After connecting the main power and circuit breakers, wire the outgoing circuits according to the intended electrical load. Make sure each wire is correctly marked for safety. “Outgoing Line Wiring Connection in Distribution Panel” In this video, you will learn how to properly connect outgoing line wires in a distribution pan. 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. It includes isolator, RCCB (Residual current circuit breaker) or RCD (Residual-current device) devices, protective fuses or MCB's (Miniature Circuit Breaker). Identifying Symbols and Labels: The first step in reading an electrical panel box wiring diagram is to familiarize yourself with the symbols and labels used.