>> All the material I've read states a level of current that is dangerous, 
>> not
>> power.
>
>  Maybe they imply that the current is maintained indefinitely, rather than
> it starting high and then dropping to zero very fast. Thus there's a time
> factor implied, which I think would then be measured with watts.

Current integrated over time gives an electrical charge, which is measured 
in coulombs, not Watts.  Anyway, you can't just state a maximum allowed 
value of coulombs, because it also depends how quickly you deliver that 
charge (ie the current).  Of course the exact criteria of what will or will 
not kill you is probably quite complex and can't be described by a single 
number, but for most cases it's a good enough approximation to just state a 
maximum current.  For sufficiently short periods of time, you might find 
that the number of coulombs is a good indicator, I don't know.

>  (Btw, the definition of "watt" is another one which is very difficult
> to get any clear answer to. It doesn't help that the unit is used for at
> least two, if not three, completely different physical phenomena.)

Watts is used to measure power, or the rate at which work is done or energy 
transferred.  There are obviously different types of work and energy 
(electrical, mechanical, thermal, chemical), so there are various 
definitions of "power", all with the same units.  It's very handy that they 
all use the same units, as you are able to calculate the efficiency of 
devices that convert energy with a simple calculation.

Post a reply to this message