confused on common ground

[Chris]

My first year with pixel, just finishing up design and build. I have my main unit using a Falcon F16V3 with three power supplies, and then I have 2 differential receiver setups about 150' and 175' away that will run lights on a separate building from the main house. I am assuming that the two power supplies that will be powering the pixels attached to the diff receiver do not need to be common grounded to the main units power supplies. Am I correct in this assumption, and if not how to I ground them together at such a long distance? I am using one of the main power supplies to run the Falcon controller, and the other two for power injection, then in the differential setup I will use both power supplies for power to pixels. Am I missing something?

 

[Kitman]

You generally only need a common ground when performing power injection from multiple power supplies. When running a differential expansion board you can treat that as a completely separate controller from the main controller, no need to link the ground back to the main controller, however there may already be a link back using the cable between the Falcon and the differential receivers. I am unsure what data is passed between the 2 there may be a ground wire however someone with more knowledge of the link might be able to explain more if required.