AC vs DC human pain test

AC-vs-DC-human-pain-test

Ever wondered just how much being zapped by electricity hurts? Curious if AC is worse than DC? Want to know just how many volts a human body can take? Although many people might cringe at the shear thought of it, [Mehdi Sadaghdar] is an electrical engineer who decided to turn himself into a human guinea pig and find out.

[Mehdi] measured the electrical resistance of his dry skin, his wet skin, and finally his tongue.  He found that his tongue had the least resistance, so it would feel the electricity at much lower levels. Using a bench power supply, he then used his tongue as a testing ground – slowly turning the voltage up and up until he could no longer take the pain. He tested the levels at which: he could first feel the electricity, when it began to get annoying, when it felt like torture, and when he could no longer stand the pain. He tried both AC and DC, and reports that AC is much worse.

Check out the informative, yet admittedly hilarious at times, video after the break. [Mehdi] seems like one awesome engineer! Remember – don’t try this at home.

62 thoughts on “AC vs DC human pain test

  1. AC does NOT conduct across the human body according to Ohms Law.

    It is more complicated than that…resembling somewhat conduction through a fluorescent tube.

      1. I think what he means is that ohms law only holds for DC, which is true. In order to really understand how AC current flows through something, it is necessary to take into account boundary conditions and go back to Maxwells. However when the transmission line (in this case your body) is much much smaller than the wavelength, Ohms law is a good very good approximation. Since 60Hz is such a low frequency it only gets hairy when you’re transmitting very long distances. That is where telegraphers equations come in.

        1. The Ohm’s law for AC is V=ZI where Z is the impendance of the system, which includes resistance and both inductive and capacitive reactances.

          You can calculate it using RMS values, which gives you RMS values out, or you can do it with complex numbers which preserves information about phase angles etc.

          If you have more than one wave frequency, you calculate them in parallel.

          1. Take a course in electromagnetic waves. KCL does not apply for any AC. Like I said previously, Ohms law can be a very good approximation for AC, but in many cases it isn’t.

      1. And integrated circuits don’t work.. if you don’t take the dopants into consideration since those are just a tiny fraction…

  2. But which is more dangerous to life? I remember seeing a debate on a forum full of electrical engineers with no consensus.

    Also, does he say whether he is measuring the AC peak-to-peak or RMS? (I didn’t watch the video)

    1. DC current makes your muscles cringe in one position, making it more difficult to pull you off as you grab whatever is electrocuting you with all the strength your muscles can physically provide. AC gives you a series of jolts, letting you relax your muscles 50 times a second, so you never get to grab that with all your might; a firm pull in the opposite direction will get you free.

      1. As someone who has seen someone get hung up on AC voltage before what you’re saying is absolute garbage. My college broke 2 fingers and dislocated his shoulder when his safety guard ripped him off the bus bar with a crook.

        Also AC also has a higher chance of causing fibrillation and is much more dangerous to be passed across the heart. This is one of the reason that maximum safe touch potential is defined as 110VDC and 50VAC in many countries.

          1. No need for popcorn, you’re just plain wrong. 50 Hz is at or near the tetanic fusion frequency for most major muscles, meaning a person will lock up from AC just as much as they would from DC.

          2. >>MDN
            The “grabs popcorn” meant that was a troll.

            Are you people new to the internet?

        1. +1 on the garbage comment.

          Try a 240v Ac shock and see what happens. Just about everyone in Australia (240) is taught to never ever grab or pull away a person who is undergoing a 240v shock, or your muscles will hold you on as well.

          You should take a flying leap at someone to knock them away from the source.

          And from personal experience as a child some 40 years ago, when i stuck my finger into my mother’s sewing machine light socket, thinking the power was off, I woke up a few minutes later about 20 feet away on the other side of the room, having hit the wall and blacking out for a bit.

          At least I was lucky and hadn’t grabbed a live wire.

          1. “Just about everyone in Australia (240) is taught to never ever grab or pull away a person who is undergoing a 240v shock”

            Really? Must’ve missed that class.

            I remember a while back “experiencing” 240 volts. An AT power supply with the power switch cable dangling out the side of the case because the case was too old for a regular AT supply (Might’ve been an older XT case or something?). I touched the “wrong” part of the switch – gave me a good enough jolt. I think i even “felt” the vibration of 50hz as well. I invested in a proper case after that little lesson.

        2. Real countries use 240 VAC!
          I always “test” with the outside of my fingers first.

          Another neat effect is that with a high enough frequency, the skin effect will prevent the current going too deep into your body. (I did not try that yet)

  3. I know about IV relationships but clinical electrical neurostimulators use current sources and they are not difficult to build. I’m sure this is a funny video, I’ve seen this guy before xD

  4. The path from one fingertip to the other is much longer than the maximum distance that he could place the electrodes apart on his tongue, so I’m pretty sure his claim that the resistance of the tongue is “at least 30 times less than the resistance of dry skin” is pretty incorrect.

    1. Most of the resistance is indeed in penetration of the skin – after that, it traverses using your wet salty innards whose resistance is much less (some 1-2 digit K-ohms). You can confirm this checking an ohmmeter with one lead in each hand, then put both leads on the same finger. The resistance may change, but not drastically.

      If the leads pierce the skin you can measure some very low resistances. EMD (electromuscular disruption) devices such as Tasers (NOT stun gun – the kind that fires barbs into the skin) work on this principle – a low frequency (~13Hz?) AC across the torso subcutaneous can turn your legs to jelly at fairly low voltages, at least for a little while.

  5. Never been bitten directly by AC current from an electrical outlet, oh no. Instead I’ve been burned by RF energy which is essentially an AC signal. Ouch!

    1. Consider yourself lucky. A deep RF burn is painful but unlikely to be fatal. The low frequencies are what can cause your heart to miss a beat … or all the beats.

      1. Yeah – I got 50W at 28MHz. Radial on an R8 tagged me in the right ear.

        And yes – voltage and current can kill you as dead as you’ll ever be. WRT to DC I generally won’t deal with anything over 30VDC. Though the hack for triggering the coin relay on my Western Electric 1D2 payphone requires 130VDC so I cobbled together a bridge, capacitor and it goes right to the phone. Now it triggers the coin relay – but requires a relay on the other side to handle the high voltage.

      2. tell that to the guy that crossed a radar beam in a lab. He fell on the floor like a fly within seconds.

        50W RF okay, but you were likely protected by the 50 ohm source impedance that was in series with you.

  6. DC: You think it was just a momentary discharge from a capacitor, until you notice your skin heating up.

    From experience. I agree AC is more painful. Both AC and DC are dangerous, for different reasons.

  7. Which one is more painful? It depends on the points of contact. A 20 mm gap across the tongue? OK, DC it is. But a conduction path through your hands, arms, and your central nervous system, the results will be much different. Or one that goes just through one side of the body, but results in currents high enough to cook your arm in under a few microseconds (i.e. an arc flash for example)? Probably difficult to quantify “how much it hurts”……….perhaps “can’t feel anything ’cause I’m dead” might be an accurate description.

  8. Funny thing is to know that a reaally serious nerve passes trough the tongue, in the middle, directly connected to the cortex. Piercers are really careful when doing a tongue because of it. Even if they can’t kill someone, one can loose speech ability…! The point is peoples are dying every year from testing 9V batteries with their tongue.

    1. Yeah I heard that on youtube, people are dying of 9 volt batteries.. oh and it’s the fault of the zionist cabal if I remember correctly.

      Also why doesn’t HaD ever publish the schematics of perpetuum mobiles? IT’S A SECRET DEAL TO DEPRIVE US!

  9. At some point, the writers for this page got the idea that the “a day” part of “hack a day” totally literally, and here we are, full-retard. Is this HaD or Jackass?

  10. It’s called “Guess the Voltage.” My friend and I played this back in college years ago. It’s especially fun the night before you have a lab report due.

  11. Silly amateur !

    I’ve extracted more confessions from enemies of the people,
    by using wet sponges attached to a high voltage variac !! – it
    is quite satisfying when the traitor betrays his comrades.

  12. Humm, let the third world do the job? Well, here in Brazil we are good on it, but we start the torture at from 220VAC.

  13. The guy is funny… I’ve watched him before.
    Obviously a bit dangerous, I’m about fedup with the useless content on HAD though…….

  14. I’m reminded of the time, over 20 years ago, we checked out a radar (Air Traffic Control – SURAD – 1.5MW pulse output @ about 1.2GHz, from memory). We cable-tied a raw steak to the dish mesh, got to a safe distance to monitor [with binoculars], and started it up.
    The steak didn’t last very long.

    1. And throwing a piece of steel wool in front of an operating radar dish leaves no doubt as to the power in the beam (it catches fire)

  15. I love this guy’s videos :) He is definitely not afraid to make mistakes and takes some of the stuffiness out of these kind of vids. +1 :)

  16. If only the CIA would release the results from their GITMO research facility to save us doing this painful research.

  17. Sometimes I think HAD posts hacks like this just for the internet traffic!! Hilarious video – love it, bottom line be careful with any voltage especially if you don’t know what your doing…

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