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USB-C and proprietary laptop chargers are double insulated Class II devices. This means that the metal chassis is essentially floating and can charge up if ther

by fsh 6y ago

USB-C and proprietary laptop chargers are double insulated Class II devices. This means that the metal chassis is essentially floating and can charge up if there is some leakage in the charger circuit. I don't see any way how the wiring of the building can influence this behavior.

justusthane 6y ago
My anecdotal experience: I’ve never noticed this with my 2014 MBP until I was at my parents’ recently, plugged into an extension cord from their garage. With my feet on the ground, the metal body of my MacBook was “tingly” all over. Feet off the ground, no more tingling. I’d love to better understand what was going on (and whether it’s potentially dangerous). FWIW, I was using the Mac power cord with the ground pin. Does this just mean that the wiring in their garage isn’t properly grounded?
kube-system 6y ago
Just grabbed my multimeter -- my MagSafe MacBook has continuity from the metal chassis to the grounding lug of the power adapter. It stands to reason that a properly grounded outlet used in conjunction with the 3-prong cable would dissipate such a charge -- and potentially, a live ground could introduce a charge.
- zdragnar 6y ago
  I actually only notice it about 5% of the time I use it, and it is almost always plugged in at the same outlet, with the same charger (in this case, the two prong adapter). I seem to recall having tested all of the outlets in the house with an outlet tester, but it was two years ago so I'm not 100% sure.
  - GekkePrutser 6y ago
    Here in Europe the clip on plugs (duckheads) are not grounded. The extension cord you get with the MacBook too, is. So use that. Not sure about US. But I think it's the same as the duckheads are only 2-prong iirc so they can't possibly be grounded.
    - kube-system 6y ago
      Yes, it's the same in the US.
    - rogual 6y ago
      They don't even include the extension cord anymore. I don't know why Apple thinks it's okay for my computer to run a current through my body. I would love to know what happened at Apple that caused this situation. It's just patently insane.
      - GekkePrutser 6y ago
        Oh I didn't know that, I haven't bought a Mac recently. It's been like this since the earliest days of the metal PowerBooks. Though the un-grounded duckheads appeared only with the later models (the "hockey puck" power supply always had grounding and in fact always had an extension cord). In my house the living room sockets didn't have grounding (at that time it was only mandatory in "wet areas") so I noticed it even then. It's mainly an issue because of the metal enclosure. On a plastic one you wouldn't notice. And it's not serious current, it's just some induction of the power transformer on the internal shielding. But yeah I agree, even the duckheads should have proper grounding! The grounding is done through the ground 'pin' that the duckhead clips on to, so technically it should be able to get a third-party duckhead with all three pins. Though I never looked to see if they were available.

by fsh 6y ago

justusthane 6y ago

My anecdotal experience: I’ve never noticed this with my 2014 MBP until I was at my parents’ recently, plugged into an extension cord from their garage. With my feet on the ground, the metal body of my MacBook was “tingly” all over. Feet off the ground, no more tingling. I’d love to better understand what was going on (and whether it’s potentially dangerous). FWIW, I was using the Mac power cord with the ground pin. Does this just mean that the wiring in their garage isn’t properly grounded?

kube-system 6y ago

Just grabbed my multimeter -- my MagSafe MacBook has continuity from the metal chassis to the grounding lug of the power adapter. It stands to reason that a properly grounded outlet used in conjunction with the 3-prong cable would dissipate such a charge -- and potentially, a live ground could introduce a charge.

zdragnar 6y ago
I actually only notice it about 5% of the time I use it, and it is almost always plugged in at the same outlet, with the same charger (in this case, the two prong adapter). I seem to recall having tested all of the outlets in the house with an outlet tester, but it was two years ago so I'm not 100% sure.
- GekkePrutser 6y ago
  Here in Europe the clip on plugs (duckheads) are not grounded. The extension cord you get with the MacBook too, is. So use that. Not sure about US. But I think it's the same as the duckheads are only 2-prong iirc so they can't possibly be grounded.
  - kube-system 6y ago
    Yes, it's the same in the US.
  - rogual 6y ago
    They don't even include the extension cord anymore. I don't know why Apple thinks it's okay for my computer to run a current through my body. I would love to know what happened at Apple that caused this situation. It's just patently insane.
    - GekkePrutser 6y ago
      Oh I didn't know that, I haven't bought a Mac recently. It's been like this since the earliest days of the metal PowerBooks. Though the un-grounded duckheads appeared only with the later models (the "hockey puck" power supply always had grounding and in fact always had an extension cord). In my house the living room sockets didn't have grounding (at that time it was only mandatory in "wet areas") so I noticed it even then. It's mainly an issue because of the metal enclosure. On a plastic one you wouldn't notice. And it's not serious current, it's just some induction of the power transformer on the internal shielding. But yeah I agree, even the duckheads should have proper grounding! The grounding is done through the ground 'pin' that the duckhead clips on to, so technically it should be able to get a third-party duckhead with all three pins. Though I never looked to see if they were available.