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Okay.

My laptop was running out of battery. I grabbed my charger (outputting 19.5 V 6.5 A DC) which was plugged into the wall, and as I touched the end of the charger I got some electric shock going through my body to my other hand which was resting on the PC.

And I'm basically freaking out now. It felt far from good, but honestly I don't know if it is placebo (I'm kind of scared of electrical shocks).

So... How dangerous was this?

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migrated from electronics.stackexchange.com Feb 1 at 2:43

This question came from our site for electronics and electrical engineering professionals, students, and enthusiasts.

    
What country, what mains voltage? 2-pin or 3-pin mains plug? Is it the sort of 2-pin plug you can put in the wall reversed? If it was an unpleasant tingle, probably tens of microamps, quite safe, but if it felt ten times worse than a wasp sting get your wiring checked out... – Brian Drummond Jan 31 at 0:01
    
Sweden. 3-pin, grounded. These big round plugs. Thank you for your answer! – Noah Jan 31 at 0:23
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From your description, it may not even be the fault of the charger. The current flow as described is tip of charger cable, through your body, then the laptop. Now where does the current go from the laptop? So a guess is that the laptop is connected to something else that completes the current path. So there are at least two possibilities, charger leaks current from power line to the secondary side and the other laptop connection completes the path. Or the other laptop connection leaks current from line and the charger completes the path. Something is wrong and you should find out the cause. – rioraxe Jan 31 at 0:39
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@Noah Then this is going to be a bit hard to answer. As it has been mentioned in other answers, something had to complete the circuit. You're sure you got shocked when you touched the laptop and not before? Could it be that you stepped on something? Only thing that I can think of now would be to get a multimeter and use it to check the voltage between outside of the PSU's jack and pretty much all stuff you have near it. – AndrejaKo Jan 31 at 0:54
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laptop audio out wasn't plugged into an amplifier? – Jasen Jan 31 at 4:25

It's unlikely it was a placebo, if you felt it well enough to be able to say things like the path it took through your body. I certainly don't wish to worsen your fears (though honestly, a little more fear or respect concerning electricity is probably a good thing, it's easy to become complacent, I could probably stand to use more caution at times myself), but the shock was probably real.

The grounding where you are plugging in the laptop is bad. That's the third prong on the outlet. Either you're using a 'cheater' plug to circumvent the ground and plug a 3 prong plug into a 2 prong outlet, or that outlet (or your house/building) is incorrectly wired and either the ground isn't connected at that outlet, or worse, it's mis-wired as live.

9.5V (or, more likely, 19.5V, which I think is what you meant to type) would not be sufficient to be felt so strongly. Plus, if you're touching the DC prong, then it's not connected to the laptop, and all shocks require a circuit, or a loop, and there is no loop or return connection if the adapter is unplugged. No, this is a problem with the outlet or wiring in your house, unfortunately.

I would advise not using that outlet, or better, maybe that entire circuit, again until you can have an electrician or other qualified person check it for proper wiring. I have had this exact thing happen to me. In fact, at one point, I had a laptop with a metal case that experienced a fault where the outside casing become tied to live, which normally would throw the breaker, but the outlet wasn't grounded, so instead I kept getting shocks (I was standing barefoot on concrete, which is actually rather conductive and usually grounded to some degree in houses).

You're sure it wasn't just a static discharge? Like you get from shuffling across the floor in wool socks and touching someone's ear (if you're a joker like me). Was it continuous, or just a pop and over, even though you were still touching the adapter and laptop? If it isn't a continuous thing, and just happened once, it was almost certainly just static discharge. The outside prong will be tied to the outlet ground for safety, providing a terrific path for static electricity built up on, say, a plastic laptop, to discharge. These discharges are a fact of life, but also harmless. They are many thousands of volts, so will happily discharge through the relatively low impedance of your body, and other times, it can be YOU discharging, as you are the thing that has built up static charge. If it was that, do not worry. It wasn't anything to do with the charger or your laptop, so much as your laptop can build up a static charge like any other object, and you happened to be the path to ground for the discharge.

If you want to avoid this, grounding metal desks, or even yourself with a grounding strap, will prevent these build ups, but it's also kind of inconvenient. And again, they really are harmless.

BUT, if it is not static in nature and something that will happen for as long as you're in contact, then it is definitely a grounding problem. Where do you live? Or what voltage is your power grid there? If you're in the US, this is significantly less dangerous than if you're in a country with 230VAC+. Let me know, I'll update my answer.

Also, was it unpleasant, or was it actually painful? Was it mostly scary and weird and unpleasant, or was there a pin-prick sensation, a very sharp pain? Either at one or both points of contact, or even through your entire body?

More importantly, did it cause any involuntary muscle contractions? This is what can make a shock dangerous, but if there was no noticeable contractions, there is too much impedance for a dangerous amount of current to flow.

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I have no idea why you are getting downvoted. First of all - thank you for a massive and well-written answer! The plug on the charger is definitely not a cheater one. It is the stock Dell charger that came together with my laptop. And yes, I meant 19.5 V as I wrote in the title, not 9.5 V. Embarrassing that I can't even keep my numbers straight when I ask for help. Oh well. (continued in next comment) – Noah Jan 31 at 0:35
    
I am sure it wasn't a static discharge, since it was no "snap" at all. It was a feeling that continued until I lifted my hand from the laptop. No muscle contractions or really sharp pain though, it was simply a slightly painful but VERY uncomfortable feeling from my hand holding the charger to the one resting on the PC, through the chest. And it persists even now, on hour after it happened. (Might still be amplified in my head since I am scared of these things). I live in sweden, I think we have 230V in our outlet where I live. – Noah Jan 31 at 0:40
    
IIRC European outlets (the "big round ones") are 2-pin 230V with notches @ the top+bottom of the connector that have inset contacts to interface with spring-loaded ground "pins" in the outlet (something like the inner workings of a phono outlet). I have seen many european-style outlets whose ground "pins" were bent/broken & plugs with no metallic ground comtacts at all. However, mlst European style charging cords wouldn't have any exposed conductive "ground" surfaces, so my best guess is that @Noah contacted a part of the ac wire with damaged insulation & rec'd an ac capacitive shock. – Robherc KV5ROB Jan 31 at 2:52
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Most Swedish houses built before the 90's do not have grounded outlets and the (grounded) "Schuko" plugs like on the laptop charger in question fit these outlets. So, most computers in Sweden are most likely used without a ground connection without there being a "fault" with the wiring at all! – Johannes Jan 31 at 13:10
    
@RobhercKV5ROB, there are two distinct connectors types. Compact "Europlug" aren't grounded and typically rated 2.5A and grounded Schuko which are 16A as per standard. Schuko socket is compatible with Europlug. See ikea.com/ru/ru/images/products/… – Free Consulting Jan 31 at 19:33

It's quite common on switching power supplies that may look like they use the earth prong (but actually don't) to use EMC filter capacitors from the DC output side to the rectifed AC on the power input connections. The capacitors are normally about 1nF in size and you can get a tingle doing what you did but it won't kill you: -

enter image description here

Note C13 at the top of the picture - it's 2.2 nF.

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There are screw drivers for electricians with a discharge light inside for checking for live voltage. Check your power supply (be sure not to shorten it, just touch the laptop-side plug on the outside) with it while plugged into the wall.

Do the same with your PC. If both have three-pin power plugs, either one of the powerr supplies or its cables is malwired, or, unfortunately almost more likely, your power socket is. Check out the earth contact with your screw driver. That will tell you whether it is malwired (the worst case). Another possibility is that it's not wired at all (or the wire came off): that's harder to check and more like an electrician's job. But you can cross-check with other power sockets (assuming that there is at least one sane one).

Note that the power sockets usually have two orientations. Results may differ depending on how you plug in your plug. So for comparing results from one socket to another, try both orientations on either socket.

If it's the socket, complain to your landlord. This is a life-threatening building fault.

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Well, you're not injured, so you're going to be fine. You didn't get shocked by the 19.5V/6.5A, you got shocked because you were probably charged up to a few kV by static electricity (this is common in the winter, when humidity is lower, and you often wear wool socks) and then this energy jumped from your finger to a "ground" on the charger. I put "ground" in quotes, because it was likely not a real ground, but still able to absorb the static shock.

I don't know if there have been any reliable studies of the chronic effects of static electricity on the human body. I can tell you (having played around with ESD test equipment) that human body model shocks over 20kV are rather painful, but seem to have absolutely no lasting effects. Obviously, sustained shocks at these voltages are a completely different story.

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Thank you for your answer! However, this didn't feel much like static electricity since it was no "snap" at all - it was a awful feeling that continued until I rose my hand of the laptop. I might be exaggerating how bad it was since I'm scared about these things, but it was certainly not pleasant. As long as it is not dangerous, Ill feel well. Otherwise I'll throw the cable out. Not knowing if this was bad scares me. – Noah Jan 31 at 0:16
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Noah, I've actually experienced a fault where the outside of my laptop was at mains potential and was continually shocking my hand (I was grounded through concrete) while using it at a LAN party. It's not going to kill you, but its definitely not ok. What you're describing is something that does sometimes happen. It often must be a problem with both the wiring in the outlet, AND an electrical fault in the power brick (the cable is irrelevant, its the power brick itself that would have the problem). See my answer. – metacollin Jan 31 at 0:29
    
@Noah Don't trow the cable out!!! If you do, and it's not just the cable, you could be hiding symptoms of a much more serious issue!!! Keep the cable until you determine what's the fault. – AndrejaKo Jan 31 at 0:41
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Oh. Well then. That's not good. If it wasn't static electricity, something is not right; either your house wiring or the charger has a serious fault. From your comments, it sounds like 230V is somehow making its way through the charger. I've touched 230V and 120V before, and while it won't kill you unless you're unlucky, it's definitely not pleasant. @metacollin's answer is definitely more relevant: an electrician is in order. – uint128_t Jan 31 at 0:50
    
You guys are awesome. I'll try to convince my landlord to get an electrician to our apartments. A massive thank you all for all the help, it's kind of amazing to have competent and kind people helping complete strangers on the internet. BIG kudos! :) – Noah Jan 31 at 0:55

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