Currents from 100 to 200 milliamperes generally cause death because the heart usually goes into fibrillation, a condition in which the heart begins to “quiver” and the pumping action stops. Currents above 200 milliamperes cause the heart to squeeze shut. When the current is removed, the heart usually returns to a normal pumping action.

Work with One Hand When PossibleThe worst kind of electric shock occurs when the current path is from one hand to the other, which permits the current to pass directly through the heart. A person can survive a severe shock between the hand and foot that would cause death if the current path were from one hand to the other.

Of all the rules concerning safety, this one is probably the most important. No amount of safeguarding or idiot proofing a piece of equipment can protect a person as well as taking time to think before acting. Many technicians have been killed by supposedly “dead” cir-cuits. Do not depend on circuit breakers, fuses, or someone else to open a circuit. Test it yourself before you touch it. If you are working on high-voltage equipment, use insulated gloves and meter probes to measure the voltage being tested. Think before you touch some-thing that could cost you your life.