Calculation of wire cross-section according to power consumption. Features of the calculation

This article will talk about how to calculate the cross-section of the wire according to power consumption independently. You need to know this not only when installing wiring in the house, but also when working in cars, for example. If the cross-section of the wire is insufficient, it will begin to heat up very much, which will lead to a significant loss of security. Given all the recommendations that will be outlined below, you can independently calculate the parameters of the wires for the installation of electricity in the house. But if you are not confident in your abilities, it is better to contact specialists in this field. Moreover, it should be noted that the calculation of the wire cross-section by power consumption (12V and 220V) is carried out similarly.

Calculation of the length of the wiring

For any type of electronic system, the most important condition for stable and trouble-free operation is the competent calculation of the cross-sections of all wires for current and power. The first step is to calculate the maximum length of the entire wiring. There are several ways to do this:

1. Measuring the distance from the shields to sockets, switches according to the installation diagram. Moreover, this can be done with a ruler on a pre-prepared wiring plan - it is enough to multiply the obtained length values ​​by the scale.
2. And the second, more accurate way is to arm yourself with a ruler and walk through all the rooms, taking measurements. Moreover, it must be borne in mind that the wires must somehow connect, so there should always be a supply - at least one or two centimeters from each edge of the wiring.

Now you can proceed to the next step.

Calculation of wiring load

To calculate the total load, you need to add up all the minimum power consumers in the home. Suppose you are calculating for a kitchen, it has fixtures, a microwave, an electric kettle and a stove, a dishwasher and so on. All power must be summarized (see the power consumption on the back covers, but you will have to calculate the current yourself on this parameter). After multiplying by a correction factor of 0.75. It is also called the coefficient of simultaneity. Its essence is clear from the name itself. This figure, which will result from the calculations, you will need in the future to conduct calculations of the parameters of the wires. Please note that the entire power supply system must be safe, reliable and robust. These are the basic requirements that must be taken into account when calculating the wire cross-section according to the consumed power of 12V and 220V.

Current consumption of electrical installations

Now about how to calculate the current consumption of an electrical device. You can do this in your mind, or you can on a calculator. See the instructions for the device, what value of power consumption it has. Of course, an alternating current with a voltage of 220 volts flows in a household electrical network. Therefore, using a simple formula (power consumption divided by the supply voltage), you can calculate the current. For example, an electric kettle has a power of 1000 watts. So, if you divide 1000 by 220, we get a value approximately equal to 4.55 amperes. It is very simple to calculate the cross-section of the wire according to power consumption. How to implement this is described in the article. In operating mode, the kettle consumes 4.55 amperes from the mains (for protection, a larger circuit breaker must be installed). But note that this is not always the exact value. For example, if the design of the appliance has a motor, you can increase the obtained value by about 25% - the current consumption of the motor in start-up mode is much greater than during idling.

PUE recommendations

But you can use the set of rules and standards. There is such a document as the Rules for the installation of electrical installations, it regulates all the rules for wiring not only in private estates, but also in factories, factories, etc. According to these rules, the wiring standard is the ability to withstand a load of 25 amperes for a long time. Therefore, in apartments, all electrical wiring should be performed only using copper wire, its cross-section is not less than 5 square meters. mm Each core must have a cross section of more than 2.5 square meters. mm The diameter of the conductor should be 1.8 mm.

To ensure that all electrical wiring works as safely as possible, an automatic circuit breaker is installed at the input. He will protect the apartment from short circuits. Recently, most homeowners have been installing residual current circuit breakers, which instantly act on a change in resistance in the circuit. In other words, if you accidentally touch exposed wires while energized, they will instantly de-energize and you won’t get hit. Circuit breakers must be calculated by current, and it is necessary to choose with a margin so that there is always the opportunity to install any kind of electrical appliance in the house. Proper calculation of the wire cross-section according to power consumption (you will learn how to make the right choice of wires from this material) is the guarantee that the power supply will function correctly and efficiently.

Materials for making wires

As a rule, the installation of electrical wiring in a private house or apartment is done using three-wire wires. Moreover, each core has a separate insulation, all of them have different colors - brown, blue, yellow-green (standard). A vein is precisely that part of the wire through which current flows. It can be either single-wire or multi-wire. Some wire brands use a cotton braid over the cores. Materials for the manufacture of wire conductors:

1. Steel.
2. Copper.
3. Aluminum.

Sometimes you can find combined ones, for example, a multi-wire copper wire with several steel conductors. But such were used for the implementation of field telephone communications - a signal was transmitted through copper, and steel were used for the most part for mounting to supports. Therefore, this article will not talk about such wires. For apartments and private houses, copper wire is ideal. It is durable, reliable, and its performance is much higher than that of cheap aluminum. Of course, the price of a copper wire bites, but it is worth mentioning that its service life (guaranteed) is 50 years.

Wire brands

For wiring, it is best to use two brands of wires - VVGNG and VVG. The first has the ending "-ng", which indicates that the insulation is not lit. It is used for electrical wiring inside structures and buildings, as well as in the ground, in the open air. Stably works in the temperature range -50 ... +50. Guaranteed service life - at least 30 years. The cable can be with two, three or four cores, each cross section in the range of 1.5 ... 35 sq. mm Please also pay attention to the fact that it is necessary to calculate the cross-section of the wire according to power consumption and length (in the case of an air long line).

Carefully watch that there is no letter “A” in front of the name of the wire (for example, AVVG). This suggests that inside the cores are made of aluminum. There are also foreign analogues - the NYM brand cable, which has a round shape, meets the standards adopted in Germany (VDE0250). Copper cores, insulation is not subject to burning. The round shape of the wire is much more convenient if it is necessary to carry out installation through the wall. But for domestic wiring it turns out to be more convenient to flat domestic.

Aluminum wires

They are light weight, and most importantly, low cost. Therefore, they are useful for those cases when you need to lay long lines through the air. If all the work is carried out correctly and correctly, you will get the perfect air line, since aluminum has one huge advantage - it is not susceptible to oxidation (unlike copper). But often wiring made of aluminum was used in homes (usually in old ones). The wire used to be easier to get, and it cost a penny. It should be noted that the calculation of the cross-section of the wire according to the power consumption (the features of this process are known to every electrician) is the main step in creating a project for power supply at home. But you need to pay attention to one feature - the cross section of the aluminum wire must be larger than copper to withstand the same load.

Table for calculating the power section

It is also necessary to mention that the maximum permissible current load on aluminum wires is much less than for copper. The table below will help to calculate the cross-section of the conductors of aluminum wiring.

Wire cross section depending on wiring type

There are two types of installation of electrical wiring in homes - outdoor and indoor. As you know, this nuance should be taken into account when making calculations. Hidden is mounted inside floors, as well as in grooves and channels, in pipes, etc. Closed wiring has higher requirements, since it has less cooling ability. And any wire with prolonged exposure to a large load heats up very much. Therefore, in the case when you are calculating the cross-section of the wire according to the power consumption, be sure to consider the effect on heating. The following parameters must also be taken into account:

1. Long current load.
2. Loss of voltage.

As the length of the wire increases, the voltage decreases. Therefore, in order to reduce voltage losses, it is necessary to increase the cross section of the wire conductors. If we are talking about a small house or even a room, then the value of the losses is extremely low, they can be neglected. But if the calculation of a long line is carried out, there is no escape from this. After all, the calculation of the cross section of the wire according to the power consumption (the influence of the length is very large) depends on such a parameter as the length of the line.

Power calculation

So, you need to know the following characteristics:

1. The material of which the cable cores are made.
2. The maximum power consumption.
3. Supply voltage.

Please note that when any current flows, the temperature rises and a certain amount of heat is released. Moreover, the amount of heat is proportional to all the power that is dissipated on a piece of wiring. If you select the wrong section, then excessive heating will occur, and the result can be disastrous - ignition of the wiring and fire. Therefore, it is worthwhile to conduct an accurate calculation of the wire cross-section according to power consumption. Risk factors are too large, and there are many.

Optimal parameters

Optimal sections:

1. For wiring outlets - 2.5 square meters. mm
2. Lighting group - 1.5 square meters. mm
3. High power electrical appliances (electric stove) - 4-6 square meters. mm

At the same time, pay attention to the fact that copper wires can withstand the following loads:

1. 1.5 sq. Wire mm - up to 4.1 kW (current load - 19 amperes).
2. 2.5 sq. mm - up to 5.9 kW (current - up to 27 amperes).
3. 4-6 square meters mm - more than 8-10 kW.

Therefore, with an increase in load, you will always have a fairly large reserve.

Conclusion

Now you know how to calculate the cross-section of the wire according to the power consumption (you now know the definition of important characteristics and other small factors). Based on all the above data, you can independently, without resorting to the help of professionals, draw up the correct electricity supply plan for your house or apartment.