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I've recently started consistently getting electric shocks from either touching the tip of my laptop charger while it's plugged in, or from touching the metal rim of the laptop while it's charging. Just now I got two in a row, seconds apart, one from touching the tip while picking it up to plug the laptop in, then seconds later from touching the rim after plugging it in, and others in my household have experienced the same. It's definitely not from static electricity.

I don't really know how to grade electric shocks but these are painful enough that I gasped audibly and jolted my arm before I knew what was happening, but the pain then went away quickly and there's no lingering burning sensation or visible burns on the skin. The charger is 19V, 4.7A (three pin UK-style plug, metal third pin, when these are metal it usually indicates that it's to earth). It certainly felt worse than 19V.

I've read How to Earth (ground electrically) my laptop which mentions the possibility that AC is "leaking" through the charger and that this could be dangerous, and it recommends replacing the charger (which is very difficult given my current location).

I'm also considering that the socket I'm connecting to might not be properly earthed, or otherwise misbehaving, particularly after reading Got shocked by a native dell laptop charger outputting 19.5 V 6.5 A DC. It was REALLY uncomfortable, but was that dangerous?.

The electrics in this building are a bit dodgy, and there was recently a problem resulting in both the neighbourhood mains transformer being replaced and our compound's diesel generator briefly going haywire and outputting too high a voltage with many surges up to 400V, blowing several bulbs and fuses, which turned out to be related to bad wiring (I didn't entirely understand the electrician's explanation, but it sounded like something to do with crossed wires and power leaking back into the generator). There were also strange goings-on, since fixed, like for example, I had a certain battery charger where if I plugged it in to any wall outlet, the power for the entire house would instantly go out until I unplugged it, when it came straight back on again (and this charger never worked again after this happened - presumably it blew a fuse but there's no obvious user-accessible fuse I can check).

Also, the surge protector socket I connect the laptop charger to has been behaving oddly recently, feeling very hot to the touch when it's on, and its in-built USB sockets stopped working when the power surges from the generator happened (but its regular sockets still work).

How can I safely test whether it's a) the charger, b) the surge protector sockets or c) the wall outlet that is causing these shocks?

I don't currently have one of those live voltage checking screwdrivers mentioned in the second linked question, but I do have a regular digital multimeter. I'm considering using it on the adaptor plug in AC mode (while wearing rubber gloves!) to see if there is in fact AC leaking through the adaptor and at what voltage, and seeing if it's all the wall outlets, just one, or only when connected to the surge protector, but I'd like some expert guidance before attempting anything.

Update - here's the info on the adaptor block. It's the official adaptor for a Wacom Cintiq Companion 2 bought in Europe.

enter image description here

I'm not entirely sure if this means it's double insulated or not, based on Earthing: Is it important for laptops, there's a GS symbol but it's slightly different to that linked one and too small to read. It does however definitely say:

ONLY CONNECT TO GROUNDED OUTLET

Related on the electronics site: Why is this laptop adapter grounded?

Update: I just had another shock, this time from the metal casing while the charger was plugged in but not switched on, several hours after it was last used.

Second update: I've tried the plug with a multimeter, in both AC and DC modes, while plugged in and not plugged in, and it picks up no volts each time. Still works fine. So it seems like there's nothing coming through unless it's connected to something that is trying to draw power.

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  • I know this is old, but did you ever figure this out? I'm having the same issue.
    – pfinferno
    Commented Feb 23, 2020 at 17:26
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    @pfinferno It's a while ago but if I remember right, I figured out that some of the wall sockets in that apartment building weren't earthed (grounded) and some were, and I simply stopped using the non-earthed ones and never had the problem again. I think I tested them using a particular cable which had an LED that lit up if the socket it was plugged into was or wasn't earthed. But the cause might be very different in your case.
    – user56reinstatemonica8
    Commented Feb 23, 2020 at 17:33
  • Thank you! I'm leaning towards my wall outlet being the culprit as well. I'll have to look into that type of cable that lights up.
    – pfinferno
    Commented Feb 23, 2020 at 21:41
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    @pfinferno You'd be better off going to a hardware store and looking for something designed for the purpose ("socket tester" appears to be a thing), I just happened to have one of those lying around.
    – user56reinstatemonica8
    Commented Feb 23, 2020 at 21:43

3 Answers 3

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No testing needed. Nothing wrong with the outlet can do this in a double insulated device. Replace your charger, ASAP.

This is a safety issue, because it only takes 30 milliamps of 60 Hz current across your chest to stop your heart...

In the United States, the Occupational Safety and Health Administration (OSHA) has published an online brochure that makes the point that grounding won't save you. A grounded (earthed) outlet prong only works if the insulation fault in the equipment is fully connected to a proper ground (cold water pipe or ground stake deep enough in the earth). If you're a better conduction path than the ground conductor, you get the shock instead of the ground wire.

Better than grounding is double insulation -- as long as the device isn't tampered with or damaged, a double insulated device can't shock unless it gets wet or is exposed to conductive dust (metal shavings, etc.). These are recognized by a two-conductor power connection, and often an all-plastic housing.

The only dependable protection (according to OSHA) from insulation fault shocks is a Ground Fault Circuit Interrupter (they go by different names in other countries). These detect tiny differences in the current on the hot and neutral wires (ignoring the ground wire) and shut off the circuit if the two aren't equal. Before you can perceive a shock, the GFCI will shut off the power to the device and trip its warning (usually a visible button popped up, similar to a circuit breaker showing tripped). That's your cue to replace the device, or get it repaired by a professional.

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  • Interesting, according to Earthing: Is it important for laptops I can check if my adaptor is double insulated from symbols on the block. It has a symbol similar to one of the symbols on that link, but not identical, and the block says "CONNECT ONLY TO GROUNDED OUTLET" - I'm added a photo to the question
    – user56reinstatemonica8
    Commented Mar 17, 2016 at 11:17
  • I've edited to add more electrical safety information, but read again my second sentence: NO FLAW IN THE OUTLET CAN CAUSE THIS if your device isn't faulty as well.
    – Zeiss Ikon
    Commented Mar 17, 2016 at 11:29
  • I wonder if it's possible something like what is described here is happening
    – user56reinstatemonica8
    Commented Mar 17, 2016 at 11:50
  • It would be rather bad practice in devices that run on 5V or less, to connect the case to 120V (or 230V in Europe), even via a capacitance. The AC leakage across the capacitor would be enough to destroy CMOS IC circuits. And even if that's the case, it's not a flaw in the outlet, it's bad design in the charger.
    – Zeiss Ikon
    Commented Mar 17, 2016 at 12:26
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In my country, grounding outlet pin is not connected. So, I wired my desktop casing to steel nail on the wall. It succeed to eliminate electric shock from my desktop casing.

I also added separate wire for my electric water heater grounding outlet.

In your case - if your ground pin outlet is not connected to anything - you can connect to steel nail on the wall. (Do not use domestic plumbing as grounding!)

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  • Grounding to a nail in a wall? That sounds like something way dangerous
    – htmlcoderexe
    Commented Dec 20, 2020 at 13:27
  • htmlcoderexe why dangerous? Not going to puncture anyone.
    – RainerJ
    Commented Dec 29, 2020 at 0:19
  • Because the point of grounding is to provide an alternative path for the current that has "gone astray", for example, energising an appliance's conductive outer shell. This alternative path is set up so that the current 1) is more "willing" to take it - so a low resistance towards "ground" where it simply disperses... sorta and 2) causes less damage / damages less valuable things on its way. A nail in a wall is not guaranteed to do 1) if the part of the wall it goes through has nothing conductive and 2) if it does provide a path, it is unpredictable (could be through water pipes for example)
    – htmlcoderexe
    Commented Dec 29, 2020 at 0:27
  • 1. I don't really prefer the way, but better than nothing (it works!), 2. We are talking about trickle leak currents here, not dangerous mains.
    – RainerJ
    Commented Dec 29, 2020 at 0:30
  • We don't know exactly the amount of leaking - and it seems a generally bad practice that will get someone shocked at some point. You also mentioned an electric water heater, I hope that isn't grounded to a nail as well. What country is it? Often it should be possible to retrofit a proper ground even if the code doesn't require it (which is sorta strange). I am not an electrician by trade, though, so I hope a proper sparky will see us discussing and explain one way or the other.
    – htmlcoderexe
    Commented Dec 29, 2020 at 0:37
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In my case it is Boat 65W GAN charger PD 3.0 (DC Volatages 5, 9, 12, 15, 20 depending on item to be charged, 2 pin type, without any grounding ) It developes 93V AC when measured on metal part with earth. If body / finger not fully dry, it gives electric shock. On touching with dry finger and foot, it is reducing to 55V (boat replaced 3 times already) without perceivable shock. The short circuit AC current is 4.3 Amp

It may be noted my earthing system is ok as indicated by earthing healthiness instrument and The leakage AC voltage is in reference to the same earth only (If it is cut, or damageged, 4 amp short circuit current cannot passed and earthing of other laptop chargers cannot be effective.

In similar condition ,for other low wattage chargers 18w, 24w (DC Volatages 5, 9, 12) the max AC voltage is 10V Max and once we touch metal part the voltage is dropping to like zero to 2 V AC. I have another charger (similar i.e plug type 3 pin type 19.7 V but round pin type, it's exposed metal round part has zero AC voltage.

Regular round jack laptop chargers (I am having Dell 65W, 120W) always have 3 pins at input and they are not at all having any AC voltage at exposed metal part of Jack.

I have purchased Dell 65W USB C , it also has ac leakage voltage problem @100V

Since it is giving electric shock if our fingers not fully dry (like just bathed), there is design fault or manufacturing defect.

Update on 05.06.2024

In view of above on request one shop person has agreed for AC voltage checking. I have gone with multimeter and milti socket plug. He offered same Dell USB C charger and to my surprise it has only 0.0 V AC. But it is 90w and having led on USB C plug. I have purchased it for Rs1800 and power cord for Rs 100.00 I came back to home and repeated the test , at home it is at AC 2.405 V.

So not every USB C charger develop a leakage AC volatage 90 to 100v i.e with proper design and implementation it can be eliminated. After coming back

From the above experience and technical point of view.

AC potential develops but it will be suitably earthed so that no potential exist in 3 pin type chargers.

  1. If it was working normal before this incidence, please check the healthiness of your building earthing or charger's AC potential discharge circuit became defective.

  2. If it is faulty from the beginning (if healthiness of building earthing is Ok) it is a design fault (like in my case above) or manufacturing defect.

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