How many milliamperes can humans typically tolerate before harm occurs?

Answer 1

It really depends on how much voltage is present in relation to the current; your physiogamy (heart condition, pacemakers, etc,) and how/where it is applied, age and your individual body resistance. Is it across the arms from voltage source to ground (one hand to the other) crossing through the chest? Is it a lightning strike?

A typical television's high voltage section runs at 15,734 hz. per second and generally ranges from an average of 19,500 to 23,000 volts. The average current available is seven milliamps, or .007 amps. Most people can handle a discharge from a TV, but it most likely will cause an adrenaline release in your body. Then, for about 45 minutes or so, you'll feel great. Then after that, you can expect a feeling of heavy fatigue as the adrenaline dissipates. I've been personally zapped several times over the years and that's about the only ill effects I've ever encountered.

ON the other hand, an electronic ignition coil can put out anywhere from approximately 35,000 to 100,000 volts at a much higher current. It too produces the same effect as a TV high voltage discharge, plus a numbing of the extremity inviolved.

Yet, we know too, that people have survived lightning strikes, and we're talking roughly a million volts at thousands of amps, and they too have survived the incident with little or no apparent damage (but not in all cases).

Having been burned by radio frequency from a ham transmitter running at 75 watts output, I encountered a very nasty little burn as I brushed up against the antenna with my thumb, which bore a perfectly round, 1/8" hole into my skin, cauterized the wound and left it complete with a scab to cover the hole. That was an especially nasty wound and it hurt for several days afterward, but I suffered no other ill effects.

It's possible place your hands on both terminals of a car battery at 12 volts, yet it has the storage capacity of a few hundred "cold cranking amps" and not feel a thing. Stick a 9 volt transistor radio battery to your tongue and you'll definitely feel a tingle, but on a "dead short" that same battery can deliver up to a whopping 80 amps for a fraction of a second.

How many milliamps? At what frequency? AC, pulsed DC or RF? At what voltage? For how long?

The whole point is that it varies from individual to individual and on many other conditions. Simple rule of thumb: Keep one hand in your pocket when working on anything where the potential to shock you is present, and don't believe "trueisms" concerning electricity.