micky wrote:
Why do laptop power supplies, the ones with black rectangular things in
the middle of the cord, have 3-prong plugs when everything you can touch
is plastic or "rubber"?

And, I believe, when there's nothing more dangerous than a lamp
underneath the plastic and the rubber? Less dangerous because some
light bulbs ger really hot!

The ac can use ground as part of a filter, capacitor to ground. I have seen
ground fed to common on laptop, sometimes causes ground loop problems.

Greg