There are grounded duckheads for this purpose, e.g. 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...)
replyif 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-e...)
Got a bunch of cheap ones from Ali Express and they worked fine.
replyApple sells a 3-pin extension cable
replyUS Version: https://www.apple.com/shop/product/mw2n3ll/a/power-adapter-e...
I don't know if this link will work - 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.
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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
replyThere'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.
replyNo they isolate L and N not PE.
replyHowever it’s wired up the fact is the electric buzzing feeling goes away if you use a grounded extension cable instead of two pin.
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