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Comment by hedora | Hacker News Reader

Would this explain all apple devices shocking me while charging?

(But to varying degrees, depending on the day, and not if I use a three prong plug for the USB power source.)

You already nailed it. Use the three prong plug. If you don’t, stray voltages can occur on the metal casing of your device. I also learned that some usb-c cables connect ground to your device (via the charger) and some don‘t. It‘s not as universal as it is marketed.

EDIT: Your neutral is probably ok.

I’ve been annoyed for the longest time that Apple in North America only sticks grounded plugs on their 1m+ power cables. Very inconvenient for travel. I don’t want to bring an extra 1m cable in my carry-on. I want the little two-prong “duck head” adapter—just with three prongs.

Turns out there’s one third party making them now! (Sadly, their jack doesn’t fold flat like the two-prong ones do, but I’m willing to take that compromise.) https://www.amazon.com/Grounded-Duckhead-Apple-Mac-Adapter/d...

No, that's a different (and often "officially allowed") thing. I believe it has to do with stray capacitance. A lot of 2-prong devices are doubly insulated (the symbol on the charger is 2 concentric squares). Weirdly though I have noticed that "tingly" feel even with my 3-pronged laptop charger.

wow, to a Dane the US electricity rules are something out of a 3rd world country!!

> US electricity rules are something out of a 3rd world country

If you read about the CEE 7 standard that aims to unify power plugs and sockets in European countries [1], which includes the "Europlug" [2] mentioned in a sibling comment, you'll see that the situation is not any better than in the US.

For example, about the CEE 7/7 plug which bridges the difference between socket types in Germany (2-pronged - also in Denmark, Spain, etc.) and France (3-pronged - also in Belgium, Czechia, Poland), it mentions:

> This plug can be inserted into a Danish Type K socket, but earthing is not enabled.

[1] https://en.wikipedia.org/wiki/CEE_7_standard_AC_plugs_and_so...

[2] https://en.wikipedia.org/wiki/Europlug#Compatibility

The issue they are talking about can (but shouldn't) also happen with the "Europlug" which is also used in Denmark: https://en.wikipedia.org/wiki/Europlug

I assuming that you’re taking what I wrote as US electricity rules but the devices/rules I mentioned were for European products. My iPad that gives me a slight tingle was purchased from the Apple store in The Hague so it’s EU compliant. (I’m Indian and I believe India too has similar rules. Double insulation is generally pretty safe, if a little annoying.)

Even in the UK, which has quite stringent electric regulations, you can get two-conductor cables with a plastic earth pin (which is always required even if you don't need grounding as otherwise the shutters covering the live and neutral holes are not withdrawn). On the other end, it could have a "figure-of-8" IEC connector.

And I definitely noticed a tingle on some metal laptops even when they have a 3-pin plug and a "Mickey mouse" IEC connector on the cable to the power brick.

It's allowed in Europe and Denmark as well. Some µA of leakage current are acceptable.

Happens because of Y capacitor leakage in switching power supplies.

Are you talking about the bumpy feeling when moving your hand along the chassis? I get that on a metal-body Dell sometimes too. And it doesn't seem to happen if I press hard while moving my hand.

> it doesn't seem to happen if I press hard

I would assume that's because you're increasing the contact area and therefore more of your nerve endings are getting a lower voltage, pushing it below the detectable range.

In my case it's not just nerves that feel it. I can get my fingers to vibrate at presumedly 50 hz by stroking the laptop lid. There is an audible hum.

It happens with just one charger I have. The other charger just went out with a bang that tripped the fuse. So guess which one I use now.

Wait until you're using it on your chest in bed and accidentally poke your lips with the corner! It's a surprisingly good zap for an allowed amount of stray

Not that I've ever done that

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