Symbols on electrical diagrams according to GOST: alphabetic, graphic

To understand what is specifically drawn on a diagram or drawing, you need to know the decoding of those icons that are on it. This recognition is also called drawing reading. And to facilitate this lesson, almost all elements have their own conventional icons. Almost, because the standards have not been updated for a long time and some elements are drawn by everyone as best they can. But, for the most part, symbols in electrical circuits are in regulatory documents.

Normative base

There are about a dozen varieties of electrical circuits, the number of different elements that can be found there is in the tens, if not hundreds. To facilitate the recognition of these elements, uniform symbols have been introduced in electrical circuits. All rules are written in GOSTs. There are a lot of these standards, but the main information is in the following standards:

Studying GOSTs is a useful thing, but it takes time, which not everyone has enough of. Therefore, in the article we present symbols in electrical circuits – the main element base for creating drawings and wiring diagrams, circuit diagrams of devices.

Designation of electrical elements on the diagrams

Some experts, having carefully looked at the circuit, can say what it is and how it works. Some may even immediately give out possible problems that may arise during operation. It’s simple – they know the circuitry and the element base well, and are also well versed in the symbols of the circuit elements. Such a skill has been developed over the years, and, for “dummies”, it is important to remember the most common ones to begin with.

Electrical panels, cabinets, boxes

On the power supply diagrams of a house or apartment, there will necessarily be a designation of an electrical panel or cabinet. In apartments, the terminal device is mainly installed there, since the wiring does not go further. In houses, they can design the installation of a branching electrical cabinet – if a route goes from it to illuminate other buildings located at some distance from the house – a bathhouse, a summer kitchen, a guest house. These other designations are in the next picture.

If we talk about images of the “stuffing” of electrical panels, it is also standardized. There are symbols for RCDs, circuit breakers, buttons, current and voltage transformers, and some other elements. They are shown in the following table (there are two pages in the table, scroll by clicking on the word “Next”)

Element base for wiring diagrams

When drawing up or reading a diagram, the designations of wires, terminals, grounding, zero, etc. will also come in handy. This is what a novice electrician simply needs or in order to understand what is shown in the drawing and in what sequence its elements are connected.

An example of the use of the above graphics is in the following diagram. Thanks to the letter designations, everything is clear even without graphics, but duplication of information in the diagrams has never been superfluous.

Picture of sockets

On the wiring diagram, the installation locations of sockets and switches should be marked. There are many types of sockets – for 220 V, for 380 V, hidden and open type of installation, with a different number of “seats”, waterproof, etc. To give the designation of each is too long and useless. It is important to remember how the main groups are depicted, and the number of contact groups is determined by the strokes.

Sockets for a single-phase 220 V network are indicated on the diagrams in the form of a semicircle with one or more segments sticking up. The number of segments is the number of sockets on one housing (illustrated in the photo below). If only one plug can be plugged into the outlet, one segment is drawn up, if two, two, etc.

If you look at the images closely, notice that the symbolic image on the right does not have the horizontal bar that separates the two halves of the icon. This feature indicates that the socket is flush-mounted, that is, it is necessary to make a hole in the wall under it, install a socket box, etc. The option on the right is for surface mounting. A non-conductive substrate is attached to the wall, and the socket itself is attached to it.

Also note that the bottom of the left schematic is crossed out with a vertical line. This indicates the presence of a protective contact, to which grounding is applied. The installation of sockets with grounding is mandatory when turning on complex household appliances such as a washing machine or dishwasher, oven, etc.

You can’t confuse the symbol of a three-phase socket (for 380 V) with anything. The number of segments sticking up is equal to the number of conductors that are connected to this device – three phases, zero and ground. Total five.

It happens that the lower part of the image is painted over with black (dark). This means that the outlet is waterproof. These are placed on the street, in rooms with high humidity (baths, pools, etc.).

Switch display

The schematic designation of switches looks like a small circle with one or more L- or T-shaped branches. Branches in the form of the letter “G” designate an open-mounted switch, with the form of the letter “T” – flush-mounted. The number of taps displays the number of keys on this device.

In addition to the usual ones, there may be walk-through switches – for the possibility of turning on / off one light source from several points. Two letters “G” are added to the same small circle from opposite sides. This is the designation of a single-key pass-through switch.

Unlike conventional switches, in these, when using two-button models, one more bar is added parallel to the top one.

Lamps and fixtures

Lamps have their own designations. Moreover, fluorescent lamps (fluorescent) and incandescent lamps differ. The diagrams even show the shape and size of the fixtures. In this case, you just need to remember how each type of lamp looks on the diagram.

Radioelements

When reading circuit diagrams of devices, you need to know the symbols for diodes, resistors, and other similar elements.

Knowing the conditional graphic elements will help you read almost any diagram – some kind of device or electrical wiring. The ratings of the required parts are sometimes affixed next to the image, but in large multi-element diagrams they are written in a separate table. It contains the letter designations of the circuit elements and the denominations.

Letter symbols

In addition to the fact that the elements on the diagrams have conditional graphic names, they have letter designations, which are also standardized (GOST 7624-55).

Please note that in most cases Russian letters are used, but the resistor, capacitor and inductor are indicated in Latin letters.

There is one subtlety in the designation of the relay. They are of different types, respectively marked:

• current relay – RT;
• power – RM;
• voltage – PH;
• time – RV;
• resistance – RS;
• index – RU;
• intermediate – RP;
• gas – RG;
• with time delay – RTV.

Basically, these are only the most conventional symbols in electrical circuits. But most of the drawings and plans you can now understand. If you need to know images of rarer elements, study GOSTs.