Ok this is where there is lots of confusion. If you want to run lights that pull more than 4 amps the issue is two fold.
#1 - the cat5 feeding the ssc is not heavy enough to be pulling more than 4 amps so you need a way to get power to the string with heavier cable. So you can not feed it with cat 5. This is striaght forward.
#2 - But you need to understand that even if the cat5 could handle the current you still will run into the issue of the voltage dropping too low if you go too long. The wire on the string has resistance and is causing the voltage to drop, how much? Well this depends on the size and length of the cabling, this is the part that sets the resistance we are fighting. then you also need to know how much current we are going to pull.
Think of it this way. the same string pulling 4 amps will not have as much voltage drop and be fine. Then you up the amperage and with nothing else changed the drop is much higher. double the current you are drawing on the same string the voltage drop will double no matter how big the wire from the power supply is. If you want to over come this you need heavier wire on the strings, or shorter strings.
From the point of view of power, when we inject power we are making shorter strings. If you do need to inject, feed both power and ground other wise you do not get the full benefit. When you figure voltage drop you are looking at the power moving from one side of the circuit to the other so the lenght total of your ground and power together is what matters. so leaving the ground off only shortens the power run. But does it?
? If we run a wire all the way to the other end of the string we have a wire equal in lenght to the string. So in the end it is simply that we ran a larger wire that is makeing the difference. or if you use the same size wire the drop in solder connections alone helps.
( I am still trying to figure out why we need brighter nodes on the strings. I have to set mine lower in software to keep from lighting up the yard and washing everything else out. Better nodes yes / higher current brighter ones not for me. I like not having to fool around with all this power injection. one cable works great for me!) Besides when you see what I am working on it solves this issue anyway.
RJ
