Table of contents:
- Why are cross section calculations made and which cable to choose
- How to make section calculations: basic rules
- Nuances of calculations for various equipment
- Calculations of the cable cross-sectional area using the example of a fully equipped kitchen
- Power Distribution Cabinet Equipment
- Cable markings used in domestic power networks
- Consequences of choosing the wrong wire size for the outlet
- Conclusions on the information provided
The time comes when the old electrical wiring in an apartment or a private house becomes unusable. The reason for this is time, which especially affects aluminum cables. Also, the ever-increasing number of household appliances that load the home power network can become the reason for the need for replacement. When updating it, you will need to make certain calculations in order to determine the optimal wire cross-section for sockets. This must be done for your own safety. Today's article will tell about such calculations.
Why are cross section calculations made and which cable to choose
The wire material plays a very important role. Aluminum products will cost much less, but it should be understood that in this case you will have to purchase cores with a large cross section, yesand the service life will be much less than that of copper. It is for these reasons that experts advise using more expensive cables.
Calculation of the wire cross-section for sockets in an apartment is important for the normal functioning of the home power network, the absence of heating of the cores during operation. Cables that are too thin may not withstand the load when turning on several household appliances. Many may say that it is better to purchase a thicker wire, however, there are also disadvantages here. An excessive cross section entails useless expenditure of financial resources and effort during installation - it will be much more difficult to lay them.
How to make section calculations: basic rules
Before you start calculations, you need to rewrite all the data on the power consumption of electrical appliances in the house. In this case, it is necessary to calculate not only the total consumption for the apartment, but also the same indicator for individual rooms. This is necessary to determine the number of lines that will be brought into the premises. For example, you can take an apartment with 4 rooms. In this case, the lines will be distributed as follows:
- Kitchen sockets.
- Living room with home theater, computer and sound system installed in it.
- Two bedrooms and an entrance hall - there is no special load on the outlets.
Nuances of calculations for various equipment
If, when adding 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, it would be optimal to use the most common cross-section of a copper cable, equal to 2.5 mm 2. Exceeding 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. This data is necessary when calculating the wire cross-section for sockets.
Calculations of the cable cross-sectional area using the example of a fully 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 appliances (indicating the power in watts):
- toaster – 1000;
- coffee maker – 1000;
- electric kettle – 1000;
- oven – 1500;
- electric stove – 2500;
- refrigerator - 500;
- Microwave oven – 750.
Now you should understand what section of wire for sockets will be required. To do this, add the power indicators and divide the resulting value by the mains voltage. We get 8250/220=37.5 A. This will be the current consumed by the devices.
Now choose the material of the conductor. When using copper, we perform the following calculations: we add a margin in the form of 5 A, after which we get (37, 5 + 5) / 10=42, 5/10=4, 25. This means that the answer to the question of what section should bewire for sockets under such a load, will be 4.5 mm2.
Power Distribution Cabinet Equipment
To correctly calculate the parameters of protective automation, you will need not only the power consumption of household electrical appliances, but also lighting, which must be powered from one or two separate groups. Most often, this is the division of the apartment into the lines “bedroom / kitchen / hallway” and “living room / children's / bath / bathroom”. Here, with cables, everything is quite simple. In modern homes, it is rare to find halogen lighting with increased power consumption - today LEDs are more often used. Therefore, if the question of what section of wire is needed for sockets is important, then everything is elementary with lamps. Most often, a copper cable of one and a half squares is used for lighting lines.
Cable markings used in domestic 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 from the marking, which consists of several letters and numbers indicating the number of cores and the wire cross section. For a socket, the best option would be 3 × 2, 5. But it’s worth dwelling on the lettering in more detail.
VVG - polyvinyl chloride insulation in 2 layers. Such a copper wire is perfect for an outlet, but it should be remembered that it does not have the ability to self-attenuate.
VVGng - the same cable, but already in non-combustible insulation, as they say2 last letters.
VVGng-LS is a non-combustible cable in polyvinyl chloride that does not spread acrid smoke when exposed to high temperatures. Often used in preschool and other educational institutions.
The letter NYM denotes a more expensive variety of German-made VVGNG.
If the letter “A” (AVVG, AVVGng) is in front of the listed markings, this means that the cable cores are made of aluminum.
Consequences of choosing the wrong wire size for the outlet
If you ignore the detailed calculations of this parameter, you can later regret it very much. As a result of such actions, people lose their property, and sometimes their lives. Of course, much depends on the protective automation located in the inlet 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 choose the right emergency shutdown equipment.
Too small cross-section of the wire for the outlet under high load leads to its heating. The consequence 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 the triggered machine does not solve anything. If the partitions in the house are wooden, 2-3 minutes are enough for the whole building to blaze. And it is not a fact that this will not happen at night, when everyone is sleeping. In cases like this, it's rare for anyone to get out.
Addshazards and cabinet furniture. When the cable ignites, even in concrete partitions, the level of temperature increase is quite enough to ignite the wallpaper, followed by the closet, which is installed close to the wall. There is no need to talk about poisonous smoke from a blazing chipboard.
Conclusions on the information provided
Despite the fact that a person today cannot imagine life without electricity, it can be called quite dangerous. But this statement is true only if the approach to its use is wrong. What section of the wire for the sockets will be chosen, it is up to the home master to decide. The main thing is that all the necessary calculations are made, and the cable does not turn out to be thinner than required. Seen from this angle, the thicker wires, although difficult to install, provide a reliable voltage supply, eliminating the risk of overheating and ignition.