Wiring diagram

A circuit diagram, and circuit diagram or schematic is a used in electrical engineering and electrical installation technology graphical representation of an electrical circuit usually at the level of individual modules or in the area of electrical installation technology -used elements such as switches, fuses, contactors, electric motors and light bulbs. It does not reflect the real shape and arrangement of the components, but it is an abstract representation of the electrical functions, and the current characteristics.

A circuit diagram is generally understood as a document, which is intended for the customer to an approval authority to the builder or to the maintenance electrician. The symbols used partially overlap exists with the circuit diagrams used in electronics.


It can be used ( usually standardized ) symbols. In addition, a designation system in which each component is assigned to a group and finally with an identification number. Reference information will allow you to quickly find within the plan.

Circuit diagrams are defined to represent the off, de-energized, and empty situation of the associated machine or system. If deviated, then this must be explained by a written notice (eg " tank full" ). Circuit diagrams are among the function-related documents in accordance with DIN EN 61 082 These plans created at the beginning of the design of a system, a device or a board and are also required later for repairs and maintenance.


Electrical circuit diagrams can be customized, company-specific or created according to standards, which include for example the following current standard specifications exist:

  • DIN EN 60617 Graphical symbols for diagrams
  • DIN EN 61082 documents used in electrotechnology
  • DIN EN 61355 Classification and designation of documents for plants, systems and equipment

The elements of the circuit ( electrical equipment and cables ) are standardized graphical symbols, also called symbols represented. You can use the whole or parts of circuits such as work or only control circuits, the steps of the workflow, the components of the circuit with its labeling and lines, and connections. The spatial arrangement of the components is not included in the rule.

In industrial production, the schematics can be supplemented with other documents such as assembly drawings, wiring diagrams, terminal diagrams, etc..

Design types

Some typical embodiments of circuit diagrams of electrical installation technology in practice particularly common:

  • The wiring diagram, sometimes called " circuit diagram in a coherent presentation " -, the circuit is such that the effect of context is visible, for example by adjacent positioning of the functional symbols of related components and additional symbol representation mechanical lines of action. All components of the circuit are integrated to the real structure in the plan in approximately true.
  • The circuit diagram to distinguish sometimes called " circuit diagram in resolution representation " - represents the circuit strictly according to the individual current traversal sequence of the components represents the active connection is obtained by tracking the alphanumeric labels of related parts ( signal name ), allowing multiple pages to display a device used can. In circuit diagrams electrical engineering, the outer conductor, neutral conductor and protective conductor of the main supply lines usually run horizontally at the top and bottom of the whole drawing. In between, the individual current paths are drawn. The circuit diagram then often several meters long resolution can then be divided into sections with specific assemblies ( motor circuits, control circuits, lighting, etc. ).
  • The overview diagram is a variant of the circuit diagram, in which, among other parallel lines with the same components result summarized graphically to " one-dimensional " representation, the number of parallel strands is marked by dashes or numbers. This is especially for circuits with many three - to five -pole AC lines or parallel data buses of the case. Electronic circuits can be combined function blocks ( block diagram ).
  • The installation plan is similar to the general plan, except that in addition to rendering the wiring even pieces of furniture, doors and windows of the room to be developed are shown in the installation diagram.
  • A single phase diagram is a simplified form of the circuit diagram which is used primarily in the area of ​​electrical power engineering such as power plant construction. In Einliniendiagrammen are circuits, and multi-phase circuits, reduced to simple lines, giving a rough overview allowed.

Laws and standards

  • DIN EN 60617 Graphical symbols for diagrams
  • DIN EN 61355 Classification and designation of documents for plants, systems and equipment