Circuits connect similar electrical components to form an electrical system. Once created, you can edit circuits to add or remove components, connect a circuit to a panel, add wiring runs, and view circuit and panel properties. Wiring is not necessary, but can be used to show wiring that is exposed or concealed within walls, ceilings, and floors.
You can add a device to an existing circuit when its distribution system matches that of the existing circuit. When adding a device with the distribution system specified as instance parameters, the distribution system for the device will assume the values of the circuit where it is being added.