CrossRoads:
Gonna need some hefty traces for that much current.
Yeah, the entire underside of the PCB is the voltage rail. The entire piece is only 29cm long with 48 RGB LEDs on one side. Four of those pieces together pulling off of the same power supply ... The wires connecting them to the power supply will have to be nice and hefty.
Thanks for the links, I'm gonna go do some studying. Question: would it make any difference if I use one large relay, or two smaller ones in parallel? So instead of looking for a single 12A one, use two 6A ones instead?