In basic diagrams, the standard symbols for the circuit components are arranged in correspondence with the operational principle of the device, as well as to facilitate the reading of the diagram. In design diagrams, all or some of the components are represented as equivalent circuits; in such diagrams, sources of electromotive force, current, resistance, inductance, capacitance, and so on are assumed to be components with lumped parameters.
The path taken by an electric current in flowing through a conductor through one complete run of a set of wires from a power source, such as a panelboard, to various electrical devices and back to the same power source. The wires used for various circuits are prescribed by codes, such as the National Electrical Code.
A block diagram consists of two basic functional units that represent system operations. The individual block symbols portray the dynamic relations between the input and output signals. The second type of unit, called a summing point, is represented by a circle with arrows feeding into it.
Circuit diagrams can be classified into four types: schematic diagrams, wiring diagrams, basic diagrams, and design diagrams. Schematic diagrams depict the functional components of an electric circuit and their interconnections. Wiring diagrams (for connections and junctions) show the arrangement of circuit components and of connecting wires.