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Re: A dangerous thing?

Hi Mark,

	I just wanted to thank you for this great information!!  That's what is so
great about this list.  There is always a cardiac specialist around when we
have some difficult issue like this!

	I wanted to point out that at say 15000 volts, the skin resistance really
is so low that the only thing limiting the current is the capability of the
voltage source.  Neons, will probably limit around say 60mA after the cap
has "pulsed" one with ~200 amps (perhaps 250000 times the leathal dose!) Of
course, with pig systems, you may have to wait until the breaker trips. :-(
 There are a million variables about how the current decides to travel
through the body but...  Bottom line is, you REALLY don't want to get
shocked in the first place!  Obviously, sitting an a secondary with a
streamer burning your earlobe off is not a safe place to be.  What can you
do... jump down to the primary to safety :-((

	Also, when one gets hit by the kind of voltages and currents we use.
There is often too much physical damage for CPR and such to be of much use.
 The chances of getting hit by just enough current to fibrillate the heart
without doing so much damage that it can't be restarted are small.  It is
my understanding that the three people I mentioned were all well beyond CPR
doing any good (but learn it anyway).  Most people that live through power
line contacts are saved by the explosion blowing them clear.  Still not a
comforting thought!

	"IF" anyone were going to do such stunts.  There are only two suggestions
I would give them.  First, be sure those around you do not jump into the
mess trying to save you and thus increasing the death toll.  The first
human reaction as one is doing the "Forth of July" thing, is for friends to
try and grab you.  You need friends that are well aware of electrical risks
and will react safely and properly.  Of course, such friends will not let
you do it in the first place.  Second, if you do get killed, arrange for
someone to let us know.  It would be a shame for a bunch of people to be
killed by something like this (if they haven't already) without others
having the opportunity to learn from them.

	Terry



At 07:53 AM 5/15/99 +0930, you wrote:
>At 20:52 13/05/99 -0600, Terry Fritz wrote:
>
>>	I don't mean to be morbid in our usually upbeat group but once in a while
>>we need to stop and remember.  Ours is a VERY dangerous hobby!  Below are
>>the brief accounts of the three people (that I am aware of) who have been
>>killed...
>
>... SNIP ...
>
>>It should be noted that the last two of these incidents may have gone
>>unnoticed if it were not for the Internet.  The possibility of there being
>>others that we don't know about is very high.
>
>Yes, I too was killed once, but I didn't tell anyone ;-)
>
>But seriously, Terry is quite right.  Many coilers are not in groups and
>unless the incident is non-fatal (such as the recent episode of Cabbott's
>finger) it is more likely *not* to be reported.
>
>There is just no gain in the fancy "stage stunts".  You can have plenty of
>fun with HV without exposing yourself to obvious risk.  I see plenty death,
>misery and sorry in my work ........ I don't want to hear about it on the
>weekend when I'm relaxing !
>
>The comments about RF not inducing VT/VF and death are **relatively**
>correct.  The propensity to induce VF depends upon:
>
>1.  the current passing through the heart (skin resistance and current
>path), both of which vary (determined in part by Volts)
>
>2.  frequency, viz.
>
>Current to induce VF
>  ^
>  |                                                           *
>  |                                                     *
>  |                                               *
>  |                                           *
>  |                                       *
>  |                                   *
>  |  *                            *
>  |    *                     *
>  |        *            *
>  |_______*_________________________________>  increasing F
>
>	.... and YES, the nadir *is* at 50-60 Hz
>
>3.  duration to a variable extent.
>
>4.  The individuals predisposition to cardiac arrhythmia.  A significant
>proportion of the population have an anomalous pathway between atria and
>ventricles and are at **far greater** risk of induced arrhythmia.  Problem
>is, you don't know until you get it !!
>___________________________
>
>Now, you don't need to be Einstein to work out from the above, one man's
>cute HV demo is another man's demise.
>
>Remember the safety FAQ document <http://www.pupman-dot-com/safety.htm> for
>those few who haven't read this it should be considered mandatory.
>
>Now, IF you are still going to perform the highly dangerous, remember to
>NEVER work alone and to have your "mates" well trained in CPR.  But then as
>we heard from Terry's post, this doesn't always guarantee a good outcome.
>
>cheers
>
>mark
>
>..... from the "Halls of Endless Sorrow"
>
>
>
>___________________________________________________________
>
>Mark Finnis			Hm:  61 8 82895205
>Staff Specialist			Wk:  61 8 82224000
>Intensive Care Unit			Fax:  61 8 82236340
>Royal Adelaide Hospital		Mbl:  041 23242268
>www.health.adelaide.edu.au/icu
>___________________________________________________________
>