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Comment by elevaet | Hacker News Reader

What's with that? I'm constantly getting minor shocks from my Macbook, often when the inside of my forearm or wrist touches a corner of the case. I thought it was a problem with my old one, but my new one does it too.

There is also a constant light vibration when you run your fingers lightly along the body. It's quite Shocking that this is apparently "normal". None of this happens when it's running on battery.

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I was honestly questioning whether there was something wrong with the wiring in my house that was causing this (after having multiple MacBooks with the same issue), because the alternative that a company of Apple’s size had such a basic issue seemed so unlikely.

You or your neighbour probably have some cheap chinese device that puts out high frequency noice on the power line.

Either you get rid of that device or you buy something like this: https://www.google.com/search?q=apple+grounded+extention+cab...

Unless you're running some serious industrial level machinery, home devices have nothing to do with power line noise. It's cause by the air around the lines and the condition of the lines themselves.

I think you are talking about another type of power line noise.

I am pretty sure a bad switch mode power supply, can push out some nasty stuff.

Given that many (most, I'd bet, by far) people don't experience this while you've experienced it on several devices, I wouldn't give up on checking out the wiring in your house.

Are you using your Macbook with an ungrounded (two prong) plug or in an ungrounded outlet ? That's the typical cause of this behaviour (or a badly-grounded outlet, which is rare, fortunately).

The shocks you observe are caused by your body slightly grounding the conductive case. They are seen with any conductive case equipment used without grounding. Fortunately, they are not dangerous on doubly-insulated equipment like Macbooks.

Don't Apple wall warts have only two prongs? It doesn't matter if the outlet is grounded if the device doesn't use the ground pin.

You can get an extension cord for Apple (computer) chargers which also carry a ground signal. Highly recommended.

https://www.apple.com/shop/product/MK122LL/A/power-adapter-e...

Typical Apple, making you pay extra for something that should come standard.

It used to be standard. I don't know why they stopped including it. Well, actually I do know - $$$

There's a large ground under the removable power plug in iPad/Mac chargers.

It can also, possibly intentionally, be used as a bottle opener.

My new Macbook is ungrounded, my old one was grounded. I experience these shocks anywhere I plug in, not just in one home/office, although some places are worse than others.

It's due to non-isolated converters where an EMI filter is a part of the line side using X/Y capacitors to cross over. The device isn't solidly grounded but it's also not totally floating either. There's some leakage across it.

Thank you. This seems like the only reasonable explanation I've come across after a ton of reading around.

> There is also a constant light vibration when you run your fingers lightly along the body. It's quite Shocking that this is apparently "normal". None of this happens when it's running on battery.

I always assumed that was just because the surface has a strange microscopic pattern. I don't have one now, but I believe it only happens in one direction.

The thing I'm talking about feels like a texture but it goes both ways and disappears when its unplugged.

Got our kids windows laptops this christmas, and they behave exactly like this when plugged in with the included USB type-c chargers!

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