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by simondotau 1694 days ago
Why don't Apple offer grounded duckheads? For that matter, why haven't any third parties made grounded duckheads? This has been irritating me for the past decade or more.

The ground connection, where available, occurs through the metal stud which the duckhead slides into. Correct me if I'm wrong, but even the UK (Type G) duckhead doesn't connect ground even though the physical ground pin is mandatory.

I know that most DC adapters are unearthed, but my lived experience is that you can often feel electrovibration in the aluminium Macbook chassis when ungrounded and it goes away when the Apple DC adapter is grounded.

4 comments

It's not just your experience. When using the Apple-supplied charger, the surface of the macbook feels slightly fuzzy, and even delivers minor shocks.
getting zapped by ~50/100v (depending on what voltage your country uses) through the x rated capacitor, at a very low current. I don't use macbooks, but tried very hard to find a usb charger that actually has a ground prong for the same reason, and they seem to straight up not exist.

It's also weird to me, since they have exposed metal and a transformer winding shorting could lead to passing through line voltage to the usb port/your phone chassis. So how does it count as double insulated?

I'm so glad you mentioned this. I thought it was just me!
The UK/Ireland 3 prong duckhead is grounded. I have no idea why third parties haven't produced grounded versions, other than the obvious (no demand and anyone who cares has a solution, use the extension cable).

[1] https://www.amazon.com/Replacement-Adapter-Duckhead-Universa...

It is most certainly not. The ground is done over the round pin that slides into the duckhead. If you check the rail where the pin slides in, it's all plastic.

The extension cable is the only one that's grounded.

They used to, in Australia at least. I can't remember if it came with my iBook G4 or one of the Intels soon afterward, but out of the box I got both a two-prong stub that attaches directly to the brick and a ~1.5m cable that goes to a three-prong plug. I sold the original laptop long ago but kept the old grounded cable all the way up to my current work MBP. Personally the buzzing drives me nuts.

The first time I noticed it I was a bit worried about it all. I had a volt stick from work (a safety device to identify live wiring) and surprisingly it illuminated when I brought it near the metal chassis of my macbook. Some further tests with an oscilloscope showed that it was floating a good couple of hundred volts, but the capacitance was so low that the energy payload was never going to do any harm to a human. I don't care, I still just ground the thing.

The no-longer-standard extension cable is properly grounded, the duckhead (what you called a "stub") has never been. This is the case in all countries including Australia, where I live.
It’s kind of interesting that it’s not a code requirement. I presume that the power charger is double insulated, hence the option for 2 prongs, but the laptops sure aren’t double insulated.