# Is 220 V, 50 A equally dangerous for a person as 1A, 11000 V? [duplicate]

The question is self-explanatory. I'm a high school student so feel free to use scientific terms.

# Falling from the 100th floor vs. from the 3rd

It only takes 0.1 - 0.2 A to kill a person, assuming the current goes over the heart or through the brain. So both 50 A and 1 A can kill, with ample margin.

You have an error in your reasoning though, in that you assume that both electrical sources will deliver a fixed voltage (220 V and 11000 V respectively) and a fixed current (50 A and 1 A respectively).

This is not true.

The voltage is fixed, but the current depends on the impedance of the body. This is further complicated by the fact that the body has different impedance not only depending on where the current enters and exits the body, or how wet the body is, (or a number other factors that vary from person to person)... but also on how large the voltage is. The larger the voltage, the lower the impedance will be (note: this is rather unusual, normally impedance/resistance does not vary with the voltage over it, but for the human body it does vary).

In general, the following apply:

• The lower the impedance, the bigger the current.
• The higher the voltage, the bigger the current.
• The higher the voltage, the lower the impedance (for the human body)

For 50% of the population, 220 V hand-to-hand is an impedance of 1,350 Ω. This gives a current of roughly 0.2 A. This is lethal, but only just within that range. You can get lucky here and survive.

That same impedance, for 11 000 V could potentially give a current of nearly 10 A. Your power source in this example cannot drive that since you said it can at most drive 1 A. But that 1 A is clearly enough to kill a person and do so quickly.

So your question is comparable to asking if it is equally bad to fall from the 3rd floor of a building vs falling from the 100th. Answer: both of them are really bad. In both cases you are very likely to die. But for the 100th floor fall, the drop is guaranteed to kill you. In the 3rd floor drop, you might survive.

Hence the answer is: no, the 11 000 V voltage is more dangerous and a guaranteed death, while the 220 V voltage is possibly survivable.

[I think this probably belongs on another SE site, but I don't know how to suggest it be migrated to one not on the standard list, so here's an answer anyway.]

Probably not. The current only matters insofar as it might limit the current that can be driven through you, depending on your resistance. The resistance of a person is rather complicated, but it looks like $1000\,\mathrm{\Omega}$ is a reasonable compromise figure: the resistance of dry skin to low voltages can be very much higher than this, but as soon as the voltage gets reasonable it drops rapidly to somewhere in this region.

So we can compute the current that the voltage 'wants' to drive through you:

• for $220\,\mathrm{V}$ this is $0.22\,\mathrm{A}$, with a resulting power dissipation in the body of about $50\,\mathrm{W}$;
• for $11000\,\mathrm{V}$ this is about $11\,\mathrm{A}$, so the thing us current-limited, and I will assume that the voltage drops to $1000\,\mathrm{V}$ which is the point at which it will drive an amp through you. So the power dissipation in this case is $1000\,\mathrm{W}$.

The second case is going to burn you pretty badly, the first isn't. Both, in the right circumstances, can foul up your nervous system and, in particular, stop your heart, but the second case is going to cause massive physical damage as well if sustained for any length of time.