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Muscular contraction and nerve damage occur.

At 1,000–4,300 mA, there is ventricular fibrillation.

The individual cannot let go, and death is possible.

At 50–150 mA, there will be extreme pain, respiratory arrest, and severe muscular contractions.

At this level, many humans cannot get their muscles to work, and they can’t open their hand to let go of a live conductor.

The 9–30 mA level is called the freezing current or “let-go” range.

At 6–25 mA, there is painful shock, and muscular control is lost.

The average individual can let go, but involuntary reactions can lead to injuries.

At 5 mA, you feel a slight shock, not painful but disturbing.OSHA documents spell out the general relationship between the amount of current received and the reaction when current flows from the hand to the foot for just one second. The refinement of transistor technology provided a means of sensing currents as low as 0.003 A (3 mA) to energize a relay that would decouple the power supply. These studies found that as little as 70 mA through the heart was enough to cause fibrillation. Extensive research in the 1960s determined the amount of current and voltage needed to cause ventricular fibrillation (where a heart stops beating) in humans. It doesn’t take much ground-fault current to cause harm. Ground fault detection is critical to protecting people and animals from shock or death. The return path of the fault current is through living beings or equipment touching the grounding system. Ground faults arise when current flows from an energized conductor to ground inadvertently.