Symbols in electrical circuits: decoding graphics and alphanumeric characters

Reading electrical drawings requires certain knowledge, which can be gleaned from regulatory documents. A unique “language” for reading is the symbols in electrical circuits – a system of signs and symbols, mainly graphic and alphabetic. In addition to them, denominations are sometimes indicated in numbers.

Agree, understanding standard designations is simply necessary for any home master. This knowledge will help you read an electrical diagram and independently draw up a wiring plan in an apartment or private house. We offer you to understand all the intricacies of writing project documentation.

The article describes the main types of electrical circuits, and also provides a detailed explanation of the basic images, symbols, icons and alphanumeric markers used in drawing up drawings for the electrical network.

What types of electrical circuits might be useful?

Let's consider the design information from the point of view of an amateur electrician who wants to change the wiring in the house with his own hands or draw up a drawing for connecting the dacha to electrical communications.

First you need to understand what knowledge will be useful and what will not be needed. First step – this is an introduction to the species electrical diagrams.

Shield diagram using real images of switching and protective devices - electrical connections are depicted with colored wires. In fact, it has nothing to do with the professional documentation that accompanies home energy supply projects

All information about the types of circuits is presented in the new edition of GOST 2.702-2011, which is called “ESKD. Rules for the execution of electrical circuits."

This is a duplicate of an earlier document – GOST 2.701-2008, which talks in detail about the classification of circuits. There are 10 types in total, but in practice only one may be needed – electric.

In addition to the type classification, there is also a standard one, which divides all drawing documents into structural, general, etc., with a total of 8 points.

The home craftsman will be interested in 3 types of diagrams: functional, schematic, installation.

Type #1 - functional diagram

The functional diagram does not contain details; it indicates the main blocks and assemblies. It gives a general idea of ​​how the system works. For the electrical supply of a private home, it does not always make sense to draw up such drawings, since they are usually standard.

But when describing a complex electronic device or for equipping a workshop, studio or control room with electrical equipment, they can be useful.

Sample functional diagram. It contains a minimum of symbols. All information is presented in blocks with captions - names of devices. From the drawing you can understand how the elements are connected to each other

Type #2 - circuit diagram

Schematic diagram, as opposed to functional – This is a set of symbols, without knowledge of which it is difficult to understand the structure of the network as a whole.The drawing indicates all devices and connections between them. If the circuit is complex, containing, for example, redundant circuits, then operators use operational circuits that give an idea of ​​“the current situation of switching devices.”

If you need to reflect only power lines, it is enough to draw a linear diagram, but to depict all types of circuits with monitoring and control devices you will need a complete one.

A variant of a schematic diagram for the power supply of a house with the designation of sockets, switches, connector for connecting an electric stove, a bell and its button, lamps, automatic fuses

Type #3 - wiring diagram

Wiring diagram – a document that is convenient to use when installing networks. Using it you can find out which devices should be connected, where exactly and how far from each other they are located.

The location of elements such as switches and sockets, lamps, circuit breakers. You can set the values ​​and lengths of the circuits directly in the diagram.

A sample of a primitive, but clear and readable wiring diagram for the electrical wiring of a private house, which you can create yourself using a limited set of symbols

Requirements for all types of schematic documentation are set out in GOST 2.702-2011, this is what you should be guided by in the future when drawing up your own projects.

Here you can also find full links to other useful documents, which contain tables of graphic and letter symbols of various elements used in electrical circuits, as well as rules for their use.

Graphic images in electrical circuits

An electrical network drawing is a set of graphic elements that together form an inextricable system. In practice, this is a set of devices connected by wires.

Most of the notation – graphic. Letters and numbers are used to symbolically designate individual elements, their denominations and distances between objects.

Main base images

Electrical circuits lead to devices and installations that are equipped with contacts that can break or connect these circuits.

The simplest example – ordinary switch. All contacts are divided into make, break and switch contacts – These are the ones that are displayed in the diagrams.

To depict the switching devices included in the electrical system, 4 main symbols are used. In addition to the function of switching from one circuit to another, the 3-position changeover contact also has a neutral position

The functions of the contacts are also indicated by symbols, which are indicated in the diagrams. They are divided into two groups: the functions of moving contacts - there are only two of them, and the functions of fixed contacts - seven more (+)

The listed graphic images are mandatory when drawing up circuit diagrams and are usually understandable even to a novice electrician.

Single Line Diagram Symbolism

Drawings are also used to assemble electrical panels. They are usually a single line diagram labeled RCD, circuit breakers, contactors and other protective equipment.

Some graphic symbols are similar to each other, so special attention is required when drawing up a diagram. For example, a contactor and a switch are designated the same, the difference is in a small element on the fixed contact.

Graphics for single line diagrams used in electrical panel assembly. It is not necessary that all symbols must be present on a specific diagram - the drawing depends on the “filling” of the shield, the need for certain devices (+)

Relay coils are designated by special symbols – All images use a rectangle as a basis.

Small graphic elements printed outside or inside the rectangles distinguish the coils of various relays - contactor, photo, time or pulse (+)

To remember icons, associations or alphabetic clues are often used. For example, a motor drive is represented by a circle with the letter “M” inside it.

Diagram of symbols for measuring instruments (voltmeter, ammeter, etc.), connections (sockets, terminal blocks) and associated elements - two types of light bulbs, a motor, a heating element (+)

When drawing up a diagram, it should be borne in mind that quantity is also important for designating some symbols.

For example, if you need to indicate a 4-pin terminal block, then you should draw four crossed out circles in a row, and not one. Paired checkmarks when depicting sockets – this is the number of wires.

How are tires and wires depicted?

For tire designations, cables and wires line graphics are used – Almost all symbols consist of straight lines.

Conductor connections are indicated by dots. If there is no mark at the junction of two lines, then this is a simple intersection.

Symbols for wires, cables, buses, mergers and intersections of two (possibly more) lines, branches. There is also a separate icon for the protective conductor

Wires vary in type, purpose, load, and installation method. All this can also be shown schematically.

Table of designations for various current-carrying lines. Using additional notes, you can indicate the number of conductors in one cable, the voltage in the circuit, the material of the wire, etc. (+)

Additional characteristics facilitate the selection of materials and installation of the electrical network. In the future, thanks to the characteristics indicated in the diagram, one can judge the potential capabilities of the already installed electrical system.

Sockets and switches on diagrams

The designation of switches is divided into several groups – By degree of protection, installation method (hidden or open). There are separate switches for two directions. 2- and 3-gang switches are designated differently.

Some light source control devices are not labeled, such as push-button devices and dimmers.

Schematic representation of switches and switches. The icons are easy to remember. For example, devices with protection IP44 or more are distinguished by a filled circle, and all “open” modifications resemble keys (+)

Nowadays, to save energy in large rooms, it is often install pass-through switches, which are controlled from 2 or 3 points. You can also find corresponding icons for them.

Sockets, like switches, are divided into groups according to the degree of protection. Within groups, devices are divided by the number of poles and the presence of protection. To designate blocks, alphanumeric signatures are used, indicating the number and purpose of installations in one block.

Schematic representation of different types of sockets - hidden (built-in) and open (surface).Like switches, installations with IP44 protection are indicated by shaded symbols (+)

When memorizing the designations of various electrical elements on the diagrams, each conventionally depicted device should be correlated with a real product.

For example, popular types of sockets look like this:

Now the most popular are hidden type devices with grounding. External devices are usually installed where it is not recommended to install hidden wiring, that is, in wooden buildings (+)

In reality, electrical installation devices look like this:

Switches and sockets – These are some of the most “in demand” elements in circuits for home use, so they should be remembered first. Read more about the designation of such devices in drawings and diagrams in this article.

Designation of light sources

Separate symbols are also provided for different types of lamps and fixtures. Conveniently, there are special icons for LED and fluorescent light bulbs.

Table of symbols for light sources. Linear and slot devices have a rectangular shape, the rest are round or close to it. There are special symbols for cartridges

Standard images of various types of lamps are often used to draw up installation diagrams.

If you use the same symbols, you will have to include additional clarifications, but with standard symbols you can draw a diagram much faster.

Elements for drawing up electrical circuit diagrams

The basic symbols for circuit diagrams differ little, but in addition to them there are also special symbols for designating all kinds of radio elements: thyristors, resistors, diodes, etc.

Conventions for drawing up or reading electrical circuit diagrams. In addition to graphic symbols, alphanumeric markings can be used if it is necessary to indicate the characteristics of the elements (+)

There are separate symbols for radio devices, but they are usually not required when designing a home electrical network.

Letter designations on electrical circuits

To provide more complete information about the device, it is signed with an abbreviated letter designation. Number of letters – 2 or 3. Sometimes the letter designation turns into an alphanumeric one if you put the device serial number next to it.

Table of designations of schematic elements in international format. A distinctive feature is that the letters are written in Latin. By the designations you can determine the device, the number of identical elements, the connection between them (+)

Along with international ones, there are also Russian standards. They are listed in GOST 7624-55, but this document is declared invalid.

The article does not provide information about all symbols. Complete materials on graphic symbols can be found in GOST 2.709-89, 2.721-74, 2.755-87.

Conclusions and useful video on the topic

From the drawing – to the circuit diagram:

Example of reading electrical circuit diagrams (part 1):

Continuation, or rather, part 2 about the intricacies of reading electrical circuit diagrams (part 2):

Details about creating your own diagrams:

Knowledge of reading and drawing electrical diagrams can be useful for installation work on home improvement and for repairing electrical appliances. There is no point in inventing your own symbols when there is a professional system of symbols, which is not so difficult to learn.

Do you have anything to add, or do you have questions about drawing up and reading electrical diagrams? You can leave comments on the publication, participate in discussions and share your own experience in developing drawings. The contact form is located in the lower block.