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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?

#81

Post by SyneRyder »

cs2818 wrote: post #53

I sometimes run into an interesting variation of this kind of problem. I often work with a Microsoft Surface tablet laying in front of my MacBook Pro, with my arms stretched over the tablet to type at times. If the Surface is plugged in (no ground pin) and the MacBook Pro is also plugged in (ground pin), and my arms touch both at the same time, I can feel a tingling that quickly becomes unpleasant. Unplugging one or…

That solves an issue I've had as well, though it shows the MacBook Pro isn't really the fault. I have a Samsung TV (no ground-pin) and I would often watch it while using my MacBook Pro plugged in (ground pin). Because I didn't have wireless headphones yet I'd run a cable from the Samsung's headphone socket and plug my Bose headphones into that. If I was touching the MacBook case with one hand and grazed the metal parts of the 3.5" audio cable, I'd get quite a strong tingling & that almost becomes painful. Hadn't considered that the fault was the TV's lack of grounding.

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

#82

Post by shakna »

ganeshkrishnan wrote: post #29
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

It took me 6 months to get PowerCor to understand the shower was trying to use me as an earth, because they couldn't reproduce it. They told me I was just being sensitive, despite every flat reporting similar issues.

The hot water pipes were being used as the earth, and the electricity could leap across the pipe in bad weather.

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

#83

Post by sduff »

Hydraulix989 wrote: post #72
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…

Shark used to make an (otherwise excellent) upright consumer vacuum cleaner with a metal strip in the handle. The vacuum's power cable did not have a ground. This vacuum had the most five-star reviews on Amazon, but then a minority of people started complaining and leaving one-star reviews, saying they were getting shocked. The reactions from the fanboy crowd were non-sympathetic ("you're imagining it," "it's just st…

Why would you still buy from the same manufacturer that denied bad (and potentially deadly) design?

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

#84

Post by analog31 »

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…

I've experienced this with appliances other than computers, such as an old fluorescent desk lamp with a two prong cord, and I wonder if it was common before the adoption of double insulation. I looked at the computers in my house, and realized that they all have plastic enclosures.

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

#85

Post by hexane360 »

josefdlange wrote: post #54
forgettableuser wrote: post #45

Earlier quoted context omitted.

I knew a guy in college who rented a house that didn't have any outlets with a ground plug. This became such a problem, he made his own ground by using a big metal pipe outside the house that was already deep in the earth, and running a wire from it to where he kept all his equipment. Then he used stuff like in that picture to make sure he could ground all his equipment.

This is the right way to use those! It's so rare to hear of proper usage.

You can also screw them to the outlet box, which should already be grounded, especially if it uses older BX sheathing.

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

#86

Post by hexane360 »

gh02t wrote: post #68
Hasz wrote: post #37

Earlier quoted context omitted.

Actually, for things with a non-conductive casing (think cheap nightlights, or those apple wall warts) there's no need for a ground. If anything, it's another part and more cost, thus it isn't included. In highly sensitive A/V systems, an isolation transformer is often used as well, neglecting a ground.

You have to be careful with isolation transformers because there is one gotcha... the ground pin normally passes through to earth. I've witnessed someone blow up a nice $5000 Agilent oscilloscope before I could stop them because they didn't understand how to use an IT and plugged the scope into it so they could probe AC. Bad news, you're supposed to plug your test device into the IT not the scope because the BNC conn…

Humorous demonstration of the same mistake: https://youtu.be/sI5Ftm1-jik?t=2m20s

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

#87

Post by Hydraulix989 »

sduff wrote: post #83
Hydraulix989 wrote: post #72

Earlier quoted context omitted.

Shark used to make an (otherwise excellent) upright consumer vacuum cleaner with a metal strip in the handle. The vacuum's power cable did not have a ground. This vacuum had the most five-star reviews on Amazon, but then a minority of people started complaining and leaving one-star reviews, saying they were getting shocked. The reactions from the fanboy crowd were non-sympathetic ("you're imagining it," "it's just st…

Why would you still buy from the same manufacturer that denied bad (and potentially deadly) design?

Like I said, it was otherwise, an excellent vacuum. Any how, I know about Lenovo's Superfish and recently its attempts to block Linux installs, but I am still a die-hard Thinkpad user because these are very large organizations where all it takes is one single person's oversight to cause a mistake.

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

#88

Post by Teever »

kalleboo wrote: post #78
bschwindHN wrote: post #75

Earlier quoted context omitted.

> and scary to think that two-prong outlets and appliances are legal anywhere In Japan, two prong outlets make up the vast majority of sockets, it kinda sucks.

I don't think I've ever seen a three-prong outlet in Japan (maybe only new installations?), but "earth screws" are quite common (any room prepared for an air conditioner will have one at least) http://www.hakusui-trading.co.jp/safety/img/img02.jpg

What? That's crazy looking! Why not just put the third prong in there if it's wired up to handle a screw?

What's the point?

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

#89

Post by sangnoir »

xenadu02 wrote: post #36
kosma wrote: post #23

Earlier quoted context omitted.

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).

> 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). You are wrong. In the US the NEC requires this. If you bother to look inside your breaker panel you will find the neutral and ground wires are literally screwed down to the same bus bar. Any path your body (or the so…

> You are wrong. In the US the NEC requires this.

OP's very first sentence clearly stated they are in India, where this is obviously dangerous advice because most devices (and piping) connect their surfaces to Earth, which is new Neutral.

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

#90

Post by dingaling »

xenadu02 wrote: post #36
kosma wrote: post #23

Earlier quoted context omitted.

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).

> 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). You are wrong. In the US the NEC requires this. If you bother to look inside your breaker panel you will find the neutral and ground wires are literally screwed down to the same bus bar. Any path your body (or the so…

I downvoted you because again this is potentially dangerous advice for the plurality of people who live outside the USA, without referring to local standards.

For example in the UK neutral is traditionally grounded at the electrical substation, which serves several hundred homes, and all lines are separate / unbonded within the house.

In the most recent PME standard in the UK the earth and neutral are bonded back to the substation as the Protected Earthed Neutral but that is achieved on the supply-side, not the in consumer equipment.

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