I am in the midst of designing a project that will require two wall power supplies: one 12V, 10A and the other 5V, 10A. Part of my components are running off the 12V, while others are running off the 5V. There is some digital communication between the parts (e.g. Arduino to a motor driver), so I am wondering if I need to take measures to establish a common ground between the two wall supplies or not.
Both wall supplies have a 3-conductor setup (i.e. they both have a "ground" pin).
Thanks!
Edit: alternatively, would it be better for me to just use a single 12V, 20A power supply and use a converter to step down 12V to 5V for the 5V-components?
Your project almost certainly needs a common ground for its supplies. The exception would be if
you communications were opto-isolated at some point.
Do you know if either of your supplies is isolated or uses mains earth for its output ground? This
you check with a multimeter (with everything powered off and unplugged of course!)
The communications are not opto-isolated, so I see that I would need a common ground. Both of the power supplies use mains earth for their output to ground, but I suppose that I was wondering if I would need another common ground between them apart from mains earth.
At this point I'm actually thinking that using a single higher-power source may be more worth-wild (as in one 12V, 20A source with a converter down to 5V for the 5V components).
You have a problem - any fault currents in the mains earth could travel through your ground
commoning wire as things stand. Make sure both power supplies are plugged into the same outlet
to avoid this (wire them into one plug perhaps).