This AutoCAD DWG file includes a complete Single Line Diagram (SLD) of a Distribution Board, showing circuit breakers, wiring connections, and load distribution for lighting, power, and mechanical systems. Distribution box The system diagram usually shows the electrical connection and configuration inside the distribution box in a graphical way, including busbars, circuit breakers, fuses, load devices and other elements. Each component plays a specific role. Smart DB boxes have extra parts like energy monitoring units and communication modules. Residual-current device (RCD) or Residual current circuit breaker (RCCB) is used to dis-connect the circuit when the electrical current in not balanced between the return neutral conductor and energized conductor. 3) Circuit Breakers Circuit breaker is a switching.