A wiring diagram is a simplified conventional pictorial representation of an electrical circuit.
It shows the components of the circuit as simplified shapes, and the power and signal connections between the devices.
Architectural wiring diagrams show the approximate locations and interconnections of receptacles, lighting, and permanent electrical services in a building.
Interconnecting wire routes may be shown approximately, where particular receptacles or fixtures must be on a common circuit.
On large projects symbols may be numbered to show, for example, the panel board and circuit to which the device connects, and also to identify which of several types of fixture are to be installed at that location.