Shadow-Caster 4-Channel Underwater Light Relay Module [SCM-PD4CH]4 Channel Underwater Light Relay Module The SCM PD4CH is a 4 position power distribution box that provides a convenient way to connect up to 4 Shadow Caster underwater lights. Digital over current protection for each output ensures the safe operation of multiple lights and provides an easy way to manage the relatively high current switching needs of multiple light installations. The SCM PD4CH is housed in a compact waterproof box that is ideal for