Do the amps or volts kill?

[Sigmoid]

About 5 years ago, I had this argument with a very opinionated (and possibly a little arrogant) experienced EE with a PhD. I told him that as little as 20mA through your body could kill you. He responded, "!!! You need at least a couple of hundred milliamps across the heart to kill a person." To avoid the argument escalating, I let it go and forgot about it. A couple of hours later he came up to me to apologise and admit he was wrong. He had done some research. I respected him for doing the research and having the humility to apologise.

20mA through the heart is not the same (not by far) as 20mA through the body. 20mA through the heart means your chest opened up, and electrodes affixed to the surface of your beating heart.

You will find 20 x nine volt batteries plugged together in series could kill you if you touched each end with sweaty hands (DC is more dangerous than 50 or 60 Hz AC by the way). Don't try it!

Yea, don't try it, but I don't think that's accurate. ESR, DC resistance of the skin, various current paths through and on the body, and all that.

I knew a friend of my brother who climbed a 220KV power line tower. He was electrocuted and died instantly.

Well, THAT will kill you. There's a ridiculous amount of energy transported through those. Literally enough to power small towns.

[LabSpokane]

And the answer is *still* Chuck Norris. Electrons flow because they are afraid Chuck Norris will neutralize them.

[retrolefty]

I agree with AG6QR, it's the current (at certain near constant value) that causes the damage, the voltage required is a variable that has to overcome the specific resistance and source impedance in a specific condition.

Current can kill, voltage it depends.

[VK3DRB]

I believe grabbing hold of AC is safer than DC because of the muscles' response. It is nothing to do with the current through the heart. You can let go of AC easier than DC, even though the RMS values are the same.

[Tinkerer]

Lethal values are usually listed in amps(ok mA).
Keep in mind that static electricity can have thousands of volts behind it yet we dont have people being electricuted every day because of static. You can have thousands of volts going across your heart but if no oomph in the form of any significant amperage is present, you arnt going to feel anything.
Voltage is likened to water pressure and amperage to the amounts. You can have water at extremely high pressure, but if you are only squirting out a few milligrams, you arnt going to have any damage occur. Contrast with this low pressure but a huge amount of water and you can most certainly have problems.

[rs20]

Simple: Any statement or question of the form "is it the amps or the volts that kill you" is a stupid, ill-defined false dichotomy. There are some people here saying "you need at least a fairly fixed current through your heart to kill you", and then others saying that "you need a certain amount of voltage across your skin to kill you". These facts are both true, linked by V=IR, showing what a stupid question it is.

However, if you ask "given a particular situation, how do I establish whether it is hazardous or not", that's a proper question, and one that has been answered already in this thread.

You can have thousands of volts going across your heart but if no oomph in the form of any significant amperage is present, you arnt going to feel anything.

Wrong, if the potential source can't provide significant amperage, then you will not have thousands of volts across your heart. V=IR geez.

[Psi]

This vid explains it well

[SteveyG]

Well perhaps I should have used the word energy instead of power. The only thing that kills is energy it simply does not mater if its electrical, kinetic or chemical or mechanical if you take crushing into account feed enough energy into a living organism and it comes to the point where it no longer lives.

Yes this is correct. This is why when we design things like defibrillators, we specify energy as it is the only reliable unit for having a consistent effect on the heart. Power x Time is the important factor, although obviously there are a whole multitude of other ways you can die from electrical contact.

Lethal values are usually listed in amps(ok mA).
Keep in mind that static electricity can have thousands of volts behind it yet we dont have people being electricuted every day because of static. You can have thousands of volts going across your heart but if no oomph in the form of any significant amperage is present, you arnt going to feel anything.

Static discharge can have huge current associated with it, but the discharge is very short, so the total energy is quite low.

[amyk]

Lethal values are usually listed in amps(ok mA).
Keep in mind that static electricity can have thousands of volts behind it yet we dont have people being electricuted every day because of static. You can have thousands of volts going across your heart but if no oomph in the form of any significant amperage is present, you arnt going to feel anything.

Static discharge can have huge current associated with it, but the discharge is very short, so the total energy is quite low.

Agreed. With voltages that can penetrate the skin any significant amount, it's the energy which matters.

A static shock which is several tens of kV will produce a very high instantaneous current, but the capacitance is usually tiny so there's not much energy in one.

[fubar.gr]

Do the amps or volts kill?

The problem with this question is that most of the people who ask it, have minimal understanding of what volts or amps are and their physical significance.

And to make things worse, the effects of electrocution depend on many unpredictable and hard to quantify external factors, like source impedance, total stored energy, duration of the electric shock, human body chemistry and whatnot.

So the problem is that this question doesn't have a simple this or that answer and the full answer won't be understood by laymen.

I think the best advice that can be given is to steer clear from high voltages and you'll be safe.

[tyguy2]

After all of this, my friend FINALLY admitted he was wrong. 

[Halcyon]

I guess some people can't accept that they are wrong.

You can only lead someone to proven, scientific evidence, but you can't make them accept it. I've learnt to not waste my breath with people like that (just accept that probably deep down they know you're correct, yet they'll never bring themselves to say it).

Reminds me of a friend of mine who is a self-proclaimed audiophile (more like audiophool). He has tried (unsuccessfully) to convince me that his fairly high-end Bluray player can produce better looking video from his 4GB compressed H.264 movies by using interpolation and extrapolation than VLC media player can using a raw Bluray stream straight off the disc. (Also the same guy tried to convince me that his "high end" AC power cables made his audio system sound better.)