Reading circuit diagrams correctly

Learning to understand electrical circuits: Practical tips for reading circuit diagrams.

Reading circuit diagrams correctly
Symbols and terms on circuit diagrams
How to read wiring diagrams correctly

Circuit diagrams represent circuits graphically using symbols and designations. Electronic circuit diagrams can be both simple and complex with a large number of pages. Sometimes the circuit diagram corresponds to a circuit diagram, which is considered in more detail in this guide. In many other cases, however, the term circuit diagram has a slightly different meaning, which makes it necessary to be able to read and understand electrical circuit diagrams correctly. This is the only way to avoid serious mistakes during installation. The word ‘circuit diagram’ is often a collective term that encompasses various diagrams. Types of circuit diagrams are, for example, the installation diagram, the overview diagram and the circuit diagram. They each have different functions, which are also explained later in this guide. What can you find in circuit diagrams? How can they be read easily and correctly? What are the differences between the various types of circuit diagrams? In the following article, we answer these and many other basic questions about circuit diagrams.

Why it is important to be able to read circuit diagrams correctly

Circuit diagrams exist for all types of electrical systems: for example, for the electrical supply in houses, for vehicle electronics and electronic production machines. Being able to read a circuit diagram can help to set up, reproduce, repair or add to an electrical system. The function of the circuit diagram in the construction of an electrical system as well as in repairs and additions can be easily explained using the electrical installation in houses and flats.

For the new installation of an electrical system, the plans show anyone who can read them the intended position of switches, lamps and sockets, as well as the type of circuit. For example, alternating or cross circuits, the type of cable and the connection of the equipment to the power supply. In this case, they are the instructions on how to set up the electrical installation in the new building.

They also help to quickly record the circuits during repairs and extensions to the electrical installation of existing buildings. In this way, they can help to ensure that electrical components are added according to plan and that repairs are completed without errors and in the shortest possible time. Being able to read a circuit diagram is of course important for professionals. But it can also be useful for non-professionals when it comes to appliances or domestic installations. They can then better understand what the experts are suggesting and, if necessary, have a dialogue with the specialists on an equal footing.

Basics: What symbols and terms can be found on circuit diagrams?

If you want to read a circuit diagram, you should first get an overview of the rules that apply to the electrical engineering symbols and labelling on the diagram or diagrams. This is important for complex circuit diagrams that consist of many individual documents: Firstly, you should get an overview of what is available. If there are reading rules, they should be the first thing you look at.

In the case of complex switching systems, the individual parts of the circuit diagram together provide a complete picture of an electrical system. The circuit diagram then often begins with a cover sheet, a table of contents and reading rules. This is followed by parts such as an overview circuit diagram and a circuit diagram, whereby the specific composition of the circuit diagrams differs from case to case, depending on the type and size of the electrical system to be represented.

With this basic knowledge, you can tackle the less complex diagrams and then gradually move on to the more complex ones. This means: First come plans such as the installation or overview circuit diagram, then the circuit diagram

Tips and tricks for reading circuit diagrams

Complex circuit diagrams in particular can quickly seem overwhelming when you see them in their entirety. In this case, you should go into detail and follow the circuit diagram so that you can understand the circuit diagram piece by piece in order to be able to read and understand electrical circuit diagrams at the end.

What symbols and terms can be found on wiring diagrams?

Circuit symbols for wiring diagrams are available for typical electrical components such as switches, diodes and resistors, but also for household appliances such as washing machines, ovens and freezers. The latter are particularly important for installation plans to show the positioning of individual appliances in rooms in a property. Symbols can vary depending on the type of wiring diagram.

Important circuit symbols for electronic components are, for example:

Step-by-step guide: How do you read a circuit diagram correctly?

Signs and labelling are particularly important for the legibility of circuit diagrams, as they need to be understood by people working with the diagrams. For this reason, standards that standardise the symbols and labelling of circuit diagrams as far as possible are crucial. The following standards are among the most important standards that contribute to being able to read a circuit diagram:

DIN EN 60617

DIN EN 60617 standardises graphic symbols in circuit diagrams. This means that on circuit diagrams that are based on this standard, components are symbolised with the symbols specified in the standard.

DIN EN 81346-2

DIN EN 81346-2 is the successor to DIN EN 61346-2 and defines how electrical components in circuits are labelled. In both standards, for example, an ‘R’ stands for resistors and an ‘S’ for switches.But there are also differences. Lamps are labelled ‘H’ in the old standard and ‘E’ in the new one.

DIN EN 61082

This standard contains rules on how information should be presented in documents. There are special rules for circuit diagrams, tables and drawings in electrical engineering. The standard regulates, for example, the presentation of electrical connections.

DIN EN 61355

It formulates rules for the ‘Classification and labelling of documents for installations, systems and equipment’. For example, the labelling of an all-pole circuit diagram from electrical engineering begins with the letter combination ‘EFS’. ‘E’ stands for electrical engineering, “F” for “function-describing documents” and “S” for “circuit documents”.

IEC 60757 and VDE 0100-510

The two standards IEC 60757 and VDE 0100-510 deal with the colour coding of cables. While VDE 0100-510 specifies which colours should be used for which cables, IEC 60757 defines abbreviations for colours in electrical engineering. ‘BN’ stands for blue, for example. But beware: The VDE 0100-510 standard does not apply to all applications. For example, DIN 72551 is used for cable colours in motor vehicles, although this standard is not binding for car manufacturers.

Of course, not every wiring diagram worldwide complies with the standards listed here. If you want to read a wiring diagram from the USA, for example, you will most likely be confronted with characters from the ANSI standard Y32 (IEEE Standard 315). They differ from the European standards. One example of this is the characters for resistors:

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