If you are talking about a small 4X8 layout or something simular, I would give it a try by pairing or even quadrupling the "running" leads. Cat 5 has 8 wires, that would give you 4 negatives and 4 positives, Im guessing several amps worth. NOT ideal for a huge layout, but should work fine something smaller. Im using 22 gauge every six feet, all of them tied to an 18 guage wire near the center of the layout, measuring with a DVOM im not seeing more than a 1/10 of a volt difference anywhere on the lay out. phase 2 is 4 x 8, phase 1 is 3 x 6 and is wired the same way, phase 3 is 2 x 8 and is also wired the same way.
Dont wire from Cat 5 to Cat 5
14, 16, or 18 to Cat 5
Then do it again
JR&SON