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i know this is a silly question, but i couldn't manage to wrap my head around it. I am kinda new to electronics.

My home's outlets provide 220V. Upon doing some (a lot) research, the current that this voltage can supply is enough to kill me. However, when i try to do the maths myself, i can't seem to get the correct answer.

according to google, the current needed to kill a person is between 0.1 and 0.2 amps and the human body has a resistance of 100,000 ohms.

Say one day i decide that i don't want to live anymore and put both my fingers inside the outlet completing the circuit.

So, considering the formula V=I*R,

220 = I * 100,000 -> I = 0.0022A

which is way less than 0.1A that is needed to kill a person. I know that i am doing something wrong here, but i just couldn't figure it out. Some help would be really appreciated.

[edit] this question was just to ask if my maths is correct. I am trying to build a toy stun gun (harmless stun gun?) But, i wouldnt want to just find out if i got the voltage right by testing it on myself. So i figured if my maths is correct, i can calculate how dangerous my toy stun gun will be (i can not find something like that on the market where i live) do you have any advice? Or is it just too dangerous for me to even try?

[edit 2] Thanks to everyone for answering my question. I have come to conclusion that stun guns are way more dangerous than i first assumed and not something i should mess around with. gotta find another project, i guess~

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    $\begingroup$ From Wikipedia: The NIOSH [National Institute for Occupational Safety and Health] states "Under dry conditions, the resistance offered by the human body may be as high as 100,000 ohms. Wet or broken skin may drop the body's resistance to 1,000 ohms," adding that "high-voltage electrical energy quickly breaks down human skin, reducing the human body's resistance to 500 ohms" And here's an article from 1884(!) $\endgroup$
    – Philip
    Commented May 28, 2020 at 16:29
  • $\begingroup$ Firstly I don't know what to say to this'"Say one day i decide that i don't want to live anymore and put both my fingers inside the outlet completing the circuit." Also, there are several other higher sources of electricity... $\endgroup$
    – user600016
    Commented May 28, 2020 at 16:38
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    $\begingroup$ "I am trying to build a 'toy' stun gun" Please do not do this. How would you feel if one of your "victims" has an undiagnosed heart condition and your toy taser sends them into cardiac arrest? $\endgroup$
    – PM 2Ring
    Commented May 28, 2020 at 18:47
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    $\begingroup$ I believe the human body is more like a capacitor than a resistor which is why AC current is more deadly than DC current at the same voltage. We all know Q=CV so the derivative wrt time is I=CdV/dt so find the C $\endgroup$
    – ChemEng
    Commented May 29, 2020 at 2:47
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    $\begingroup$ @KağanAtalay For the sake of whatever family and friends you currently have, I still suggest you don't do this, even if you only use it on yourself. $\endgroup$
    – probably_someone
    Commented May 29, 2020 at 3:34

4 Answers 4

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I don't know what sources you are looking at but according to this site, the 100,000 $\Omega$ value is a high value, and other conditions (wet skin, sweat, individual variations in body chemistry, skin contact area) can make the resistance as low as 500 $\Omega$.

Other physiological factors during electrocution could lead to death. One particular event is cardiac fibrillation which can occur for 30 mA (0.030 A). Electrical skin burns could easily become infected and lead to sepsis.

And, speaking from personal experience, even with a high body resistance, a 220-V shock for as little as 1-2 s is extremely unpleasant and can take your motor skills and strength away for several hours.

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    $\begingroup$ Try 240 V for around 30 seconds. I was 9 years old at the time, but I still have a scar on my fingertip several decades later. $\endgroup$
    – PM 2Ring
    Commented May 28, 2020 at 18:58
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I would like to add that the capacitance of the human body can provide a parallel path for the current to flow, and allow a higher current to flow through your body than you might otherwise think based purely on the resistance of the body. This is why touching a live wire can shock you even when you are wearing insulating soles.

That said, at the risk of getting downvoted to oblivion, I would argue that, realistically, shocking yourself for a fraction of a second with a typical stun gun that can produce even much higher voltages than 220 V is not necessarily dangerous, as long as the terminals of the stun gun are close together, and away from your heart (or other sensitive organs). It will still be very unpleasant, and you might even get a minor burn, but it won't be lethal. This is partly because the current will be localized around the terminals, and once the terminals are in contact with your skin, your body will load the stun gun circuitry and quickly reduce the output voltage. The latter does not apply to mains voltage however, and you should not short an electrical outlet with your body.

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The result depends on where, on your body, and how well, your are grounded. I have made contact with 110 volts a couple of times. Both times I was able to walk away with no noticeable after effects, but its not something you do for fun. A friend of mine grabbed an improperly wired stern light (at 12 volts) while submerged in a warm ocean. He survived, but complained a lot. I bought a used sail boat from the widow of the owner. He drove the boat, on a trailer, with the mast up, into a power line. He died when he stepped out of the car (probably in salty wet tennis shoes).

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  • $\begingroup$ yes a taser can be 10 of thousands of volts but it is between the two points on the device so just on your finger $\endgroup$
    – ChemEng
    Commented May 29, 2020 at 3:07
  • $\begingroup$ This looks more like an account of your (and your friend's) experience with high current and voltages, rather than an answer to the OP's question. $\endgroup$
    – user258881
    Commented May 29, 2020 at 6:21
  • $\begingroup$ I was just illustrating the variability of the factors that affect the result of a shock. $\endgroup$
    – R.W. Bird
    Commented May 30, 2020 at 17:23
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This is a common misconception. Current is usually not the culprit, it is the voltage that kills. Specifically, the voltage drop across the heart.

A current is only a flow of charge. In most cases, a current flowing through a conducting body element doesn't really affect it much, because whatever charge is lost at one end, is immediately replenished at the other.

On the other hand, voltage encodes information, apart from energy. And the primary way that it kills is by disrupting the heart cycle through its information component, not its energy content.

Current is the vehicle of delivery of that energy. However, delivery of energy isn't the primary cause of death by electric shocks. Deaths by most electric shocks occur because of cardiac arrest, not because of burning.

The cardiac action potential is < 100 mV for all its phases. Thus, even a few volts applied directly to the heart is enough to disrupt the heart cycle and cause cardiac arrest. Fortunately, when we get an electric shock, most of the voltage drop doesn't occur across the heart.

In this case, the information content of the voltage is the lethal agent. A few volts applied to the heart are harmless to the tissue. However, they wreak havoc with the information pathway of the cardiac cycle leading to a cardiac arrest.

Having said that, current remains the vehicle of delivery of energy, and extremely low values wouldn't make it to the heart, however high the voltage. But once a circuit to the heart is established, it is the voltage that induces the cardiac arrest by disrupting the cardiac cycle.

This is why even a few volts applied at the wrong place on the body could be dangerous, making your plan for the toy stun gun imprudent.

An entertaining as well as instructive video on this topic was made by the popular YouTube educator Mehdi Sadaghdar.

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    $\begingroup$ "Current is relatively harmless" - Is this peer reviewed article incorrect? Fatal Current $\endgroup$
    – Alfred Centauri
    Commented May 28, 2020 at 18:06
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    $\begingroup$ I don't think you are correct. According to scienceabc.com/humans/how-many-volts-amps-kill-you-human.html and 2 more websites ive visited says the opposite $\endgroup$
    – Kağan Atalay
    Commented May 28, 2020 at 18:09
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    $\begingroup$ I also disagree with this answer. People have survived huge voltages, eg from lightning strikes. And people can easily cope with >100 kV at extremely low current from Van de Graaff generators. $\endgroup$
    – PM 2Ring
    Commented May 28, 2020 at 18:59
  • $\begingroup$ @PM2Ring As I said, it is a common misconception. It is quite well established that cardiac arrest during electric shock occurs due to voltage applied to the heart, not $i^2R$ heat damage. Having said that, current remains the vehicle of delivery of energy, and extremely low values wouldn't make it to the heart, however high the voltage. But once a circuit to the heart is established, it is the voltage that induces the cardiac arrest by disrupting the cardiac cycle. I have edited my answer to further explain my point. $\endgroup$
    – Ritesh Singh
    Commented May 28, 2020 at 19:26
  • $\begingroup$ Can you really have a high current without a high voltage? arent they intrinsically linked? $\endgroup$
    – ChemEng
    Commented May 29, 2020 at 3:06

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