An electric wiring diagram is a visual representation of an electrical circuit, showing the location of the power sources, wires, connection points and signalling mechanisms. It uses a standardised symbol and notation system to represent the main pieces of a circuit, and these conventions are internationally recognised. After the circuit has been created, electric wiring diagrams are most commonly used as a troubleshooting reference if the circuit fails.
An electric wiring diagram includes information on all the essential parts of a circuit, including resistors, capacitors and inductors. A resistor is a component that controls the amount of electricity that runs through the circuit by opposing the electric current. It is indicated on the electric wiring diagram as a zigzag line. The capacitor stores energy by holding it between two conductors and is used to charge the circuit. It is described in the electric wiring diagram as two parallel lines. Like capacitors, inductors also store energy, but store it instead in a magnetic field when electricity is moved through it. They are denoted in electric wiring diagrams as a straight line with several bumps in it.
Depending on the complexity of the electric wiring diagram, these circuit components may be uniquely labelled in addition to their symbols. For instance, if there are two capacitors used in the circuit, they will be listed on the wiring diagram as C1 and C2, short hand for Capacitor 1 and Capacitor 2. The numbering of unique components is based on their location in relevance to the main power source, which is considered the starting point of the circuit. The parts of the circuit are linked together in the diagram through connection indicators, also known as wires. Wires are indicated on the diagram as simple straight lines.
The drawing of an electric wiring diagram is one of the first steps in the creation of the actual circuit. After the wiring diagram is complete, it is converted into an image called a Printed Circuit Board that represents the basic physical placement of the various components. An Electronics Design Automation tool is then employed to sort out the optimal location for the wiring and the final design is created into an "artwork" diagram that can then be used for the physical installation of the circuit.
An electric wiring diagram does not show the physical orientation of the components, merely how they connect together. Diagrams that show the actual location of all the wiring parts are called layout designs or physical designs.
Reading electric wiring diagrams can at times be a challenge. Diagrams are meant to follow the flow of power from energy source to output mechanism, however when the circuits are very complex this is not always easy. There is no universal standard as to how they should be organised on a page, though commonly they are drawn with intent to be read from left to right and top to bottom. Larger wiring diagrams, for skyscrapers and sizeable compounds, do not fit on a single page and can require cross referencing among many pages to follow the electrical flow.