Many people experience an issue with the ground but other people notice that the vibrating/buzzing feeling doesn't go away with switching to the 3 prong plug. The feeling only appears when your hand moves across the surface but not if you keep it in one place. This leads me to believe it is the surface of the metal.
I have the same issue with the 2-prong plug only. I did some tests, and conclude that this can only be related to a grounding phenomenon, not the metal surface:
- testing between any two points on the surface of the laptop with the voltmeter in "beep" mode comes up negative, suggesting just holding the voltmeter probe on the surface of the laptop is not a good method to measure
- With the 2 prong plug, I see 0.1V difference between the house ground and the end of the magsafe plug. With the 3-prong this goes away
- moving my hand over the surface only produces a tingling sensation when the 2-prong connector is used AND when I am not insulating myself from the floor. This clearly indicates some small current flowing from the laptop through me to the floor.
The differences in comments on this issue can be explained:
- the amount of leakage probably varies from laptop to laptop
- some people well be bare-footed, others always wearing shoes, resulting in much better insulation from the floor, which may be enough to eliminate the problem
- even when using 3-prong cables, there might be a fault with the cable, the adapter, an extension cord or the grounding of the socket itself
- some people will be more sensitive to this sensation than others
I'm just disappointed that there's no grounded short plug for the adapter.