“It’s not the voltage that kills, it’s the current”

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WARNING: High voltage

Does the current kill or the voltage?

Apparently it’s still not clear for most people that it’s the voltage that kills and not the current. Not that I can blame them – it’s the high school teachers that spread this bullshit – but I’d like to debunk this thoroughly for the sake of ensuring that the truth prevails.

Ohm’s Law: how voltage causes current

Ohm’s Law tells us that V=IR. What does this mean? Voltage equals current times resistance. E.g. to send 1 amp through a 5 ohm load, you’d need 5 volts. So we can interpret this as voltage and resistance cause current to flow. Decrease the resistance, more current will flow. Increase the voltage, more current can flow. But changing the current requires changing one or both of the others. Electricity moves only because some force made it move.. and the electromotive force is.. you guessed it – voltage. Electrical potential that can cause electrons to move and thereby cause current.

In high school they often teach this misconception with the use of electrostatic discharges (aka ESD) – which can be tens of kilovolts but aren’t lethal.. why? “Because the current kills, not the voltage”.

BULLSHIT!

The difference between ESD and high voltage supplies is that yes you charge your body to a high voltage by interacting with the environment, but the body’s capacitance is so tiny, the discharge only lasts a microsecond or less.. a healthy person can handle that. But touching a continuous high voltage supply that’s delivering electricity at the same voltage (and isn’t limited to 1mA or whatever, unlike those Van De Graaff towers)? That will kill you.

And honestly.. if my teacher tells me that current kills, not the voltage.. I’d dare them to put their fingers in a wall socket, or better yet the secondary winding of a microwave transformer (2kV). Both of those voltages are lower than that of an ESD.. so they won’t kill.. right? And if the teacher kills him-/herself in the process, eh that’s one source of bullshit gone I guess.

Conclusion

So I hope that I’m clear. Whenever someone claims to “know electronics” and tells you that it’s the current that kills and not the voltage, they’re an idiot and you shouldn’t listen to them. Stay safe, don’t touch high voltage sh!t and when you do need to work with high voltage circuits, wear safety gloves to increase your resistance.

If you’d like to see more coverage on this topic, check out Afrotechmods‘ and ElectroBOOM‘s videos on the matter. Also, f*ck this moron! I dare him to touch that tower without current limiting to save his ass. Which ElectroBOOM has also debunked.. thanks Mehdi! 😀

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