Science: Shocking Facts

Every year, some 1,300 people in the U.S. die by accidental electrocution. But electricity in quantity is not nearly so deadly as most people suppose. Two-thirds of those electrified by potentially lethal currents survive the shock. In fact, the stronger the shock, the better the chance of survival: 40,000 volts or more are only about one-third as lethal as lower voltages.

These are some of the findings reported in the current Electronics by a Westinghouse engineer, H. A. Poehler. Twenty-five states have adopted electrocution as the most efficient method of capital punishment. But the electric chair stacks all the cards against its occupant. It uses moderate voltage (about 2,000) and current (less than eight amperes), and contacts moistened with salt water, to lower the occupant’s resistance. This virtually assures instant death, because moderate voltage is best calculated to disrupt the cycle of the human heartbeat.

Three Ways to Die. Electricity can cause death in three different ways: 1) by burning; 2) by paralysis of the nervous system, which stops breathing; 3) by “ventricular fibrillation” of the heart, i.e., breaking up the normal rhythm of the heart muscles. Of these, the heart effect is by far the most dangerous, for it is virtually impossible to restore the normal beat, once interrupted. Fortunately, most accidental electric shocks attack not the heart but the nervous system, and victims can usually be revived by artificial respiration.

High voltages are least likely to be,fatal because they do not cause heart fibrillation, and because they usually throw the victim clear of the circuit. Some 88% of those shocked by 40,000 volts or more recover. Engineer Poehler suggests that to free an individual from a live circuit it is better to use one’s foot than a hand; the current is then less likely to reach the heart or respiratory nervous system.

A human being’s vulnerability to electric shock is determined largely by skin resistance. Water reduces skin resistance more than a hundredfold. About the most dangerous possible electric shock is one from an ordinary, Go-cycle A.C. house circuit, received by anybody with wet hands or feet. Even at only 100 volts, it means certain death.