electric shock

In article ,
Davey wrote:
I was working on a 55VAC line-powered TV system the other day and I
could feel the power through dry fingers. I got the impression 55V
could be quite nasty with wet hands and a good earth. It was
interesting to feel this attenuated mains. The individual cycles can
be felt quite clearly. It made me wonder if the feeling of touch has
less persistence than vision. Of course the ears would turn the 50Hz
into a note.

Bill

The 'nasty' value would also depend on the available current flow,
surely? 20 Amps would do serious damage, even 2 will kill you.

It's the current flow through the body that matters - and pretty well
anything you are likely to touch will be capable of supplying the 20 mA or
so needed to kill you. Even a small battery. But then it needs enough
volts to produce that current where it matters in the body. The most
likely and shortest path is between both hands. It used to be thought less
than about 50 volts was safe under those conditions, but many reckon 30
now.

--
*I am a nobody, and nobody is perfect; therefore I am perfect*

Dave Plowman London SW
To e-mail, change noise into sound.

Martin wrote:

In one of today's newspapers there is a photo of a paraplegic guy who
has just swum between two of the Indonesian islands using special
attachments to what is left of his legs. It says he was electrocuted
whilst removing a TV aerial

This is typical of wiring in parts of Indonesia's capital Jakarta:

http://tinyurl.com/7ro8dcr

So if he was attending to an aerial above a shop front, say, then it might
well have been amongst something like that.

On Fri, 18 May 2012 18:09:40 +0100, Graham. wrote:

On Fri, 18 May 2012 17:49:13 +0200, Martin wrote:

On Fri, 18 May 2012 16:16:14 +0100, "Brian Gaff"
wrote:

Its of course across the heart you need to watch out for. Some people like
the effect of electric shocks, but obviously there are limits!

Brian

In one of today's newspapers there is a photo of a paraplegic guy who
has just swum between two of the Indonesian islands using special
attachments to what is left of his legs. It says he was electrocuted
whilst removing a TV aerial

You can't be electrocuted and live to tell the tail. By definition the
word means a fatal electric shock.

It was coined at the time of the first electric chair, a contraction
of "electric execution".

Yes. However, it was soon also used to refer to non-lethal
"electrocution" as seen in this example from the OED:

1899 Times 11 Apr. 1/4 Continuation of the Monster Holiday Show.
Marvellous performances... See to-day, at 3 and 8, Dr. Walford
Bodie electrocute a man.


--
Peter Duncanson
(in uk.tech.digital-tv)

On Fri, 18 May 2012 18:09:40 +0100
Graham. wrote:

On Fri, 18 May 2012 17:49:13 +0200, Martin wrote:

On Fri, 18 May 2012 16:16:14 +0100, "Brian Gaff"
wrote:

Its of course across the heart you need to watch out for. Some
people like the effect of electric shocks, but obviously there are
limits!

Brian

In one of today's newspapers there is a photo of a paraplegic guy who
has just swum between two of the Indonesian islands using special
attachments to what is left of his legs. It says he was electrocuted
whilst removing a TV aerial

You can't be electrocuted and live to tell the tail. By definition the
word means a fatal electric shock.

It was coined at the time of the first electric chair, a contraction
of "electric execution".


Fair enough. But what is the correct word for the survived equivalent, then?
--
Davey.

On Fri, 18 May 2012 19:26:35 +0100, Davey
wrote:

On Fri, 18 May 2012 18:09:40 +0100
Graham. wrote:

On Fri, 18 May 2012 17:49:13 +0200, Martin wrote:

On Fri, 18 May 2012 16:16:14 +0100, "Brian Gaff"
wrote:

Its of course across the heart you need to watch out for. Some
people like the effect of electric shocks, but obviously there are
limits!

Brian

In one of today's newspapers there is a photo of a paraplegic guy who
has just swum between two of the Indonesian islands using special
attachments to what is left of his legs. It says he was electrocuted
whilst removing a TV aerial

You can't be electrocuted and live to tell the tail. By definition the
word means a fatal electric shock.

It was coined at the time of the first electric chair, a contraction
of "electric execution".


Fair enough. But what is the correct word for the survived equivalent, then?

How about the subject line of this thread, perhaps qualified by
"severe", "very dangerous" etc.

--
Graham.
%Profound_observation%

On 2012-05-18, Graham wrote:
On Fri, 18 May 2012 19:26:35 +0100, Davey

Fair enough. But what is the correct word for the survived equivalent, then?

How about the subject line of this thread, perhaps qualified by
"severe", "very dangerous" etc.

I'm not sure "the severe subject line of this thread" has quite the same
ring to it...

--
David Taylor

Dave Plowman (News) wrote:

It's the current flow through the body that matters - and pretty well
anything you are likely to touch will be capable of supplying the 20 mA
or so needed to kill you. Even a small battery. But then it needs enough
volts to produce that current where it matters in the body.

But really it's about skin resistance. Yes, 50V might be able to push
30mA through your body, but your body would need to present a
resistance of about 1.7k or less to drive that much current.

I've just been downstairs, mixed up some strong brine and thoroughly
soaked both my hands in it.

With both hands still wet I gripped the probes of my multimeter as hard
as I could. By altering my grip and trying really hard, I can just
about get the reading down to 30k.

Yes, I know this is not scientific and perhaps non-linear effects might
arise with a higher voltage. But it's an indication.

I reckon you'd be really hard pressed to drive 20mA through your body
from 50V.

--
SteveT

In article , Dave Plowman (News)
scribeth thus
In article ,
Davey wrote:
I was working on a 55VAC line-powered TV system the other day and I
could feel the power through dry fingers. I got the impression 55V
could be quite nasty with wet hands and a good earth. It was
interesting to feel this attenuated mains. The individual cycles can
be felt quite clearly. It made me wonder if the feeling of touch has
less persistence than vision. Of course the ears would turn the 50Hz
into a note.

Bill

The 'nasty' value would also depend on the available current flow,
surely? 20 Amps would do serious damage, even 2 will kill you.

It's the current flow through the body that matters - and pretty well
anything you are likely to touch will be capable of supplying the 20 mA or
so needed to kill you. Even a small battery. But then it needs enough
volts to produce that current where it matters in the body. The most
likely and shortest path is between both hands. It used to be thought less
than about 50 volts was safe under those conditions, but many reckon 30
now.


As its said;

"Its the volts that jolts, but its the mill's that kills"..

You need sufficient volts to push the mills...


I do think that unless you have possibly bare skin thats soaked in a
contact solution of sufficient area and applied to the right places
you'd be hard pressed to kill anyone with say 30 volts...

--
Tony Sayer

In article , Brian Gaff
scribeth thus
Now here is a thing. We have some pylons near here, if I walk under the
lines , thn hold my white cane up in the air, I can feel the 50 hertz as i
gently run my finger over any exposed aluminium exposed area on the cane.


Yes its called "leakage" Many years ago we used old fluorescent tubes to
demonstrate this. We used to ride around in an old transit van which one
of those long fibreglass aerials on the top, the sparks you could pull
off the aerial lead were very impressive on wet nights..

If you have a railway station thats on an electrified line you can get
similar things, the volts are lower but so are the distances..

Not that I'd advise you too wave that too high of course...




Brian


--
Tony Sayer

In article , The Hemulen
scribeth thus
"Bill Wright" wrote in message
...
I was working on a 55VAC line-powered TV system the other day and I could
feel the power through dry fingers. I got the impression 55V could be quite
nasty with wet hands and a good earth. It was interesting to feel this
attenuated mains. The individual cycles can be felt quite clearly. It made
me wonder if the feeling of touch has less persistence than vision. Of
course the ears would turn the 50Hz into a note.

Bill

In my younger days I managed to get 'stuck' on the 240V mains (picked up a
live electrical item I was working on, forgetting the bottom cover was
removed). I reckon I was connected for about five seconds before the power
was removed.
I can testify you can REALLY feel the cycles! Seriously scary moment when
realised couldn't do anything about it. Arm muscles were near unusable for
days afterwards. Over twenty years on you can still see the marks on my
hands where the skin melted.


I had a similar thing happen with an old metal cased electric drill
years ago, the earth in the house that I was working in wasn't earth at
all. That was disconnected at the fuse board and the cable in those days
was lead covered rubber;!.

Drill in one hand earthed metal ladder rung in the other!....

Didn't quite have burns, but the doc said if it had gone on for much
longer it wouldn't have been a very good outcome;(.,.
--
Tony Sayer