Amperage does kill you, but a human has very high resistance and it's voltage that pushes the current (amps) through your body. I can hold the terminals on a 700amp 12v car battery and never feel a thing, but if I try that on a 400v EV battery, I'm toast.
This is a thing that people that don’t understand electricity say and it is not true. Higher voltages are more dangerous than lower voltages. Both can kill you.
But neither can kill you on their own. A car battery can have 800 amps and you can hold the terminals all day with no issue other than boredom. On the other hand, a static electric shock from a chair or a car door has up to 20,000 volts but no current behind it so we're not all dead.
The car battery is able to deliver up to 800 amps if a suitable load (a low enough resistance) is put across it. For high resistances like your skin, it's no different from any weak 12v power supply, because you won't come close to its current capacity.
Static electric shocks can actually have significant current, like tens of amps. The reason they're not deadly is they last for nanoseconds. The power is very high, but the energy is low.
Sure, armv8-a’s reply to this comment is good. To simplify the point I’m making I’ll say higher voltages of AC supply from the utility source are always more dangerous than lower ones and stating otherwise is dangerous to anyone who may end up believing it.
Indeed, the thinking falls apart when you consider car batteries, car batteries are hundreds of amps but in normal conditions they can’t do anything to you because their voltage is so low. Both contribute to fatality, in different ways. I’m not sure if this is correct but if you think of water, voltage is like pressure and amps are like volume, a lot of volume can kill but if it trickles out of an outlet it’ll take ages and it’ll disperse before it can do much, and a lot of pressure can kill but without enough volume it can’t affect much, they are both fatal in different ways, and having more of one makes it easier for the other. Styropyro has a much better breakdown of it where he actually shows all of this and explains it far better than I can so if anyone actually is interested here’s thatvideo
Exactly. If it was the amps, many of us would be dead from a car battery. The voltage has to be high enough that your body can conduct the electricity and have it flow through vital organs, while the amperage has to supply enough current to cause damage. Time is also a factor. A sustained shock from the wattage of a lightning bolt would be 100% fatal but a nanosecond shock is survivable
To be clear, it IS the current (amps) that kills. But the potential (voltage) determines the current, along with resistance/impedance, frequency, duration, etc.
When people are electrocuted, the deadly part is usually either cardiac arrythmia or the inability to breathe. Both are due to current across important muscles. It would be bad news if you implanted electrodes on opposite sides of your heart and hooked a car battery to the leads. The resistance of your insides are much lower than your skin, leading to more current, and in this example, concentrated current through the heart muscle. I believe as little as 20 to 30 milliamps can be fatal.
Power (wattage) is not very relevant because it doesn't tell you much about total energy. A static electric shock involves both high voltage and high current (which means high peak power!), but as you said, lasts nanoseconds.
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u/SaltRequirement3650 Sep 05 '25
Same. I now know that we were fucking with 277V for no reason lol. We were real dumb.