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Effects of Electrical Current in the Human Body3,4

Current Below 1 milliampere 1 milliampere 5 milliamperes

reaction Generally not perceptible. Faint tingle.

Slight shock felt; not painful but disturbing. Average individual can let go. Strong involuntary reactions can lead to other injuries.

6–25 milliamperes (women) 9–30 milliamperes (men)

Painful shock, loss of muscular control. The freezing current or "let-go" range. Individual cannot let go, but can be thrown away from the circuit if extensor muscles are stimulated.*

50–150 milliamperes

Extreme pain, respiratory arrest (breathing stops), severe muscular contrac- tions. Death is possible.

1,000–4,300 milliampe


Rhythmic pumping action of the heart ceases. Muscular contraction and nerve damage occur; death likely.

10,000 milliamperes 15,000 milliamperes

Cardiac arrest and severe burns occur. Death is probable. Lowest overcurrent at which a typical fuse or circuit breaker opens a circuit!

*If the extensor muscles are excited by the shock, the person may be thrown away from the power source. The lowest overcurrent at which a typical fuse or circuit breaker will open is 15,000 milliamps (15 amps).

Sometimes high voltages lead to additional injuries. High voltages can cause violent muscular contractions. You may lose your balance and fall, which can cause injury or even death if you fall into machinery that can crush you. High voltages can also cause severe burns (as seen on pages 9 and 10).

High voltages cause additional injuries!

At 600 volts, the current through the body may be as great as 4 amps, causing damage to internal organs such as the heart. High voltages also produce burns. In addition, internal blood vessels may clot. Nerves in the area of the contact point may be damaged. Muscle contractions may cause bone fractures from either the con- tractions themselves or from falls.

Higher voltages can cause larger currents and more severe shocks.

A severe shock can cause much more damage to the body than is visible. A person may suffer internal bleeding and destruction of tis- sues, nerves, and muscles. Sometimes the hidden injuries caused by electrical shock result in a delayed death. Shock is often only the beginning of a chain of events. Even if the electrical current is too small to cause injury, your reaction to the shock may cause you to fall, resulting in bruises, broken bones, or even death.

Some injuries from electrical shock cannot be seen.

The length of time of the shock greatly affects the amount of injury. If the shock is short in duration, it may only be painful. A longer

Section 2

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