For the Kichler Lighting LED Puck Light Cabinet Disc/Puck Light in Black (Painted) 12319BK, there are 36 inches of wire spooled inside. They are modular, so they plug directly into the 12359BK driver module, and you can connect up to three discs per driver module. You can also add length with the 12347BK extension wire. You actually would need one 12355BK dimming switch per driver module, and each module group would be dimmed separately. You cannot use one for multiple power supplies. However, you could use one 12387BK Z-Wave dimming switch per module to control all of them, but it requires that you have the Z-Wave home control system installed.