Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!apple!bloom-beacon!husc6!ogccse!cvedc!nosun!qiclab!sopwith!snoopy
From: snoopy@sopwith.UUCP (Snoopy)
Newsgroups: sci.electronics
Subject: Re: Touching a "hot" connector
Keywords: touch, sensation, live, shock
Message-ID: <248@sopwith.UUCP>
Date: 15 Jul 89 22:41:50 GMT
References: <89Jun8.160452edt.10877@ephemeral.ai.toronto.edu> <814@corpane.UUCP> <427@edai.ed.ac.uk> <322@cbnewsi.ATT.COM>
Reply-To: snoopy@sopwith.UUCP (Snoopy)
Organization: The Daisy Hill Puppy Farm
Lines: 48

In article <322@cbnewsi.ATT.COM> fiesta@cbnewsi.ATT.COM (eric.c.beck) writes:
|> Not recommended unless you don't mind the occasional jolt from the
|> mains, which probably means your skin ought to be on the dry side. I'm
|> talking about 250V mains, by the way. 120 is less lethal.
|
|From what little I've been taught about electrical shocks and resuscitation
|I seem to remember that 120 was actually "more lethal" than 240 ... something
|to do with fibrillation (from a 120 shock) versus complete stoppage of the
|heart with a 240 volt shock.  (It is harder to resuscitate an individual
|in fibrillation(?)). 

From _Electronic Components and Measurements_ by Bruce D. Wedlock and
James K. Roberge, based on an article entitled "The Fatal Current,"
originally published by Fluid Controls Corporation:

"...currents between 100 and 200mA are lethal.  In this current range,
ventricular fibrillation of the heart occurs.  Above 200mA, the resulting
muscular contractions are so severe that the heart is forcibly clamped
during the shock, and ventricular fibrillation is prevented.  Thus,
although severe burns, unconsciousness, and stoppage of breathing occur,
the shock is not usually fatal if the victim is given immediate resuscitation
or artificial respiration.  [...] The actual body resistance varies depending
on the points of contact and the condition of the skin.  The total
resistance may be as low as 1kOhm for wet skin and as high as 500kOhm for
dry skin.  Death by electrocution as been recorded from a voltage as low as
42 volts DC, implying a resistance as low as 400 Ohms."

There is a chart showing "threshold of sensation" at about 0.002A, "painful"
at about 0.01A, "cannot let go" at about 0.02A, "extreme breathing
difficulties" at about 0.08A, "death" from 0.1A to 0.2A, "breathing stops"
at about 0.3A, and "severe burns" at about 0.4A.

"*action in case of shock* [...] The resistance of the victim's contact
decreases with time so that the fatal 100- to 200-mA current may be
reached if action is delayed.

	If the victim is unconscious and has stopped breathing, start
artificial respiration *at once. Do not stop resuscitation until a medical
authority has pronounced the victim beyond help.*  It may take as long as
eight hours [ !!! ] to revive the patient."

Is it time for a frequently-asked-questions list for this group?

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