Low Voltage Does Not Mean Low Hazard
This table shows what usually happens for a range of currents (lasting one second) at typical household voltages. Longer exposure times increase the danger to the shock victim. For example, a current of 100 mA applied for 3 seconds is as dangerous as a current of 900 mA applied for a fraction of a second (0.03 seconds).
Effects of Electrical Current* on the Body
| Current | Reaction |
|---|---|
| 1 milliamp | Just a faint tingle. |
| 5 milliamps | Slight shock felt. Disturbing, but not painful. Most people can "let go." However, strong involuntary movements can cause injuries. |
|
6-25 milliamps (women)** 9-30 milliamps (men) |
Painful shock. Muscular control is lost. This is the range where "freezing currents" start. It may not be possible to "let go." |
| 50-150 milliamps | Extremely painful shock, respiratory arrest (breathing stops), severe muscle contractions. Flexor muscles may cause holding on; extensor muscles may cause intense pushing away. Heart fibrillation possible. Death is possible. |
| 1,000-4,300 milliamps (1-4.3 amps) | Rhythmic pumping action of the heart ceases. Muscular contraction and nerve damage occur; death likely. |
| 10,000 milliamps (10 amps) | Cardiac arrest and severe burns occur. Death is probable. |
| 15,000 milliamps (15 amps) | Lowest overcurrent at which a typical fuse or circuit breaker opens a circuit! |
*Effects are for voltages less than about 600 volts. Higher voltages also cause severe burns.
**Differences in muscle and fat content affect the severity of shock.
Knowledge Check Choose the best answer for the question.
1-5. Which of the following is the lowest level of electrical current that can cause heart fibrillation and death?
You forgot to answer the question!