On Tue, 07 Mar 2017 20:27:10 -0500, wrote:

If the power supply were to short power could get through the
laptop, and out the USB or headphone, or whatever jacks.?
Anyway, some require grounding by code, others don'r.

It's a good question, since the OP is right that a power supply seems
pretty well isolated by all that plastic encasement, and the output is low
DC at relatively low amps ( 10 or so amps most of the time).

There's no power transformers anymore due to the switching power supply
design.

And yet ... ... ...

I wonder if the electronics of the switching power supply require a really
good ground?