Ground and data/signal wire question.

Ground and data/signal wire question.

I understand the need to run a ground from the Arduino to the strip I’m lighting, but I’m unsure of what to do with multiple strips and power sources. I’ll present a simplified scenario (in hopes of a simple answer).

An Arduino with its own 9-volt power source, and two 50-LED strips, each with their own, individual 5-volt power sources injecting power at both ends of their respective strips.

From the Arduino the the data wire from the signal pin, and a wire from the Arduino’s ground run 100 feet to the first strip. The data/signal wire obviously connects to the strip’s data pin and – as I understand it – the ground wire from the Arduino connects to the ground wire of the strip (even though the Arduino and strip power supplies are separate, and are different voltages).

I’m unsure of the next connection setup.

Let’s say LED strip number two is another 50 feet away from strip one. A wire connects the signal/data output of strip one to the signal/data input of strip two. That part is easy.

Is an additional ground connection required as well?
If required, I’m guessing it’s because of the separate power supply for each strip?
If the additional ground is needed, does it have to originate at the Arduino and go the 150 feet to the second strip’s ground?

I know this is basic knowledge for many of you, and I apologize for what is probably a simple question, but any advice is appreciated.

Thank you!

missing/deleted image from Google+

@David_Brenchley Much appreciated! Did you mean to have this diagram for my previous question below though? There similar questions, but the first one was power specific, and this one is signal/ground specific.

Thanks again!

As far as I understand, all the grounds involved in an electric circuit should be connected.

yesterday I was working with 3 power supplies, 3 arduinos and 3 led strips. 1 power supply powered all arduinos and one led strip, and the other 2 power supplies powered each a led strip. The grounds from all power supplies and arduino were connected. yet, the third led strip was flickering, and it stopped flickering when I connected its ground to the ground of the power supplies. Even though its ground was connected to all the rest of the grounds, until I didnt kind of closed a grounds loop, the strip flickered…