 This means the C-Bus wiring, connections and circuitry can be considered Extra Low Voltage.With conventional wiring, the mains power (120 / 230 V) is wired from the distribution board (DB) to the load (for example, a ceiling light) via a wall switch.In C-Bus systems, the connections between the DB and (for example) the ceiling lights, and between the DB and the junction box (wall switch) are completely separate.