Multiple power supplies/sources for LEDs, how/where to ground with data line

Question

I have hit a point in my LED project where I am about to introduce a second power supply (5V 60A Source - Amazon Link Here) and I would like to ensure a common ground. Think of the project as one continuous LED strip with power introduced at intervals to ensure the lights are supplies with ample power.

So far, one supply has 4 terminals which can supply power to the Microcontroller and 3 different points along the LED strip. Adding a second supply brings up the question of how to share the ground.

My thought process is this:

1. The ground must be shared throughout the project/full LED strip like what we see in the image above.
2. With 2 power supply sources which are pulling from 2 seperate plugs introduces 2 different grounds, going against #1
3. Either:

A) The two power supplies should pull from the same source, like through a Distribution box (lunchbox or distro box for all us film industry folks Example of a Distro box here). So even though the 2 supplies are pulling from different 2 plugs, the source of those 2 plugs is the same line.

-OR-

B) The grounds are connected after the fact and since they are connected, it just becomes one connected ground source.

The question:

Are either of these approaches correct?

Answer 1

Maybe neither.

If your distribution boxes are decent quality and have low internal resistance then you already have the common lines connected at the Lunch Box / Power Strip. Since this is the case all that is required is that you bring the power and ground of your sixth strip from the left back to distribution box 1. This will maintain your sensible arrangement of feeding all pairs of strips from both ends. It will also avoid problems and confusion should you lose power to one of the distribution boxes. If, for example, you lost the DC into distribution box 1 then the common connection for everything on that side of the system would be through strips 6 and 5 which may burn up.