Here, you can see the wiring diagram of the 230V single-phase distribution box wiring diagram. It has the highest capacity than other MCBs used in the DB. In Single Phase supply (230V in UK, EU and 120V & 240V in the US & Canada), there are two (one is Line (aka Phase, Hot or Live) and the other one is Neutral) incoming cables from the utility poles to the kWh energy. Single-phase distribution boards are mostly used in domestic house wirings such as houses offices, shops, etc. In India, a 230V single-phase AC supply is used for domestic so here all the devices used in the DB is operating with a 230V AC supply whereas in USA 110 or 120V AC supply is used for. In this video, we'll walk you through the process of wiring a home distribution box with a detailed connection diagram. What is Distribution Board? Distribution board. Distribution Board or DB is an electricity supply system or a common enclosure that distributes the electrical power feed into subcircuits.