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DA N G E r S O F E L E C T r I C A L S H O C K

shock (lasting a few seconds) could be fatal if the level of current is high enough to cause the heart to go into ventricular fibrillation. This is not much current when you realize that a small power drill uses 30 times as much current as what will kill. At relatively high currents, death is certain if the shock is long enough. However, if the shock is short and the heart has not been damaged, a normal heartbeat may resume if contact with the electrical current is elimi- nated. (This type of recovery is rare.)

The greater the current, the greater the shock!

Severity of shock depends on voltage, amperage, and resis- tance.

resistance—a material's ability to decrease or stop electrical current

ohm—unit of measurement for electrical resistance

Lower resistance causes greater currents.

The amount of current passing through the body also affects the severity of an electrical shock. Greater voltages produce greater currents. So, there is great- er danger from higher volt- ages. Resistance hinders current. The lower the resistance (or impedance in AC circuits), the greater the current flow will be. Dry skin may have a resistance of 100,000 ohms or more. Wet skin may have a resis- tance of only 1,000 ohms. Wet working conditions or broken skin will drastically reduce resistance. The low resistance of wet skin allows current to pass into the body more easily and give a greater shock. When more force is applied to the contact point or when the contact area is larger, the resistance is lower, causing stronger shocks. Power drills use 30 times as much current as what will kill.

Currents across the chest are very dangerous.

The path of the electrical current through the body affects the severi- ty of the shock. Currents through the heart or nervous system are most dangerous. If you contact a live wire with your head, your ner- vous system may be damaged. Contacting a live electrical part with one hand—while you are grounded at the other side of your body— will cause electrical current to pass across your chest, possibly injur- ing your heart and lungs.

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Section 2

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