Since the power supply will most likely be mounted on a junction box not close in proximity to the load, long output wiring will be needed to reach the load. The distance from the power supply to the load must be determined in order to select the correct gauge of the wire. The correct gauge should be selected to minimize a voltage drop on the wiring. The above link shown here provides recommended wire gauges for various lengths. These recommendations are based on a maximum voltage drop of 10%. The permissible voltage drop on the output wiring should be calculated based on the operating voltage tolerance of the load.