also use a conductive
paste. After all you are not assessing body resistance, etc, but determining
the maximum current flow that your torso is capable of flowing without
suffering ventricular fibrillation. If you don't report back we can all hold
a wake for you.
ian field
"Spehro Pefhany" <spef...@interlogDOTyou.knowwhat> wrote in message
news:g6eoa21q5hm8ldsa9...@4ax.com...
When I was a kid the tongue test for PP3 batteries was very common, but I
abandoned this method after discovering that a loaded test with a multimeter
proved that the strength of the "tongue-tingle" was a very unreliable test
of a battery's state of charge.
John Larkin
What the heck is wrong with you people? This thread is about how much
*voltage* might be dangerous to work with. A simple way to get an idea
would be to set up a reasonable engineering-workbench type of
situation, start at zero voltage, and work up to get some points on
the graph. I did it for DC, per the OP's question, and reported the
numbers. Everybody else theorizes and postures and bluffs, except one
brave soul who screwed up his courage and licked a 1.5 volt battery,
then wrote a 1000-word essay on why he dared not go further.
Keep on typing, folks; it suits you.
John
redbelly
John Larkin wrote:
> One can test a 9-volt battery by applying it to the tongue, and it's
> about as unpleasant as one would voluntarily undertake. So there's
> another data point.
>
> So much talk, so little experiment.
>
> John
Been following this thread, and decided to do this experiment. I
connected a DMM to one lead of a 9V battery, and did the "tongue test".
Battery, meter, and tongue form a simple circuit loop. Here's what I
found:
With an old, standard 9V battery (7V open circuit voltage), I get
0.7-0.8 mA.
With a relatively new lithium 9v battery (9.5V open circuit), I get 2
mA.
In both cases, you get that uncomfortable-but-bearable tingle.
Mark
ian field
"Mike Monett" <N...@email.adr> wrote in message
news:Xns97F81D6B38...@208.49.80.251...
Is all that stuff about mould toxins for real? - The mental case in the flat
above went through a phase of repeatedly breaking the water pipe and
flooding me out about a decade ago, the flat still has a smell of mould that
I can just about mask with plug-in air fresheners in every room, and my
health has been deteriorating for years!
ian field
"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in message
Do a search for Nazi archived data - they were expert at using just enough
electricity to torture without killing!
John Larkin
I wonder if the I:V graph of a human tongue (or skin) is nonlinear. I
suspect so.
John
John Larkin
wrote:
Do a search? Right, more typing. In the words of another Nazi,
"One experiment is worth a thousand expert opinions."
- Wernher von Braun
John Larkin
What is this fascination you have with excrement?
John
Mike Monett
> Is all that stuff about mould toxins for real? - The mental case in
> the flat above went through a phase of repeatedly breaking the water
> pipe and flooding me out about a decade ago, the flat still has a
> smell of mould that I can just about mask with plug-in air fresheners
> in every room, and my health has been deteriorating for years!
Ian,
If you smell mold, get it fixed or move immediately. Yes, all the stuff you
have read is true. The problem is you don't realize the damage it is doing
until it is to late. That's what happened to me.
While I was living at 175 Greenbank Rd in Ottawa, my neighbour was living
in a house with a similar mold problem next door at 173 Greenbank. Both of
us were in excellent health before living there. She now has a serious
heart problem where nothing was wrong before, and I haven't heard from her
in years so she may have died. The decline in her health was extremely
dramatic and very serious.
The lady that moved into my old house had an infant girl. She became
constantly ill with all kinds of problems, and the mother started having
headaches, the same as me. I do not know what happened to her either.
Air freshners should be outlawed. They do not solve the root problem.
Get the mold problem fixed right away, or leave. Immediately.
This is the most important task in front of you right now. Once you lose
your health, you can never get it back.
Regards,
Mike Monett