How Much Current Does It Take To Electrocute a Person?

Electric current is measured in amperes.

An ampere is a huge unit of electric current, equivalent to 6 billion billion (6 followed by 18 zeros) electrons passing by every second. So you often hear talk of milliamperes or milliamps,  thousandths of amperes.

One milliamp passing through your body will cause a mild tingling sensation. Ten to twenty milliamps can cause muscle spasms that may prevent you from letting go of the “hot” object. Two hundred milliamps, or two-tenths of an ampere, make the heart fibrillate (beat uncontrollably) and can be fatal. Larger currents can stop the heart entirely, but they may not always be lethal because the heart can sometimes be restarted to beat normally again.

A typical automobile battery is capable of delivering a hundred amperes or more; it takes that much current to do the job of turning over an engine.

The only reason that auto mechanics aren’t dropping like flies is their electrical resistance; every substance resists the flow of electricity to a certain degree, and the resistance of human bodies is quite high. That’s why it takes a substantial voltage to force enough electrons through a person to electrocute him or her. A 12–volt auto battery doesn’t have that much force.

We may encounter dangerous electricity in many different circumstances. I’ll assume that you are not terribly concerned about being formally electrocuted while seated in a special chair. But what about lightning?

The surge of electrons between a cloud and the ground, or between two clouds, is powered by tens of millions of volts, and that can force tens of thousands of milliamps through the air, which ordinarily won’t conduct electricity at all. Get in the way, and a lot of those milliamps can go through you.

How do you “get in the way”? By being close to an object that is offering the lightning’s current an easy path to the ground. If ever there were a situation in which the expression “path of least resistance” applies, this is it. The lightning’s electrons will flow through the best conductors, materials having the least electrical resistance, that they can find. If you offer them an attractive detour through your body, they’ll take it.

Of all materials, metals are the best conductors of electricity; they have the lowest electrical resistance. That’s because the electrons in metal atoms are very loose and can flow right along as part of the current. So when sudden thunderstorms have come up on the greens, a bag of metal golf clubs has been many a duffer’s ticket to that great fairway in the sky.

Because air is such a poor conductor of electricity, the lightning will take almost any other available path rather than plowing through the air for those last several yards to the ground. Trees, with their nice, juicy sap inside, offer lightning a preferred alternative, so taking shelter from a thunderstorm under a tree may also earn you a trip to the ultimate nineteenth hole.

But even if you’re out on the seventh green with no trees nearby when a storm comes up, little old you, sticking up only six feet off the ground, can be the lightning’s preferred route. Your best lie, so to speak, is flat on the ground, away from your clubs and cart.