Re: Watts or Amperes

[Ken Kiehlbauch <kk@wi.net>]

> Why does it kills you when touching for instance
> the electrode of a car battery? (12V & 30-400A)
> Is it the high current the can supply or the
> power? may be both thing depending on the quantity
> of watts or amperes the can supply us when we touch
> the battery?
>
> My believe was that our body-cells get burned hence
> power was responsible.

I don't believe that anyone can get killed with a car battery, unless it 
is dropped on their head.  I have read that the lowest voltage anyone 
has ever been electrocuted at is 40 V.  Of course, someone might want to 
go for the records books and try killing themselves with a lower 
voltage.  

I have read that the current is what kills, but generally the current is 
determined by the voltage (and other things, such as grounding, skin 
moisture, what part of the body is in contact with the voltage source, 
and even frequency of the voltage).

I have also read that low currents, say below 20 mamps, are 
uncomfortable, and high currents, perhaps above 70 mamps (I'm going from 
memory) will stop the heart altogether.  It is the middle currents that 
are most dangerous, because they send the heart into useless 
filibration. A stopped heart may be restarted with CPR, but a 
filibrating heart generally needs the "paddles" seen on various TV 
shows.

Finally I have read that one should never conclude that an electrocution 
victim is beyond help even if the heart is stopped and the victim was 
hit with a tremendous shock, such as lightning.  This is because a 
massive shock stops the heart completely, and CPR may revive them 
(though often with serious burns and other injuries).

Ken Kiehlbauch
kk@wi.net