The amount of current which flows at a given voltage will depend on the
characteristics of the person's skin, how sweaty they are (this is
different than saliva because of the higher salt content and the fact that
sweat is already inside the tiny tubes through the skin to the sweat
glands, so it provides paths through the skin), how thick their skin is
(especially the topmost layer, the stratum corneum, which is highly
insulating). On top of this, different people are more or less sensitive to
current flow.

I work every day with 48V battery systems and I often come into contact
with 48VDC (although I do try to avoid it). Most of the time I cannot feel
it. However, there have been times when I was sweaty where it was downright
painful.

Also - beware that the skin is the main insulator protecting your body.
Once that breaks down or is cut, the remaining resistance is on the order
of 10 to 100 ohms depending on the path through the body. 20 to 30mA can
prevent you from letting go and 100mA can stop your heart (even lower if
the whole current is directed through your heart more directly). Even less
than 100mA can induce fatal heart arrhythmias.

I generally try not to touch anything over 12V and I show increasing levels
of caution as the voltage rises from there.

Sean



On Thu, Nov 21, 2013 at 11:51 PM, William "Chops" Westfield
<westfw@mac.com>wrote:

> > 30 volts is certainly enough to feel unpleasant
>
> Really?  I have a 50V supply, and I just licked my finger and put it
> across the terminals at 30V, and I didn't feel a thing.
> Not at 50V, either=85
> Now, I remember getting an almost-unpleasant tingle out of a 90V drycell
> back in the neon-bulb oscillator days=85
>
> Worse if you have cuts, and salt water, and stuff, of course=85
>
> BillW
>
>
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