Fri, 10 Mar 2017 07:55:44 GMT in alt.home.repair, wrote:

On Fri, 10 Mar 2017 01:58:15 -0000 (UTC), Diesel
wrote:

I prefer the ones that dont, because, sometimes, the
3 prong ones generate unwanted background hum when fed to external
audio amplifiers while plugged into their chargers.

That implies that the ground is connected to the DC common. Not sure
why they would want to do that unless it is just for RF filtering.



I've suspected the issue is a ground loop based on prior experience
with that...I haven't tried to open one of these and take a look
inside, so it's entirely possible it is connected, but, due to some
filtering circuitry in between, I'm unable to do a simple continuity
test on it. By unable, I mean that it doesn't read as completing a
circuit when tested in that manner.


http://www.channld.com/hum.html

This works well to remedy the problem...

https://www.amazon.com/Mpow-Ground-I...F6E7CCRCVEDNNN

--
Sarcasm, because beating the living **** out of deserving people is illegal.