I have a 5V and a 12V power supply. Both have a N, L, Ground
connections for the AC side. Both also have a V- and V+ connection.
Measuring between V- and V+ I get the correct voltages, i.e. 5V and
12V. Measuring between ground (AC side) and V- on both the 5V and 12V
gives 0V. Measuring between ground (AC side) and V+ on the 5V supply
gives 0V and on the 12V supply 12V.

Why does the 5V power supply not show 5V from ground to V+? Note that
the 5V can deliver up to 6A and it is under a 0.6A load when I measure
the voltage.

Thanks