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Whenever my MacBook Air is connected to the AC power and I have my hands on the palm rest, I feel it passes some electricity to me. If I unplug it from the AC power it stops doing that.

This has recently became obvious, when other people can feel this tingling by touching my skin after I've been working for a while.

I have two questions:

1- Is this normal in unibody Macs?

2- Is this harmful for my health in the long run?

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2  
Seems to be normal. Happens on all MBPs I have ever used. Bad anodisation I suppose. –  Konrad Rudolph Mar 21 '11 at 18:54
    
I just bought a macbook air, 3 days ago and I have the same problem! I find those shocks very enjoying and it's a very unpleasant feeling... Do you guys think it's normal? I think I should bring it back to the apple store and let them check my macbook... I am using the grounded cable, but the problem remains :s –  user13598 Nov 13 '11 at 10:42

6 Answers 6

up vote 17 down vote accepted

Electrical current passed from e.g. a MacBook Air can be avoided by plugging your Mac into a grounded power outlet. I sometimes get this too when using a non-grounded power outlet.

I am assuming you are referring to being able to sense "vibrations" as you e.g. slowly and lightly move your fingers upwards on the palm rest?

I have found that when I have my Macbook Pro plugged into a non-grounded outlet and I touch something that grounds me - e.g. a radiator, I can feel the vibrations. If I stop touching the radiator, the vibrations cease!

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Uhm, how do you do that? MBP plugs have no earth pin. –  Konrad Rudolph Mar 21 '11 at 19:01
4  
Actually they do, see the post by mspasov below. The "small" plug does not have an earth pin, but the extension cord does (EU). The outer pins on the MagSafe plug are ground. On the actual power supply, the large metal knob is what connects to the power cord ground when available. –  fnurl Mar 21 '11 at 21:00
1  
@fnurl the same is true for US style plugs. Extension has ground, wall-wart adapter does not. –  sholsinger Sep 8 '11 at 18:51

Ok, I can feel it too with my MBP 7,1. It's not harmful for you and should not be in any way harmful for your computer. Ways to stop this:

  1. Try rotating the power adapter (plug it the other way, if this is possible with your power outlets - in some countries it's not).
  2. Use a grounded cable and socket - The default US/EU adaptors plug does not have a ground, however if you use the extension cable with the charger, you will use the ground pin of the charger (ground pin is the metal ring, you can see when you remove the adapter, just above the serial number).

    Default Plug on the left (EU) and extension cable on the right

  3. A very easy (and ugly) solution would be to ground the macbook itself - just tape a naked strand wire to the alu shell and the other end to a ground (by ground I mean ground).

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How do you know it is not harmful? I was left with a buzz in my head for about 2 hours afterwards. Did you know that in the UK and Singpoare, Apple does ship the standard connector with a 3pin GOUNDED connector, so the problem does not occur in those countries. By contrast, in the US and Australia, it ships the 2 pin connector (not grounded). Seems a very stupid decision ... to save 5c on a pin, and leave yourself open to product returns, safety recalls and lawsuits. –  wolfies 16 hours ago

If you think your mac is giving you an electric shock while plugged into the mains then you need to unplug it from the mains and not plug it in again until you've been to an Apple store (or other reputable computer repair place) and had it tested.

This is absolutely not normal and potentially very unsafe. In fact consider that a default position for any consumer electronics you interact with. Electric shocks are not normal!

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4  
It seems to be very frequent with the unibody laptops, though. –  Thilo Mar 22 '11 at 11:22
1  
I own a unibody mac and manage 50 of them where I work, and haven't got, or heard of anyone getting, a shock from any of them or from any of the rest of the 1200 machines I manage. So it might be frequent but it clearly isn't "every machine" so the question still stands "is it normal behaviour" imho. –  RobM Mar 22 '11 at 11:35
    
It's not a shock, it's a small current flowing through your body if you don't have shoes for example. That's a missing ground plug, as already stated in other responses. –  Martín Marconcini Jun 8 '12 at 14:00
    
A current flowing through your body, when touching a domestic appliance, is the definition of a shock. It occurs because the product (a) ships with a cheap 2-pin connector that is not properly grounded and (b) because the metal case is a great conductor of electricity to your body. It does not happen with the previous generation white plastic MacBooks, for example, even though they also used a 2-pin connector. –  wolfies 16 hours ago

I had this with my MBP when I received it. It stopped when I changed the plug to use the one with the ground connection (don't know how it's called exactly). They provovide usually two plugs. A short one, with only two pins and longer one with three pins and connection to the ground. You should use this one.

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I don't get a shock from my MBP using either kind of plug. Personally I'd still say it was a fault if I was getting any kind of shock off any kind of computer. –  RobM Mar 21 '11 at 11:46
3  
@Robert no, that's why Grounding exists. The fact that you don't feel or get some current flowing through you doesn't mean that 1) it's not there, 2) it's a faulty machine. Any electronic device (especially those made of aluminum!) are prone to carry some electricity around. For that reason we have ground… –  Martín Marconcini Mar 21 '11 at 15:39
    
@RobM I would say you don't get a shock because in the UK, Apple uses 3-pin grounded connectors. Check the connector on the white power supply to your MacBook and count the pins. The problem occurs in the countries where they have been using 2 pin connectors. –  wolfies 16 hours ago

I had this happen a lot with the TiBooks of about a decade ago but haven't had it with any unibody machines, so I wouldn't say it was normal now, perhaps there's a minor fault with your machine, I can't tell you if it's bad for you or not but I'd recommend you take it back to a store and show them at least.

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had same issue. Bought mba 11 (mid 2011) model and felt this electrostatic flow while charging my mac. Changed it to long cable adapter with ground and problem solved. People that don't experience this kind of issue might have been in a place that already have their power outlet grounded. Also check your power extension if its faulty or try to charge on different power outlet.

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protected by bmike Jun 8 '12 at 14:39

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