The electrical panel box wiring diagram provides a visual representation of the different components and connections within the panel box. It typically includes details such as the circuit breakers, neutral and ground bars, bus bars, and other essential components. The figure below shows a typical breaker panel used for 120V and 240V. Understanding the wiring diagram of an electrical panel box is essential for electricians and homeowners alike, as it allows them to troubleshoot any electrical issues, carry out repairs, or make additions to the system. What is. The panel receives power from the utility company and distributes it to the individual circuits that supply all of the fixtures, outlets and other devices in the home.