I searched a few words and threads but did not seem to fine what I was looking for.
In "the old days" wall wart power supplies had a transformer in them, and one could power separate portions of a circuit with two or three wall warts, and they were all isolated, floating, and independant of each other. The grounds were not tied to each other back through the 120 VAC building wiring.
With the newer, physically smaller and more effieicent switching wall warts, are the V+ and Gnd leads isolated from the 120 VAC terminals, and hence floating with respect to earth ground, and building neutral?
A simple test with an ohm meter indicated that they were, but I'm not familiar with the circuitry used inside them.
For a quick testbed project it would be easier if they truely floated with respect to each other.