Current level (in milliamperes)
Probable effect on human body
1 mA
Perception level. Slight tingling sensation. Still dangerous under certain conditions.
5 mA
Slight shock felt; not painful but disturbing. Average individual can let go. However, strong involuntary reactions to shocks in this range may lead to injuries.
6-30 mA
Painful shock, muscular control is lost. This is called the freezing current or "let-go" range.
50-150 mA
Extreme pain, respiratory arrest, severe muscular contractions. Individual cannot let go. Death is possible.
1000-4300 mA
Ventricular fibrillation (the rhythmic pumping action of the heart ceases.) Muscular contraction and nerve damage occur. Death is most likely.
10,000 mA
Cardiac arrest, severe burns and probable death.
Wet conditions are common during low-voltage electrocutions. Under dry conditions, human skin is very resistant. Wet skin dramatically drops the body's resistance.
Dry Conditions: Current = Volts/Ohms = 120/100,000 = 1mA a barely perceptible level of current Wet conditions: Current = Volts/Ohms = 120/1,000 = 120mA sufficient current to cause ventricular fibrillation
As you can see, it does not take much to lead to severe injuries and that a difference of less than 100 milliamperes exists between a current that is barely perceptible and one that can kill.
So I guess the rule should be “work live and you might die. There is nothing “macho” about being dead: ask your family. Article generously provided by James Norton, President of the JHN Group. He can be contacted regarding Machine Safety Consulting at jamesnorton@jhngroup.com or online at www.jhngroup.com.
