What voltage and amps are and why high volts may not kill you but high amps will
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Long rambling tirade ahead:
Electrons exist statically in everything. We apply voltage to get them to move. They move through circuits we design to make things happen. However, they move really fast, nearly the speed of light. So when they move they generate heat and tend to blow things up trying to return to the source. So we add resistors. Resistors can take the form of insulation, a load (a fan motor), or… well… resistors in a circuit board. An ampere is actually a specific amount of electrons (6.241509074×10¹⁸ electrons) moving past a point every second.
Think of the relation of voltage to amps like a pressure washer. The pressure washer can move 2 gallons per minute. Increasing the voltage is like closing the valve to make the stream of water thinner, lowering the voltage is like opening the valve wider but It’s moving the same amount of water per minute, that is wattage. Using joules law which is power = voltage X current (amps) we can give some examples. 10 amps at 100 volts gives us 1000 watts, 1 amp at 1000 volts gives us 1000 watts, 100 amps at 10 volts gives us 1000 watts.
Now since moving electrons create heat, we need bigger conductors to hold more electrons in any given part of the conductor. A 14 gauge copper wire is rated for 15 amps continuous. Too much more than that for too long and the wire will heat up and possibly melt the insulation and catch fire and melt the conductor. Conductor size is strictly a limit on the amperage that can pass through the wire. The insulation limits the how far the current can reach out away from the conductor to other things we don’t want energized. Insulation just serves as a barrier to isolate the conductor from its surroundings (and can be dyed to color code conductors) and different insulators are rated for different voltages and installation conditions. Air is a decent and inexpensive insulator and that’s why we have 500kv lines high up in the air. If you were to look up a 4/0 wire on google you’ll see that it’s not tooo much smaller than the lines that hang in your neighborhood. Well your house may have a 200 amp main breaker and that 4/0 AL is good for a 200 amp service. So how do those little lines power this whole street?
That’s where transformers come in. Transformers step down the voltage from the primary (the power lines) to the secondary (your house). Increasing the voltage means you can push more amps through the same size wire and service more customers. That 200 amps at 120 volts (which you’ll probably never actually reach) is actually only like 0.8 amp I wanna say? There’s also a good chance the wire size above you is around 500 kcmil copper which is rated for 320 amps. At 30kv that’s 509 kcmil wire can service 400 homes pulling 200 amps 120v each. Again that’ll never happen. Sorry for the long rant.
But to answer your actual question. Your skin is an insulator and resists low voltages. I’ve experienced about 50v and barely felt it. I touch low 24-30v with bare fingers all the time and don’t feel it. It’s only when the voltage is high enough to overcome your bodies (and shoes) resistance that things become deadly. It takes comparatively minuscule amount of current to actually kill you as you’ve read in the comments by now, I was messing with a fridge the other day and it only pulled 1.5 amps. That’s a pretty tiny amount of current and is also like like 7x more then enough current to kill you.
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