6 ms·

Oh is that why it happens? Was wondering why the spot directly under my wrist was pitted into a sawblade. I also filed it, though just enough to remove the pitt

Oh is that why it happens? Was wondering why the spot directly under my wrist was pitted into a sawblade. I also filed it, though just enough to remove the pitting, nothing like the OP did. It's easy for me to feel the mains frequency while gently rubbing the top surface of the MacBook while it's plugged in. Really feels unsafe, but neither me nor the computer have suffered any serious injuries yet.

ajam1507 6mo ago
Using a 3 prong extension cable on the charger will prevent this.
- imglorp 6mo ago
  How? The (US) charger's only got 2 pins so ground stays unconnected.
  - Tsiklon 6mo ago
    The extension cable they used to include in box with the computers, it has the third pin for the charger brick connector which is wired to ground
    - 15155 6mo ago
      There's zero chance that the DC ground in the laptop is tied to earth ground in the charger: they use LLC resonant converters and flyback converters (depending on vintage) - an earth ground tie would defeat the purpose of these isolated topologies.
      - jahnu 6mo ago
        However it’s wired up the fact is the electric buzzing feeling goes away if you use a grounded extension cable instead of two pin.
      - namibj 6mo ago
        No they isolate L and N not PE.
  - bombcar 6mo ago
    I don't know if this link will work - https://www.chargerlab.com/wp-content/uploads/2022/06/2022061718103949.jpeg https://www.chargerlab.com/wp-content/uploads/2022/06/202206... but that metal round pin thing is a ground; and the three-prong cable connects to it.
  - pxx 6mo ago
    There are grounded duckheads for this purpose, e.g. https://amzn.to/4cnzuef https://amzn.to/4cnzuef (note out of stock. I guess your best bet is to use a UK duckhead, but half of those have a dummy ground...) if you take the plug part from the brick you'll note that there's only two pins but the button-like thing is a ground as noted in a sibling, the power adapter extension cable does plumb the ground through (https://www.apple.com/shop/product/mw2n3ll/a/power-adapter-extension-cable?cid=aos-us-seo-pla-accessories https://www.apple.com/shop/product/mw2n3ll/a/power-adapter-e...)
    - jahnu 6mo ago
      Got a bunch of cheap ones from Ali Express and they worked fine.
  - BobAliceInATree 6mo ago
    Apple sells a 3-pin extension cable US Version: https://www.apple.com/shop/product/mw2n3ll/a/power-adapter-extension-cable https://www.apple.com/shop/product/mw2n3ll/a/power-adapter-e...
- CGamesPlay 6mo ago
  That cuts it by about 90%. But as others have said, the default US plug doesn't ship with a ground pin (though the extended cord does IIRC).
- Barbing 6mo ago
  No way, that's why it's "fixed" sometimes, thanks
normie3000 6mo ago
> It's easy for me to feel the mains frequency while gently rubbing the top surface of the MacBook I haven't been a regular Mac user, but I've had maybe 3 work MacBooks since 2010 and I recall having this issue with all of them. Why haven't they fixed it?
- msephton 6mo ago
  It's also an issue on the new Neo. It was the first thing I noticed when I tried one in the Apple Store. I unplugged the power cable and it went away, replugged and it came back. I'm in the UK so I expected grounded electricity supply.
  - normie3000 6mo ago
    Disappointing. I understood Neo doesn't come with a power plug in UK; was yours the official one?
    - msephton 6mo ago
      It was just me trying one in the Apple Store
  - SeasonalEnnui 6mo ago
    If you buy the UK 1.8-metre Power Adapter Extension Cable, this has a metal ground pin that grounds through the metal clip on the power brick. I switched all my MacBook & iPad chargers to this, no more earth leakage sensation from metal casing.
- sitharus 6mo ago
  They can’t, it’s caused by the capacitors required to suppress electromagnetic interference caused by the switch-mode power supply. These allow a very very tiny amount of current to leak through from the mains side, which is then capacitively coupled to the metal case (IIRC Apple do not connect the case to power negative) reducing it further, but it’s enough for humans to sense it. It can be avoided by using a grounded power supply, but because there are large countries that have ungrounded outlets in common use the most designs are ungrounded.
leptons 6mo ago
Maybe you're holding it wrong? j/k Seriously though, that does not sound safe at all.
userbinator 6mo ago
Really feels unsafe, but neither me nor the computer have suffered any serious injuries yet. That's due to interference suppression capacitor in the PSU. The safety standard puts the "touch current" limit at something like 300uA (0.3mA), which is definitely in "painful but not dangerous" territory. You do need to exercise caution when plugging in other devices that are also connected to the mains, since that amount of current and voltage can certainly damage sensitive electronics. Old but good page on such measurements: http://www.aplomb.nl/SMPS_leakage/Doc_ie.html http://www.aplomb.nl/SMPS_leakage/Doc_ie.html
- Doxin 6mo ago
  > since that amount of current and voltage can certainly damage sensitive electronics Like for instance the magic mouse. I've completely destroyed three magic mice by sometimes accidentally touching the mouse to the laptop. It'd not do much of anything initially, but at some point touching them together would kill the connection for a couple seconds, and over time it evolved into the mouse just refusing to connect altogether. I'm glad my boss pays for this hardware because I'd be incensed to have a mouse THAT expensive break that quickly.
rlonstein 6mo ago
Finally. Someone else has mentioned this, I thought it was just me who I experiences the sensation of there being stray current on MacBook frames.
Brian_K_White 6mo ago
I have super dry skin and I also feel that weird ac effect when lightly touching and moving along the surface of pretty much any aluminum mac device since they started making them aluminum. And almost no other device I've ever used. My aluminum Framework does not do it. My wifes magnesium LG Gram does not do it. I have felt it on other things but only extremely rarely. It's bizarre that whatever it is they're doing different, it's probably wrong, and they've kept doing it in every device for decades. To describe the effect in more detail for anyone who doesn't already know: It's like the case is alternately grabbing and releasing your skin at 60hz. It's a bit like chatter, ie the periodic friction you use to ring a wine glass by wetting the rim and then running your finger along it. It rings because the combination of the friction, the lack of friction from hydroplaning, and the rubbery give of your skin, makes your skin alternately grab and release 30,000 times a second. Only in this case you are only barely touching the case not pressing enough to make any friction or make a squeal noise. It's like static electric charge attraction. Just touching the case you feel nothing, but move your finger along the surface and you feel it vibrate your finger without any friction to explain it. It's unsettling and displeasing, which are strange words to expect from an apple device at least when you are only talking about the design and not the tech stack or corporate behavior. It makes me think of cheap electronics from a country with no consumer safety regulations that will probably burn down every 3rd house they wind up in. It's probably harmless, but then again a lot of things that are harmless in short infrequent doses turn out to have been harmful after you did it for 10 hours a day for 20 years.

ajam1507 6mo ago

Using a 3 prong extension cable on the charger will prevent this.

imglorp 6mo ago
How? The (US) charger's only got 2 pins so ground stays unconnected.
- Tsiklon 6mo ago
  The extension cable they used to include in box with the computers, it has the third pin for the charger brick connector which is wired to ground
  - 15155 6mo ago
    There's zero chance that the DC ground in the laptop is tied to earth ground in the charger: they use LLC resonant converters and flyback converters (depending on vintage) - an earth ground tie would defeat the purpose of these isolated topologies.
    - jahnu 6mo ago
      However it’s wired up the fact is the electric buzzing feeling goes away if you use a grounded extension cable instead of two pin.
    - namibj 6mo ago
      No they isolate L and N not PE.
- bombcar 6mo ago
  I don't know if this link will work - https://www.chargerlab.com/wp-content/uploads/2022/06/2022061718103949.jpeg https://www.chargerlab.com/wp-content/uploads/2022/06/202206... but that metal round pin thing is a ground; and the three-prong cable connects to it.
- pxx 6mo ago
  There are grounded duckheads for this purpose, e.g. https://amzn.to/4cnzuef https://amzn.to/4cnzuef (note out of stock. I guess your best bet is to use a UK duckhead, but half of those have a dummy ground...) if you take the plug part from the brick you'll note that there's only two pins but the button-like thing is a ground as noted in a sibling, the power adapter extension cable does plumb the ground through (https://www.apple.com/shop/product/mw2n3ll/a/power-adapter-extension-cable?cid=aos-us-seo-pla-accessories https://www.apple.com/shop/product/mw2n3ll/a/power-adapter-e...)
  - jahnu 6mo ago
    Got a bunch of cheap ones from Ali Express and they worked fine.
- BobAliceInATree 6mo ago
  Apple sells a 3-pin extension cable US Version: https://www.apple.com/shop/product/mw2n3ll/a/power-adapter-extension-cable https://www.apple.com/shop/product/mw2n3ll/a/power-adapter-e...
CGamesPlay 6mo ago
That cuts it by about 90%. But as others have said, the default US plug doesn't ship with a ground pin (though the extended cord does IIRC).
Barbing 6mo ago
No way, that's why it's "fixed" sometimes, thanks

normie3000 6mo ago

> It's easy for me to feel the mains frequency while gently rubbing the top surface of the MacBook I haven't been a regular Mac user, but I've had maybe 3 work MacBooks since 2010 and I recall having this issue with all of them. Why haven't they fixed it?

msephton 6mo ago
It's also an issue on the new Neo. It was the first thing I noticed when I tried one in the Apple Store. I unplugged the power cable and it went away, replugged and it came back. I'm in the UK so I expected grounded electricity supply.
- normie3000 6mo ago
  Disappointing. I understood Neo doesn't come with a power plug in UK; was yours the official one?
  - msephton 6mo ago
    It was just me trying one in the Apple Store
- SeasonalEnnui 6mo ago
  If you buy the UK 1.8-metre Power Adapter Extension Cable, this has a metal ground pin that grounds through the metal clip on the power brick. I switched all my MacBook & iPad chargers to this, no more earth leakage sensation from metal casing.
sitharus 6mo ago
They can’t, it’s caused by the capacitors required to suppress electromagnetic interference caused by the switch-mode power supply. These allow a very very tiny amount of current to leak through from the mains side, which is then capacitively coupled to the metal case (IIRC Apple do not connect the case to power negative) reducing it further, but it’s enough for humans to sense it. It can be avoided by using a grounded power supply, but because there are large countries that have ungrounded outlets in common use the most designs are ungrounded.

leptons 6mo ago

Maybe you're holding it wrong? j/k Seriously though, that does not sound safe at all.

userbinator 6mo ago

Really feels unsafe, but neither me nor the computer have suffered any serious injuries yet. That's due to interference suppression capacitor in the PSU. The safety standard puts the "touch current" limit at something like 300uA (0.3mA), which is definitely in "painful but not dangerous" territory. You do need to exercise caution when plugging in other devices that are also connected to the mains, since that amount of current and voltage can certainly damage sensitive electronics. Old but good page on such measurements: http://www.aplomb.nl/SMPS_leakage/Doc_ie.html http://www.aplomb.nl/SMPS_leakage/Doc_ie.html

Doxin 6mo ago
> since that amount of current and voltage can certainly damage sensitive electronics Like for instance the magic mouse. I've completely destroyed three magic mice by sometimes accidentally touching the mouse to the laptop. It'd not do much of anything initially, but at some point touching them together would kill the connection for a couple seconds, and over time it evolved into the mouse just refusing to connect altogether. I'm glad my boss pays for this hardware because I'd be incensed to have a mouse THAT expensive break that quickly.

rlonstein 6mo ago

Finally. Someone else has mentioned this, I thought it was just me who I experiences the sensation of there being stray current on MacBook frames.

Brian_K_White 6mo ago

I have super dry skin and I also feel that weird ac effect when lightly touching and moving along the surface of pretty much any aluminum mac device since they started making them aluminum. And almost no other device I've ever used. My aluminum Framework does not do it. My wifes magnesium LG Gram does not do it. I have felt it on other things but only extremely rarely. It's bizarre that whatever it is they're doing different, it's probably wrong, and they've kept doing it in every device for decades. To describe the effect in more detail for anyone who doesn't already know: It's like the case is alternately grabbing and releasing your skin at 60hz. It's a bit like chatter, ie the periodic friction you use to ring a wine glass by wetting the rim and then running your finger along it. It rings because the combination of the friction, the lack of friction from hydroplaning, and the rubbery give of your skin, makes your skin alternately grab and release 30,000 times a second. Only in this case you are only barely touching the case not pressing enough to make any friction or make a squeal noise. It's like static electric charge attraction. Just touching the case you feel nothing, but move your finger along the surface and you feel it vibrate your finger without any friction to explain it. It's unsettling and displeasing, which are strange words to expect from an apple device at least when you are only talking about the design and not the tech stack or corporate behavior. It makes me think of cheap electronics from a country with no consumer safety regulations that will probably burn down every 3rd house they wind up in. It's probably harmless, but then again a lot of things that are harmless in short infrequent doses turn out to have been harmful after you did it for 10 hours a day for 20 years.