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
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 to stop people selling fakes.
As mentioned below, a reasonable estimate of the cost is $30.
They could also sell replacement user swappable magsafe cords and defang many of the complaints. But then they couldn't effectively charge $90 for a replacement cord.
I have wanted that cord to be replaceable forever. At least it finally is now. Given how many the kids and dog destroy I consider it an improvement.
I have wondered if the degradation of the cord wasn't some sort of safety guarantee rather than planned obsolescence. When the cord wears out you buy a new one instead of using the ancient one from eight years ago.
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
However I still noticed "buzzing" in the MBP, MBA and even iPad when I would touched them.
Took the MBP in to the store. It didn't buzz there. They gave me a new power supply anyways and recommended I connect the plug directly into the wall socket.
Turned out that the power strip I was using is not grounded even though it has three pin sockets !
When I plug Apple devices directly into the wall socket I don't notice any "buzzing".
So now I don't connect the Apple devices via a power strip.
I would rather at least try to disassemble it before throwing away - otherwise it is likely that someone will pull it from the bin and use it or sell it.
My UK MacBook came with two plugs; one with a long cable and an earth connection, and one "short" one that's just the plug head, with no earth connection (the slot that the earth ring from the transformer connects to is just plastic inside).
I get the shocks when using the short connector, and always have.
Here is a DIY guide by someone who figured out how to fix the issue (danger, electricity, don't kill yourself)
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 have this problem every winter. With my Macbbok it was the worst, it even caused the trackpad to stop functioning once, but it has also happened to some of my other devices as well.
It's happened so often to me that I've trained myself to touch something to discharge the static before touching my equipment.
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.
> At the breaker box the neutral and ground are supposed to be bonded together.
Note this advice is country-specific. In some countries, the bonding is done further away from the house.
In any case, you should never trust the neutral line to be an earth. If a fault occurs that disconnects the neutral line from the supply, your neutral line will have deadly voltage on it by virtue of being connected to live through your appliances. Moreover, depending on the multimeter you use, if you measure the voltage between neutral and earth, you could possibly trip the RCD in the distribution unit (if you have one).
The rules are simple in most countries - if it has any touchable metal parts, it must be earthed.
I noticed the vibrations while charging in France and Germany with my American iPhone and MBP, but just chalked it up to my universal power adapters being not 100% native.
Reading jordwest's 60Hz comment, it seems to do with grounding. So do MBPs and iPhones purchased in Europe still experience this issue if the apartment isn't grounded properly?
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 because his only tool was a regular bulb with two exposed wires that he jammed into the socket.
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 soil outside) can provide back to the generator pales in comparison to the neutral tap provided by the transformer. Grounding to dirt is about static electrical discharge, not the voltage provided by the generating station.
The safety of providing a grounding wire is that metal parts of appliances must be connected to that ground. The ground wire itself is both bonded to neutral and connected to a metal grounding rod driven into the dirt. If any part of the appliance's internal works becomes energized and touches the metal casing the direct path to ground is designed to create a short circuit and trip the breaker immediately, rather than sitting there waiting for a human to come along and complete the circuit.
If ground weren't bonded and the ground dried out or the grounding rod weren't properly installed then the scenario you describe would occur. A single faulty appliance would back-feed voltage onto every grounded appliance in the building. So in fact bonding is what creates safety, not the other way around.
> 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.
It could be different in US, but in modern European installations the PE and N bars are separate; older installations use common PEN; and even older ones don't even have PE. Each of the wiring schemes requires different approach and poses different hazards. There's no single recipe that would work on all of them.
My bottom line is: don't make arbitrary connections in the breaker box without proper knowledge and training; and don't give random electrical advice on the internet without knowledge of local codes.
> It could be different in US, but in modern European installations the PE and N bars are separate
In the US a single PE+N wire feeds into the building. All building wiring is separated as in Europe. They are tied together in only one location, usually wherever the main switch is.
Just like Europe, really old installs in the US don't have ground (PE). Some are retrofitted with ground like my house in SF. One thing people should never do is connect neutral to ground at a secondary point. It can be tempting when you don't have access to run a ground wire but creates a serious potential for safety problems. The way to handle that is to install a GFCI (RCD) plug and put a sticker on it stating "No equipment ground" - the outlets actually come with those stickers for that purpose :)
As far as I know in European systems where the building has separate PE+N feeds they are still bonded together, it just happens at the transformer. I could be wrong about that though!
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.
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.
Yes. In my previous place in India the RCD was repeatedly tripping up.
Earth here was a metal rod into the ground, and I only found out much later they fixed the RCD issue by disconnecting the rod and I started getting electric shocks from touching my fridge while my crappy toaster was connected.
That's when I decided to not mess with electrics in India. It's dangerous enough as it is.
As for the 70V, I eventually managed to reach someone in the electrics company that understood my issue, and they told me a local transformer for the whole street was broken. And they didn't have any plan to fix it.
Same here, with some PCs back in a shop area. Come to find out, the outlets weren't getting a good ground due to painted conduit. And without a good ground, a cheap surge suppressor ended up dumping about 30 volts into the ground pin.
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.
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 static," etc.), and they mass downvoted every one-star review. Some of the people claimed they were getting shocked PRETTY HARD, too, as in it knocked them over. IIRC, even Shark responded saying that it was impossible for the vacuum to shock you.
I remember seeing this while looking at vacuums for my elderly mother who has a heart condition. To the electrical engineer in me, everything made sense!
I started defending every single one-star reviewer person, and I wrote my own very detailed review with photos of the handle. Soon, the tide turned, and more people started upvoting my review than downvoting it; and I even received personal "thank you" messages from the people who got shocked ("finally someone believes me").
It eventually got to the point where a year later in 2014, Shark released an updated model with no more metal strip. Seeing this, I bought the new model for my mother. I'd like to think I can give myself SOME credit for causing them to do that.
Not only that, the upvotes from that alone were a good part of the reason I became an Amazon Top Reviewer.
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.
They didn't "attempt to block Linux", they just shipped hardware without a Linux driver.
And later released a workaround to make the hardware work in a slower, more power consuming backwards compatibility mode so Intel can continue not properly supporting the hardware in Linux.
Different divisions doing different things. Intel is extremely interested in Linux for their HPC Itanium/Xeon range, moderately interested in Linux for other server and business hardware, as well as mobile; and Intel's consumer PC division doesn't give a fuck at all.
Lenovo initially released a BIOS with a goto statement added to jmp out of the disk controller mode setting (which is normally present and allows the user to change back to AHCI mode). Reverse engineers on the Lenovo forums discovered this modification while studying the disassembly.
Then, one user patched the BIOS and manually reflashed it using an SPI flasher and some soldering, and Linux worked just fine by detecting the drive.
Yes, the ideal solution is that Intel gives specs to OSS devs to build a driver (or even builds on themselves), but the path of least resistance is to have Lenovo unblock that BIOS setting, which amounts to changing one line of code, or 15 minutes of one engineer's time.
> Lenovo initially released a BIOS with a goto statement added to jmp out of the disk controller mode setting
Because switching to AHCI mode with Windows installed would brick the machine (Yay, Microsoft), and Lenovo foolishly assumed that people who wanted to use Linux would buy one of the Linux certified machines instead (X1 Yoga and 60 series Yoga devices are all certified: https://support.lenovo.com/us/en/documents/pd031426 – but I'm sure that's just more proof that Lenovo hates Linux for some reason).
> the path of least resistance is to have Lenovo unblock that BIOS setting, which amounts to changing one line of code, or 15 minutes of one engineer's time.
I guess I should go further: some vacuum cleaners have to have a ground connection in the hose, to try to discharge the dust. If they removed it for unrelated reasons, they probably lowered the overall quality of the product overall.
My toughbook does this as well. One of the replies there says thinkpads have the same problem, and I have an IBM power adapter, so that could be the culprit. IIRC it's high frequency, so probably created by the supply itself rather than a floating neutral in the building wiring.
My understanding is that it's caused by Y capacitors in the power supply's EMI filter leaking minimal amounts of current onto the case. As others have mentioned, proper grounding usually fixes the issue - although in one case I had to rewire an entire apartment because someone had a very lopsided idea what the PE wire is for. It was for a friend with a metal Macbook Pro, an exceptionally sensitive skin, and way too much time & money on their hands. :D
The usual word of caution: I'm trained in electrical installations. A layperson - even one skilled with a multimeter and a soldering iron - should never attempt to modify ground connections or power distribution. There are dozens of potential (and very deadly) failure modes that require proper training to recognize and prevent.
I have a mid 2015 13" MacBook Pro and I've measured up to 48v off the chassis between ground on properly wired circuits. I began investigating this after getting mild shocks after working out (sweaty) and while working on the MacBook in my lap while working on a PC laptop on my desk which also has an aluminum chassis. I tried an isolation transformer and the issue disappeared. I contacted Apple about it but crickets. I then did some current measurements and it was very low and of no concern at that voltage so I decided not to push the issue. As other have said, the solution is to use the three pronged cord that came with the power brick.
You can feel this effect for yourself by using the two pronged plug and finding something grounded to the chassis to touch. With one hand, hold the grounded item while moving the palm of your other hand around the backside of the led. It's a bit dependent on the conductivity of your hands but I've found most people can feel it, even my dad who's a farmer and has very dry hands. Remember, if you get electrocuted, it's not my fault, it's Apple's. They have much deeper pockets than me.
Ungrounded adapter + clean mains power = probably no zap
Grounded adapter + bad mains power = probably no zap
Grounded adapter + clean mains power = no zap
It's not just the adapter and it's not just the mains power; it's when both come together. Electricity follows pretty simple rules when it comes down to it.
Always always always ground your A/C connections. Why wouldn't you?
Also, never use one of these unless you've attached the little wire/alligator terminal to a ground somewhere:
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.
These are all better and more knowledgeable points than my own! I definitely only speak out of an abundance of caution having known people whose bad electricity and habits have damaged property.
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 connectors in almost all oscilloscopes are connected straight through to the earth pin.
I heard "POW" from across the lab as soon as he clipped the probe on and knew I should have warned him. Nobody was hurt apart from our lab budget.
I can't tell, the second boom where he holds the resistor in place was that on purpose? If so holy shit that's a dangerous way to make the point. If it was also an accident then he is lucky to be alive since he doesn't seem to know what he is doing.
I know this video is supposed to be funny, but I couldn't bring myself to laugh. Too many people die making the same mistakes.
He does know what he's doing and it certainly was deliberate. While most of his stunts probably hurt he doesn't set them up exactly as he presents them (I.e. it's usually not mains).
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.
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 noticeable when connected to older buildings.
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?
The socket isn't grounded the laptop on your desk and you are, so you get socked, I had the same thing with my tower case when I moved a flat I discovered that the socket I was using had the ground and hot terminals switched.
This is a common problem, the power cable from the power adapter to your laptop is also usually connected to ground, if the ground is hot then you get shocked.
Laptops are indeed powered off of DC, which means that there will be a constant voltage measured across the positive and negative pins of the MagSafe plug.
However, the voltage measured from either pin to ground might very well fluctuate. Without the grounding pin on the power supply, the DC side of the supply may 'float' with respect to earth ground. If you plot the voltages measured from each pin to ground, it probably looks like a pair of sine waves, one shifted 20 volts above the other.
Right, so there's no relative phase change between negative and positive terminals but there is a phase change between the terminals and ground (which can be interpreted as a frequency relative to ground)? And since I'm grounded I experience that frequency? Interesting. Is there a relation between the "float frequency" and the AC freqency? Is it the same because of how commutators work?
I suspect that the float frequency is generally equal to the AC frequency, but I suppose it may be possible for it to be some subharmonic of the switching frequency, assuming you've got a switching power supply.
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.
I felt this on an Apple laptop in California a couple of years ago, in an apartment with only two-prong outlets in it. I'd describe the feeling more like the laptop cover was vibrating, rather than bumpy. The feeling went away and the laptop cover became smooth and normal if I lifted my feet off of the ground.
Once all the outlets were rewired to be three-prong, with ground, I used a three-prong power cord and the problem went away.
Pretty scary feeling, and scary to think that two-prong outlets and appliances are legal anywhere. I'd also be surprised if Apple hasn't been sued at some point by someone getting electrocuted when using their laptop and a non-grounded, two-prong power cord.
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
Just guessing here but I think it's to allow easy grounding of old appliances and other equipment that might risk contact with electricity but are not grounded by default. Metal frame desk as example.
I think it's just a legacy thing - historically, the only things that needed grounding were static appliances like fridges, washing machines and air conditioners. The manual in our fridge has this instruction for earthing http://mayoyo.tokyo/jIe.jpg
I need to revise my comment that "I don't think I've ever seen a three-prong outlet in Japan", because now that I have power sockets on my mind, I just saw a three-prong outlet at my gym. So I guess newer buildings have them.
They're starting to become more common in newer apartments. For some reason my apartment has one outlet panel with two of the three-prong outlets, but the rest are two-prong. Except for the air conditioner and laundry machine sockets, which have the earth screw like you described.
My macbook was stolen years ago, but I remember it doing this exact thing. I never really looked it up or thought about it until now. It is a totally weird feeling for sure.
I'm deeply curious about this! Is it possible to recreate the situation at home, or does this require something miswired with the mains power supply or power adapter, or an older MacBook Pro?
connect the two prong adapter, take your shoes and socks off, feet on the ground... feel the vibe! the best shocks you get at the edges or at the pointy edges in that groove to lift the display up.
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.
Easy way to cause it -- connect something that's got it's own cheapo AC power supply (eg. phone charger, speakers) to your computer via USB. The DC grounds are linked via USB, but the different power supplies end up with a wildly different DC ground wrt AC ground from each other, which can cause buzzing noises or the surface feel you're talking about.
This doesn't only happen with the two-prong adapters, I have noticed this on a few MacBooks, plugged in using the standard 3-prong UK plugs (sometimes with my phone too). An even weirder feeling is when someone else is touching the laptop, if you run your finger over their arm you'll notice the same bumpy feeling.
Oh my god, this is the feeling my ex and I could never figure out. One of us would touch the other, and there was a weird vibrating sensation as one would move their hand along the other's skin. I can't believe I never thought that it might be the laptop.
This has been happening to me in both UK and Ireland, which use three pin plugs as standard, with every metal-bodied Mac I've owned since the Titanium PowerBook came out in 2001
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 plastic...
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:
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 plastic...
For those of you who don't have access to proper grounding (because, for example, the wiring lacks PE or it's faulty): a plain separation transformer (1:1) between mains and your laptop might be able do the trick. Unfortunately if you have a larger setup (speakers, monitor, etc.) you have to connect everything to the separation transformer, otherwise you'll create leakage a path to mains some other way (say, through the audio jack).
Caveat emptor: If you decide to go that route, make sure you can return the transformer if it doesn't to the job.
I've had this on every metal-chassis Mac I've ever owned. The chassis typically floats around 50V AC at 50Hz (in the UK, at least) - making it noticeably vibrate and tingle when you touch it, especially with the palm of your hands when typing. It also seems to make RSI worse.
The solution, as everyone's pointed out, is to ensure you are correctly grounded.
Well, that explains it. Just last week my son was complaining that he was getting tiny shocks from the chassis of his Macbook. I thought he was just making excuses to not do his homework and told him to stop imagining it.
My first summer job was doing IT for a small outfit, who worked out of an old house converted into an office. They had eight machines, all connected to a LaserJet printer via a parallel port switch. The parallel cables ran down into a crawlspace under the house, and it wasn't uncommon for one of the cables to work its way loose. No problem, tighten the parallel port connection at both ends, and you're back in business. But, being an old house, many outlets were missing ground pins. I must of electrocuted myself twenty times that summer.
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 the other seems to be a work around.
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.
This happens to me regularly when I go back home (to a foreign country not the US). All the sockets have ground but the ground doesn't actually go anywhere... So you still get shocked. My solution was a bit lazier: plugin my MBP only when I'm not using it...
Due to EMI reasons, for switching converters, the hot and neutral terminals of mains input is generally capacitively connected to the Earth prong via high frequency capacitors. That means if the earth prong isn't properly connected to actual earth, the earth prong now has your mains voltage divided by two on it. If the earth connection happens to be connected to the chassis, there's your shock.
It probably won't kill you unless you have a weak heart or if you're really unlucky because the EMI suppression caps are small enough to not supply lethal current, but can be really annoying.
I've had this on two MacBook Pros here in Australia. On the first one I took it in to a Genius Bar appointment and, while they acknowledged it happens to a "rare number of people", they basically said tough luck and to use the earthed power cable which is about 1.5m longer. By the second time I just accepted it as part of owning a MBP.
As an aside, I should buy a lottery ticket given the number of rare issues that happen to my Apple products.
164 comments
[ 4.6 ms ] story [ 257 ms ] threadIf 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...
Now that I think about it, my iPad's the same when charging.
[1] https://9to5mac.com/2016/10/19/amazon-fake-apple-chargers-ca...
http://www.righto.com/2015/11/macbook-charger-teardown-surpr...
The author also does consider the cost of the components.
They could also sell replacement user swappable magsafe cords and defang many of the complaints. But then they couldn't effectively charge $90 for a replacement cord.
I have wondered if the degradation of the cord wasn't some sort of safety guarantee rather than planned obsolescence. When the cord wears out you buy a new one instead of using the ancient one from eight years ago.
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
However I still noticed "buzzing" in the MBP, MBA and even iPad when I would touched them.
Took the MBP in to the store. It didn't buzz there. They gave me a new power supply anyways and recommended I connect the plug directly into the wall socket.
Turned out that the power strip I was using is not grounded even though it has three pin sockets !
When I plug Apple devices directly into the wall socket I don't notice any "buzzing".
So now I don't connect the Apple devices via a power strip.
I get the shocks when using the short connector, and always have.
Here is a DIY guide by someone who figured out how to fix the issue (danger, electricity, don't kill yourself)
http://garethhayes.net/apple-power-plug-not-earthed/
It's happened so often to me that I've trained myself to touch something to discharge the static before touching my equipment.
I've experienced it a few more times at different peoples houses as well.
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.
Note this advice is country-specific. In some countries, the bonding is done further away from the house.
In any case, you should never trust the neutral line to be an earth. If a fault occurs that disconnects the neutral line from the supply, your neutral line will have deadly voltage on it by virtue of being connected to live through your appliances. Moreover, depending on the multimeter you use, if you measure the voltage between neutral and earth, you could possibly trip the RCD in the distribution unit (if you have one).
The rules are simple in most countries - if it has any touchable metal parts, it must be earthed.
Reading jordwest's 60Hz comment, it seems to do with grounding. So do MBPs and iPhones purchased in Europe still experience this issue if the apartment isn't grounded properly?
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 because his only tool was a regular bulb with two exposed wires that he jammed into the socket.
"Look sir, light, power working"
sigh.
You can fix it by bonding the neutral to ground at the breaker box.
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 soil outside) can provide back to the generator pales in comparison to the neutral tap provided by the transformer. Grounding to dirt is about static electrical discharge, not the voltage provided by the generating station.
The safety of providing a grounding wire is that metal parts of appliances must be connected to that ground. The ground wire itself is both bonded to neutral and connected to a metal grounding rod driven into the dirt. If any part of the appliance's internal works becomes energized and touches the metal casing the direct path to ground is designed to create a short circuit and trip the breaker immediately, rather than sitting there waiting for a human to come along and complete the circuit.
If ground weren't bonded and the ground dried out or the grounding rod weren't properly installed then the scenario you describe would occur. A single faulty appliance would back-feed voltage onto every grounded appliance in the building. So in fact bonding is what creates safety, not the other way around.
It could be different in US, but in modern European installations the PE and N bars are separate; older installations use common PEN; and even older ones don't even have PE. Each of the wiring schemes requires different approach and poses different hazards. There's no single recipe that would work on all of them.
My bottom line is: don't make arbitrary connections in the breaker box without proper knowledge and training; and don't give random electrical advice on the internet without knowledge of local codes.
In the US a single PE+N wire feeds into the building. All building wiring is separated as in Europe. They are tied together in only one location, usually wherever the main switch is.
Just like Europe, really old installs in the US don't have ground (PE). Some are retrofitted with ground like my house in SF. One thing people should never do is connect neutral to ground at a secondary point. It can be tempting when you don't have access to run a ground wire but creates a serious potential for safety problems. The way to handle that is to install a GFCI (RCD) plug and put a sticker on it stating "No equipment ground" - the outlets actually come with those stickers for that purpose :)
As far as I know in European systems where the building has separate PE+N feeds they are still bonded together, it just happens at the transformer. I could be wrong about that though!
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.
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.
If you have a sub-panel feeding the main panel, the neutral and ground are Not bonded.
(I mentioned it because the subpanel is overlooked a lot, and wired wrong, or not to code.)
Earth here was a metal rod into the ground, and I only found out much later they fixed the RCD issue by disconnecting the rod and I started getting electric shocks from touching my fridge while my crappy toaster was connected.
That's when I decided to not mess with electrics in India. It's dangerous enough as it is.
As for the 70V, I eventually managed to reach someone in the electrics company that understood my issue, and they told me a local transformer for the whole street was broken. And they didn't have any plan to fix it.
I had a grounding issue and I used to get shocked by my tower all the time, this is pretty common.
The hot water pipes were being used as the earth, and the electricity could leap across the pipe in bad weather.
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 static," etc.), and they mass downvoted every one-star review. Some of the people claimed they were getting shocked PRETTY HARD, too, as in it knocked them over. IIRC, even Shark responded saying that it was impossible for the vacuum to shock you.
I remember seeing this while looking at vacuums for my elderly mother who has a heart condition. To the electrical engineer in me, everything made sense!
I started defending every single one-star reviewer person, and I wrote my own very detailed review with photos of the handle. Soon, the tide turned, and more people started upvoting my review than downvoting it; and I even received personal "thank you" messages from the people who got shocked ("finally someone believes me").
It eventually got to the point where a year later in 2014, Shark released an updated model with no more metal strip. Seeing this, I bought the new model for my mother. I'd like to think I can give myself SOME credit for causing them to do that.
Not only that, the upvotes from that alone were a good part of the reason I became an Amazon Top Reviewer.
And later released a workaround to make the hardware work in a slower, more power consuming backwards compatibility mode so Intel can continue not properly supporting the hardware in Linux.
But sure, it was totally "Lenovo blocking Linux".
Lenovo initially released a BIOS with a goto statement added to jmp out of the disk controller mode setting (which is normally present and allows the user to change back to AHCI mode). Reverse engineers on the Lenovo forums discovered this modification while studying the disassembly.
Then, one user patched the BIOS and manually reflashed it using an SPI flasher and some soldering, and Linux worked just fine by detecting the drive.
Yes, the ideal solution is that Intel gives specs to OSS devs to build a driver (or even builds on themselves), but the path of least resistance is to have Lenovo unblock that BIOS setting, which amounts to changing one line of code, or 15 minutes of one engineer's time.
Because switching to AHCI mode with Windows installed would brick the machine (Yay, Microsoft), and Lenovo foolishly assumed that people who wanted to use Linux would buy one of the Linux certified machines instead (X1 Yoga and 60 series Yoga devices are all certified: https://support.lenovo.com/us/en/documents/pd031426 – but I'm sure that's just more proof that Lenovo hates Linux for some reason).
> the path of least resistance is to have Lenovo unblock that BIOS setting, which amounts to changing one line of code, or 15 minutes of one engineer's time.
Which is exactly what Lenovo did: https://forums.lenovo.com/t5/Lenovo-Yoga-Series-Notebooks/Yo...
There are tons of BIOS settings that could "brick" my machine though, it's a weak argument, really. My car didn't come with a lock on the hood.
"Which is exactly what Lenovo did"
Okay, you're acting like it didn't require any teeth pulling on our end to get them to release it (check out the 30+ page forum topics).
It's the devices responsibility to design for that.
The usual word of caution: I'm trained in electrical installations. A layperson - even one skilled with a multimeter and a soldering iron - should never attempt to modify ground connections or power distribution. There are dozens of potential (and very deadly) failure modes that require proper training to recognize and prevent.
You can feel this effect for yourself by using the two pronged plug and finding something grounded to the chassis to touch. With one hand, hold the grounded item while moving the palm of your other hand around the backside of the led. It's a bit dependent on the conductivity of your hands but I've found most people can feel it, even my dad who's a farmer and has very dry hands. Remember, if you get electrocuted, it's not my fault, it's Apple's. They have much deeper pockets than me.
Ungrounded adapter + clean mains power = probably no zap
Grounded adapter + bad mains power = probably no zap
Grounded adapter + clean mains power = no zap
It's not just the adapter and it's not just the mains power; it's when both come together. Electricity follows pretty simple rules when it comes down to it.
Always always always ground your A/C connections. Why wouldn't you?
Also, never use one of these unless you've attached the little wire/alligator terminal to a ground somewhere:
http://www.prestonelectronics.com/audio2/ttip/images/gndadap...
In highly sensitive A/V systems, an isolation transformer is often used as well, neglecting a ground.
I heard "POW" from across the lab as soon as he clipped the probe on and knew I should have warned him. Nobody was hurt apart from our lab budget.
I know this video is supposed to be funny, but I couldn't bring myself to laugh. Too many people die making the same mistakes.
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.
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 noticeable when connected to older buildings.
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?
This is a common problem, the power cable from the power adapter to your laptop is also usually connected to ground, if the ground is hot then you get shocked.
However, the voltage measured from either pin to ground might very well fluctuate. Without the grounding pin on the power supply, the DC side of the supply may 'float' with respect to earth ground. If you plot the voltages measured from each pin to ground, it probably looks like a pair of sine waves, one shifted 20 volts above the other.
Once all the outlets were rewired to be three-prong, with ground, I used a three-prong power cord and the problem went away.
Pretty scary feeling, and scary to think that two-prong outlets and appliances are legal anywhere. I'd also be surprised if Apple hasn't been sued at some point by someone getting electrocuted when using their laptop and a non-grounded, two-prong power cord.
In Japan, two prong outlets make up the vast majority of sockets, it kinda sucks.
What's the point?
I think it's just a legacy thing - historically, the only things that needed grounding were static appliances like fridges, washing machines and air conditioners. The manual in our fridge has this instruction for earthing http://mayoyo.tokyo/jIe.jpg
I need to revise my comment that "I don't think I've ever seen a three-prong outlet in Japan", because now that I have power sockets on my mind, I just saw a three-prong outlet at my gym. So I guess newer buildings have them.
You can also die if you stick your finger for a long time (24H) in a small current.
http://electronics.stackexchange.com/questions/19103/how-muc...
Feet on the floor => shocks.
Feet on the beam of a wooden stool => no shocks.
Users enjoying electric shocks. Reality distortion field operating at nominal.
Bring back transformers! (ok, don't, but...)
TeslaTouch: Electrovibration for Touch Surfaces:
http://www.ivanpoupyrev.com/e-library/2010/teslatouchUIST201...
Video: https://www.youtube.com/watch?v=FiCqlYKRlAA
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 plastic...
https://qph.ec.quoracdn.net/main-qimg-05fa7f5f0e6ce0dc43bf8c...
http://imgur.com/a/cNzXx
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 plastic...
Caveat emptor: If you decide to go that route, make sure you can return the transformer if it doesn't to the job.
There's an interesting post about the internals: http://www.righto.com/2015/11/macbook-charger-teardown-surpr...
The solution, as everyone's pointed out, is to ensure you are correctly grounded.
https://www.amazon.com/Sperry-Instruments-GFI6302-Outlet-Tes...
If this says good (two amber lights) and you're still getting shocked, follow up with a voltmeter and/or qualified electrician.
Time to buy a 3 pin adapter!
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 the other seems to be a work around.
It probably won't kill you unless you have a weak heart or if you're really unlucky because the EMI suppression caps are small enough to not supply lethal current, but can be really annoying.
As an aside, I should buy a lottery ticket given the number of rare issues that happen to my Apple products.