Electrified Cases on Macbook Pro!! More common problem?

Carl,

One half of the line voltage!? You're insane. That could easily be fatal, especially in Europe, and would never be "well within international standards."

Oh, I get it. An attempt at humor. Right?


RRS

One half the line voltage on the chasis? Nonsense.

I challange you to prove this and explain the purpose such a design. You are saying the chasis is purposefully floating at potential above logic ground of the circuitry? That would be nuts.

You claim the power delivered via this potential is low. Limited by what, exactly? The only thing limiting the power of your line voltage is the 20 amp breaker in your home's breaker box.

Look, no grounding system in perfect and you will sometimes have a potential develop on a chasis, but I can think of no reason to float the chasis above logic ground and you dang sure wouldn't put half the line voltage there...or any of the line voltage for that matter.

Are you telling me that if I measure the chasis of MBP relative to earth I will measure potential of half the line voltage? Have you measured this supposed potential?

I will go home tonight and measure for a potential on the chasis on my wife's PowerBook. If you are right, I'll come back and eat my words.

Message was edited by: Peter Arnold1

The MBP Users Manual is located here: http://manuals.info.apple.com/en/MacBookPro_UsersGuide.pdf
Regards,

Clearly a lot to be said for the nice safe british three pin plug where one is earth!

Hey Bill,

According to my take and investigation of the UL standards for external power supplies, Apple does NOT meet them. The specs are a bit ambiguous though. I will say this, there is no reason to have the tingly feeling (heck the electric discharge) and Apple really needs to get rid of the two prong adapter.

Bob

Bob,

Thank you for the link. Now I understand the different mains connection options Apple is providing.

Howard

Dual 1 GHz Power PC G4 Mac OS X (10.3.7)

Bob,

Either the power supply was certified as Class I equipment with an earthed mains connection or Class II with an unearthed mains connection. It would be a violation of basic safety principals to provide Class I equipment with an unearthed mains connection.

It would be very helpful if you would describe what is printed on the label for the external power supply. Was the power supply certified by UL or CSA? Is there a symbol for double insulation?

Symbol for double insulation: http://en.wikipedia.org/wiki/Image%3ADouble-insulated-symbol.png

Howard


Dual 1 GHz Power PC G4 Mac OS X (10.3.7)

Actually, one of the two prongs of an American standard, two-prong connector is connected to earth. Some here have implied that you need to use a three-prong adaptor for a product to have an earth-grounded system. That is simply not true. In most installations, the line neutral provides an earth ground of equal quality to the third prong. In all buildings that are wired to code, the neutral is bonded to earth ground at the breaker box. So, MPB power supply is earth grounded.

By the way, I'm not saying that there is not some issue with the MBP's grounding system. I don't own one, so I can't test it. But, I can promise you that product is not designed to have any potential on the case and certainly none of the line voltage. And, the power supply is earth grounded even with a two-prong plug.

Power Mac G4 (AGP) 500MHz Mac OS X (10.4.5)

That 'textured' feel is just the harddrive spinning, making it vibrate which makes it feel like what you think is shock. If you put your lip on the latch...THAT is a shock.

(don't ask how I ended up with my lip on the latch)