How to choose an electrical wire for an apartment. How to choose the cable cross section for power? Calculation

No residential or non-residential premises can do without electrical wiring. But the variety of wires is simply amazing. What is the best choice for a private house? Much depends on what load will be placed on the wiring in a particular room. What do you mean and what are the types of cable? This will be discussed in the article.

Introductory cable

The input cable is the one that comes from the pole to the meter and from the meter comes to the house. In these two cases, you will need not the same cable. If you look closely at the cable that comes from the table to the meter, you will notice that it has large cores and they are twisted together. Depending on how many phases are introduced into the house, the number of cores can be two or four. For these purposes, a conductor is used, which is marked with SIP. The marking is deciphered as a self-supporting insulated cable. Additionally, after the cable marking, a number can be indicated. Most often it is 4 or 6, the full marking may look like SIP-4 or SIP-6. This indicates the number of wires inside one core.

The cores of the SIP cable are made of aluminum. Neither are intertwined and protected by a sheath made of a certain type of plastic. Depending on what total load will be placed on the cable, its cross section can be 16 or 25 mm 2. The second type of section is most often used for three-phase connection. If the span from the house to the pole does not exceed 25 meters, then there is no need for additional supports. If the span is longer, then one or more poles will need to be installed. For fixing on the poles, a special holder is used, which is a metal hook with plastic sponges.

The connection of the SIP to the supply line is carried out using a special piercing clamp. Such installation work must be carried out by a professional with a certain tolerance and category. Most often, SIP is fixed on the facade or gable of the house. For this, a sip clamp is used, which is fixed to the wall with a hook. In some areas there is a requirement that from the place of fixation to the wall of the house to the CIP meter be in a non-combustible plastic corrugation.

A completely different cable goes from the meter to the house. It can be either aluminum or copper. Two cables made of different materials cannot be connected directly to each other, so special blocks are used, but in the shield with the meter, their role is played by automatic machines. The role of such a cable can be AVVG or VVGng. The AVVG cable is a flat product with aluminum conductors, as indicated by the first letter. Each core is in a separate braid, and they are all assembled in another common braid. The braid is made of PVC plastic. Such a cable has sufficient flexibility, so it is quite easy to mount it.

The VVG cable is the same design, but the cores are made of copper and are monolithic. For a private house, a cable with or without the “ng” marking can be used. She says that the braid in the cable is made of non-flammable plastic. Depending on the material from which the core is made, their cross section will differ. For example, for aluminum, the cross section can be 10 mm 2 at rated load. For copper, this figure can be reduced to 6 mm 2. If the load is increased, then the cable cross section can be increased. The input cable from the meter comes to a switchboard, which is mounted directly in the house.

Distribution for living rooms

From the switchboard, the wiring is routed through all living rooms. The use of a conductor marked VVG is not economically justified, since its price is significant and it is more suitable for outdoor installation. Therefore, depending on the master who will carry out the installation, a conductor marked PPV or GDP can be purchased. It is better to refuse offers to make posting using APPV. This is an aluminum cable that was used in construction during the Soviet Union. The products mentioned above have copper conductors. Both in the first and in the second version they are monolithic, which is an important condition.

Note! Said conductors are flat in shape.

The conductor marked PPV is two or three monolithic cores, which are placed in a single braid. This cable is used if you want to save money. The best option would be GDP. Here, each core is in its own braid, and they are additionally combined into a PVC braid. Such a cable is laid in a strobe or passed over a false ceiling. In the second case, it must be placed in a non-combustible plastic corrugation. If we talk about the cross section that is needed, then a conductor with a cross section of 4 mm 2 is laid between the junction boxes, and an element with a cross section of 2.5 mm 2 is pulled from the box to the outlet.

Note! Usually this is enough, because the socket cannot withstand a load of more than 3.5 kW, and a copper cable with a cross section of 2.5 mm2 has a margin of up to 5 kW, which the connected device can consume.

Bathroom

A double-braided cable is required to enter the bathroom, because this room has high humidity, which can lead to corrosion and short circuits.

Boiler connection

Depending on how the boiler will be connected, a different cable is used. If a separate outlet is intended for it, then it must be waterproof. Therefore, you will need to use part of the conductor that will connect the boiler and the outlet. Usually, PVA 2 × 1.5 is enough for these purposes. PVA wire is a round conductor. There are two more cores in the common braid, each of them has its own braid. The cores are not monolithic. Such a wire is very flexible, so it is easy to give it the required shape. Before inserting the wire strands into the boiler clamps, they must be put on lugs. If this is not done, then the bolt will not be able to press all the wires, from which the contact will be poor and the junction will constantly heat up under load.

Note! Connecting the washing machine and dryer is carried out in a similar way. They usually come with built-in wires, so it is enough to bring a wire of the required cross section to a waterproof outlet.

Kitchen

There are several categories of consumers in the kitchen, each of which requires a separate type of wire.

Connecting the hood

The hood has a low consumption, so it does not require wires with a large cross section. If a socket is provided for it, then the supply will be carried out with a 2.5 mm 2 GDP cable. In the case when the hood does not have its own power cable, then the wire ShVVP 2 × 0.75 mm 2 will be enough for it. Such a conductor is able to withstand a load of up to 1.5 kW per core, which is almost never achievable for a hood, since more often its consumption does not exceed 200 watts.

Connecting an electric stove

If an electric stove is installed in the house, then its power may require a three-phase connection. In this case, a separate supply is made directly from the shield. This cable may have a larger cross section than the one that goes from one junction box to another. Usually this is also GDP, but with a cross section that can reach 6 mm 2. The oven can be connected in the same way, but most modern ovens require a single-phase connection, since they do not consume more than 3.5 kW.

Hallway

In the hallway, as a rule, there is no special power for connection, so the wiring is done in the same way as in the living rooms. An exception may be various lamps and floor lamps. A cable with a core cross section of 0.75 mm 2 can be connected to them.

For each individual circuit in the house, its own machine must be provided. Separately, an automatic machine for lighting and sockets should be installed. This will eliminate the possibility of equipment failure when a short circuit or overload occurs on only one line. Also, a circuit breaker must be provided for each powerful appliance. This applies to electric ovens and ovens. A differential automat must be installed for the boiler and instantaneous heater. It catches possible leaks and prevents electric shock if the integrity of one of the conductors is lost.

The wires are connected in junction or junction boxes. Previously, the wires were connected by twists. They were additionally welded to make the connection more reliable. In modern practice, Wago pads and tips are an excellent solution. They do not require any tool for installation, it is enough to insert the bare area into the place intended for it, and the clamps will do their job. Tips are used when performing twisting. There should not be a junction box installed inside the bathroom. It is installed externally so that moisture does not corrode the conductors.

Most often, wiring is carried out with a three-core cable. Two of them are power, and the third is connected to the ground loop. In some cases, a single core cable may be required. In its role, PV3 is used. It is a copper cable in a single braid, the core in which is non-monolithic. Additionally, a voltage relay can be mounted in the shield. They display the current voltage and, when it jumps, cut off the power line so that the connected consumers in the house do not fail. When connecting the lighting, it is worth remembering that it is not the neutral, but the phase wire that should be broken on the switch. This will make it possible to save the one who will be replacing the lamp or servicing the lamp. You can learn more about choosing a cable and machines from the video below.

Summary

As you can see, different types of cable can be used for different purposes and devices. It is important to choose the right section and type of braid. If you have to transfer the power line from the house to the outbuildings, then it is better to do it directly from the meter. In this case, an AVVGt cable can be used. A cable is additionally fused into its outer braid, which will hold it in weight. The cross section of the cores is selected depending on the expected load. In some cases, the cable supply to a private house can be carried out underground. A special conductor is purchased in several braids, one of which is soaked in a special composition that prevents moisture from entering inside. During work, it is always necessary to observe safety regulations, as well as use tools with insulated handles.

It is important to choose all components for electrical work, including cable products. A lot will depend on the section, brand and even the manufacturer, starting from the durability of the home electrical network and ending with the safety of its use. In this article, we will try to explain in detail how to choose a cable for electrical wiring in an apartment and a house (including a wooden one).

Cable or wire?

The first thing you need to understand is that for wiring electricians in a residential area, you need to use an electrical cable. There are several reasons why it is impossible to select a wire for electrical wiring:

1. It is allowed to lay electrical wires either in a hidden way inside the walls, or when wiring in the floor. Moreover, the conductor must be placed in a corrugated or HDPE pipe.
2. The wires are less resistant to prolonged heating, moreover, they can have a single insulation, and therefore their protective properties are not sufficient, and the likelihood of fire is many times higher.
3. Cables have better performance characteristics, including service life (30 years compared to 10).

As you can see, there are quite good reasons (and this is not all) because of which it is better to choose a cable for electrical wiring, rather than a wire. That is why further we will talk about the rules for choosing cable products for distributing electricity around the house and apartment.

Criterias of choice

To choose the right cable for wiring, consider the following recommendations:

The conductor must be three-core(as in the photo below) , because Today it is very important to do grounding in residential buildings. Even if you don’t have it yet, but you plan to replace the wiring in the apartment, it’s better to choose a three-core conductor and just temporarily not use the yellow-green wire (isolate it).

Lived material - required copper. Aluminum wiring is no longer used and is also prohibited by the rules of the PUE. You can read about it in our separate article.

It is very important to choose the right section cable for wiring. To do this, you need to know the total power of all electrical appliances or perform a more accurate calculation of the cross section - according to the current load. Knowing the current strength, it is enough to use the table below and choose the appropriate core size. You can learn more about it in our article. If we talk about standard sections, then 1.5 mm2 is used for lighting, and 2.5 mm2 must be selected for the power line (socket). To connect an electric stove and other household appliances where there is a large consumption of electricity, the cross section of the electrical wiring must be at least 4 mm2. Values ​​are for copper conductor.

Also, one of the most important criteria for choosing a cable for electrical wiring is its brand. Since there are quite a lot of different product names on the cable products market, you need to study the characteristics of commonly used ones and choose the appropriate option for your own conditions. For home wiring, we recommend using, or (the last two conductors do not spread combustion, so they are best chosen for electrical wiring in a wooden house and a dressing room in a bath). VVG can be used for electrical wiring in an apartment, as well as in outbuildings, for example, in a garage. Directly in the steam room of the bath, it is advised to use heat-resistant. On the street, from the pole to the house, it is better to stretch.

Well, the last thing you should pay attention to when choosing - manufacturer cable products. Beware of fakes and unverified brands, because in this case, for reasons of economy, the plant can save on the cross section of conductors, the thickness of the insulation and the very quality of the insulating layer. As a result, this can lead to adverse consequences, for example, overheating and ignition of the electrical wiring when connecting the load for which it should have been designed. ABOUT

The article discusses the main criteria for choosing a cable section, gives examples of calculations.

In the markets, you can often see handwritten signs indicating which one the buyer needs to purchase depending on the expected load current. Do not believe these signs, as they mislead you. The cable cross section is selected not only by the operating current, but also by several other parameters.

First of all, it must be taken into account that when using a cable at the limit of its capabilities, the cable cores heat up by several tens of degrees. The current values ​​shown in Figure 1 assume heating of the cable cores up to 65 degrees at an ambient temperature of 25 degrees. If several cables are laid in one pipe or tray, then due to their mutual heating (each cable heats all other cables), the maximum allowable current is reduced by 10 - 30 percent.

Also, the maximum possible current decreases at elevated ambient temperatures. Therefore, in a group network (a network from shields to lamps, sockets and other electrical receivers), as a rule, cables are used at currents not exceeding 0.6 - 0.7 of the values ​​\u200b\u200bgiven in Figure 1.

Rice. 1. Permissible continuous current of cables with copper conductors

Based on this, the widespread use of circuit breakers with a rated current of 25A to protect socket networks laid with cables with copper conductors with a cross section of 2.5 mm2 is dangerous. Tables of reduction factors depending on the temperature and the number of cables in one tray can be found in the Electrical Installation Rules (PUE).

Additional limitations arise when the cable is longer. In this case, the voltage losses in the cable can reach unacceptable values. As a rule, when calculating cables, they proceed from the maximum losses in the line no more than 5%. Losses are not difficult to calculate if you know the resistance value of the cable cores and the estimated load current. But usually, tables of the dependence of losses on the load moment are used to calculate losses. The load moment is calculated as the product of the cable length in meters and the power in kilowatts.

Data for calculating losses at a single-phase voltage of 220 V are shown in table 1. For example, for a cable with copper conductors with a cross section of 2.5 mm2 with a cable length of 30 meters and a load power of 3 kW, the load moment is 30x3 = 90, and the losses will be 3%. If the calculated loss value exceeds 5%, then a larger cable should be selected.

Table 1. Load moment, kW x m, for copper conductors in a two-wire line for a voltage of 220 V for a given conductor cross section

According to table 2, you can determine the losses in a three-phase line. Comparing tables 1 and 2, you can see that in a three-phase line with copper conductors with a cross section of 2.5 mm2, 3% losses correspond to six times the load torque.

A triple increase in the magnitude of the load moment occurs due to the distribution of the load power over three phases, and a double increase due to the fact that in a three-phase network with a symmetrical load (the same currents in the phase conductors), the current in the neutral conductor is zero. With an unbalanced load, the losses in the cable increase, which must be taken into account when choosing the cable section.

Table 2. Load moment, kW x m, for copper conductors in a three-phase four-wire line with zero for a voltage of 380/220 V for a given conductor cross section (click on the figure to enlarge the table)

Cable losses have a significant effect when using low-voltage lamps such as halogen lamps. This is understandable: if 3 Volts drop on the phase and neutral conductors, then at a voltage of 220 V we most likely will not notice this, and at a voltage of 12 V, the voltage on the lamp will drop by half to 6 V. That is why transformers for powering halogen lamps must be maximally approach the lamps. For example, with a cable length of 4.5 meters with a cross section of 2.5 mm2 and a load of 0.1 kW (two 50 W lamps), the load torque is 0.45, which corresponds to a loss of 5% (Table 3).

Table 3. Load torque, kW x m, for copper conductors in a two-wire line for a voltage of 12 V for a given conductor cross section

The tables given do not take into account the increase in the resistance of conductors from heating due to the flow of current through them. Therefore, if the cable is used at currents of 0.5 or more of the maximum allowable current of the cable of a given section, then a correction must be introduced. In the simplest case, if you expect to get losses of no more than 5%, then calculate the cross section based on losses of 4%. Also, losses can increase if there are a large number of cable core connections.

Cables with aluminum conductors have a resistance 1.7 times greater than cables with copper conductors, respectively, and the losses in them are 1.7 times greater.

The second limiting factor for long cable lengths is the excess of the permissible value of the resistance of the phase-zero circuit. To protect cables from overloads and short circuits, as a rule, circuit breakers with a combined release are used. Such switches have thermal and electromagnetic releases.

The electromagnetic release provides instantaneous (tenths and even hundredths of a second) shutdown of the emergency section of the network in case of a short circuit. For example, a circuit breaker, designated C25, has a thermal release of 25 A and an electromagnetic release of 250 A. Circuit breakers of group "C" have a ratio of the breaking current of the electromagnetic release to the thermal release from 5 to 10. But when the maximum value is taken.

The total resistance of the phase-zero circuit includes: the resistance of the step-down transformer of the transformer substation, the resistance of the cable from the substation to the input switchgear (ASU) of the building, the resistance of the cable laid from the ASU to the switchgear (RU) and the resistance of the cable of the group line itself, the cross section of which is required define.

If the line has a large number of cable core connections, for example, a group line from a large number of lamps connected by a loop, then the resistance of the contact connections must also be taken into account. With very accurate calculations, the resistance of the arc at the point of closure is taken into account.

The total resistance of the phase-zero circuit for four-core cables is given in Table 4. The table takes into account the resistance of both the phase and neutral conductors. The resistance values ​​are given at a cable core temperature of 65 degrees. The table is also valid for two-wire lines.

Table 4

In urban transformer substations, as a rule, transformers with a capacity of 630 kV or more are installed. A and more, having an output resistance Rtp less than 0.1 Ohm. In rural areas, 160 - 250 kV transformers can be used. And, having an output impedance of the order of 0.15 Ohm, and even transformers for 40 - 100 kV. A, having an output impedance of 0.65 - 0.25 ohms.

Power supply cables from urban transformer substations to ASUs of houses are usually used with aluminum conductors with a phase conductor cross section of at least 70 - 120 mm2. With a length of these lines of less than 200 meters, the resistance of the phase-zero circuit of the supply cable (Rpc) can be taken equal to 0.3 Ohm. For a more accurate calculation, you need to know the length and cross section of the cable, or measure this resistance. One of the instruments for such measurements (the Vector instrument) is shown in fig. 2.

Rice. 2. Device for measuring the resistance of the phase-zero circuit "Vector"

The resistance of the line must be such that, in the event of a short circuit, the current in the circuit is guaranteed to exceed the operating current of the electromagnetic release. Accordingly, for the C25 circuit breaker, the short-circuit current in the line must exceed 1.15x10x25 = 287 A, here 1.15 is the safety factor. Therefore, the resistance of the phase-zero circuit for the C25 circuit breaker should be no more than 220V / 287A \u003d 0.76 Ohm. Accordingly, for the C16 circuit breaker, the circuit resistance should not exceed 220V / 1.15x160A \u003d 1.19 Ohm and for the C10 machine - no more than 220V / 1.15x100 \u003d 1.91 Ohm.

Thus, for an urban apartment building, assuming Rtp = 0.1 Ohm; Rpk = 0.3 Ohm when using a cable with copper conductors with a cross section of 2.5 mm2, protected by a C16 circuit breaker, in the socket network, the resistance of the cable Rgr (phase and neutral conductors) should not exceed Rgr = 1.19 Ohm - Rtp - Rpc = 1.19 - 0.1 - 0.3 \u003d 0.79 ohms. According to table 4, we find its length - 0.79 / 17.46 \u003d 0.045 km, or 45 meters. For most apartments, this length is enough.

When using the C25 circuit breaker to protect a cable with a cross section of 2.5 mm2, the circuit resistance must be less than 0.76 - 0.4 \u003d 0.36 Ohm, which corresponds to a maximum cable length of 0.36 / 17.46 \u003d 0.02 km, or 20 meters.

When using the C10 circuit breaker to protect a group lighting line made with a cable with copper conductors with a cross section of 1.5 mm2, we obtain the maximum allowable cable resistance 1.91 - 0.4 = 1.51 Ohm, which corresponds to the maximum cable length 1.51 / 29, 1 = 0.052 km, or 52 meters. If such a line is protected by a circuit breaker C16, then the maximum length of the line will be 0.79 / 29.1 \u003d 0.027 km, or 27 meters.

When laying electrical wiring, you need to know what kind of cable with conductors you will need to lay. The choice of cable section can be done either by power consumption or by current consumption. You also need to take into account the length of the cable and the method of installation.

We select the cable cross-section by power

You can select the cross section of the wire according to the power of the devices that will be connected. These devices are called load and the method can also be called "by load". Its essence does not change from this.

We collect data

To begin with, find the power consumption in the passport data of household appliances, write it out on a piece of paper. If it's easier, you can look at the nameplates - metal plates or stickers fixed on the body of equipment and equipment. There is basic information and, most often, there is power. The easiest way to identify it is by units of measurement. If the product is manufactured in Russia, Belarus, Ukraine, the designation is usually W or kW, on equipment from Europe, Asia or America, the English designation of watts is usually W, and the power consumption (it is needed) is indicated by the abbreviation "TOT" or TOT MAX.

If this source is not available either (the information has been lost, for example, or you are just planning to purchase equipment, but have not yet decided on the model), you can take the average statistical data. For convenience, they are summarized in a table.

Find the equipment that you plan to install, write out the power. It is sometimes given with a wide spread, so it is sometimes difficult to understand which figure to take. In this case, it is better to take the maximum. As a result, when calculating, you will have a slightly overestimated power of the equipment and you will need a cable with a larger cross section. But for calculating the cable section, this is good. Only cables with a smaller cross-section than necessary are lit. Routes with a large cross section work for a long time, as they heat up less.

The essence of the method

To select the wire cross-section according to the load, add up the power of the devices that will be connected to this conductor. At the same time, it is important that all powers are expressed in the same units of measurement - either in watts (W) or in kilowatts (kW). If there are different values, we bring them to a single result. To convert, kilowatts are multiplied by 1000 to get watts. For example, let's convert 1.5 kW to watts. This will be 1.5 kW * 1000 = 1500 watts.

If necessary, you can carry out the reverse conversion - convert watts to kilowatts. For this, we divide the figure in watts by 1000, we get kW. For example, 500 W / 1000 = 0.5 kW.

To find the required cable section in the corresponding column - 220 V or 380 V - we find a figure that is equal to or slightly more than the power we calculated earlier. We select the column based on how many phases there are in your network. Single-phase - 220 V, three-phase 380 V.

In the found line, we look at the value in the first column. This will be the required cable cross-section for a given load (power consumption of devices). A cable with conductors of such a cross section will have to be looked for.

A little about whether to use copper wire or aluminum. In most cases, with, cables with copper conductors are used. Such cables are more expensive than aluminum ones, but they are more flexible, have a smaller section, and are easier to work with. But, copper cables with a large cross section are no more flexible than aluminum ones. And at high loads - at the input to the house, to the apartment with a large planned power (from 10 kW and more), it is more expedient to use a cable with aluminum conductors - you can save a little.

How to calculate the cable cross-section by current

You can choose the cable cross-section for current. In this case, we carry out the same work - we collect data on the connected load, but we are looking for the maximum current consumption in the characteristics. Having collected all the values, we summarize them. Then we use the same table. We are only looking for the nearest higher value in the column labeled "Current". In the same line, we look at the cross section of the wire.

For example, it is necessary with a peak current consumption of 16 A. We will lay a copper cable, therefore we look in the corresponding column - the third from the left. Since there is no value of exactly 16 A, we look in line 19 A - this is the nearest larger one. Suitable cross section 2.0 mm 2 . This will be the minimum value of the cable cross-section for this case.

When connecting powerful household electrical appliances, a separate power line is pulled from it. In this case, the choice of cable section is somewhat simpler - only one value of power or current is required

It is impossible to pay attention to a line with a slightly lower value. In this case, at maximum load, the conductor will be very hot, which can lead to the fact that the insulation will melt. What could be next? Might work if it's installed. This is the most favorable option. Household appliances may fail or a fire may start. Therefore, always make the choice of cable section by a larger value. In this case, it will be possible to later install equipment even a little more in terms of power or current consumption without rewiring.

Cable calculation by power and length

If the power line is long - several tens or even hundreds of meters - in addition to the load or current consumption, it is necessary to take into account the losses in the cable itself. Usually long distances of power lines at. Although all data must be specified in the project, you can play it safe and check. To do this, you need to know the allocated power to the house and the distance from the pole to the house. Further, according to the table, you can select the wire cross-section, taking into account the losses along the length.

In general, when laying electrical wiring, it is always better to take some margin over the cross section of the wires. Firstly, with a larger cross section, the conductor will heat up less, and hence the insulation. Secondly, more and more devices powered by electricity appear in our lives. And no one can guarantee that in a few years you will not need to install a couple of new devices in addition to the old ones. If a stock exists, they can simply be turned on. If it is not there, you will have to be smart - either change the wiring (again) or make sure that powerful electrical appliances do not turn on at the same time.

Open and closed wiring

As we all know, when current passes through a conductor, it heats up. The more current, the more heat is generated. But, when the same current passes through conductors with different cross sections, the amount of heat generated changes: the smaller the cross section, the more heat is released.

In this regard, with an open laying of conductors, its cross section may be smaller - it cools faster, since heat is transferred to the air. In this case, the conductor cools faster, the insulation will not deteriorate. With a closed gasket, the situation is worse - heat is removed more slowly. Therefore, for a closed installation - in pipes, in a wall - it is recommended to take a larger cable.

The choice of cable cross-section, taking into account the type of its laying, can also be carried out using the table. The principle was described earlier, nothing changes. There is just one more factor to consider.

And finally, a few practical tips. When you go to the market for a cable, take a caliper with you. Too often, the claimed cross section does not match reality. The difference can be 30-40%, and this is a lot. What threatens you? Burnout wiring with all the ensuing consequences. Therefore, it is better to check right on the spot whether this cable has the required core cross-section (diameters and corresponding cable cross-sections are in the table above). And more about the definition of the section cable by its diameter can be read here.

Hello. The topic of today's article Cable cross section by power". This information is useful both at home and at work. It will be about how to calculate the cable cross-section by power and make a choice according to a convenient table.

Why do you need choose the right cable size?

In simple terms, this is necessary for the normal operation of everything related to electric current. Whether it's a hair dryer, washing machine, motor or transformer. Today, innovations have not yet reached the wireless transmission of electricity (I think they will not reach it soon), respectively, the main means for the transmission and distribution of electric current are cables and wires.

With a small cross section of the cable and high power equipment, the cable can heat up, which leads to the loss of its properties and the destruction of the insulation. This is not good, so proper calculation is necessary.

So, selection of cable cross-section by power. For selection, we will use a convenient table:

The table is simple, I think it is not worth describing it.

Let's say we have a house, we carry out the installation of closed electrical wiring with a VVG cable. We take a sheet of paper and rewrite the list of equipment used. Done? Fine.

How to find out the power? You can find power on the equipment itself, usually there is a tag where the main characteristics are recorded:

Power is measured in Watts (W, W), or Kilowatts (kW, KW). Found? Write data, then add.

Let's say you get 20,000 watts, that's 20 kW. The figure tells us how much energy all electrical receivers consume together. Now you need to think about how many devices you will use at the same time for a long time? Let's say 80%. The simultaneity coefficient in this case is equal to 0.8. Doing calculation of the cable cross-section by power:

We believe: 20 x 0.8 = 16(kW)

To do selection of cable cross-section by power, look at our tables: