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.

Comments

  1. BobFeg says:

    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.

    • vic says:

      Looks like the trend of humorous electronics commentary is catching on.

    • Fred says:

      Thousands of people every year would respectfully disagree, including myself trying to fix a fan when I was a kid.

      • Larry says:

        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.

        • Dax says:

          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.

          • Tim says:

            I’m pretty sure the RMS values can only be used like that if the signals are sine waves.

          • Dax says:

            Such systems can be viewed as a superposition of multiple sinusoidal waveforms.

          • Larry says:

            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.

    • Sven says:

      What? AC conducts fine through the human body, the human body is basically salt water, meaning a pure resistive load.

  2. kwagattack says:

    i ove this guys videos. gets me everytime!lol.

  3. Dan says:

    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)

    • ChalkBored says:

      RMS

    • Fred says:

      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.

      • Garbz says:

        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.

        • Fred says:

          I forgot the *grabs popcorn*
          *grabs popcorn*

          • MDN says:

            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.

          • CopperMaze says:

            Wants some beer ?
            pssht *opening a can*

          • Blue Footed Booby says:

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

            Are you people new to the internet?

        • Paul says:

          +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.

          • smee says:

            Tell me more about the explosive potential of sewing machines.

          • Frank says:

            “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.

        • jaap says:

          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)

  4. SYNTRONIKS says:

    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

  5. benboy00 says:

    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.

    • Tim says:

      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.

  6. ejonesss says:

    thats the same way you can test 9 volt batteries though not all devices will work on weak battery for example the rem pod used by paranormal investigators and some emf detectors can give false readings on weak battery

    http://www.google.com/search?hl=en&output=search&sclient=psy-ab&q=rem+pod&btnK=

  7. MrX says:

    Check out his other videos, the guy is quite funny.

  8. truthspew says:

    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!

    • Garbz says:

      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.

      • truthspew says:

        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.

      • openmakersdaily says:

        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.

  9. Chris C. says:

    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.

  10. Joseph A. Bonasses says:

    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.

  11. CopperMaze says:

    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.

  12. Jay Mounes says:

    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?

  13. Axl Laruse says:

    Darwin Award waiting to happen.
    GO FOR IT! Amuse me!

  14. Cricri says:

    HaD should be weary about copyright infringement for posting clips from “Jackass the movie”.

  15. morganism says:

    Nine volt will kill you, even away from the tongue.

    somewhere on this website, and

    http://www.theregister.co.uk/2006/07/28/the_odd_body_death_by_battery/

  16. Mitch says:

    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.

  17. El_C0MmanDantE says:

    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.

  18. Fabricio says:

    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.

  19. CorrosiveOne says:

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

  20. sa_penguin says:

    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.

  21. HC says:

    He clearly said the AC hurts half as much as the DC, which would match common safety regulations.

  22. Sean says:

    Human schmooman. Which one kills an elephant faster?

  23. Bill Gander says:

    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 :)

  24. Oren Beck says:

    And then – there’s the opposite of pain:

    http://wireheading.com/wirehead.html

  25. Me says:

    What a Dickhead

  26. DaveO says:

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

  27. Grovenstien says:

    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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