The time comes when the old wiring in an apartment or a private house becomes unusable. The reason for this is time, which especially affects aluminum cables. Also, the cause of the need for replacement may be an ever-increasing number of household appliances that load the home power network. When updating it, you will need to perform certain calculations to determine the optimal wire cross section for outlets. This must be done for your own safety. About such calculations and tell today's article.
Why section calculations are made and which cable to choose
The material for the manufacture of wires plays a very important role. Aluminum products will cost much cheaper, but it is worthwhile to understand that in this case you will have to purchase conductors with a large cross section, and the service life will be much less than that of copper. For these reasons, experts advise using more expensive cables.
The calculation of the cross-section of the wire for outlets in the apartment is important for the normal functioning of the home power network, the lack of heating of the wires during operation. Too thin cables may not support the load when turning on several household appliances. Many may say that it is better to purchase a thicker wire, but there are drawbacks here. Excessive cross-sectional value entails the useless costs of financial resources and forces during installation - it will be much more difficult to stack them.
How to make section calculations: basic rules
Before proceeding with the calculations, it is necessary to rewrite all the data on the power consumption of electrical appliances located in the house. In this case, it is necessary to calculate not only the total consumption of the apartment, but also the same indicator for individual rooms. This is necessary to determine the number of lines that will be installed in the premises. For example, you can take an apartment with 4 rooms. In this case, the lines will be distributed as follows:
- Kitchen outlets.
- Living room with a home cinema, computer and speaker system.
- Two bedrooms and an entrance hall - there is no special load on the sockets here.
The nuances of computing for various equipment
If when adding up the power consumption of devices located on the same line, the indicator was less than 3 kW, then further calculations can be omitted - in this case, the most common use of the most common section of a copper cable equal to 2.5 mm 2 will be optimal. Exceeding a value of 3 kW requires further calculations.
Important information! The bandwidth of copper and aluminum cables is different. In the first case, it will be 10 A / mm, in the second 8 A / mm. These data are necessary when calculating the cross-section of the wire for sockets.
Calculation of the cable cross-sectional area using the example of the most equipped kitchen
Based on the fact that there is a lot of various equipment in the room, it should be understood that the wires will be thicker than those that fit the living room. The kitchen is equipped with the following devices (indicating power in watts):
- toaster - 1000;
- coffee maker - 1000;
- electric kettle - 1000;
- oven - 1500;
- electric stove - 2500;
- refrigerator - 500;
- Microwave oven - 750.
Now you need to understand what section of the wire for outlets is required. To do this, add up the power indicators and divide the resulting value by the mains voltage. We get 8250/220 = 37.5 A. This will be the current consumption consumed by the devices.
Now select the material of manufacture of the conductor. When using copper, we perform the following calculations: add a margin of 5 A, after which we obtain (37.5 + 5) / 10 = 42.5 / 10 = 4.25. This means that the answer to the question of what section should be the wire for outlets at such a load is 4.5 mm 2 .
Power Enclosure Equipment
For the correct calculation of the parameters of protective automation, you will need not only the power consumption of household appliances, but also lighting, which must be powered from one or two separate groups. Most often, this is the separation of the apartment on the line "bedroom / kitchen / hallway" and "living room / children / bath / bathroom." Everything with cables is quite simple here. In modern homes, it is rarely possible to meet halogen lighting with increased power consumption - today, LEDs are more often used. Therefore, if the question of what section the wire is needed for outlets is important, then with lamps everything is elementary. Most often, copper lines of one and a half squares are used for lighting lines.
Marking cables used in home power networks
When purchasing a cable, you need to pay attention to its insulation. It is not possible to visually determine its composition, however, all parameters can be found in the marking, which consists of several letters and numbers indicating the number of cores and the cross section of the wire. For the outlet, the best option would be 3 × 2.5. But the letter designation is worth dwelling in more detail.
VVG - polyvinyl chloride insulation in 2 layers. Such a copper wire is perfect for an outlet, however, it should be remembered that it does not have the possibility of independent attenuation.
VVGng is the same cable, but already in non-combustible insulation, as the last 2 letters say.
VVGNG-LS is a non-combustible cable in polyvinyl chloride that does not spread caustic smoke when exposed to high temperatures. Often used in preschool and other educational institutions.
The NYM letter denotes a more expensive variety of German-made VVGng.
If the letter “A” (AVVG, AVVGng) is located before the listed markings, this means that the cable cores are made of aluminum.
The consequences of the wrong choice of wire cross section for the outlet
If you ignore the detailed calculations of this parameter, you can subsequently very much regret it. As a result of such actions, people lose their property, and sometimes life. Of course, a lot depends on the protective automation located in the opening distribution cabinet, but it is unlikely that a person who does not pay due attention to the thickness of the cable will be able to correctly select the emergency shutdown equipment.
Too small cross-section of the wire for the outlet at high load leads to its heating. The result of further operation is the ignition of the cable, as a result of which the insulation burns out and a short circuit occurs. Most often, by this time the apartment is already engulfed in fire, so an automatic machine that has worked does not solve anything. If the partitions in the house are wooden, 2-3 minutes are enough for the whole building to burn. And not the fact that this will not happen at night when everyone is sleeping. In such cases, rarely is anyone able to get out.
Adds dangers and cabinet furniture. When the cable is ignited, even in concrete partitions, a level of temperature increase is enough to light up the wallpaper, and then the cabinet, which is installed close to the wall. You can’t talk about the toxic smoke from the burning chipboard.
Conclusions on the information provided
Despite the fact that people today can not imagine life without electricity, it can be called quite dangerous. But this statement is true only with the wrong approach to its use. Which cross section of the wire for the sockets will be chosen is for the home master to decide. The main thing is that all the necessary calculations should be made, and the cable should not be thinner than required. If you look from this side, the thicker wires, although difficult to install, provide a reliable voltage supply, eliminating the risk of overheating and ignition.