
How can I avoid my MacBook Pro giving me minor shocks? - luu
http://apple.stackexchange.com/questions/32417/how-can-i-avoid-my-macbook-pro-giving-me-minor-shocks
======
jordwest
What's fascinating to me about this phenomenon is that you can actually _feel_
the 60Hz AC by running your hand across the lid.

It feels as if the surface is slightly bumpy, but the width of the bumps
changes as you adjust the speed your finger moves.

Unplug from mains, and the surface becomes smooth.

As the answer notes, this only happens when using the two-prong adapter
without earthing. It also seems to be more noticeable when connected to older
buildings.

~~~
pmoriarty
I felt this on an Apple laptop in California a couple of years ago, in an
apartment with only two-prong outlets in it. I'd describe the feeling more
like the laptop cover was vibrating, rather than bumpy. The feeling went away
and the laptop cover became smooth and normal if I lifted my feet off of the
ground.

Once all the outlets were rewired to be three-prong, with ground, I used a
three-prong power cord and the problem went away.

Pretty scary feeling, and scary to think that two-prong outlets and appliances
are legal anywhere. I'd also be surprised if Apple hasn't been sued at some
point by someone getting electrocuted when using their laptop and a non-
grounded, two-prong power cord.

~~~
bschwindHN
> and scary to think that two-prong outlets and appliances are legal anywhere

In Japan, two prong outlets make up the vast majority of sockets, it kinda
sucks.

~~~
kalleboo
I don't think I've ever seen a three-prong outlet in Japan (maybe only new
installations?), but "earth screws" are quite common (any room prepared for an
air conditioner will have one at least) [http://www.hakusui-
trading.co.jp/safety/img/img02.jpg](http://www.hakusui-
trading.co.jp/safety/img/img02.jpg)

~~~
Teever
What? That's crazy looking! Why not just put the third prong in there if it's
wired up to handle a screw?

What's the point?

~~~
Too
Just guessing here but I think it's to allow easy grounding of old appliances
and other equipment that might risk contact with electricity but are not
grounded by default. Metal frame desk as example.

~~~
LaurentVB
Very clever actually.

------
algesten
I have this problem in India. I suspected the mains was dodgy, because during
the many power outages i never got the shocks when on UPS.

I got a multimeter and measured. The neutral was 70V and the phase 300ish. So
the difference was roughly 230V but a switched power adapter would make this
hover around 70 too (I believe an old coil based would probably been fine).

The Indian electrician didn't understand my problem because his only tool was
a regular bulb with two exposed wires that he jammed into the socket.

"Look sir, light, power working"

sigh.

~~~
Hydraulix989
Shark used to make an (otherwise excellent) upright consumer vacuum cleaner
with a metal strip in the handle. The vacuum's power cable did not have a
ground.

This vacuum had the most five-star reviews on Amazon, but then a minority of
people started complaining and leaving one-star reviews, saying they were
getting shocked.

The reactions from the fanboy crowd were non-sympathetic ("you're imagining
it," "it's just static," etc.), and they mass downvoted every one-star review.
Some of the people claimed they were getting shocked PRETTY HARD, too, as in
it knocked them over. IIRC, even Shark responded saying that it was impossible
for the vacuum to shock you.

I remember seeing this while looking at vacuums for my elderly mother who has
a heart condition. To the electrical engineer in me, everything made sense!

I started defending every single one-star reviewer person, and I wrote my own
very detailed review with photos of the handle. Soon, the tide turned, and
more people started upvoting my review than downvoting it; and I even received
personal "thank you" messages from the people who got shocked ("finally
someone believes me").

It eventually got to the point where a year later in 2014, Shark released an
updated model with no more metal strip. Seeing this, I bought the new model
for my mother. I'd like to think I can give myself SOME credit for causing
them to do that.

Not only that, the upvotes from that alone were a good part of the reason I
became an Amazon Top Reviewer.

~~~
sduff
Why would you still buy from the same manufacturer that denied bad (and
potentially deadly) design?

~~~
Hydraulix989
Like I said, it was otherwise, an excellent vacuum. Any how, I know about
Lenovo's Superfish and recently its attempts to block Linux installs, but I am
still a die-hard Thinkpad user because these are very large organizations
where all it takes is one single person's oversight to cause a mistake.

~~~
creshal
They didn't "attempt to block Linux", they just shipped hardware without a
Linux driver.

And later released a workaround to make the hardware work in a slower, more
power consuming backwards compatibility mode so Intel can continue not
properly supporting the hardware in Linux.

But sure, it was totally "Lenovo blocking Linux".

~~~
mavhc
How come Intel is one of the top contributors to linux, but doesn't ship
drivers for all their hardware?

~~~
creshal
Different divisions doing different things. Intel is extremely interested in
Linux for their HPC Itanium/Xeon range, moderately interested in Linux for
other server and business hardware, as well as mobile; and Intel's consumer PC
division doesn't give a fuck at all.

------
kosma
My understanding is that it's caused by Y capacitors in the power supply's EMI
filter leaking minimal amounts of current onto the case. As others have
mentioned, proper grounding usually fixes the issue - although in one case I
had to rewire an entire apartment because someone had a very lopsided idea
what the PE wire is for. It was for a friend with a metal Macbook Pro, an
exceptionally sensitive skin, and way too much time & money on their hands. :D

The usual word of caution: I'm trained in electrical installations. A
layperson - even one skilled with a multimeter and a soldering iron - should
never attempt to modify ground connections or power distribution. There are
dozens of potential (and very deadly) failure modes that require proper
training to recognize and prevent.

~~~
patcheudor
I have a mid 2015 13" MacBook Pro and I've measured up to 48v off the chassis
between ground on properly wired circuits. I began investigating this after
getting mild shocks after working out (sweaty) and while working on the
MacBook in my lap while working on a PC laptop on my desk which also has an
aluminum chassis. I tried an isolation transformer and the issue disappeared.
I contacted Apple about it but crickets. I then did some current measurements
and it was very low and of no concern at that voltage so I decided not to push
the issue. As other have said, the solution is to use the three pronged cord
that came with the power brick.

You can feel this effect for yourself by using the two pronged plug and
finding something grounded to the chassis to touch. With one hand, hold the
grounded item while moving the palm of your other hand around the backside of
the led. It's a bit dependent on the conductivity of your hands but I've found
most people can feel it, even my dad who's a farmer and has very dry hands.
Remember, if you get electrocuted, it's not my fault, it's Apple's. They have
much deeper pockets than me.

------
josefdlange
Ungrounded adapter + bad mains power = zap!

Ungrounded adapter + clean mains power = probably no zap

Grounded adapter + bad mains power = probably no zap

Grounded adapter + clean mains power = no zap

It's not just the adapter and it's not just the mains power; it's when both
come together. Electricity follows pretty simple rules when it comes down to
it.

Always always always ground your A/C connections. Why wouldn't you?

Also, never use one of these unless you've attached the little wire/alligator
terminal to a ground somewhere:

[http://www.prestonelectronics.com/audio2/ttip/images/gndadap...](http://www.prestonelectronics.com/audio2/ttip/images/gndadapter.jpg)

~~~
Hasz
Actually, for things with a non-conductive casing (think cheap nightlights, or
those apple wall warts) there's no need for a ground. If anything, it's
another part and more cost, thus it isn't included.

In highly sensitive A/V systems, an isolation transformer is often used as
well, neglecting a ground.

~~~
gh02t
You have to be careful with isolation transformers because there is one
gotcha... the ground pin normally passes through to earth. I've witnessed
someone blow up a nice $5000 Agilent oscilloscope before I could stop them
because they didn't understand how to use an IT and plugged the _scope_ into
it so they could probe AC. Bad news, you're supposed to plug your test device
into the IT not the scope because the BNC connectors in almost all
oscilloscopes are connected straight through to the earth pin.

I heard "POW" from across the lab as soon as he clipped the probe on and knew
I should have warned him. Nobody was hurt apart from our lab budget.

~~~
hexane360
Humorous demonstration of the same mistake:
[https://youtu.be/sI5Ftm1-jik?t=2m20s](https://youtu.be/sI5Ftm1-jik?t=2m20s)

~~~
gh02t
I can't tell, the second boom where he holds the resistor in place was that on
purpose? If so holy shit that's a dangerous way to make the point. If it was
also an accident then he is lucky to be alive since he doesn't seem to know
what he is doing.

I know this video is supposed to be funny, but I couldn't bring myself to
laugh. Too many people die making the same mistakes.

~~~
rcxdude
He does know what he's doing and it certainly was deliberate. While most of
his stunts probably hurt he doesn't set them up exactly as he presents them
(I.e. it's usually not mains).

------
hatsunearu
Due to EMI reasons, for switching converters, the hot and neutral terminals of
mains input is generally capacitively connected to the Earth prong via high
frequency capacitors. That means if the earth prong isn't properly connected
to actual earth, the earth prong now has your mains voltage divided by two on
it. If the earth connection happens to be connected to the chassis, there's
your shock.

It probably won't kill you unless you have a weak heart or if you're really
unlucky because the EMI suppression caps are small enough to not supply lethal
current, but can be really annoying.

------
BJBBB
Geez peoples - so much misinformation. Touch current test methods and limits
are well-defined through out the world. Poor power 'quality' may affect this
measurement, but is not a significant contributor to the magnitude of
potential leakage through the ground wire or through exposed metal surfaces.
It is a function of the power conversion equipment connected to, or internal,
to the device. Even where wiring does not meet code, the upper limit to this
measurement is well defined per the simulated fault conditions required in the
test methods.

People that claim to be engineers need to read and understand the basic
physics behind the product safety standards scoped by your equipment. For EU,
code is defined in BS7671/IEC60364; and NFPA70 (mostly article 250) in the
U.S.; and similar stuff in C22.1 for Canada.

ITE power supplies must meet the locally harmonized version of IEC60950-1
(soon to be obsoleted by IEC62368-1). Where there is no ground pin, North
American power supplies must meet UL1310/CSA No.223. These standards all have
specific limits for voltage, current, and VA levels that can be exposed to the
end-user, for both normal and abnormal operating conditions.

~~~
phee
> Where there is no ground pin, North American power supplies must meet
> UL1310/CSA No.223

So, as far as I can tell, with a brief skim of the standard, a class 2 device
should have no more than 0.5 mA leakage current, right?

I just measured the leakage from my macbookpro through my body to ground and
it's about 50 μA. Well within the limits.

So I guess that's why they never did anything about it. Still amazing that you
can clearly feel this current: if you lightly brush your wrist around the
sharp edges it actually hurts. I wonder how 500 μA would feel.

~~~
BJBBB
Depends on the 'bandwidth' of the signal and the test equipment and the
individual. Generally consider many non-medical measurements below 025mA
suspect, as few design engineers make an effort to understand the various
frequency components of the voltage and current leakage signals, and/or
understand the effects to the signal of instrument impedances.

Have had several discussions with Mr.Pete Perkins (he sits on several STCs and
has written several IEEE papers) on this subject, and we agree that the human
body model referenced by these safety standards being used for the measurement
network (IEC60990) have problems because the medical community does not
understand physics. As the various standards committees continue to look at
the body of work being done by bioengineers, will probably see better
measurement methods being codified.

Human response and perception to electricity has significant variance and
resultant effects/affects. My wife can detect less than 10uA at 200Hz/42V. My
detection threshold is at least an order of magnitude greater, even at 50Hz.

~~~
BJBBB
Need to correct some stuff.

Class 2 (arabic numeral) is for limited power sources, regardless of
construction class.

Class II (roman numeral) indicates a construction class where safety cannot be
dependent on a ground bond.

Class I (roman numeral) indicates safety is dependent on a reliable ground
bound.

Class I equipment, depending on the scoped end-use equipment safety standard,
can have up to 25mA of leakage.

Class II equipment, depending on the end-use environment, can be limited to
0.25mA of available touch leakage.

A good reference for Class 2 and 3 equipment is the UL5085-x series (same as
CSA No66.x).

For the EU, there are no harmonized standards in the Low Voltage Directive
that have an equivalent Class 2/3 construction, although there are several
safety standards that address requirements for 'inherently limited' power
sources.

------
Arathorn
I've had this on every metal-chassis Mac I've ever owned. The chassis
typically floats around 50V AC at 50Hz (in the UK, at least) - making it
noticeably vibrate and tingle when you touch it, especially with the palm of
your hands when typing. It also seems to make RSI worse.

The solution, as everyone's pointed out, is to ensure you are correctly
grounded.

------
sfifs
Don't use Macs but I'm surprised Apple apparently didn't give an earthed power
adapter by default on a metal skin product. This seems like negligence.

Now that I think about it, my iPad's the same when charging.

~~~
stillworks
In the U.K. they come with earthed plug.

However I still noticed "buzzing" in the MBP, MBA and even iPad when I would
touched them.

Took the MBP in to the store. It didn't buzz there. They gave me a new power
supply anyways and recommended I connect the plug directly into the wall
socket.

Turned out that the power strip I was using is not grounded even though it has
three pin sockets !

When I plug Apple devices directly into the wall socket I don't notice any
"buzzing".

So now I don't connect the Apple devices via a power strip.

~~~
nicky0
Throw away that power strip.

~~~
mnw21cam
As in, right now. It violates every electric safety law around.

------
chiph
Test the outlet for proper wiring. If you're in the US, buy one of these:
(there are similar models for use in other countries)

[https://www.amazon.com/Sperry-Instruments-GFI6302-Outlet-
Tes...](https://www.amazon.com/Sperry-Instruments-GFI6302-Outlet-
Tester/dp/B000RUL2UU)

If this says good (two amber lights) and you're still getting shocked, follow
up with a voltmeter and/or qualified electrician.

------
arikrak
I never had that issue in the US (even when using a two-holed outlet), but I
had that problem when I was visiting Israel. So it seems to only be an issue
when using 220 volts and not a proper ground connection.

~~~
burger_moon
I get it in my apartment (I live in the U.S.) which is brand new with 3 prong
sockets if I have my feet on the ground (concrete floor) while roughing the
laptop.

I've experienced it a few more times at different peoples houses as well.

~~~
xenadu02
You might buy an outlet tester and see if your hot/neutral are reversed or if
ground isn't connected. If it all checks out you can use a multimeter* to
check potential between neutral and ground. If your apartment is wired
_correctly_ there should be almost no voltage between the two.

At the breaker box the neutral and ground are supposed to be bonded together.
That means only minor induced charges inside the building wiring would show up
between the two. If there is any significant voltage then something is leaking
on one of the lines or ground might not be bonded... it could even be floating
if they didn't bother driving the grounding stake deep enough and the soil
dried out a bit.

~~~
mnw21cam
> At the breaker box the neutral and ground are supposed to be bonded
> together.

Note this advice is country-specific. In some countries, the bonding is done
further away from the house.

In any case, you should never trust the neutral line to be an earth. If a
fault occurs that disconnects the neutral line from the supply, your neutral
line will have deadly voltage on it by virtue of being connected to live
through your appliances. Moreover, depending on the multimeter you use, if you
measure the voltage between neutral and earth, you could possibly trip the RCD
in the distribution unit (if you have one).

The rules are simple in most countries - if it has any touchable metal parts,
it must be earthed.

------
Animats
Doesn't anybody have a DVM around? If you can feel a stray voltage, measure
it, and find the source.

As someone else pointed out, get an outlet tester.[1] They're about $7. You
may have an open ground, or reversed hot/neutral. Once you've eliminated that,
suspect the power supply.

Make sure you have a UL-listed power supply. If you're getting stray AC
voltage on the output side of a UL-listed supply, report it to UL. Here's the
form.[2] There's no excuse for that.

[1] [https://www.amazon.com/Amprobe-ST-101B-Socket-
Tester/dp/B008...](https://www.amazon.com/Amprobe-ST-101B-Socket-
Tester/dp/B008E07IEO) [2] [http://www.ul.com/customer-resources/market-
surveillance-dep...](http://www.ul.com/customer-resources/market-surveillance-
department/market-surveillance/)

~~~
phee
About reversed hot/neutral. We have these[1] symmetrical adapters in Europe.
How are you supposed to know the proper orientation? You are not. Because you
either have an earthed metal case or you have a double insulated device.

My magsafe adapters have a "double insulation" symbol, a tiny tiny one near
"UL Japan", but still need a earthed prong to not feel any shock from the
laptop metal case.

1\. [http://images.apple.com/support/assets/images/products/ac-
wa...](http://images.apple.com/support/assets/images/products/ac-wall-
adapter/eur_adapter.png)

------
cs2818
I sometimes run into an interesting variation of this kind of problem. I often
work with a Microsoft Surface tablet laying in front of my MacBook Pro, with
my arms stretched over the tablet to type at times.

If the Surface is plugged in (no ground pin) and the MacBook Pro is also
plugged in (ground pin), and my arms touch both at the same time, I can feel a
tingling that quickly becomes unpleasant. Unplugging one or the other seems to
be a work around.

~~~
SyneRyder
That solves an issue I've had as well, though it shows the MacBook Pro isn't
really the fault. I have a Samsung TV (no ground-pin) and I would often watch
it while using my MacBook Pro plugged in (ground pin). Because I didn't have
wireless headphones yet I'd run a cable from the Samsung's headphone socket
and plug my Bose headphones into that. If I was touching the MacBook case with
one hand and grazed the metal parts of the 3.5" audio cable, I'd get quite a
strong tingling & that almost becomes painful. Hadn't considered that the
fault was the TV's lack of grounding.

------
Osmium
FYI, I can't remember which way round it is, but only some of the UK 3-pronged
adapters are actually earthed (as I discovered after having this problem
myself).

I think it's the extension cord that is properly earthed, whereas just the
plug attachment that goes directly into the power brick is not. You can tell
by looking up into the adapter (the part that plugs into the power brick) and
seeing if it's metal or plastic...

~~~
josefdlange
A certain vintage of Apple adapters have plastic posts where the ground would
otherwise attach. This image is iPad 10W adapters, but the same follows for
some older iBook/MacBook chargers:

[https://qph.ec.quoracdn.net/main-
qimg-05fa7f5f0e6ce0dc43bf8c...](https://qph.ec.quoracdn.net/main-
qimg-05fa7f5f0e6ce0dc43bf8c4124459cae?convert_to_webp=true)

~~~
hatsunearu
Double insulated appliances are fine, the circuit just needs to be designed
with double insulation in mind.

------
taneq
I've run across this before - once I measured the shell of my MBP at 90 volts
DC.

If you don't have access to a 3-pin charger, you could always use a separate
earthing setup, such as an antistatic mat:
[https://en.wikipedia.org/wiki/Antistatic_device#Antistatic_m...](https://en.wikipedia.org/wiki/Antistatic_device#Antistatic_mat)

~~~
avn2109
90 volts above earth ground? Or relative to something else?

~~~
taneq
It was a long time ago, but iirc it was relative to the nearest available
metal object, which I think was the metal frame of a desk. It wasn't a super
rigorous test. :P

------
ah-
I had the same happen to me while using a cheap ebay charger. Never happened
with a genuine one.

There's an interesting post about the internals:
[http://www.righto.com/2015/11/macbook-charger-teardown-
surpr...](http://www.righto.com/2015/11/macbook-charger-teardown-
surprising.html)

------
lifepillar
Some time ago, Apple launched a recall program for defective power adapters:

[http://www.apple.com/support/ac-wallplug-
adapter/](http://www.apple.com/support/ac-wallplug-adapter/)

I had the problem mentioned in the subject. Replacing the plug adapter has
fixed it.

------
kosma
For those of you who don't have access to proper grounding (because, for
example, the wiring lacks PE or it's faulty): a plain separation transformer
(1:1) between mains and your laptop _might_ be able do the trick.
Unfortunately if you have a larger setup (speakers, monitor, etc.) you have to
connect everything to the separation transformer, otherwise you'll create
leakage a path to mains some other way (say, through the audio jack).

Caveat emptor: If you decide to go that route, make sure you can return the
transformer if it doesn't to the job.

~~~
hatsunearu
Yeah no, that won't work.

~~~
xenadu02
Why not? Hospitals used to use isolating transformers for surgical electrical
supply precisely to prevent any possibility of electrocuting patients.

------
scw
My first summer job was doing IT for a small outfit, who worked out of an old
house converted into an office. They had eight machines, all connected to a
LaserJet printer via a parallel port switch. The parallel cables ran down into
a crawlspace under the house, and it wasn't uncommon for one of the cables to
work its way loose. No problem, tighten the parallel port connection at both
ends, and you're back in business. But, being an old house, many outlets were
missing ground pins. I must of electrocuted myself twenty times that summer.

------
taitems
I've had this on two MacBook Pros here in Australia. On the first one I took
it in to a Genius Bar appointment and, while they acknowledged it happens to a
"rare number of people", they basically said tough luck and to use the earthed
power cable which is about 1.5m longer. By the second time I just accepted it
as part of owning a MBP.

As an aside, I should buy a lottery ticket given the number of rare issues
that happen to my Apple products.

------
phee
The point is, how did Apple manage to get away with it for all these years?
why weren't they enforced to ship only the properly grounded adapter?

~~~
thrillgore
With a trotted meme/slogan like "You're holding it wrong" sorta explains it
all does it not?

I say this as a happy MacBook Air owner but i'm traveling soon and this had
better not be an issue...

------
rando444
I've noticed a similar problem. I have a macbook pro and a macbook air and
whenever I have both of them plugged in and am touching both of them at the
same time (usually one arm laying across both of them)

I can feel where my arm is touching the laptops start to hurt/burn. I figured
the electricity is now going through my body, but assumed it was a problem
with the laptop, not necessarily the electricity.

------
thrusong
My iMac, specifically the USB keyboard (I needed the numpad), gives a slight
electrical sensation when I touch it anywhere other than a key.

~~~
misja111
I experienced the same with an aluminium Apple keyboard connected to a non-
Apple PC; small electric shocks now and then when I touched the aluminium. I
contacted Apple about it and they said it was impossible .. Luckily I had
purchased the keyboard online and I could still return it.

------
snarfy
I'm curious if this would trip a GFCI when you touched the lid.

People often judge whether they will get shocked based on resistance, but
humans are also capacitors. The casing of a macbook is a machined aluminum
frame which will act as one plate in a capacitor. Your hand is the other
plate. Unlike DC, AC passes through capacitors.

------
ti32x
Also worth noting: some of the cheap knockoff magsafe adaptors available on
ebay have an earthing "pin" inside the adaptor (the mushroom thing) which is
actually just coated in a metallic coloured covering/paint.

This doesn't actually provide contact to the existing ground pin, so you have
this issue.

------
Gracana
My toughbook does this as well. One of the replies there says thinkpads have
the same problem, and I have an IBM power adapter, so that could be the
culprit. IIRC it's high frequency, so probably created by the supply itself
rather than a floating neutral in the building wiring.

------
captainmuon
Maybe a stupid question, but why is the case grounded at all (I mean as in
"put on a common zero potential", not as in "connected to earth")? I imagine
it is convenient to use the case as common ground, but it seems wierd. Is is
unavoidable production-wise?

------
anonu
This happens to me regularly when I go back home (to a foreign country not the
US). All the sockets have ground but the ground doesn't actually go
anywhere... So you still get shocked. My solution was a bit lazier: plugin my
MBP only when I'm not using it...

------
azsrz
I had the same problem with the small plug. Using the extension cord with the
ground solved it.

------
bitL
I still remember some Dell Precision workstation having a "magic touchpad" as
it reacted even when your fingers were an inch away - must have been a pretty
powerful electromagnetic field! And the case was always giving shocks at
random times.

------
cyberferret
Well, that explains it. Just last week my son was complaining that he was
getting tiny shocks from the chassis of his Macbook. I thought he was just
making excuses to not do his homework and told him to stop imagining it.

Time to buy a 3 pin adapter!

------
chunkiestbacon
Happened to me too with my 2011 macbook air and my 2010 macbok pro 15' when
using the 2 prong adapter at home in Europe. Currently typing this on a 13''
late 2014 13'' MBP with 2 prongs in Japan. No problems.

------
gravypod
If you can get a shock from this, and as someone else is saying that they can
feel it when they wave their hand over the lid, then how is this passing any
EMI screening?

That's got to be noisier then an old ham radio.

------
return0
I would suspect it's a common problem with aluminum casings in general. They
also have that cold feeling. IT's one of the reasons i prefer the matte
plastic of thinkpads.

------
nikolay
I have the same issues when I'm in Bulgaria during the summer (220V, 50Hz),
and always wondered how Apple did something so basic so terribly wrong!

------
thrillgore
Well this is just great. I'm traveling overseas to a country with 220v (South
Korea) and I am concerned my Air will end up shocking me.

------
edpichler
I thought I was the only person to get shocks of my Macbook Pro, and that it
had some problem. All because of the lack of a third pin.

------
voltagex_
I'm assuming this is the same phenomenon with a metal-body camera I have -
even though it was only charging off 5VDC at ~1A.

------
londons_explore
This problem is common.

You can solve it by opening up the power supply and ripping out the bright
blue Y capacitor inside. It looks like a slim M&M with 2 legs. Both apple
official and 3rd party power supplies will have one.

Do not damage the capacitor without removing it - that could lead to an
electric shock. You can remove it by cutting it off with pliers or wire
cutters.

The power supply will work fine afterwards, but might emit a bit of radio
interference, although generally not too much.

~~~
derefr
> might emit a bit of radio interference, although generally not too much

It might not cause the FCC to knock down your door, but what will it do to the
laptop's own wireless and Bluetooth connectivity?

------
amelius
Could somebody draw a simple diagram with resistors and perhaps capacitors to
illustrate what the problem is?

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ksec
So i am guessing the UK plug wont have this problem?

