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Comment by Lukas_Skywalker | Hacker News Reader

MacBooks and iPads had the "spicy case" issue for quite a long time. In certain countries, the Apple power supply comes with two adapters for plugging it into the wall - one with two contacts, and one with three contacts. Only the one with three contacts is grounded.

When using the ungrounded adapter, the entire case of my 2011 MacBook Air and the iPad 2 got slightly "spicy", although it felt more as if the case suddenly changed texture and was more wavy (probalby an artifact of europes 50Hz mains frequency).

The strangest thing was turning on my touch controlled desk light while working on the laptop. If I touched the light and the laptop at the same time, the light shocked me quite noticeably.

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I noticed this when I was playing guitar and using my laptop at the same time. The strings and bridge on an electric guitar are grounded. When I had my arm touching the bridge and I put my hand on the MacBook's case, I would get a mild shock.

I measured the voltage difference and, if I recall correctly, it was something like 20V. I started using the 3-prong adapter and haven't had any more issues.

You should absolutely make a habit of not touching anything else as long as any part of your body touches the strings, bridge, tuners or other conductive parts of the guitar. This includes not touching the mic grill with your lips. This is why singing guitarists should keep a foam mic cover handy. It's also the reason keeping your spring cavity closed (if you have one) is a good idea.

In many places electrical wiring in homes is just two wires and what wiring monstrosities await you in shabby clubs and shady rehearsal spaces is just beyond belief. Be safe.

If the voltage was high enough to be dangerous, would a foam mic cover protect you?

First of all, it's not just the voltage that is dangerous. Though, higher voltage means the arc is more probable, of course. A foam cover is a poor insulator, but at least it helps keeping the minimal distance from the conductive microphone grill. In this case we're talking mostly about avoiding unpleasant shocks, not some life-endangering situations.

I've noticed "textured screen when charging" on a range of mobile devices which I've nearly always been able to correlate with cheap USB chargers. Other family members seem oblivious, though to me it's clear as night and day.

it's because of the current that is leaked by the class y capacitor connecting primary and secondary of the power supply to suppress EMI. this will mean there's something like 50 - 100v potential to earth on your macbook, but at a very low (non dangerous) current. that's why you get zapped or feel a tingle. if you have the earth connection, that power will be sunk through the earth lead, but otherwise a metal case will generally be connected to the DC ground (and also earth if present on the plug), which will have this low current AC voltage present.

> MacBooks and iPads had the "spicy case" issue for quite a long time. In certain countries, the Apple power supply comes with two adapters for plugging it into the wall - one with two contacts, and one with three contacts. Only the one with three contacts is grounded.

Thanks a lot for you comment. I had noticed that myself with two old Mac Book Airs.. Actually, that's how I knew if plugs were grounded or not: I could immediately tell.

But, over the years, I always wondered if there were any electrical issue (in several houses) or if it was normal.

It's not "normal" but it may be common. The MacBook should be fine on two wires; but something else may not be, causing it to be spicy.

They are spicey everywhere though, even in cardiac protected areas that are checked regularly by electricians. New builds, rebuilds etc.

This isn’t a building wiring issue.

I really wish the North American adapter’s direct-to-wall connector (the one that’s not a cable) came in an optional 3-prong configuration. As it is, I have to bring an extra cord around with me any time I bring my laptop somewhere, simply to ensure it’s grounded. (I used to get those shocks from it too, until I did, and I really don’t want to go back to them, let alone know what they’re doing to the electronics.)

Try aftermarket? https://smile.amazon.com/Grounded-Duckhead-Apple-Mac-Adapter...

Shouldn't be able to hurt you THAT much ...

I noticed the same issue. But does the ground connection of the wall plug side of the transformer actually make a difference? I'm not good with electrics but I always thought the other side of a transformer is electrically isolated and the sides don't share a ground.

I think some AC to DC transformers bond the AC neutral and the DC negative.

Hm interesting. I'm in europe on 50 Hz, none of my apple power adapters are grounded, not even the mac mini power cord is, and i've never noticed any issue.

However the electrical wiring for my apartment is only about 20 years old...

Apple might also have improved this for newer devices. I remember it being a problem for devices from around 2011 to 2014.

Edit: MertsA added some more info below: https://news.ycombinator.com/item?id=33572585

Definitely still occurred on my 2017 macbook pro.

Still occurs with my 2021 M1 MBP

2021 MBP 14 has this issue for me with the stock charging brick (NZ - which has 3-pin sockets): but Apple don't ship the stock charging brick with an extra extension to the socket, so the transformer/brick plugs (via a corner adapter) directly into the socket, which isn't grounded.

If I replace the direct corner adapter of the brick with an older (from a 2015 MBP 15) extension which is grounded, i.e. you can't then literally plug the charging brick directly into the power socket, there's an "extension" chord in between (and not just a generic one, this is Apple specific for the connector to the brick), the issue goes away.

I paid attention a little and there is a spark when i plug the laptop charger in. 2018 mbpro. With the short plug in the charger, not the long power cord.

No other symptoms though.

I thought one of the two wires should be equal to ground?

That’s how it could be done in theory but it’s never because you would kill people.

Instead one wire is neutral, one is phase, and the third, optional, is ground.

Can you supply a good "this is how it actually works" reference for European electricity?

In the US there is one neutral and one hot line. Then there is the ground that is grounded at the box preferably. You can sometimes have a 240 line split to feed two 120 outlets where the hot lines from each are at a 240 difference to each other. If one line has a large load relative to the other, the neutral won't be that close to ground. Is that was is happening with these laptops?

>If one line has a large load relative to the other, the neutral won't be that close to ground.

Shouldn't it still be pretty close voltage wise? If we hold the neutral is always at 0v at the panel, since that's where it's tied to ground, the voltage on the neutral between the panel and the outlet should still be pretty low because copper wire has a pretty low resistance (by V=IR). I'd have to break out my calculator (and look up the actual standard values of copper wire resistance), but I'd guess even >20V would be quite unusual without some other fault...

At dc for sure, at 60hz perhaps imaginary impedance could create "spicy case". I only thought about it because I used to use a welding cable adapter for my dryer port that had a "bootleg ground" and the internet warned me a shock from the case could be a result.

Why would it kill people?

https://portablepowerguides.com/ground-to-neutral-both/

Because it can cause power to go unexpected ways.

All the "power safety" stuff does nothing if everything is correct and perfect, but if it fails, and ground and neutral are bonded anywhere EXCEPT at the panel, you can get power flowing through you.

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