Electrical formulae and calculations http://www.sengpielaudio.com/calculator-ohm.htm
What currents are dangerous? http://engineering.dartmouth.edu/safety/electrical/TheFatalCurrent.html
Taken from the above site:
While any amount of current over 10 milliamps (0.01 amp) is capable of producing painful to severe shock, currents between 100 and 200 mA (0.1 to 0.2 amp) are lethal. Currents above 200 milliamps (0.2 amp), while producing severe burns and unconsciousness, do not usually cause death if the victim is given immediate attention. Resuscitation, consisting of artificial respiration, will usually revive the victim.
It’s not volts that kills, it’s current.
Really great site for limits and electrical safety while working. http://www.allaboutcircuits.com/vol_1/chpt_3/4.html
Keep hands clean and dry and remove jewelry when working with electricity.
In industry above 30V is considered a conservative threshold value for dangerous voltage.
Using one hand when working increases resistance of the body.
If there are downed electrical lines, standing on one foot or running (only one foot contacting at any one time) will also reduce the chances of you creating a path for the current – in one foot and out the other 8)