Can the grounds of two different power supplies each supplying different voltages be connected?

If not, why?

And if they can, what about the theory of isolation? For instance in the case where a microprocessor operating at 5V is connected to a device using 240V, the have to be isolated from each other?

 

Originally posted by Honeybee@Nov 7 2005, 03:20 AM
Can the grounds of two different power supplies each supplying different voltages be connected?

If not, why?

And if they can, what about the theory of isolation? For instance in the case where a microprocessor operating at 5V is connected to a device using 240V, the have to be isolated from each other?

[post=11490]Quoted post[/post]​

Yes, you can connect _floating_ grounds from different supplies together, which would make them not isolated from each other anymore.