For SSCs (pixelnet) I use ethernet (cat5) cables, cut off one plug and replace it with a 4-core waterproof connector.
To join the waterproof connector I solder the wires, and use shrink tube over each connection -- and a larger shrink tube over the entire splice. I use the wiring scheme described in the wiki for 4-core powered pixelnet.
I keep one rj45 plug to continue using the jacks on the hubs.
the big reason is for the cat5 is the twisted pair to have the long distance between hub and controller.
most of my cables are 25ft in length since they are the original cables that I purchased 4 years ago for SSC. I have also made some "cat5 extensions" with both male and female waterproof connectors when my standard 25ft cables are not long enough... they fit between the 25ft rj45/4-core wore and the controller.
In the first year I had water problems with the cat5 and my connectors were damaged on one end, so it made sense to cut them off.
I do use 5ft 3-core cables from ray ON THE CONTROLLER TO PIXEL connection because the twisted pair is not needed... there is a single data wire, not a pair of pixelnet + and - wires... so there is not extended distance.
Also, I limit the 3-core cables to 5ft because of the max distance between controller and first pixel.