I know the mantra, "it's the current that kills you, not the voltage," except it seems that's not the full story. Presumably the voltage does matter, because of the high resistance of skin (maybe cause by inefficiency)? Or is X amps at Y volts really the same as X amps at 10*Y volts, when applied to the outside surface of the skin? Then there seems to be time factor. For example, when you walk across carpet and then get a jolt from touching the doorknob, the voltage and current are pretty darn high (I think) but because the duration is so short it doesn't injure you.
So...it seems there are 3 variables: current, voltage, and time (duration). Can anybody point me to a resource that might include all 3 of that might help me come up with some real-world numbers? I'm interested in both perception (at what point a human can feel it) and safety (at what point it is injurious). Can anybody point me to a good resource for this?
Some background: I'm going to be using an Arduino to control something like a photoflash charger (depending on what voltage, current, and duration I come up with) to send out bursts of electricity. It's going to be used in a saltwater environment. Having this info will help me determine the voltage, current, and duration of pulses, because it would be ideal if it didn't kill anybody if a careless wet person happens to grab onto the contacts. For now I'll assume they don't have a pacemaker. Bonus points if a person in the water next to it can't even feel it if it drops in the water.