On the RGB strips the 4 wires are marked 12v+, R, G, B, you apply +12 volts to the 12v terminal and 12v negative to whatever color led you want to light, you could apply 12v negative to "R"(red) and also from another circuit to "G"(green) and another circuit to "B"(blue) as long as those circuits use the same +12 volts.