Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!usc!elroy.jpl.nasa.gov!jato!jade!morris
From: morris@jade.jpl.nasa.gov (Mike Morris)
Newsgroups: sci.electronics
Subject: Re: Touching a "hot" connector
Message-ID: <1535@jato.Jpl.Nasa.Gov>
Date: 7 Aug 89 07:47:05 GMT
References: <89Jun8.160452edt.10877@ephemeral.ai.toronto.edu> <814@corpane.UUCP> <427@edai.ed.ac.uk> <1528@sunset.MATH.UCLA.EDU> <498@edai.ed.ac.uk>
Sender: news@jato.Jpl.Nasa.Gov
Reply-To: morris@jade.Jpl.Nasa.Gov (Mike Morris)
Lines: 52

...edited...

In article <498@edai.ed.ac.uk> cam@edai (Chris Malcolm) writes:
>I'd like to thank all those kind people who have expressed concern for
>my continued existence, given my habit of touching live wires to see if
>they are live.
>
>Well, as I promised, I tested my resistance. As I said I have dry skin.
>With a light touch. such as I use for testing mains, my resistance is
>>10MOhm. If I dampen my fingers by breathing on them, and grab the test
>prods painfully firmly, I can bring it down to around 10KOhm. That's
>still an order of magnitude under the lethal current.

Unfortunately, the numbers you have are pretty useless if they were determined
with a low-voltage VOM.  The skin resistance varies with voltage - I discovered
this with an _old_ Triplett (I think) VOM back in high school.  This old
meter used a 1.5v "D" cell for all but the highest scale where it used a 
22.5v (or maybe 30-something v) photoflash battery.  My skin resistance under
1.5v was, at times, 4 to 5 times what it was under the higher voltage.  And
years later when I was working a production line manufacturing CPU PC boards
for General Automation we used a milliohmeter to find shorted traces - it could
put out anything from 0.5 to 50v, and my skin resistance was again proven to
be a crude voltage-dependent resistor.

>Does anyone know what would happen if one inadvertently, one rainy
>night, with wet feet, pissed onto an electric fence?

The closest I can get to that is to relate a story about a stray dog...

It seems that the older brother of a high school classmate of mine had a '67
Mustang with mag wheels, and a stray dog had the bad habit of urinating on
the car at night.  Urine is acidic and did nasty things to magnesium alloy
wheels...  So said gentleman parked the car on squares of aluminum door
screen screen one night and wired the screens together and to one side of
a neon sign transformer (15-20kv at 3-400ua), with the other side wired to
the frame, and hence the wheels.  He than sat down to watch out the picture
window.  Several hours later said stray comes up to the car, lifts his leg,
and without moving a muscle jumps over 6 feet in the air - above the roof line!
He comes down running, and was never seen again.

Apparently the current traveled up the stream, and down his legs, causing a 
spasm.

NO FLAMES PLEASE.  The man asked a question.  I was in posession of pertinent
information, which I related.  I am also a animal lover and do not condone
that kind of behavior (in fact, I am typing this right now with a poodle-
maltese mix 2-year-old sound asleep in my lap).

Mike Morris
UUCP: Morris@Jade.JPL.NASA.gov
#Include quote.cute.standard   | The opinions above probably do not even come
cat flames.all > /dev/null     | close to those of my employer(s), if any.