Does the 3 Pin adaptor support grounding Or is it just a dummy ground pin?  At the back of the pin in the slider is there a metal connecter?

Effectively any 3rd pin on the adaptor is a dummy. If you look at the socket on the USB charger or Laptop mains charger when the adaptor is removed you will see that it is only 2 pin 'figure of 8' socket. This is not a safety problem as the USB and mains chargers are double insulated and the conductors are not visible (or touchable). Electric current on the body of the MAC is likely to be caused by induction rather than conduction.This means that stray electrical currents are developed in the case due to switching voltages inside the laptop much like a step down transformer. This is not unsafe! If the case became really 'live' then it would fry you as well as a lot of the computer components. Most laptops (and I expect Apple is the same) work on a maximum voltage of around 20V which might tingle if you have wet fingers but will not harm you.

• Answered by Roderick P from Solihull
• 18-Jun-2012
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