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How can I avoid my MacBook Pro giving me minor shocks?

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Re: How can I avoid my MacBook Pro giving me minor shocks?

#21

Post by josefdlange »

Osmium wrote: post #19

FYI, I can't remember which way round it is, but only some of the UK 3-pronged adapters are actually earthed (as I discovered after having this problem myself). I think it's the extension cord that is properly earthed, whereas just the plug attachment that goes directly into the power brick is not. You can tell by looking up into the adapter (the part that plugs into the power brick) and seeing if it's metal or plast…

A certain vintage of Apple adapters have plastic posts where the ground would otherwise attach. This image is iPad 10W adapters, but the same follows for some older iBook/MacBook chargers:

https://qph.ec.quoracdn.net/main-qimg-05fa7f5f0e6ce0dc43bf8c...

Re: How can I avoid my MacBook Pro giving me minor shocks?

#22

Post by taneq »

avn2109 wrote: post #16
taneq wrote: post #2

I've run across this before - once I measured the shell of my MBP at 90 volts DC. If you don't have access to a 3-pin charger, you could always use a separate earthing setup, such as an antistatic mat: https://en.wikipedia.org/wiki/Antistatic_device#Antistatic_m...

90 volts above earth ground? Or relative to something else?

It was a long time ago, but iirc it was relative to the nearest available metal object, which I think was the metal frame of a desk. It wasn't a super rigorous test. :P

Re: How can I avoid my MacBook Pro giving me minor shocks?

#23

Post by kosma »

ars wrote: post #15
algesten wrote: post #8

I have this problem in India. I suspected the mains was dodgy, because during the many power outages i never got the shocks when on UPS. I got a multimeter and measured. The neutral was 70V and the phase 300ish. So the difference was roughly 230V but a switched power adapter would make this hover around 70 too (I believe an old coil based would probably been fine). The Indian electrician didn't understand my problem…

The 70v is probably induced voltage at milliamp levels. You can fix it by bonding the neutral to ground at the breaker box.

This is potentially deadly advice. A neutral/grounding fault will energize all your home devices with live potential; same with a live/neutral swap (unlikely but possible with Indian wiring standards).

Re: How can I avoid my MacBook Pro giving me minor shocks?

#24

Post by cyphar »

jordwest wrote: post #18

What's fascinating to me about this phenomenon is that you can actually feel the 60Hz AC by running your hand across the lid. It feels as if the surface is slightly bumpy, but the width of the bumps changes as you adjust the speed your finger moves. Unplug from mains, and the surface becomes smooth. As the answer notes, this only happens when using the two-prong adapter without earthing. It also seems to be more noti…

Well that explains what the weird feeling I used to feel when touching a 2015 Macbook I was using last year. It felt exactly like that (as though the surface was bumpy) though I never got far enough into debugging it to figure out that it was actual charge leakage onto the case and that I was feeling the AC current. That's a bit scary.

Question: aren't laptops powered off DC (there's a rectifier/transformer combo in the power brick) so how would AC get to the case of the laptop?

Re: How can I avoid my MacBook Pro giving me minor shocks?

#25

Post by viraptor »

jordwest wrote: post #18

What's fascinating to me about this phenomenon is that you can actually feel the 60Hz AC by running your hand across the lid. It feels as if the surface is slightly bumpy, but the width of the bumps changes as you adjust the speed your finger moves. Unplug from mains, and the surface becomes smooth. As the answer notes, this only happens when using the two-prong adapter without earthing. It also seems to be more noti…

So that's what it is! I assumed the source of that effect is some micro vibrations from fans, or because of some weird electromagnetic effects from parts placement. It happens both a on an HP ZBook and an older Macbook Air. Thanks for solving this mystery - moving to a better connector helped.

Re: How can I avoid my MacBook Pro giving me minor shocks?

#26

Post by disillusioned »

hinkley wrote: post #12
x0x0 wrote: post #5

Earlier quoted context omitted.

There's also a good chance that, at least in part due to Apple's greed and extravagant prices for chargers / fragile power cords, many people are using knockoff chargers and don't know it. See also Amazon happily selling knockoffs as real -- Apple claims 90% of chargers it recently bought on Amazon are fake and is suing the supplier, though unfortunately is not suing Amazon [1], which might help Amazon find the will…

Have you seen a tear down of the authentic chargers? There's a lot going on in there.

Right, but even still, you don't think Apple's commanding actual profit from them? They're up to $90...

Re: How can I avoid my MacBook Pro giving me minor shocks?

#28

Post by xenadu02 »

burger_moon wrote: post #10
arikrak wrote: post #4

I never had that issue in the US (even when using a two-holed outlet), but I had that problem when I was visiting Israel. So it seems to only be an issue when using 220 volts and not a proper ground connection.

I get it in my apartment (I live in the U.S.) which is brand new with 3 prong sockets if I have my feet on the ground (concrete floor) while roughing the laptop. I've experienced it a few more times at different peoples houses as well.

You might buy an outlet tester and see if your hot/neutral are reversed or if ground isn't connected. If it all checks out you can use a multimeter* to check potential between neutral and ground. If your apartment is wired correctly there should be almost no voltage between the two.

At the breaker box the neutral and ground are supposed to be bonded together. That means only minor induced charges inside the building wiring would show up between the two. If there is any significant voltage then something is leaking on one of the lines or ground might not be bonded... it could even be floating if they didn't bother driving the grounding stake deep enough and the soil dried out a bit.

Re: How can I avoid my MacBook Pro giving me minor shocks?

#29

Post by ganeshkrishnan »

algesten wrote: post #8

I have this problem in India. I suspected the mains was dodgy, because during the many power outages i never got the shocks when on UPS. I got a multimeter and measured. The neutral was 70V and the phase 300ish. So the difference was roughly 230V but a switched power adapter would make this hover around 70 too (I believe an old coil based would probably been fine). The Indian electrician didn't understand my problem…

I had the same problem in Australia. I thought it was just me being over-sensitive to static electricity

Re: How can I avoid my MacBook Pro giving me minor shocks?

#30

Post by nunofgs »

an_account wrote: post #7
sfifs wrote: post #3

Don't use Macs but I'm surprised Apple apparently didn't give an earthed power adapter by default on a metal skin product. This seems like negligence. Now that I think about it, my iPad's the same when charging.

They do give one by default, but you can disconnect it if you so choose. FWIW, I have never had a problem using the two pronged plug in the US. It's interesting to see all this preexisting problems with MacBooks surfacing after the recent release of the MBP

They don't include them anymore in the 2016 MacBooks
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