11 ms·

My Laptop Bit Me – The Shocking Truth (2012)

136 points by tomduncalf 8y ago

mjlee 8y ago
I've noticed that even with an earthed power supply I still have the problem with the newer USB-C MacBooks. I find it rather uncomfortable on my wrists. A MacBook I had quite a few years ago had a cracked chassis - touching that when using a non-earthed power supply was enough to be a little bit painful.
- howard941 8y ago
  I have the same problem with a bog-standard Dell laptop power supply. The safety ground (earth) lead is bonded to neutral way the hell back at the meter so there's too much inductance in the lead and through the whole house to do much good other than prevent electrocution.
  - fb03 8y ago
    Can't you simply unplug this connection and install a proper earth at your place? That's what I did (literally: huge copper bar buried) and a lot of stuff (including the shower, which in my country is electrically heated) stopped giving me tingles.
    - howard941 8y ago
      There's an 8 foot long copper rod as the earth ground now. Replacing the existing connection would be nasty, the power company would have to come out to pull the meter (it's sealed) to get at the bonding strap inside the box and it's doubtful they'd reenergize the place without a visible bond.
    - mises 8y ago
      That sounds smart, though I can't imagine a huge copper bar came cheap. You can get something for as little as $17 off Amazon, and maybe cheaper if you look harder: https://www.amazon.com/Skywalker-Signature-Ground-Rod-4ft/dp/B009OMMRMO/ https://www.amazon.com/Skywalker-Signature-Ground-Rod-4ft/dp...
      - mindslight 8y ago
        Grounding rods are generally copper clad steel. In the US, proper ones are 8ft. $13 at Home Depot. An electrician can either measure the actual impedance or put in two rods with some spacing, so they're often just used in pairs. Back when Radio Shack was closing I put the damper on some guy who was going to buy all the grounding rods thinking he'd scrap the copper. I did him the favor of disappointing him before he spent his money.
      - nielsbjerg 8y ago
        Does not have to be copper. I've done several of these using galvanized steel hammered into the ground. We'd hammer in rods of 2 meters length until the resistance was low enough (around 1600 ohms Iirc). This would ensure hpfi tripped below 50mA
    - sandworm101 8y ago
      Be very careful about this. Grounding isn't always as easy as hammering in a spike. Some soils don't conduct properly, something that can change throughout the year as water tables move. A few US soldiers in Iraq were wounded in showers because while the electrical system was not properly ground, the shower drains were.
      - balabaster 8y ago
        We used to frequently have problems with the electric fences on our farm for this same reason. Once every few weeks I pour a 5 gallon pail of water over the grounding rod to keep the fence at 7,000V. Works like a charm. This is particularly problematic where soil is a shale/gravel mix and drains quickly leaving little moisture. Grounding requires moisture for maximum conductivity. Good grounding is also required to complete the electrical circuit when you touch the fence.
        Scoundreller 8y ago
        Salty water (or acidic, or basic water) would be even more conductive, no? And the salt would reduce evaporation (and remain until it rains) until next time. Would probably kill any crops, which will help retain even more moisture.
        balabaster 8y ago
        I hadn't considered this, but yes, now that you mention it, given that salt water is more conductive, it would perhaps be more effective. My fences appear to provide maximum output (on a standard livestock electric fence tester) with our regular well water, so it hadn't occurred to me to give this any further thought.
        coryrc 8y ago
        There are already sufficients ions in the soil to conduct well.
        Scoundreller 8y ago
  - abakker 8y ago
    Have you actually checked the ground for continuity? IN my house, I found that many of the upstairs outlets (wired with BX) had their grounds bonded to the water pipes in my house, instead of run directly to the box, and then the water pipe was bonded to the box down near the service entrance. Unfortunately, there was no ground continuity because at some point a pipe segment had been replaced with PVC instead of copper and the continuity ended. Bonding grounds to pipes was very common in older houses and is a common source of bad ground loops and electrical noise.
    - sandworm101 8y ago
      >> a pipe segment had been replaced with PVC instead of copper Which is why when you do that you are supposed to always install a wire to jump over the now non-conductive section of pipe.
      - abakker 8y ago
        Exactly what I did. I’m not sure the original homeowner knew that it mattered. I first noticed the issue with a stepper motor project I was working on. It was very interesting to hear the reduction in audible noise from the motors when the grounding was fixed.
      - atesti 8y ago
        Also if current runs over pipes, there might be more corrosion when different kinds of metal meet. You should never run ground over pipes, but instead use a dedicated copper wire
    - fastaguy88 8y ago
      This is a true story. One night, I went down into my basement and heard a snapping sound, and looked to see sparking between a 12-14G copper ground wire (from somewhere) and my water supply pipe. It turns out that my 1952-build house did NOT have a ground/earth for the panel, and a squirrel had chewed all but the last few strands of the neutral coming from the power pole. Most of the return from the house was going through this piddly ground strap, and it was not happy. I called the power company, and they were kind enough to install an new neutral almost immediately (perhaps at night). I then called an electrician, who grounded my panel. I am still amazed that my refrigerators and ovens worked, and wonder what would have happened if I had not heard the snapping sound.
  - rini17 8y ago
    This is the standard everywhere in Europe, with separated earth and neutral wires which are connected and grounded somewhere farther. It is done for a purpose and not a problem when done properly. The resistance nor inductance is never enough to allow so high potential, even at kHz frequencies of switching power supplies. So this indicates a problem on earth wire that should be fixed by a professional, not by blindly adding some makeshift earthing.
    - shawnz 8y ago
      It's the standard in North America too, neutral and ground are bonded at the panel and can't be connected anywhere closer than that (which would be referred to as a 'bootleg ground' and could create electrocution risks if the wiring is wrong)
- jakejarvis 8y ago
  Same for the back of my iPad Pro at times, too. I appreciate this post – thought I was crazy!
- krisrm 8y ago
  Mildly off-topic: is "earthed" a European-ism? I've only ever heard "grounded" until reading through this article and thread.
  - soneil 8y ago
    British English - the author is Australian.
  - sonofgod 8y ago
    It's certainly British English.
  - magduf 8y ago
    >Mildly off-topic: is "earthed" a European-ism? Yes. We say "grounded" in the US English, but in UK English it's usually called "earthed".
    - dylan604 8y ago
      Grounded means no tv or video games for 2 weeks. I’ve done enough reading for electrical wiring for both small electronics and electrical power that I’ve seen both terms frequently enough that neither seems out of place to me.
  - Sujan 8y ago
    Maybe also a translation thing, in German "grounding" is translated to "erden" which means "putting into or connecting to the ground", but "Erde" is also the substantive meaning "earth".
    - gowld 8y ago
      Words take on a range of meaning. "ground" and "earth" have overlapping meanings.
      - iforgotpassword 8y ago
        Sure. In English though it's fine to refer to e.g. the street as "ground", like when you drop your ice cream outside. In German, "Grund" would be something like the ground of a lake, your ice cream would drop on the "Erde". So they have the same meaning but in the overlapping area English is biased towards ground and German towards earth. Or something like that.
IshKebab 8y ago
> It's current that kills, not volts. I wish people wouldn't say that, it's a complete mischaracterisation of how voltage and current work.
- LeonM 8y ago
  When it comes to lethality, time is also an important factor. A very short burst of high current is not lethal. So if you really want to be correct, it's electrical charge that kills. edit: typo
  - dcbadacd 8y ago
    If you take time into account then it's power dissipated that matters. But again, with high-frequency AC the skin effect comes into play and you also probably won't die as easily as you would with same power being dissipated by DC going trough you. It's simply not as simple as just one sentence.
  - magduf 8y ago
    No, this isn't true either. The way that most people die of electrocution is from heart fibrillation, not from having their arms blown off by extreme voltage and current levels. It doesn't take much current to cause your heart to fibrillate; only about 100mA across your heart. So getting a shock that conducts that much current through your foot or hand probably won't hurt you, but getting a shock that conducts that current across your heart can. In short, it's more complicated than anything being said here.
    - MrBuddyCasino 8y ago
      Even if the heart muscle doesn't kill you, you can still die from the chemical imbalance caused by subjecting to your whole body to electrolysis. So if you got shocked, visit a hospital immediately! You can still die hours later.
      - magduf 8y ago
        Citation needed. We were taught about electrical safety and its effect on the human body in college EE classes, and there was nothing said of this.
dingo_bat 8y ago
I don't know why only macbooks seem to have this problem.
earthboundkid 8y ago
2012.
- idlewords 8y ago
  The unchanging laws of electricity still make this article... ...current
  - spronkey 8y ago
    You have my upvote for that electric witticism.
  - dhimes 8y ago
    This isn't about the laws of electricity but about how the power supply is designed. I was surprised recently when my Mac-using colleague needed a three-pronged extension cord. I don't carry those around in my backpack because everything I need is two-pronged. I thought it was silly that Apple would force this on their users. With a regular transformer/diode bridge/capacitor power supply this isn't needed. The traditional use of a ground-plug in these situations is to protected the user against electric shock should "hot" a wire get loose and touch the metal case. But when the voltage is dropped to non-lethal amounts (or if you have a plastic case) this is unnecessary. In fact, most "third wires" don't even make it to the device- they terminate in the transformer box. So the Mac plug was truly a bit perplexing. But now I know why.
- kzcqt 8y ago
  Doesn't look like the laws of physics have changed much since 2012, have they?
wongarsu 8y ago
> It's worth noting that the fuzzy-electronics effect can be felt if you use an earthed power point but the power point's Active and Neutral are wired back to front. That's an interesting issue, since in continential Europe (and a lot of the rest of the world) the plugs are symmetrical and don't distuingish between active and neutral. I guess if this happens to me with a three-pronged plug I should try flipping it.
- dsfyu404ed 8y ago
  >That's an interesting issue, since in continential Europe (and a lot of the rest of the world) the plugs are symmetrical and don't distinguish between active and neutral. It really doesn't matter much with A/C since the voltage is always flip flopping. You're basically a bird on a wire at all times but that wire is the earth itself. I can't think of any situation where a properly manufactured device would care which contact is neutral and which one is power. Ground is (in theory) always separate from neutral on the device (it should go without saying that it's separate from the line otherwise you have a short to ground). Plugs in the US used to be symmetrical too. Edit: Since apparently I'm Wrong(TM) does anyone want to tell me why?
  - gowld 8y ago
    (1) Your advice could kill people, and (2) it's not reasonable to claim that decades of expensive electrical mains and appliance design&manufacturing was done for no benefit. The ground wire connects to non-electrified portion of the device, as a protection against accidental electrification. Neutral closes the mains circuit also is grounded, protecting the electrified portion against accidental activation. https://en.wikipedia.org/wiki/Ground_and_neutral https://en.wikipedia.org/wiki/Ground_and_neutral That article also has a section about how mechanized-farm cow milk production is harmed by the issue discussed in the OP
    - dsfyu404ed 8y ago
      Of course you don't want to use the ground as your neutral. In normal wiring it's not designed to do that job so it sucks at it. I'm talking about the polarity of the line and the load as it relates to the device being powered. Your comment seems like a complete and total non-sequitur to that. I'm talking about a directional plug here. > Your advice could kill people, I am not giving any advice. I'm saying that unless you're doing something complex involving the neutral and ground no technical reason the neutral and the hot contacts on any given device are not interchangeable because the electrons are going both directions anyway. > it's not reasonable to claim that decades of expensive electrical mains and appliance design&manufacturing was done for no benefit. You can still get devices in 2019 that are not grounded (common) and do not have a directional plug (rare). >Neutral closes the mains circuit also is grounded, protecting the electrified portion against accidental activation. How is this related to what I said? Yes neutral and ground are both "grounded to the ground" at some point (usually the panel) but the device being plugged in doesn't know the difference between the neutral and the live wire because its getting its electrons from both (because AC).
thedanbob 8y ago
I felt this effect for the first time when I was living in Israel for a few months. I couldn't rest my wrists on my MBA while it was plugged in because of how painful it was. People said the power was "dirtier" over there than in the US (lots of voltage spikes? rougher waveform? not sure) so maybe that made it worse.
- jseutter 8y ago
  Assuming you're coming from North America, I found across Europe when my laptop was plugged into 240V I would get this, while 120V in North America was fine. It would also vary depending on the power draw - when the battery was recharging it would be worse (I think). I ended up unplugging and running off battery as much as possible, and eventually buying a smallish bluetooth keyboard and mouse to take on trips.
katsura 8y ago
I have the same problem with my Asus Vivobook. It has aluminimum body, and sometimes can be quite uncomfortable on my wrists as I get the constant buzzing feeling. I've been wondering if I could just buy a plastic skin that would protect me, because where I live, I can't really change the plugs.
- adrianN 8y ago
  A coat of lacquer should do it?
  - taneq 8y ago
    Or a properly earthed power supply, maybe?
    - adrianN 8y ago
      > because where I live, I can't really change the plugs.
      - taneq 8y ago
        In most of the world "changing the plugs" isn't really a thing, the problem is the design of the power supply (hence my comment.) To clarify: Floating switchmode power supplies that aren't isolated from a separately earthed conductive shell are a bad thing.
maxxxxx 8y ago
When I took my MacBook to France I noticed this too. It was enough to make me really nervous. Never noticed the tingly feeling in the US.
gnode 8y ago
It's not just an issue for humans. I often have the problem that touching my single board computer (ODROID-UX4) or plugging another mains powered device into it like a screen zaps it and causes it to fault and reset. I wonder if this is because it has a Chinese wall wort power supply with a UK adapter. Particularly, the Chinese two prong plug is symmetrical and fits the UK adapter in two orientations, so live and neutral are not differentiated.
- NullPrefix 8y ago
  >Chinese wall wort power supply What did you expect?
mcguire 8y ago
VGA external monitors were also susceptible to this, resulting in a wavy interference pattern.
CalChris 8y ago
This happened to me in around 2005. I was constantly getting shocked when I opened my MacBook. So I took it the Apple store in Berkeley and they harrumphed and said it was within spec. Still getting shocked. So I took a multimeter and measured the current and showed that to them. They harrumphed again and said that service would look at it and probably wouldn't fix it. But they fixed it.
- vertline3 8y ago
  Yeah their "genius bar" left a lot to be desired, I switched away for that reason. At first they were great, but over the years the one I went to just stopped really trying and instead shifted more to sales.
  - CalChris 8y ago
    Service did fix it. To be fair, it was the only MacBook of mine that's had that problem. I've had many.
  - dontbenebby 8y ago
    I hate that there is no literal "genius bar" anymore - now you have to fight for table space like it's a SoMa coffee shop.
    - crooked-v 8y ago
      Every Apple store I've been to in the last five years seem to have been designed for half the number of occupants they actually have.
      - saagarjha 8y ago
        I mean, it's not surprising why: they were likely designed before Apple was as popular as it is today.
mindslight 8y ago
Does this ever get bad enough to feel without touching something else to directly complete the circuit? I would predictably get this when using laptop (on lap) and resting my arm on a metal heater next to me. I ended up returning a few AC adapters because the leakage was too damn high, and eventually they offered me a three prong version that came with many more regulatory marks. The problem with two prong devices is that a designer has to assume either wire could be hot, because it could be plugged in backwards. I've got to wonder if a change in the regulations that would allow for a single cap to the probable neutral could solve this. It would double the leakage current if the thing were actually plugged in backwards, but as long as it was just more uncomfortable rather than dangerous this would be a win. Also there are a few handwavey things at the bottom of the post that just leave me scratching my head: > Even though the MagSafe power supply itself is not connected to the mains earth, there is just enough inductance leakage for the floating charge to dissipate through the plastic sheath of the mains cable. There could be something to what is being said, but if there is he's not describing it well. > It's worth noting that the fuzzy-electronics effect can be felt if you use an earthed power point but the power point's Active and Neutral are wired back to front That's an odd diagnosis, because three prong means the output is being directly grounded. Instead, I would infer that the ground (EGC) was disconnected (like say an old home where someone improperly changed two prong to three prong outlets when remodeling).
gambiting 8y ago
So that's why I always have this tingly feeling under my fingertips whenever I use my macbook! I always wondered what that was.
bcaa7f3a8bbc 8y ago
The real question is, if the common wisdom is to ground the chassis when possible, and even the induced voltage on the chassis is harmless, they are seen as a widely recognized annoyance. So, my (Question 1) then why does the hardware designers keep using ungrounded design in the first place? Just because they think the output through a isolated transformer is safe enough (also can meet safety regulations), so they want to then omitting the Protective Earthing to simply make the power supply smaller and they think it's okay to give the users some small shocks? Or it's something else? And here's another question I don't understand. When a piece of electronics don't have a Protective Grounding connection, the common explanation is: the low voltage is created by a SMPS, and an isolation transformer at the output side of the SMPS makes the voltage no longer being Earth-referenced, so in the worst possibly scenario, if a grounded person touches the "hot" output wire, nothing would happen. But if you ground the chassis to the Protective Ground (often the ground of the PCB is connected to the chassis), the output becomes Earth-referenced again and loses the protection of isolation. This is why an isolation transformer has a unconnected Protective Ground at its output side, and many SMPS-based appliances don't use the Protective Ground. So my Question 2, according to the common wisdom and many regulations, most appliances should be grounded, but from the principle of isolated power supply, it should not be grounded. And in real life, we clearly see lots of laptops use DC power supply without the ground connector, and others with the ground connector. And to further complicated the issue, some DC power supplies only use the ground internally for the EMI filter circuity and/or its own enclosure, but the DC output itself is isolated and is not ground referenced. Then how can an isolated power supply with the ground plug help stopping the induced voltage on a laptop's enclosure, if the output is isolated? Something related to the leakage current of the X/Y capacitors? It seems there's lots of inconsistency here. Just why?
- gumby 8y ago
  > So, my (Question 1) then why does the hardware designers keep using ungrounded design in the first place? Ungrounded sockets are still very common (just off the top of my head, in Japan, Philippines, Australia, all through Europe, India...). Even as building codes change it takes many decades for the housing tock to upgrade. Even when the code requires upgrades to commercial buildings it rarely will of residential. If the leakage is harmless (or "harmless) why risk the user buying a product, getting home, and then being unable to use it. The OOBE is terrible and possibly fatal. This is also why the "international travel kit" for Apple power supplies contains non-grounded plugs. The authors final and correct point about Apple is fortunately now obsolete as since it was written Apple has switched to standard Type C connectors. On the other hand they no longer ship grounded connectors by default (in the USA at least).
jayalpha 8y ago
I had this with a Dell XPS in India but it was connected somehow to the power supply. Maybe some voltage crept to the ground wire. Dunno.
abledon 8y ago
Electric exposure is such a new phenomenon in terms of human evolution... like, humans have had their hands on small charged devices for like less than 100 years. I wonder if an overweight person feels less of the electricity since they have more fat shielding their nervous system?
- fpgaminer 8y ago
  We've been exposed to static electricity through all of our history.
  - abledon 8y ago
    i think a hand rubbing against a wool sweater making a little shock is different than having a laptop over my nuts for 10 hours a day!
teekert 8y ago
I already noticed that I didn't have this with an earthed (grounded) wall socket, very nice to finally see the explanation!
mrguyorama 8y ago
I have experienced this in a very weird but completely reproducible manner. My Logitech G27 steering wheel has a power plug to run the force feedback system. If you connect the peripheral to power but not to the computer, touching the metal pedals causes strong burning sensations.
cmsj 8y ago
I've had this on lots of laptops, but the worst was a thinkpad, whose only exposed metal was a little fingerprint reader that lined up perfectly with the softest, most sensitive skin of my wrist. I hated the little shocks from that thing.
- pflanze 8y ago
  I had the same experience with a T61 I owned, and used to just tape a bit of plastic foil over the reader (I wasn't using it).
nonfamous 8y ago
I wonder is this is related to an issue with my Surface Book: when it’s plugged in to some (but not many) power outlets, the trackpad becomes unusable (the cursor skips all over the screen when you touch it). I’ve noticed it in a couple of hotels, and unplugging it and using battery eliminates the problem. I wonder if it’s related to this surface (pun not intended) charge caused by bad grounding?
menacingly 8y ago
I thought this would be about how an XPS 13 will literally bite you with its hinge. I got a few blisters having my finger in the wrong place when I open the lid.
samdung 8y ago
I had (still have lying around) a Toshiba Portege purchased way back in 2012. It had quite sharp edges that gave out a shock whenever my elbows grazed them. The shock was mild but very discomforting and made me very conscious when using the laptop. Over time i discovered that using a 3 pin plug avoided the shock. In 2015 i switched to a macbook pro which also has this issue. Thanks to this article i know whats happening.
julianlam 8y ago
That's quite interesting! I always wondered why there was a "tingliness" when I ran my fingers lightly over the top of my laptop when it was plugged in, good to know. It is a little concerning that this was with my Asus Zenbook, which comes with a 3-prong power adapter...!
- andrelaszlo 8y ago
  Are your outlets properly grounded?
stordoff 8y ago
I've noticed this a few times - it's usually what e when a stray Lightning/USB cable is touching another part of my body.
dmitrygr 8y ago
The description of how SMPS works in thei article is shockingly inaccurate! > To simplify, an SMPS essentially > takes the AC input and turns it on > and off very quickly (between 10,000 > and 20,000 times per second), with > the output voltage being determined > by the duty cycle - the amount of > time it is on for each flipflop. The > shorter it is on, the lower the > voltage. This is fed into regulators > and capacitors to produce a stable > AC voltage, which is then converted > into DC. Literally no part of that is accurate. SMPSs generally rectify first,then PWM, then smooth
- Animats 8y ago
  Right. But not the real issue. See [1][2]. Most switching power supplies have a small capacitor between the AC line and output sides of the transformer, to provide a somewhat tenuous path to ground for RF noise on the output side. That's a fundamentally bad idea, but cheap. Better approaches involve either a real ground, with a 3-prong plug, or some new designs which handle RF noise in a way that doesn't need a path to ground.[3] Here's a patent (in Chinese) for a solution without a bypass capacitor.[4] [1] https://i.stack.imgur.com/fV15S.png https://i.stack.imgur.com/fV15S.png [2] https://electronics.stackexchange.com/questions/216959/what-does-the-y-capacitor-in-a-smps-do https://electronics.stackexchange.com/questions/216959/what-... [3] https://ieeexplore.ieee.org/document/7488992 https://ieeexplore.ieee.org/document/7488992 [4] https://patents.google.com/patent/CN202818110U/en https://patents.google.com/patent/CN202818110U/en
jlokier 8y ago
I've felt that uncomfortable tingling and occasional shocks on a number of laptops, be they metal chassis (Macbook) or plastic. Some friends report being zapped by their Macbooks. The weirdest for me was my first laptop. I kept getting shocks from the palm rest, even though it was all plastic and presumably a good insulator. I didn't understand how a shock could reach me through solid plastic.
blunte 8y ago
I never felt a buzz through my laptops when I lived in the US, but I feel it fairly often in Netherlands. What is really strange is that occasionally I could feel the buzz while gently moving my fingertips across my girlfriend's shoulder while in bed. It was not an imagined sensation - it was exactly like with the laptop. We were on a waterbed, but I don't think that could have anything to do with it. The laptop mystery is solved, but this one is still a curious mystery.
VibrantClarity 8y ago
I had an old Acer laptop, the C710 i think, where the touchpad would only work if you grounded it. Only the whole chassis was plastic so you could only operate it with one hand because the other had to touching the little band of metal around the VGA port.
okmokmz 8y ago
When my old macbook air is plugged in I can feel the electricity in my palms resting on the aluminum while typing. It was kind of like those old prank shock pens, but less intense
floatingatoll 8y ago
Note that using an Apple laptop charger with its included three-prong charger cord will provide a grounded charge (no buzz), as opposed to Apple’s or any two-prong connector (or a third-party three-prong that’s missing the female grounding connector inside the charger-side plug).
elektriker99 8y ago
Are there alternative solutions to this problem, that are not interesting for industry, but feasible for hackers? E.g.: remove those two capacitors that bridge the primary and secondary sides of the power supply. Tingle is now gone, but the supply is now emitting a lot of EMF noise. How about arresting that with some bulky ol' ferrite cores?

136 points by tomduncalf 8y ago

I've noticed that even with an earthed power supply I still have the problem with the newer USB-C MacBooks. I find it rather uncomfortable on my wrists. A MacBook I had quite a few years ago had a cracked chassis - touching that when using a non-earthed power supply was enough to be a little bit painful.

howard941 8y ago
I have the same problem with a bog-standard Dell laptop power supply. The safety ground (earth) lead is bonded to neutral way the hell back at the meter so there's too much inductance in the lead and through the whole house to do much good other than prevent electrocution.
- fb03 8y ago
  Can't you simply unplug this connection and install a proper earth at your place? That's what I did (literally: huge copper bar buried) and a lot of stuff (including the shower, which in my country is electrically heated) stopped giving me tingles.
  - howard941 8y ago
    There's an 8 foot long copper rod as the earth ground now. Replacing the existing connection would be nasty, the power company would have to come out to pull the meter (it's sealed) to get at the bonding strap inside the box and it's doubtful they'd reenergize the place without a visible bond.
  - mises 8y ago
    That sounds smart, though I can't imagine a huge copper bar came cheap. You can get something for as little as $17 off Amazon, and maybe cheaper if you look harder: https://www.amazon.com/Skywalker-Signature-Ground-Rod-4ft/dp/B009OMMRMO/ https://www.amazon.com/Skywalker-Signature-Ground-Rod-4ft/dp...
    - mindslight 8y ago
      Grounding rods are generally copper clad steel. In the US, proper ones are 8ft. $13 at Home Depot. An electrician can either measure the actual impedance or put in two rods with some spacing, so they're often just used in pairs. Back when Radio Shack was closing I put the damper on some guy who was going to buy all the grounding rods thinking he'd scrap the copper. I did him the favor of disappointing him before he spent his money.
    - nielsbjerg 8y ago
      Does not have to be copper. I've done several of these using galvanized steel hammered into the ground. We'd hammer in rods of 2 meters length until the resistance was low enough (around 1600 ohms Iirc). This would ensure hpfi tripped below 50mA
  - sandworm101 8y ago
    Be very careful about this. Grounding isn't always as easy as hammering in a spike. Some soils don't conduct properly, something that can change throughout the year as water tables move. A few US soldiers in Iraq were wounded in showers because while the electrical system was not properly ground, the shower drains were.
    - balabaster 8y ago
      We used to frequently have problems with the electric fences on our farm for this same reason. Once every few weeks I pour a 5 gallon pail of water over the grounding rod to keep the fence at 7,000V. Works like a charm. This is particularly problematic where soil is a shale/gravel mix and drains quickly leaving little moisture. Grounding requires moisture for maximum conductivity. Good grounding is also required to complete the electrical circuit when you touch the fence.
      - Scoundreller 8y ago
        Salty water (or acidic, or basic water) would be even more conductive, no? And the salt would reduce evaporation (and remain until it rains) until next time. Would probably kill any crops, which will help retain even more moisture.
        balabaster 8y ago
        I hadn't considered this, but yes, now that you mention it, given that salt water is more conductive, it would perhaps be more effective. My fences appear to provide maximum output (on a standard livestock electric fence tester) with our regular well water, so it hadn't occurred to me to give this any further thought.
        coryrc 8y ago
        There are already sufficients ions in the soil to conduct well.
        Scoundreller 8y ago
- abakker 8y ago
  Have you actually checked the ground for continuity? IN my house, I found that many of the upstairs outlets (wired with BX) had their grounds bonded to the water pipes in my house, instead of run directly to the box, and then the water pipe was bonded to the box down near the service entrance. Unfortunately, there was no ground continuity because at some point a pipe segment had been replaced with PVC instead of copper and the continuity ended. Bonding grounds to pipes was very common in older houses and is a common source of bad ground loops and electrical noise.
  - sandworm101 8y ago
    >> a pipe segment had been replaced with PVC instead of copper Which is why when you do that you are supposed to always install a wire to jump over the now non-conductive section of pipe.
    - abakker 8y ago
      Exactly what I did. I’m not sure the original homeowner knew that it mattered. I first noticed the issue with a stepper motor project I was working on. It was very interesting to hear the reduction in audible noise from the motors when the grounding was fixed.
    - atesti 8y ago
      Also if current runs over pipes, there might be more corrosion when different kinds of metal meet. You should never run ground over pipes, but instead use a dedicated copper wire
  - fastaguy88 8y ago
    This is a true story. One night, I went down into my basement and heard a snapping sound, and looked to see sparking between a 12-14G copper ground wire (from somewhere) and my water supply pipe. It turns out that my 1952-build house did NOT have a ground/earth for the panel, and a squirrel had chewed all but the last few strands of the neutral coming from the power pole. Most of the return from the house was going through this piddly ground strap, and it was not happy. I called the power company, and they were kind enough to install an new neutral almost immediately (perhaps at night). I then called an electrician, who grounded my panel. I am still amazed that my refrigerators and ovens worked, and wonder what would have happened if I had not heard the snapping sound.
- rini17 8y ago
  This is the standard everywhere in Europe, with separated earth and neutral wires which are connected and grounded somewhere farther. It is done for a purpose and not a problem when done properly. The resistance nor inductance is never enough to allow so high potential, even at kHz frequencies of switching power supplies. So this indicates a problem on earth wire that should be fixed by a professional, not by blindly adding some makeshift earthing.
  - shawnz 8y ago
    It's the standard in North America too, neutral and ground are bonded at the panel and can't be connected anywhere closer than that (which would be referred to as a 'bootleg ground' and could create electrocution risks if the wiring is wrong)
jakejarvis 8y ago
Same for the back of my iPad Pro at times, too. I appreciate this post – thought I was crazy!
krisrm 8y ago
Mildly off-topic: is "earthed" a European-ism? I've only ever heard "grounded" until reading through this article and thread.
- soneil 8y ago
  British English - the author is Australian.
- sonofgod 8y ago
  It's certainly British English.
- magduf 8y ago
  >Mildly off-topic: is "earthed" a European-ism? Yes. We say "grounded" in the US English, but in UK English it's usually called "earthed".
  - dylan604 8y ago
    Grounded means no tv or video games for 2 weeks. I’ve done enough reading for electrical wiring for both small electronics and electrical power that I’ve seen both terms frequently enough that neither seems out of place to me.
- Sujan 8y ago
  Maybe also a translation thing, in German "grounding" is translated to "erden" which means "putting into or connecting to the ground", but "Erde" is also the substantive meaning "earth".
  - gowld 8y ago
    Words take on a range of meaning. "ground" and "earth" have overlapping meanings.
    - iforgotpassword 8y ago
      Sure. In English though it's fine to refer to e.g. the street as "ground", like when you drop your ice cream outside. In German, "Grund" would be something like the ground of a lake, your ice cream would drop on the "Erde". So they have the same meaning but in the overlapping area English is biased towards ground and German towards earth. Or something like that.

IshKebab 8y ago

> It's current that kills, not volts. I wish people wouldn't say that, it's a complete mischaracterisation of how voltage and current work.

LeonM 8y ago
When it comes to lethality, time is also an important factor. A very short burst of high current is not lethal. So if you really want to be correct, it's electrical charge that kills. edit: typo
- dcbadacd 8y ago
  If you take time into account then it's power dissipated that matters. But again, with high-frequency AC the skin effect comes into play and you also probably won't die as easily as you would with same power being dissipated by DC going trough you. It's simply not as simple as just one sentence.
- magduf 8y ago
  No, this isn't true either. The way that most people die of electrocution is from heart fibrillation, not from having their arms blown off by extreme voltage and current levels. It doesn't take much current to cause your heart to fibrillate; only about 100mA across your heart. So getting a shock that conducts that much current through your foot or hand probably won't hurt you, but getting a shock that conducts that current across your heart can. In short, it's more complicated than anything being said here.
  - MrBuddyCasino 8y ago
    Even if the heart muscle doesn't kill you, you can still die from the chemical imbalance caused by subjecting to your whole body to electrolysis. So if you got shocked, visit a hospital immediately! You can still die hours later.
    - magduf 8y ago
      Citation needed. We were taught about electrical safety and its effect on the human body in college EE classes, and there was nothing said of this.

dingo_bat 8y ago

I don't know why only macbooks seem to have this problem.

earthboundkid 8y ago

2012.

idlewords 8y ago
The unchanging laws of electricity still make this article... ...current
- spronkey 8y ago
  You have my upvote for that electric witticism.
- dhimes 8y ago
  This isn't about the laws of electricity but about how the power supply is designed. I was surprised recently when my Mac-using colleague needed a three-pronged extension cord. I don't carry those around in my backpack because everything I need is two-pronged. I thought it was silly that Apple would force this on their users. With a regular transformer/diode bridge/capacitor power supply this isn't needed. The traditional use of a ground-plug in these situations is to protected the user against electric shock should "hot" a wire get loose and touch the metal case. But when the voltage is dropped to non-lethal amounts (or if you have a plastic case) this is unnecessary. In fact, most "third wires" don't even make it to the device- they terminate in the transformer box. So the Mac plug was truly a bit perplexing. But now I know why.
kzcqt 8y ago
Doesn't look like the laws of physics have changed much since 2012, have they?

wongarsu 8y ago

> It's worth noting that the fuzzy-electronics effect can be felt if you use an earthed power point but the power point's Active and Neutral are wired back to front. That's an interesting issue, since in continential Europe (and a lot of the rest of the world) the plugs are symmetrical and don't distuingish between active and neutral. I guess if this happens to me with a three-pronged plug I should try flipping it.

dsfyu404ed 8y ago
>That's an interesting issue, since in continential Europe (and a lot of the rest of the world) the plugs are symmetrical and don't distinguish between active and neutral. It really doesn't matter much with A/C since the voltage is always flip flopping. You're basically a bird on a wire at all times but that wire is the earth itself. I can't think of any situation where a properly manufactured device would care which contact is neutral and which one is power. Ground is (in theory) always separate from neutral on the device (it should go without saying that it's separate from the line otherwise you have a short to ground). Plugs in the US used to be symmetrical too. Edit: Since apparently I'm Wrong(TM) does anyone want to tell me why?
- gowld 8y ago
  (1) Your advice could kill people, and (2) it's not reasonable to claim that decades of expensive electrical mains and appliance design&manufacturing was done for no benefit. The ground wire connects to non-electrified portion of the device, as a protection against accidental electrification. Neutral closes the mains circuit also is grounded, protecting the electrified portion against accidental activation. https://en.wikipedia.org/wiki/Ground_and_neutral https://en.wikipedia.org/wiki/Ground_and_neutral That article also has a section about how mechanized-farm cow milk production is harmed by the issue discussed in the OP
  - dsfyu404ed 8y ago
    Of course you don't want to use the ground as your neutral. In normal wiring it's not designed to do that job so it sucks at it. I'm talking about the polarity of the line and the load as it relates to the device being powered. Your comment seems like a complete and total non-sequitur to that. I'm talking about a directional plug here. > Your advice could kill people, I am not giving any advice. I'm saying that unless you're doing something complex involving the neutral and ground no technical reason the neutral and the hot contacts on any given device are not interchangeable because the electrons are going both directions anyway. > it's not reasonable to claim that decades of expensive electrical mains and appliance design&manufacturing was done for no benefit. You can still get devices in 2019 that are not grounded (common) and do not have a directional plug (rare). >Neutral closes the mains circuit also is grounded, protecting the electrified portion against accidental activation. How is this related to what I said? Yes neutral and ground are both "grounded to the ground" at some point (usually the panel) but the device being plugged in doesn't know the difference between the neutral and the live wire because its getting its electrons from both (because AC).

thedanbob 8y ago

I felt this effect for the first time when I was living in Israel for a few months. I couldn't rest my wrists on my MBA while it was plugged in because of how painful it was. People said the power was "dirtier" over there than in the US (lots of voltage spikes? rougher waveform? not sure) so maybe that made it worse.

jseutter 8y ago
Assuming you're coming from North America, I found across Europe when my laptop was plugged into 240V I would get this, while 120V in North America was fine. It would also vary depending on the power draw - when the battery was recharging it would be worse (I think). I ended up unplugging and running off battery as much as possible, and eventually buying a smallish bluetooth keyboard and mouse to take on trips.

katsura 8y ago

I have the same problem with my Asus Vivobook. It has aluminimum body, and sometimes can be quite uncomfortable on my wrists as I get the constant buzzing feeling. I've been wondering if I could just buy a plastic skin that would protect me, because where I live, I can't really change the plugs.

adrianN 8y ago
A coat of lacquer should do it?
- taneq 8y ago
  Or a properly earthed power supply, maybe?
  - adrianN 8y ago
    > because where I live, I can't really change the plugs.
    - taneq 8y ago
      In most of the world "changing the plugs" isn't really a thing, the problem is the design of the power supply (hence my comment.) To clarify: Floating switchmode power supplies that aren't isolated from a separately earthed conductive shell are a bad thing.

maxxxxx 8y ago

When I took my MacBook to France I noticed this too. It was enough to make me really nervous. Never noticed the tingly feeling in the US.

gnode 8y ago

It's not just an issue for humans. I often have the problem that touching my single board computer (ODROID-UX4) or plugging another mains powered device into it like a screen zaps it and causes it to fault and reset. I wonder if this is because it has a Chinese wall wort power supply with a UK adapter. Particularly, the Chinese two prong plug is symmetrical and fits the UK adapter in two orientations, so live and neutral are not differentiated.

NullPrefix 8y ago
>Chinese wall wort power supply What did you expect?

mcguire 8y ago

VGA external monitors were also susceptible to this, resulting in a wavy interference pattern.

CalChris 8y ago

This happened to me in around 2005. I was constantly getting shocked when I opened my MacBook. So I took it the Apple store in Berkeley and they harrumphed and said it was within spec. Still getting shocked. So I took a multimeter and measured the current and showed that to them. They harrumphed again and said that service would look at it and probably wouldn't fix it. But they fixed it.

vertline3 8y ago
Yeah their "genius bar" left a lot to be desired, I switched away for that reason. At first they were great, but over the years the one I went to just stopped really trying and instead shifted more to sales.
- CalChris 8y ago
  Service did fix it. To be fair, it was the only MacBook of mine that's had that problem. I've had many.
- dontbenebby 8y ago
  I hate that there is no literal "genius bar" anymore - now you have to fight for table space like it's a SoMa coffee shop.
  - crooked-v 8y ago
    Every Apple store I've been to in the last five years seem to have been designed for half the number of occupants they actually have.
    - saagarjha 8y ago
      I mean, it's not surprising why: they were likely designed before Apple was as popular as it is today.

mindslight 8y ago

Does this ever get bad enough to feel without touching something else to directly complete the circuit? I would predictably get this when using laptop (on lap) and resting my arm on a metal heater next to me. I ended up returning a few AC adapters because the leakage was too damn high, and eventually they offered me a three prong version that came with many more regulatory marks. The problem with two prong devices is that a designer has to assume either wire could be hot, because it could be plugged in backwards. I've got to wonder if a change in the regulations that would allow for a single cap to the probable neutral could solve this. It would double the leakage current if the thing were actually plugged in backwards, but as long as it was just more uncomfortable rather than dangerous this would be a win. Also there are a few handwavey things at the bottom of the post that just leave me scratching my head: > Even though the MagSafe power supply itself is not connected to the mains earth, there is just enough inductance leakage for the floating charge to dissipate through the plastic sheath of the mains cable. There could be something to what is being said, but if there is he's not describing it well. > It's worth noting that the fuzzy-electronics effect can be felt if you use an earthed power point but the power point's Active and Neutral are wired back to front That's an odd diagnosis, because three prong means the output is being directly grounded. Instead, I would infer that the ground (EGC) was disconnected (like say an old home where someone improperly changed two prong to three prong outlets when remodeling).

gambiting 8y ago

So that's why I always have this tingly feeling under my fingertips whenever I use my macbook! I always wondered what that was.

bcaa7f3a8bbc 8y ago

The real question is, if the common wisdom is to ground the chassis when possible, and even the induced voltage on the chassis is harmless, they are seen as a widely recognized annoyance. So, my (Question 1) then why does the hardware designers keep using ungrounded design in the first place? Just because they think the output through a isolated transformer is safe enough (also can meet safety regulations), so they want to then omitting the Protective Earthing to simply make the power supply smaller and they think it's okay to give the users some small shocks? Or it's something else? And here's another question I don't understand. When a piece of electronics don't have a Protective Grounding connection, the common explanation is: the low voltage is created by a SMPS, and an isolation transformer at the output side of the SMPS makes the voltage no longer being Earth-referenced, so in the worst possibly scenario, if a grounded person touches the "hot" output wire, nothing would happen. But if you ground the chassis to the Protective Ground (often the ground of the PCB is connected to the chassis), the output becomes Earth-referenced again and loses the protection of isolation. This is why an isolation transformer has a unconnected Protective Ground at its output side, and many SMPS-based appliances don't use the Protective Ground. So my Question 2, according to the common wisdom and many regulations, most appliances should be grounded, but from the principle of isolated power supply, it should not be grounded. And in real life, we clearly see lots of laptops use DC power supply without the ground connector, and others with the ground connector. And to further complicated the issue, some DC power supplies only use the ground internally for the EMI filter circuity and/or its own enclosure, but the DC output itself is isolated and is not ground referenced. Then how can an isolated power supply with the ground plug help stopping the induced voltage on a laptop's enclosure, if the output is isolated? Something related to the leakage current of the X/Y capacitors? It seems there's lots of inconsistency here. Just why?

gumby 8y ago
> So, my (Question 1) then why does the hardware designers keep using ungrounded design in the first place? Ungrounded sockets are still very common (just off the top of my head, in Japan, Philippines, Australia, all through Europe, India...). Even as building codes change it takes many decades for the housing tock to upgrade. Even when the code requires upgrades to commercial buildings it rarely will of residential. If the leakage is harmless (or "harmless) why risk the user buying a product, getting home, and then being unable to use it. The OOBE is terrible and possibly fatal. This is also why the "international travel kit" for Apple power supplies contains non-grounded plugs. The authors final and correct point about Apple is fortunately now obsolete as since it was written Apple has switched to standard Type C connectors. On the other hand they no longer ship grounded connectors by default (in the USA at least).

jayalpha 8y ago

I had this with a Dell XPS in India but it was connected somehow to the power supply. Maybe some voltage crept to the ground wire. Dunno.

abledon 8y ago

Electric exposure is such a new phenomenon in terms of human evolution... like, humans have had their hands on small charged devices for like less than 100 years. I wonder if an overweight person feels less of the electricity since they have more fat shielding their nervous system?

fpgaminer 8y ago
We've been exposed to static electricity through all of our history.
- abledon 8y ago
  i think a hand rubbing against a wool sweater making a little shock is different than having a laptop over my nuts for 10 hours a day!

teekert 8y ago

I already noticed that I didn't have this with an earthed (grounded) wall socket, very nice to finally see the explanation!

mrguyorama 8y ago

I have experienced this in a very weird but completely reproducible manner. My Logitech G27 steering wheel has a power plug to run the force feedback system. If you connect the peripheral to power but not to the computer, touching the metal pedals causes strong burning sensations.

cmsj 8y ago

I've had this on lots of laptops, but the worst was a thinkpad, whose only exposed metal was a little fingerprint reader that lined up perfectly with the softest, most sensitive skin of my wrist. I hated the little shocks from that thing.

pflanze 8y ago
I had the same experience with a T61 I owned, and used to just tape a bit of plastic foil over the reader (I wasn't using it).

nonfamous 8y ago

I wonder is this is related to an issue with my Surface Book: when it’s plugged in to some (but not many) power outlets, the trackpad becomes unusable (the cursor skips all over the screen when you touch it). I’ve noticed it in a couple of hotels, and unplugging it and using battery eliminates the problem. I wonder if it’s related to this surface (pun not intended) charge caused by bad grounding?

menacingly 8y ago

I thought this would be about how an XPS 13 will literally bite you with its hinge. I got a few blisters having my finger in the wrong place when I open the lid.

samdung 8y ago

I had (still have lying around) a Toshiba Portege purchased way back in 2012. It had quite sharp edges that gave out a shock whenever my elbows grazed them. The shock was mild but very discomforting and made me very conscious when using the laptop. Over time i discovered that using a 3 pin plug avoided the shock. In 2015 i switched to a macbook pro which also has this issue. Thanks to this article i know whats happening.

julianlam 8y ago

That's quite interesting! I always wondered why there was a "tingliness" when I ran my fingers lightly over the top of my laptop when it was plugged in, good to know. It is a little concerning that this was with my Asus Zenbook, which comes with a 3-prong power adapter...!

andrelaszlo 8y ago
Are your outlets properly grounded?

stordoff 8y ago

I've noticed this a few times - it's usually what e when a stray Lightning/USB cable is touching another part of my body.

dmitrygr 8y ago

The description of how SMPS works in thei article is shockingly inaccurate! > To simplify, an SMPS essentially > takes the AC input and turns it on > and off very quickly (between 10,000 > and 20,000 times per second), with > the output voltage being determined > by the duty cycle - the amount of > time it is on for each flipflop. The > shorter it is on, the lower the > voltage. This is fed into regulators > and capacitors to produce a stable > AC voltage, which is then converted > into DC. Literally no part of that is accurate. SMPSs generally rectify first,then PWM, then smooth

Animats 8y ago
Right. But not the real issue. See [1][2]. Most switching power supplies have a small capacitor between the AC line and output sides of the transformer, to provide a somewhat tenuous path to ground for RF noise on the output side. That's a fundamentally bad idea, but cheap. Better approaches involve either a real ground, with a 3-prong plug, or some new designs which handle RF noise in a way that doesn't need a path to ground.[3] Here's a patent (in Chinese) for a solution without a bypass capacitor.[4] [1] https://i.stack.imgur.com/fV15S.png https://i.stack.imgur.com/fV15S.png [2] https://electronics.stackexchange.com/questions/216959/what-does-the-y-capacitor-in-a-smps-do https://electronics.stackexchange.com/questions/216959/what-... [3] https://ieeexplore.ieee.org/document/7488992 https://ieeexplore.ieee.org/document/7488992 [4] https://patents.google.com/patent/CN202818110U/en https://patents.google.com/patent/CN202818110U/en

jlokier 8y ago

I've felt that uncomfortable tingling and occasional shocks on a number of laptops, be they metal chassis (Macbook) or plastic. Some friends report being zapped by their Macbooks. The weirdest for me was my first laptop. I kept getting shocks from the palm rest, even though it was all plastic and presumably a good insulator. I didn't understand how a shock could reach me through solid plastic.

blunte 8y ago

I never felt a buzz through my laptops when I lived in the US, but I feel it fairly often in Netherlands. What is really strange is that occasionally I could feel the buzz while gently moving my fingertips across my girlfriend's shoulder while in bed. It was not an imagined sensation - it was exactly like with the laptop. We were on a waterbed, but I don't think that could have anything to do with it. The laptop mystery is solved, but this one is still a curious mystery.

VibrantClarity 8y ago

I had an old Acer laptop, the C710 i think, where the touchpad would only work if you grounded it. Only the whole chassis was plastic so you could only operate it with one hand because the other had to touching the little band of metal around the VGA port.

okmokmz 8y ago

When my old macbook air is plugged in I can feel the electricity in my palms resting on the aluminum while typing. It was kind of like those old prank shock pens, but less intense

floatingatoll 8y ago

Note that using an Apple laptop charger with its included three-prong charger cord will provide a grounded charge (no buzz), as opposed to Apple’s or any two-prong connector (or a third-party three-prong that’s missing the female grounding connector inside the charger-side plug).

elektriker99 8y ago

Are there alternative solutions to this problem, that are not interesting for industry, but feasible for hackers? E.g.: remove those two capacitors that bridge the primary and secondary sides of the power supply. Tingle is now gone, but the supply is now emitting a lot of EMF noise. How about arresting that with some bulky ol' ferrite cores?