Originally Posted by
CliffordK
It is a combination of Volts + Amps that "kill".
For example, your standard car battery puts out 12V, and perhaps 1000A. More than enough amps to stop the heart, but under ordinary conditions, the skin provides adequate insulation to prevent getting shocked. So, while I've seen spectacular sparks with tools, I've never been zapped by a car battery.
Periodically I'll get a tingle from 110V, and believe it is probably the full force of 110V, but it is usually just enough to make me want to move my hands.
An electric fence, on the other hand hits a person with high voltage, low amps for a brief amount of time to give a strong, non-lethal jolt.
Even if the heart is stopped, it would typically resume once the power is removed unless there is some other underlying problem. However, there is also a risk of steady power causing contractions and making it difficult to release.
Anyway, caution is advised, but you should be fine as long as you're running down in the 12V range.