Finger "jumps" when touching the aluminium shell

I've noticed the same thing. The computer is electrically grounded through the shell, so I would image a little bit of electricity is leaking out through your finger. I've tried to show it to other people but they never seem to be able to feel it. I imagine it might go away if you used a grounded power plug, like the extension cable that came with the power supply. Never tried though.

Ken

I feel this on my 2010 MBA as well as when my iPhone 5 is charging (the back aluminum part)

Yall be trippin.

filmbuff said:

Yall be trippin.

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Nope, both my MBAs (2011 and 2013) exhibit this behavior. It's very easy to feel. The behavior is normal when not having the unit grounded.

Same here. Felt it on MBA 11", 13" and rMBP.

Happens when I touch my GF and my mac at the same time. No kidding.

I don't feel it on my Macbook Air but I felt it on my Macbook Pro.

Noticed this too on my 2007 MacBook Pro. Doesn't happen all the time. Maybe it happens when the outlet I'm plugged into is badly grounded. Could also have to do with the way the MagSafe connector is seated. One time I felt the tingling and then when I reached over to disconnect the MagSafe connector and re-connect it, I got a painful shock when I touched it. Looks like it may have been seated incorrectly.

I've read a previous thread that mentioned this issue is sometimes corrected when using the longer lead with the MagSafe power adapter due to the grounding

This is because the power adapter you are using does not have grounding . Change it with a connector that has 3 "pins" will solve the problem.

teffers said:

I've read a previous thread that mentioned this issue is sometimes corrected when using the longer lead with the MagSafe power adapter due to the grounding

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It doesn't just fix it sometimes, it always fixes it. The longer lead has ground pins, which the other plug doesn't. As long as the wall socket is actually grounded, it will make the issue disappear. For this reason, I always use the long lead.

I've noticed that when my MBA is charging and I plug in my powered external hard rive the metal end of the USB sparks on the aluminium

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viespace said:

This is because the power adapter you are using does not have grounding . Change it with a connector that has 3 "pins" will solve the problem.

Click to expand...

How about in the UK? All of our plugs have 3 pins!

My white MacBook would do this when I would touch one of the screws in the plastic, I'd get a little zap that wasn't static.