What is the main function of an electric circuit?

The purpose of an electrical panel board or electrical distribution panel is to supply individual circuits from the main distribution board. As the board is supplied with one circuit of high capacity , it needs to be broken down into smaller branch circuits. Breakers accomplish this obligation by plugging into the panels main bus-bars. The load side of the breaker then goes to the specific load. The size of the breaker is dependant upon the size of the load of that circuit. The conductor that feeds the load is dependant upon the size of the breaker feeding that load.