I'm planning on a home automation system, and two sub-sections will be separated by (say) 100 feet. These will be connected by a low-amp, low-voltage data connection. To avoid running significant power over that distance, I would like the "remote" sub-section to have its own supply, separate from the "primary" sub-section.
Each power supply might be a wall wart, or maybe an ATX supply.
The data connection will run at 3.3V or 5V (relative to ground/reference), and "should" only flow a few nA of current.
Can I safely run a ground wire alongside the data, and tie these two supplies together, to create a common reference for the data voltage? What is the potential for current flowing through that wire, looping through the house's AC main supply system?
I've done some reading, and haven't found an answer that directly matches up to this query about potential current flow over that ground connection. From that reading, it does appear that if I expand to multiple sub-sections, then I should connect the grounds in a "star" fashion, running each tie-in back to my primary.