MBP shocking me and wife

"2 prong plugs work perfectly well when they are connected to a properly wired AC power supply."

A two-wire AC outlet has "hot" and "neutral" - no ground. In earlier days, AC outlets were "polarized" - one AC prong wider than the other. Although it wasn't a ground, it offered protection in some instances. For example, a partially screwed in incandescent light bulb would not have a high voltage on the bulb's screw base.

An ungrounded Apple AC power adapter places one-half of the line voltage onto the chassis ground. Since the casework is metal, the voltage is present there too. The AC voltage is placed onto the chassis to attenuate the emitted radiation. A grounding wire removes the AC voltage from the chassis.

Peripherals have the same type of scheme. If you use, for example, an ungrounded USB printer connected to an Apple computer that is running on the internal battery, you will get the same shocking sensation.

In summary, I do not understand how a two-prong AC outlet can prevent the high-voltage shock, and I'd appreciate an explanation.

I don't pretend to know as much about this as you do, Carl, but I've never experienced any shocking sensation on the case of my MBP (or the Tibook that preceded it) when using either a two-prong or a three-prong connection at my home, where I've used an outlet tester on every outlet to make sure it's correctly wired.

eww, I don't know where you live, and that might be the deciding factor. In the US, with an AC line voltage of 120V, there's only 65VAC on the cover. Most people can't feel that. On the other hand, in many other countries - with a higher line voltage of 240VAC - there's 120VAC on the cover, and most people feel that.

Ah — that makes a certain amount of sense to me. Thanks!

wow thats odd, sounds dangerous too.

ALL laptops and peripheral equipment use AC current to attenuate RF emissions. The current is at a very low level, well within international safety standards.

The power adaptor that came with my MBP has 2 prongs not 3. I don't know if any of them have 3. But I've noticed to buy a new one is about AU$110, pretty steep I think. So I guess I'll just live with it.

I don't have a solution but just wanted to let you know that I am also getting static shocks only in Europe (esp. France & Germany using 3 prong grounded cables) and NOT in the USA (using 2 prong plugs).

I bought a 12" PB G4 in 2004 in the USA and more recently a 15" MBP, both using a 2 prong 110V USA plug. I get no problem with static shocks over here. Every time I travel to Europe though, I get static shocks as you guys describe, even when using the standard 3 prong grounded cable there - same laptops & different plug/cables. I have no idea why and technically, I would have thought the 2 prong plugs to have the problem, not the other way around! Also this tells me that there is nothing wrong with the laptop itself. Anyway the voltage/amps that runs on the chassis is too low to cause any harm but I always found the static annoying nonetheless.

Your power adaptor will have come with both a two pin duckhead plug and a three pin power cord, Mel. (These have been supplied with all of the square white Apple power supplies in Australia)

If you have lost the cord you should be able to obtain one as a spare part through an Apple dealer.

The part number is apparently X922-8519 Power Cord, Australia/New Zealand

Cheers

Rod

Hi,

I have got shocks off my MBP with 3 pin and two pin plugs. Do I need to take it to Genius bar to get fixed or is this "normal and acceptable". Apple please respond

Thanks

Rick

Rick, Apple don't respond in the forums.

Take it to an AASP or an Apple Store to get it checked.

You might also want to test your house wiring for correct earthing if that is where you have been using your computer when the problem has occured.

Rod

Interesting.
When I "rub" my palm over the surface of the Unibody - to the left and right of the trackpad) I get a similar feeling that one can interpret as a shock.
I tried this when the machine turned off and unplugged - same thing. I wonder if some of you just aren't used to the texture of the surface.
Somebody needs to get their hands on a voltmeter.

I just did a little experiment, I am using the three prong (USA) plug and I no longer get that "buzz." I thought it was the texture of the Aluminum case - I was wrong.
When I use the travel "adapter" with only the two prongs, I get the buzz if I am touching my metal framed desk which is grounded. If I lift my feet up, or touch the glass top - no buzz/shock.

This has the potential to be dangerous, folks. It takes less than one amp across the heart to kill a human.

THis has actually been occurring with Mac notebooks since at least the first PB12 model, Justin. It even happens with iBooks if you touch a metal component of the case. I don't think the current level is anywhere near even 1 amp, though. I've yet to hear of any real injury being sustained, but it has always perturbed me a little.

I should add that it doesn't simply affect Apple notebooks.

It also happens with Dells - see http://crave.cnet.co.uk/laptops/0,39029450,49295100,00.htm and, it would seem, reading the comments HERE to HPs , Compaqs, Sonys, Thinkpads etc etc. Seems , in fact to be a common feature of Notebook computers when using 2 pin power adaptors, though the amount of metal that is directly contactable may affect the extent which people noticing it!


Cheers

Rod

http://forums.reghardware.co.uk/forum/1/2008/01/18/dellm1530_electicshock/ provides more examples from a wide variety of makers.

Cheers

Rod