Cable cross-section. How to choose it correctly. Calculation of cable cross-section by diameter How to calculate which cable is needed

Replacing wiring in an apartment or house is a responsible process that requires competent installation work and the correct selection of electrical devices and consumables.

The main load falls on the sockets to which powerful household electrical appliances are connected. The question arises: what cross-section should the wire for sockets be? The diameter must be such that the cable can withstand the current load and does not overheat during operation of volatile equipment.

Features of installation of sockets

Repair work to replace electrical wiring must be carried out in accordance with the Rules for the operation of electrical installations. To independently install current-carrying conductors, you need to have basic experience in carrying out such work.

Installation of sockets for domestic use must comply with the following conditions:

  1. Several machines are connected from the electricity consumption meter - one for each room of the apartment or house.
  2. The machines should switch off the power supply in case of network overload, short circuit or other troubles.
  3. Each room in an apartment or house must be served by a separate distribution box and a circuit breaker.
  4. You cannot combine loaded socket groups and lighting wires into one network.
  5. The cross-section of the wire for the socket is selected depending on the power of the electrical appliances that are planned to be connected to the network.
  6. It is recommended to use copper rather than aluminum conductors for household needs, as they have a longer service life.
  7. The cross-sectional diameter of the cable for the socket must be 2.5 mm2, provided that the total power consumption of electrical appliances does not exceed 3 kW.
  8. In the kitchen, for sockets into which powerful household appliances are connected, choose a cable with a cross-section of 6 mm2 - the best option, but not less than 4 mm2, capable of withstanding heavy loads.

If only low-power devices are connected to the network in the room, you can lay a cable with a cross-section of 1.5 mm2 for the socket. But this is the minimum permissible value, therefore, if absolutely necessary, it is unsafe to plug a powerful device into such an outlet - the wire will become very hot.

Cable characteristics

In residential premises, two-core and three-core wires are mainly used for wiring installation. The former are suitable for sockets without grounding, the latter - for sockets with grounding. To organize lighting, a wire with a cross-section of 1.5 mm2 is sufficient.

The most commonly used types of cables are:

  1. VVG and VVG non-flammable - power wire that can operate in networks with voltages of 220 and 380 V. VVG stands for “vinyl-vinyl-naked” cable, that is, polyvinyl chloride plastic is used as sheath and insulation, and stranded as the conductor copper conductor. Wire cross-section - from 1.5 to 50 mm2 for 1, 2, 3, 4 wires and from 1.5 to 25 mm2 for five- and six-core conductors.
  2. PVA is a cable made of twisted copper conductors in a vinyl sheath, the insulation of which is made using polyvinyl chloride resin. It has good flexibility, corrosion resistance, and impeccable performance characteristics. Suitable for organizing wiring from a distribution box in residential premises, connecting sockets for electrical appliances. The number of current-carrying cores is 2 – 5, cross-section is 0.75 – 2.5 mm2.
  3. NYM is a wire for installation of stationary electrical wiring, manufactured using German technology. The wire structure consists of copper cores, the space between which is filled with a non-flammable non-vulcanized rubber mixture, and the conductor sheath is made of non-flammable polyvinyl chloride plastic compound. The power cable operates in networks with voltages up to 660 V at a current frequency of 50 Hz. Cable design - 2, 3, 4, 5 cores, cross-section - from 1.5 to 70 mm2.

What cross-section should the wire be for sockets in residential premises? For household wiring, when connecting sockets, it is rational to use a two- and three-core copper conductor with a cross-section of 2.5 - 6 mm2, the current-carrying parts of which are isolated from each other and protected by an outer sheath of non-flammable polyvinyl chloride.

Conductor power calculation

All energy-dependent devices used in everyday life differ in their power consumption. The main rule for organizing electrical wiring is to calculate the total power of equipment and lighting in order to select the appropriate input cable.

The table below shows the average power of household electrical appliances. Based on it, you can determine the load on the wiring in each room.

Electrical installation name Average power consumption, W
Toaster 800 – 1200
Coffee maker 1000
Electric kettle 1200
Oven, oven 1200 – 2000
Electric stove 2500 – 3000
Fridge 400 – 600
Microwave 1400 – 1800
Computer 500 – 550
Printer 500
TV 200 – 300
Iron 1000 – 1700
Hairdryer 1000 – 1200
Vacuum cleaner 1000 – 1600
Air conditioner 1500
Fan 1000
Heating tank 1500
Water pump 1000
Washing machine 2500
Lighting 2000

It should be taken into account that, as necessary, construction electrical appliances, welding, compressor, pumping and generating equipment can be connected to the network.


Maximum cable length and cross-section depending on power

The total power of the devices is multiplied by a factor of 0.75 and the value that the input cable must correspond to is obtained. The power of devices for each room is calculated in the same way.

When choosing a cable cross-section, they proceed from the technical characteristics - diameter, voltage, current, power. The characteristics of the copper power cable when installing hidden and exposed wiring for sockets are as follows:

Hidden wiring
Section, mm2 Current, A At a voltage of 220 V At a voltage of 380 V
1,0 14 3,0 5,3
1,5 15 3,3 5,7
2,5 21 4,6 7,9
4,0 27 5,9 10,0
6,0 34 7,4 12,0
10,0 50 11,0 19,0
16,0 80 17,0 30,0
25,0 100 22,0 38,0
Open wiring
Section, mm2 Current, A At a voltage of 220 V At a voltage of 380 V
0,5 11 2,4 –
0,75 15 3,3 –
1,0 17 3,7 6,4
1,5 23 5,0 8,7
2,5 30 6,6 11,0
4,0 41 9,0 15,0
6,0 50 11,0 19,0
10,0 80 17,0 30,0
16,0 100 22,0 38,0
25,0 140 30,0 53,0

You definitely need to pay attention to the brand of cable and the number of cores - the conductors are designed for different loads in the network. So, for example, a three-core VVG wire with a cross-section of 2.5 mm2 can withstand a current of 21 A, a PVS cable with three cores of the same cross-section operates at a load of up to 27 A, and a NYM power wire with three cores with a cross-section of 2.5 mm2 can be operated at current load up to 30 A.

When installing sockets, two options for laying current-carrying conductors are used - hidden and open wiring to the distribution box. Installation of hidden conductors is carried out in grooves on non-combustible bases - walls made of brick, cement.

Note! The cable is laid in the groove strictly perpendicular to the horizon line and led to the distribution box only at a right angle.

Open installation is carried out by placing the power wire in a cable duct or protective sleeve, corrugation, or baseboard to prevent the fire of fire-hazardous structures or damage to the conductors.

After choosing the cable cross-section, take into account the basic rules for laying wires when installing sockets:

  1. For hidden installation, the groove depth is at least 20 mm.
  2. Horizontal cable turns are performed at a height of 2500 mm from the floor.
  3. Open installation on flammable substrates is prohibited without laying the wire in a sleeve.
  4. Using a machine for each room is a prerequisite for installation.
  5. When choosing a power cable for sockets, they are guided not only by the cross-section and number of cores, but also by the diameter of the wire with winding in order to place it in a groove or cable channel.

Self-installation of sockets is carried out only after the room has been de-energized.

Residual shutdown devices must correspond to the power of electrical installations. This allows us to eliminate situations when, when several powerful devices are turned on, the machine is triggered as a result of exceeding the current strength in a specific section of the electrical circuit.

If you decide to independently replace or repair the electrical wiring installed around the house, you first need to answer the question: what cross-section of wire will be needed to perform this work efficiently. A properly selected cable will not only serve you for many years, but will also protect you from a lot of problems, the main one of which may be overheating of the wiring and, as a result, a short circuit or fire.

The choice of conductor material and cross-section can be done in two ways. The first is “by eye”, which is used by most home electricians, and which comes down to an arbitrary choice of electrical wire without taking into account the expected load, current consumption and other factors. The second is scientific, which is based on mathematical calculations based on electrical engineering data. Each metal used as an electrical wire has its own specific characteristics, and in order to make high-quality calculations, you need to know them. So, in a copper wire with a cross-section of 1 millimeter, the current density varies within 6-10 amperes, and in aluminum – 4-6 amperes. As the cross-sectional area increases, the throughput also increases. It is highly not recommended to exceed these figures, since the wires are not designed for high current and may not withstand the load. So, to determine the cable cross-section by power, calculate the total total power of all electrical appliances that will be connected to the network along one line. The calculation must be carried out with a reserve; to do this, multiply the resulting amount by the so-called simultaneity coefficient - 1.2. Then it is necessary to calculate the current strength sufficient to operate the devices. To do this, divide the resulting total power by your network voltage (usually 220 volts). Having received the desired value, you can easily select the wire of the required cross-section according to the table below of electrical installation rules. Calculating the cable cross-section by current strength is much simpler. You just need to look at the special table in order to make the right choice. But it should be remembered that this method has its own peculiarity - the cross-section of the cable in hidden wiring should be slightly larger than in open wiring. This is due to the fact that, when under load without air access, the cable will heat up more.


Despite the fact that you have calculated the cross-section of the wire mathematically, taking into account all the nuances and laws of electrophysics, do not forget to install a circuit breaker on the line, which, in case of excessive load, will turn off the electricity and keep you and your home safe. In addition, due to the low carrying capacity and susceptibility to breakage, it is recommended to refrain from using aluminum wires and replace them with copper ones.

In conclusion, I would like to note that, as a general rule, it is recommended to use a three-core wire, one of the wires of which will be used for grounding. Knowing this and the above information, you can easily choose a cable that can withstand the load of all electrical appliances used in your home.

Comfort and safety in the home depends on the correct choice of electrical wiring cross-section. When overloaded, the conductor overheats and the insulation may melt, causing a fire or short circuit. But it is not profitable to take a cross-section larger than necessary, since the price of the cable increases.

In general, it is calculated depending on the number of consumers, for which they first determine the total power used by the apartment, and then multiply the result by 0.75. The PUE uses a table of loads along the cable cross-section. From it you can easily determine the diameter of the cores, which depends on the material and the passing current. As a rule, copper conductors are used.

The cross-section of the cable core must correspond exactly to the calculated one - in the direction of increasing the standard size range. It is most dangerous when it is underestimated. Then the conductor constantly overheats, and the insulation quickly fails. And if you install the appropriate one, it will trigger frequently.

If the wire cross-section is increased, it will cost more. Although a certain reserve is necessary, since in the future, as a rule, it is necessary to connect new equipment. It is advisable to use a safety factor of about 1.5.

Calculation of total power

The total power consumed by the apartment falls on the main input, which enters the distribution board, and after it branches into the lines:

  • lighting;
  • groups of sockets;
  • individual powerful electrical appliances.

Therefore, the largest cross-section of the power cable is at the input. On outlet lines it decreases, depending on the load. First of all, the total power of all loads is determined. This is not difficult, since it is indicated on the housings of all household appliances and in their passports.

All powers add up. Calculations are made similarly for each circuit. Experts suggest multiplying the amount by 0.75. This is explained by the fact that all devices are not connected to the network at the same time. Others suggest choosing a larger section. Due to this, a reserve is created for the subsequent commissioning of additional electrical devices that may be purchased in the future. It should be noted that this cable calculation option is more reliable.

How to determine the wire cross-section?

All calculations include the cable cross-section. It is easier to determine it by diameter if you use the formulas:

  • S=π D²/4;
  • D= √(4×S/π).

Where π = 3.14.

S = N×D²/1.27.

Stranded wires are used where flexibility is required. Cheaper solid conductors are used for permanent installations.

How to choose a cable based on power?

In order to select wiring, use the load table for the cable cross-section:

  • If the open type line is energized at 220 V, and the total power is 4 kW, a copper conductor with a cross section of 1.5 mm² is taken. This size is usually used for lighting wiring.
  • With a power of 6 kW, conductors of a larger cross-section are required - 2.5 mm². The wire is used for sockets to which household appliances are connected.
  • A power of 10 kW requires the use of 6 mm² wiring. It is usually intended for the kitchen, where an electric stove is connected. The supply to such a load is made through a separate line.

Which cables are better?

Electricians are well aware of the cable of the German brand NUM for office and residential premises. In Russia they produce brands of cables that have lower characteristics, although they may have the same name. They can be distinguished by compound leaks in the space between the cores or by its absence.

The wire is produced monolithic and multi-wire. Each core, as well as all twisting, is insulated on the outside with PVC, and the filler between them is non-flammable:

  • Thus, the NUM cable is used indoors, since the insulation outdoors is destroyed by sunlight.
  • And as an internal cable, VVG brand cable is widely used. It is cheap and quite reliable. It is not recommended to use it for laying in the ground.
  • VVG brand wire is made flat and round. No filler is used between the cores.
  • made with an outer shell that does not support combustion. The cores are manufactured round up to a cross-section of 16 mm², and above - sector.
  • The PVS and ShVVP cable brands are made multi-wire and are used primarily for connecting household appliances. It is often used as home electrical wiring. It is not recommended to use multi-wire conductors outdoors due to corrosion. In addition, bending insulation will crack at low temperatures.
  • On the street, armored and moisture-resistant cables AVBShv and VBShv are laid underground. The armor is made of two steel strips, which increases the reliability of the cable and makes it resistant to mechanical stress.

Determination of current load

A more accurate result is obtained by calculating the cable cross-section by power and current, where the geometric parameters are related to the electrical ones.

For home wiring, not only the active load must be taken into account, but also the reactive load. The current strength is determined by the formula:

I = P/(U∙cosφ).

The reactive load is created by fluorescent lamps and motors of electrical appliances (refrigerator, vacuum cleaner, power tools, etc.).

Current example

Let's find out what to do if it is necessary to determine the cross-section of a copper cable for connecting household appliances with a total power of 25 kW and three-phase machines with a capacity of 10 kW. This connection is made with a five-core cable laid in the ground. The food at home comes from

Taking into account the reactive component, the power of household appliances and equipment will be:

  • P everyday life = 25/0.7 = 35.7 kW;
  • P rev. = 10/0.7 = 14.3 kW.

The input currents are determined:

  • I life = 35.7 × 1000/220 = 162 A;
  • I rev. = 14.3×1000/380 = 38 A.

If single-phase loads are distributed evenly across three phases, one will carry the current:

I f = 162/3 = 54 A.

I f = 54 + 38 = 92 A.

All equipment will not work at the same time. Taking into account the reserve, each phase accounts for the current:

I f = 92×0.75×1.5 = 103.5 A.

In a five-core cable, only the phase conductors are taken into account. For a cable laid in the ground, you can determine a core cross-section of 16 mm² for a current of 103.5 A (table of loads by cable cross-section).

Refined calculation of current allows you to save money, since a smaller cross-section is required. With a rougher calculation of cable power, the core cross-section will be 25 mm², which will cost more.

Cable voltage drop

Conductors have resistance that must be taken into account. This is especially important for long cable lengths or small cross-sections. PES standards have been established, according to which the voltage drop on the cable should not exceed 5%. The calculation is done as follows.

  1. The conductor resistance is determined: R = 2×(ρ×L)/S.
  2. Voltage drop is found: U pad. = I×R. In relation to the linear percentage, it will be: U % = (U falling / U linear) × 100.

The following notations are used in the formulas:

  • ρ - resistivity, Ohm×mm²/m;
  • S - cross-sectional area, mm².

Coefficient 2 shows that current flows through two wires.

Example of cable calculation based on voltage drop

  • The wire resistance is: R = 2(0.0175×20)/2.5 = 0.28 Ohm.
  • Current strength in the conductor: I = 7000/220 =31.8 A.
  • Voltage drop across carrier: U pad. = 31.8×0.28 = 8.9 V.
  • Voltage drop percentage: U% = (8.9/220)×100 = 4.1 %.

The carrier is suitable for the welding machine in accordance with the requirements of the operating rules for electrical installations, since the percentage of voltage drop across it is within the normal range. However, its value on the supply wire remains large, which can negatively affect the welding process. Here it is necessary to check the lower permissible limit of the supply voltage for the welding machine.

Conclusion

In order to reliably protect electrical wiring from overheating when the rated current is exceeded for a long time, cable cross-sections are calculated based on long-term permissible currents. The calculation is simplified if a load table for the cable cross-section is used. A more accurate result is obtained if the calculation is made based on the maximum current load. And for stable and long-term operation, an automatic switch is installed in the electrical wiring circuit.

The entire life of modern society is built on almost continuous consumption of electricity. Industry and agriculture, transport and personal housing constantly need electricity. In order for energy to flow uninterruptedly and without accidents, it is necessary to correctly calculate the cross-section of the electrical wiring.
Calculate the total length of the electrical wiring. This can be done in two ways: by measuring the distances between panels, sockets, switches on the wiring diagram and multiplying the result by the scale of the diagram, or by taking measurements directly at the place where the electrical wiring will be laid. Since the wires will be connected to each other, make allowances for the connection and lengthen each section by at least 100 mm. Calculate the total load of electricity consumed. To do this, add up the power ratings of all electrical appliances that are currently in use, and think about what other appliances may be used in the future. The calculation must be carried out with a margin of safety and reliability. Multiply the resulting amount by the simultaneity coefficient equal to 0.7.

To prevent accidents on the electrical line, it is necessary to install a circuit breaker on the input cable. In residential premises, single-phase current with a voltage of 220 V is used. Divide the calculated total load by the voltage value (220 V) and get the current that will pass through the input circuit breaker. If there is no machine on sale with this rating, buy one with similar parameters, but with a margin of current load.
Wire size for electrical wiring is calculated based on two parameters: permissible continuous current load and voltage loss. Voltage loss occurs in the wires connecting the current source and the consumer. If you are calculating electrical wiring for a separate room and low-power devices, you can ignore this indicator, since the voltage losses will be negligible.

The cable must be three-core, since one conductor is used for grounding. It is better to choose copper wire because the electrical properties of copper are better than aluminum. Decide what type of electrical installation you will use - closed or open. Now that you know the calculated current, have chosen the cable type and wiring option, find the required wire cross-section in the table.

Calculation of wire and cable cross-section

The material of manufacture and the cross-section of the wires (more correctly, the cross-sectional area of ​​the wires) are, perhaps, the main criteria that should be followed when choosing wires and power cables.

Recall that the cross-sectional area (S) of the cable is calculated by the formula S = (Pi * D2)/4, where Pi is pi equal to 3.14 and D is the diameter.

Why is the correct choice of wire cross-section so important? First of all, because the wires and cables used are the main elements of the electrical wiring of your home or apartment. And it must meet all standards and requirements for reliability and electrical safety.

The main regulatory document regulating the cross-sectional area of ​​electrical wires and cables is the Rules for the Construction of Electrical Installations (PUE). The main indicators that determine the wire cross-section:

The metal from which the conductors are made
Operating voltage, V
Power consumption, kW and current load, A

Thus, incorrectly selected wires that do not correspond to the consumption load can heat up or even burn out, simply not being able to withstand the current load, which cannot but affect the electrical and fire safety of your home. The case is very frequent when, for the sake of economy or for some other reasons, a wire of a smaller cross-section than necessary is used.

When choosing a wire cross-section, you should also not be guided by the saying “you can’t spoil porridge with butter.” The use of wires with a larger cross-section than what is actually needed will only lead to greater material costs (after all, for obvious reasons, their cost will be higher) and will create additional difficulties during installation.

Calculation of cross-sectional area of ​​copper conductors of wires and cables

So, speaking about the electrical wiring of a house or apartment, the optimal use would be: for “outlet” - power groups of copper cable or wire with a core cross-section of 2.5 mm2 and for lighting groups - with a core cross-section of 1.5 mm2. If there are high power appliances in the house, for example. email stoves, ovens, electric hobs, then to power them you should use cables and wires with a cross-section of 4-6 mm2.

The proposed option for choosing cross-sections for wires and cables is probably the most common and popular when installing electrical wiring in apartments and houses. Which, in general, is understandable: copper wires with a cross-section of 1.5 mm2 are capable of “holding” a load of 4.1 kW (current - 19 A), 2.5 mm2 - 5.9 kW (27 A), 4 and 6 mm2 – over 8 and 10 kW. This is quite enough to power outlets, lighting devices or electric stoves. Moreover, such a choice of cross-sections for wires will provide some “reserve” in the event of an increase in load power, for example, when adding new “electrical points”.

Calculation of cross-sectional area of ​​aluminum conductors of wires and cables

When using aluminum wires, it should be borne in mind that the values ​​of the long-term permissible current loads on them are much less than when using copper wires and cables of a similar cross-section. So, for conductors of aluminum wires with a cross-section of 2.mm2, the maximum load is slightly more than 4 kW (current is 22 A), for conductors with a cross-section of 4 mm2 - no more than 6 kW.

Not the last factor in calculating the cross-section of wires and cables is the operating voltage. Thus, with the same power consumption of electrical appliances, the current load on the cores of power cables or wires of electrical appliances designed for a single-phase voltage of 220 V will be higher than for devices operating on a voltage of 380 V.

In general, for a more accurate calculation of the required cross-sections of cable cores and wires, it is necessary to be guided not only by the load power and the material used to make the cores; You should also take into account the method of laying them, length, type of insulation, number of cores in the cable, etc. All these factors are fully defined by the main regulatory document - the Electrical Installation Rules.

Calculation of wires and cables.

Electrical wiring must meet the requirements of safety, reliability and efficiency. Therefore, it is important to correctly calculate the length and cross-section of the wires (cables) necessary for installing electrical wiring.
The length of the wire (cable) is calculated according to the wiring diagram. To do this, measure the distances between adjacent locations of panels, sockets, switches, branch boxes, etc. on the diagram. Then, using the scale in which the diagram is drawn, calculate the length of the cable wire sections; add at least 100 mm to the length of each segment (the need to connect the cores is taken into account).
The length of the wire (cable) can also be calculated by measuring directly on panels, panels, walls, ceilings, etc., the segments of lines along which the wires (cables) should be laid.
The cross-section of the wire (cable) is calculated based on voltage loss and permissible long-term current load. When designing small electrical installations, for example, electrical installations of individual rooms, home-made devices, etc., voltage loss in the wires can be neglected, since it is very small.
To calculate the cross-section of wires based on the permissible long-term current load, it is necessary to know the rated current that must pass through the designed electrical wiring. Knowing the rated current, the wire cross-section is found from the table. Example: rated current is 50 A; the cross-section of the copper wire must be 6 mm2,

An important part of electrical installations is electrical wiring (wiring). It consists of wires and cables with their associated fastenings, support and protective structures.
Open electrical wiring is mounted directly on the surfaces of structural elements of buildings and premises or laid in pipes previously fixed on these surfaces.
Hidden electrical wiring is laid in the voids of floors, in special channels, grooves and grooves pre-cut in the walls, as well as in insulating and steel pipes located inside the structural parts of buildings.
For installation of electrical wiring, installation and assembly wires and cables are used.
The current-carrying part of the wire is called the conductor. The cores are made of copper, aluminum or steel. The core can be single-wire or multi-wire. The cores have standard sections, in mm2: 0.5; 0.75; 1; 1.5; 2.5,; 4; 6; 10; 16; 25; 35; 50; 70; 95; 120; 150; 185; 240; 300; 400, etc.
The cores are covered with an insulating sheath made of rubber, polyvinyl chloride, polyvinyl chloride.
The insulating sheath of many wires is protected from external mechanical influences by a cotton braid.

To convert the cross-section of a wire into a diameter value, I can recommend the program: PL_SECH.exe To work with the program, unpack the zip archive and click on the exe file with the mouse. The program runs in 32-bit DOS & WINDOWS 97/XP/7 systems in a command line session. This page contains this and other useful programs.

calculation of wire cross-section cable + wires How to correctly calculate the wire cross-section for electrical wiring. Processed

Major home renovations necessarily include replacement of electrical wiring. There are two main reasons for this action.

The first is the age of this wiring itself. As a rule, major or any serious repairs are carried out 15-20 years after the apartment is handed over. During this time, even a properly made home electrical network ages and wears out. This means it potentially becomes a source of danger for the inhabitants of the home.

The second reason is the redevelopment and major renovation of individual premises with the addition of new electrical appliances. Tie-ins and other connections of new wiring with old are extremely undesirable. Due to a mismatch in the characteristics of the cable or materials in it.

So, the question of whether to change the electrical wiring is considered resolved; it remains to deal with its practical implementation. And you need to start with choosing a cable.

Cable for electrical wiring in an apartment - 300 brands and 5000 varieties

Which side should we start with? A person who is far from electrical installation will grab his head. And there is something to grab onto. Because there are not just a lot of cables and wires, they literally cannot be counted, like Don Pedro in Brazil. Even professional electricians sometimes get overwhelmed and confused by the abundance of manufacturers and products.

The choice of wire for electrical wiring in an apartment is not only a question of the cost of repairs. A much more important point is that the wiring must ensure the “delivery” of electricity to any corner of the apartment and be safe, that is, not “bite” with current. And also be fire resistant and reliable.

Attention! The key to reliable electrical wiring is finding the right electrician. A specially trained technician must do electrical work and select cables for wiring in an apartment! Who has access to electrical installation work and practical experience.

We will briefly talk about cables and wires, their cross-section, markings, materials and types. We will explain what is suitable for home wiring and what cannot be used. So that you are aware of what your electrician is doing and why.

Characteristics of wires and cables that you should pay attention to when choosing

Let us immediately clarify that we are talking about a household power cable or wire with a voltage of 220/380 V for transmitting electric current in a home network. We are not currently considering all other types such as heating, television, computer and others.

The general list of characteristics looks like this:

  • core material;
  • design;
  • section;
  • thickness of conductor insulation;
  • shell thickness;
  • marking;
  • core color;
  • package;
  • certificate;
  • product condition.

1. Material and design

According to the composition of the vein, cable products are divided into copper and aluminum. Copper products are more reliable, the resistance is lower, the current is higher, and the heating is less when compared with aluminum of the same cross-section. In addition, copper oxidizes less and is more ductile, which means the cable lasts longer without loss of properties and characteristics.

Attention! Wiring aluminum cables in an apartment is prohibited according to the requirements of the PUE (electrical installation rules).

By design single-core (single-wire) and multi-core (multi-wire) cables and wires are produced. Single-core varieties are more rigid and inflexible, especially with a large conductor cross-section.

Answering the question “which wire to use for wiring under plaster,” we can say that theoretically a single-core single-wire copper cable is also suitable. Plaster will create additional protection for such a conductor. But in fact, no one lays a single-wire home electrical network.

Multi-wire single-core cable is softer and more flexible. It tolerates bends and turns well and is suitable for both open wiring and hidden wiring under plaster. It is the three-core single-wire that is now used for laying in apartments.

Attention! Do not confuse cables in which each core consists of one conductor with wires where the core is made of several conductors. Multi-wire cable products are prohibited for permanent installation in an apartment due to the high fire hazard. Read more about them in the block“which wires should not be used for electrical wiring in an apartment”

2. Cable cross-section for wiring in an apartment

It is measured in “squares”, that is, square millimeters and shows the throughput. For a copper cable, one “square” carries 8-10 Amperes of current, for an aluminum cable only 5 A. For safe operation, the conductor should be selected with a reserve of carrying capacity, which ensures heating of the wire within the permissible value, or, more simply, so that it does not “float” under the load. insulation. In addition, with hidden wiring, it must be taken into account that it is cooled less efficiently, which means that the cross-sectional reserve must compensate for this.

Attention! Do not confuse the cable cross-section with its diameter, these are two big differences! The diameter can be measured with a ruler, or better yet, with a caliper. And then substitute it into the formula and calculate the cross-sectional area.

Also remember that the choice of cable for wiring in an apartment is always rounded up. If the calculation results in 2.3 “squares”, a two and a half cable is selected, not two “squares”.

Ideally, the cross-section should match the marking on the cable tag, but in fact it often differs to a smaller extent. Small discrepancies are acceptable because the cable is certified by resistance, not by wire cross-section. If the discrepancies are significant, it is a marriage. An experienced electrician will see it visually, and you can measure the diameter of the core and calculate the cross-section for interest or to help a friend who independently decides to buy a cable for apartment wiring.

Some electricians advise using a cable with a rating higher than the calculated one. For example, 4 “squares”, instead of 2.5, to cover the “shortage” of the section, if there is one. But then you will have to calculate the wiring protection accordingly and install the correct machines and RCDs.

Advice! For electrical wiring in an apartment, we recommend a cross-section of copper wires from 1.5 to 2.5 square meters. mm. Allow two and a half “squares” for sockets and one and a half for lighting.

3. Wire insulation thickness

Each core in a multi-core or single-core cable has insulation made of PVC plastic of the usual type or with reduced flammability; polymers and cross-linked polyethylene are also used. The thickness of the insulation is regulated by GOST standards and it must be sufficient. For household cables (rated voltage up to 660V) with a cross section of 1.5 and 2.5 mm 2 the thickness of the insulating layer according to the standard is 0.6 mm. Deviations are allowed, but the insulation should not be thinner than 0.44 mm.

Simply put, there is a range of thicknesses where the insulation must “fit” so that the wiring serves reliably and there are no problems during installation. Whether the manufacturer violated the technology cannot be determined without a micrometer unless you tinker with the cables every day. Therefore, if there is no experienced electrician nearby, you should only buy cables from well-known brands in trusted stores.

4. Shell thickness

The sheath encloses the cable over the insulated cores, secures them and protects them. It is made, like the core insulation, from PVC plastic or polymer, but is thicker. For multi-core cables, the thickness is 1.8 mm, for single-core cables - 1.4 mm. Deviations in a smaller direction are also possible, but insignificant.

The insulating shell is a mandatory element. For any residential wiring cable, even with minimal power, double insulation is prescribed. That is, first on the core, and then on top of it. This ensures the safety of people and protects the conductor itself from damage.

5. Marking

This is the inscription on the cable sheath for installing electrical wiring in the apartment. It contains all the necessary information for selection. The inscription is printed or extruded during the manufacture of cable products. It should be clear, contrasting, and easily readable.

The labeling indicates:

  • Brand of product (cable or wire), which encodes the main properties and characteristics.
  • Manufacturer's name.
  • Year of issue.
  • Number of cores
  • Section.
  • Voltage rating.

The inscription is applied along the entire length of the conductor at small intervals.

On the price tag and in catalogs of online stores, they usually do not indicate the year of manufacture and manufacturer and write the marking in the form VVGng(ozh)-0.66 kV 3x1.5 or VVG, VVGng cable 3x1.5.

It stands for three-core copper cable with a core cross-section of 1.5 “square” (3x1.5), single-wire core design (ozh). Insulation and sheath made of PVC compound (VV), flexible cable (G), non-flammable (ng). Rated voltage 660 Volts.

Remember! The letter designation of the cable brand begins with the core material; for aluminum the letter A is always used, for copper — the letter is not indicated, therefore all VVG brand cables of all modifications have a copper conductor.

6. Core colors

What you need to know about the color is that it is either a solid color or a stripe is applied to the sheath along the entire cable, approximately a millimeter wide. This is the standard. Everything else, in the form of smudges, spots, stripes across it, is from the evil one. And he says that strange people were making the cable in some basement.

There is a table for the colors of the cores that any experienced electrician knows. It describes what shade the main conductors are denoted by - phase, neutral, grounding. This was done for convenience during installation, in order to see where to connect which conductor. Phase and working conductors may differ in color, but the “ground” is always “painted” yellow-green.

7. Packaging

Standard for all types is a coil or drum. The coils are sold to stores and wound onto drums for wholesalers, builders and other large buyers. In any case, a label with a description is attached to the cable.

The contents of the tag repeat the information on the inscription on the shell with some additions. It states:

  • plant name or manufacturer's trademark
  • product brand (designation)
  • GOST or TU
  • Date of issue
  • number of segments with their length
  • drum number
  • conductor weight
  • conformity mark
  • OK mark.

If you come to buy a cable for wiring in an apartment in a whole bay of 100 m, you will receive a tag along with it. But if they cut off a piece for you, they won’t give you the label, you can just look at it.

8. Certificate

Needed to confirm that the cable is of high quality. Typically, products have 2 documents - a certificate of conformity, which is responsible for the suitability of the cable as an electrical installation material, and a fire safety certificate. You can ask the seller for them to review. The documents must be filled out indicating GOST standards for the cable and have a valid period, for example, until the end of the current year. As a rule, the documentation indicates specifications (technical conditions) in accordance with GOST and for cable products this is equivalent to compliance with GOST.

9. Condition

This is the appearance of the power wire. Pay attention to how the cable looks, because bruises, strong kinks, and compression hide an internal defect. The veins may be broken and even shorted to each other. It is clear that such material cannot be laid, therefore, do not be lazy to inspect the cable in the store, even before paying for your own purchase.

What cable is needed for wiring in an apartment?

We have already said that electrical wiring in an apartment “requires” 2 cable sections.

For sockets you need to take a cross section of 2.5 mm 2, because the switched load can reach 3-4 kilowatts. And a cable of two and a half “squares” is designed for a maximum power of up to 5.9 kilowatts and a current of up to 27 Amperes. This does not mean that you need to “load” the cable line to its limit. The choice always comes with a margin of one third of the planned load. Moreover, the cable lying under the plaster is cooled less efficiently and this is also taken into account when selecting.

For the lighting circuit, a cross section of 1.5 mm 2 is used. The load here is much less, but even if you decide to arrange illumination in the apartment, there will be plenty of current and power reserves.

Important information! Since modern electrical safety rules require grounding household electrical appliances and installing special sockets, a three-core cable is used for installation. In which there is a working phase conductor, a working zero and a protective zero.

Which cable does the online store website recommend for hidden wiring in a house or apartment?

Let us remind you that the marking contains the main characteristics of cable products. Letter designations indicate the materials of conductors, insulation, sheathing and flexibility, digital designations indicate the number of conductive conductors and their cross-section.

VVG cable

The most common domestic cable for electrical installation in an apartment. It has single-core copper conductors, insulation and a sheath made of PVC plastic, and is used in rooms with normal and high humidity. Designed for voltages up to 660 Volts. Refers to flexible, unarmored power cables. It can include from 1 to 5 cores, with a cross-section from one and a half to 240 “squares”. The conductor shape is round, flat or triangular.

VVG cables are available in several modifications:

  • VVG - basic type with vinyl insulation and sheath;
  • VVGng is a non-flammable power wire, the insulation of the cores is self-extinguishing, that is, combustion does not spread;
  • VVGng-LS - also has self-extinguishing non-flammable core insulation (ng) and a low smoke emission sheath;
  • VVGng FR-LS - in addition to non-flammability and low smoke emission, this type of cable received additional fire protection from mica tape.

All brands with the ng prefix can be mounted in bundles, that is, several cable lines can be laid in one corrugation, pipe or pit.

For sockets For switches
VVGng 3x2.5VVGng 3x1.5
VVGng-LS 3x2.5VVGng-LS 3x1.5

Conventional VVG is cheaper, but is not suitable for bundle laying and the shell is less fire-resistant and smoke-resistant. And the VVGng FR-LS brand is professional and is used in conditions of increased fire hazard in enterprises and is much more expensive.

NYM cable

European standard copper cable developed in Germany. Produced in Russian factories and complies with EU standards and GOSTs. The design is similar to the VVGng cable, rated voltage 660 V. Single-wire multi-core NYM cable with a cross-section of 1.5-10 mm2 and multi-wire with a cross-section of 16 mm2 are available. The number of cores is 1-5, the insulation and sheath are made of PVC, non-flammability is provided by the rubber filler between the core insulation and the cable sheath.

Note! In stores you can find cheap cables marked NUM. This “typo” says that this is a copy with reduced characteristics. By purchasing it, you risk receiving low-quality products. We advise you to refrain from dubious savings on security.

VVGng and NYM cables have similar characteristics and advantages of use:

  • High quality performance. The cores, insulation, and sheath comply with GOST and this makes the cable reliable.
  • Convenient installation and easy cutting. The round cable is easy to install due to the absence of twists and is easier to seal when inserting.
  • High fire resistance and safety. Compliance with standards ensures safe operation of the cable under load, and special insulation allows it to be laid in bundles, without the risk of fire from mutual heating.
  • Self-extinguishing and low smoke. The shell material is self-extinguishing and slows down combustion. It also provides low smoke without dangerous halogens. If the protection works slowly, the damage from the fire will be minimal.
  • Wide range of options in brands at a price to suit any budget.

Which wire is not suitable for wiring in an apartment?

And one more important point. We understand that for most people, “wire” and “cable” are synonymous. In fact, these are different types of cable products. The main difference is that the cable always has a very strong two-layer insulation, with the first layer on top of the conductive cores and the second covering the entire bundle. Even if the cable has one core, the insulation is always double. The wire is a weaker structure with light insulation.

Note! Wiring your apartment with wire, even stranded or stranded, is a very bad idea.

The main problem with wires is their poor resistance to prolonged heating under constant load and their high flammability. Therefore, they do not comply with the requirements of the PUE for wiring in residential premises.

PVS wire

PVS

This is a copper connection wire with vinyl insulation and sheath. Used to connect household electrical appliances to the home network and to make extension cords. The number of conductors is 2-6, the core design is multi-wire, cross-section 0.75-10 mm2. Designed for a voltage rating of 380 V.

Attention! There is no need to take PVS wire for wiring on the advice of friends or to save money.
  • Firstly, PVA have a multi-wire core structure. This means that all ends for connection must be tinned and soldered. This takes a lot of time and requires high-quality processing of the cores and extensive experience of the electrician.
  • Secondly, the multi-wire construction of the core is a factor of increased fire hazard. Such a wire heats up more, which means the insulation wears out faster, which is dangerous and can result in a short circuit.
  • Thirdly, the PVS wire cannot be laid in a bundle, like a cable. Only with the distance between the threads. That is, ditch the walls for each line separately.

So, the savings are very dubious and symbolic. The low price of the wire will be “eaten up” by the high cost of installation. And the quality of the wiring leaves much to be desired.

ShVVP and PVVP wire

ShVVP, PVVP

Installation cords or cables with single and multi-wire copper conductors. Used to connect electrical equipment and household appliances. They have a short service life; the stranded type requires processing of the ends and soldering during installation. They are not suitable for fixed wiring due to the lack of non-flammable insulation and poor characteristics.

Wire PUNP

Attention! PUNP has been banned for use for wiring since 2007 due to its unreliability.

Although there are “craftsmen” both among clients and among would-be electricians who use it. Motivating this by the fact that “all old apartments have this one.”

But “citizens” forget that since the times of the USSR, the equipment of household electrical equipment has changed greatly and its power has increased. That’s why PUNP was banned - it is low-power, has poor insulation and does not support modern loads.

cable VVGng FR-LSNYM cable

The online store site offers only high-quality cables for electrical wiring in an apartment or house. Full list of brands and types in the section:

Come in and choose your cable!

And also ask any questions. Funny and naive first of all! They are the most correct! Because it’s better to make electricians laugh than firefighters, wouldn’t you agree?

We always answer questions and talk about all the intricacies of installation. We quickly select a complete set for installing apartment wiring from cables to sockets and switches. We take into account your wishes and budget.

Call and ask! Phones

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