The most dangerous range of currents is from 0.1 to about 0.2 amp. Currents much larger than 0.1 amp do NOT result in fibrillation and instead stop the heart completely. If the duration of the current is short, the heart will usually start to beat by itself after the current is removed. The amount of current which passes through a body depends on the ratio of the voltage of the electricity to the resistance of your body. As examples, an AA battery provides voltage of 1.5 volts, a car battery 12 volts and an electrical outlet 110 volts.
Wet skin has a much lower resistance to current than dry skin.
If the resistance of a body is as low as 100 ohms, a voltage as small as 20 volts can lead to fatal currents. The path of current through a body also determines the magnitude of the effect. Current entering a body wants to travel a path of least resistance and exit through the part of the body touching the ground. Because the heart is on the left side of the body, touching a live wire with your left hand means that the shortest path to the ground involves passing through your heart. If current travels through the right side of the body, the current is less likely to affect the heart.