You are viewing a single comment's thread.

view the rest of the comments →


[–] bluefascist 0 points 41 points (+41|-0) ago 

I got news for you.

When he took the juice, it was 220V, not the 5V chargers put out.

The chargers put out 5V at 500mA. This would never cause the reaction seen in the video.

What happened is that due to terrible engineering, the 220V source somehow made it the the wires meant to carry 5V at 500 mA. The current draw would depend on the conductivity of his body. I doubt it was 500 mA. Quite a bit more is likely.

And this is why electrical engineering is a discipline that requires study and mentorship.


[–] Behuvius 0 points 11 points (+11|-0) ago  (edited ago)

I agree with your assessment. In engineering school, I think we estimated each limb to be 300 - 500 ohm.

V = I * R 500ohm *.5A = 250V Or 440ohm * .5A =220V Anyway somewhere in there. Definitely not 10ohm (5V/.5A)

Its gets tricky if you dont know what limb the voltage grounded out at.


[–] MyDrunkAccount 0 points 4 points (+4|-0) ago 

Witch! You think I wouldn't recognize your sigils and hexes hidden among real words? Be gone!

[–] [deleted] 0 points 1 points (+1|-0) ago 



[–] TalkingAboutThings 0 points 0 points (+0|-0) ago 

Your insides might be that low, but the skin is relatively high impedance. You have to get enough current through it to cause it to burn/melt/break down for it to dip into the neighborhood of 300- 500 ohms. If you actually measure contact resistance from one hand, across your chest, to the other, it's going to be at least 100k - 200K. With wet fingers, you might be able to get it down to 60-70k.

Most people think a lot of current passes through your body when you touch electrical mains because they're capable of supplying so much and most people don't know Ohm's law or the typical resistance of a human body. Unless it burns through your skin to the gooey insides, you're looking at ~4-5mArms (max) through your body when touching 240V mains. Which is still enough to kill you, of course.


[–] malloryquinn 0 points 0 points (+0|-0) ago 

Most power strips and breakers are 10 or 15 amp


[–] 12702164? 0 points 6 points (+6|-0) ago 

Yes, it's the current that kills, but the magnitude of current depends on the voltage received, since the body has a different resistance / impedance than the elements the voltage will typically exist across. 5 V is not nearly enough to produce the necessary current through a human body to be fatal. 220 V could do it.


[–] myvoicefromhell 0 points 6 points (+6|-0) ago 

Because of some jackass electrician short wired an electrical box, I got hit with 240v one time and partially welded the metal cover to the box. I was kneeling on joists up in the ceiling over the men's restroom in a mall. I almost fell through. That shock fucking hurt my left arm for an hour or so. It wasn't any kind of fun. No permanent damage, though.


[–] BlackGrapeDrank 0 points 5 points (+5|-0) ago 

"When he tried to pull the cord out, he got shocked and cried out. Then he touched it again and his foot hit the steel pipe underneath the desk," his brother explained."

Poor China kid became a conductor to their shit grounded power system with no surge protection.

He got the full wack.

[–] [deleted] 0 points 3 points (+3|-0) ago 



[–] karmatic 0 points 3 points (+3|-0) ago 

500mA is what proper USB is going to try to limit things to. There are a few ways to signal a computer to allow more, and many chargers let you draw more (and signal the device that it can).

This is going to be a failure in the transformer, so that the low and high voltage sides are connected. At that point, I wouldn't count on any current limiting circuitry doing anything.

Once an initial shock starts, the resistance of the human body drops to around 500 ohms. At that point, Ohm's law will limit you to around 500mA. That's not going to blow the breaker, so that really sucks.