Selecting the power cable cross-section
The additional data you need is elementary: the material of the wires( copper or aluminum) and the characteristics of your network( 220 or 380V).Having determined the total power consumption for each group and using this value, you use the simple PES tables to find the cross-section of the desired cable. True, with a slight correction.
Example. Copper wire, 220V network, the total capacity of electrical appliances is 10.2 kW.According to Table 1, the nearest value for open wiring is 9.8 kW and a cross-section of 2 mm2, we recommend taking it with a margin, i.e. Next 2.5 sq. m. For closed is similar.
Table 1. Open wiring
| S | Brass Aluminum conductor wires | |||||
| mm2 | current | Moschn.kVt | current | Moschn.kVt | ||
| A | 220 380 A | 220 | 380 | |||
| 0.5 2.4 | 11 | - | - | - | - | |
| 0,75 | 15 | 3,3 | - | - | - | - |
| 1 | 17 | 3,7 | 6,4 | - | - | - |
| 1,5 | 23 | 5 | 8,7 | - | - | - |
| 2 | 26 | 5.7 | 9.8 | 21 | 4.6 | 7.9 |
| 2.5 | 30 | 6.6 | 11 | 24 | 5.2 | 9.1 |
| 4 | 41 | 9 | 15 | 32 | 7 | 12 |
| 5 | 50 | 11 | 19 | 39 | 8.5 | 14 |
| 10 | 80 | 17 | 30 | 60 | 13 | 22 |
| 16 | 100 | 22 | 38 | 75 | 16 | 28 |
| 25 | 140 | 30 | 53 | 105 | 23 | 39 |
| 35 | 170 | 37 | 64 | 130 | 28 | 49 |
Table 2. Closed wiring
| S | Brass Aluminum conductor wires | |||||
| mm2 | current | Moschn.kVt | current | Moschn.kVt | ||
| A | 220 380 A | 220 | 380 | |||
| 0,5 | - | - | - | - | - | - |
| 0,75 | - | - | - | - | - | - |
| 1 | 14 | 3 | 5,3 | - | - | - |
| 1,5 | 15 | 3,3 | 5,7 | - | - | - |
| 2 | 19 | 4,1 | 7.2 | 14 | 3 | 5.3 |
| 2.5 | 21 | 4.6 | 7.9 | 16 | 3.5 | 6 |
| 4 | 27 | 5.9 | 10 | 21 | 4.6 | 7.9 |
| 5 | 34 | 7.4 | 12 | 26 | 5.7 | 9.8 |
| 10 | 50 | 11 | 19 | 38 | 8, 3 | 14 |
| 16 | 80 | 17 | 30 | 55 | 12 | 20 |
| 25 | 100 | 22 | 38 | 65 | 14 | 24 |
| 35 | 135 | 29 | 51 | 75 | 16 | 28 |
As you can see, everything is quite simple, If at the preliminary stage you have correctly identified the appetites of your electric friends.
When it is necessary to calculate the cable cross-section by power
Design, calculation of the wire cross-section for the expected load and installation of electrical wiring in our city apartments have been done for us by professional designers and builders. How much their assessments correspond to modern realities is another matter. Strobit concrete walls and make a new layout of electrical wires for such cases in this article we will not. Let's turn to the private sector, where many active citizens try to make many fascinating work with their own hands. 
The question is rather rhetorical. Always, when an external consumer of electricity is connected to electrical networks. In industrial and capital housing construction problems are solved by specialists at the project stage, in our case, the calculators will be the respected gardeners, summer residents and owners of private houses.
Consider three typical cases where they all wonder: how to calculate the cable cross-section and buy the correct wire without overpayment and with a guarantee of long-term operation.
- Forced replacement of old wiring that failed due to melting, destruction and aging. The situation is familiar for old country cottages, where the calculation of the cable by load( if it was) clearly does not correspond to modern conditions.
- Replacement of the distribution switchboard or automat for the switchboard, designed to improve the operation of electrical systems in the house. It's bad when an electric kettle and a microwave oven cut the electricity in the house together. The circuit breakers are selected with a margin, and the wires do not withstand the load.
- Electric wiring in a new country house. This is a separate story, with the example of which we will try to explain how to calculate the cross-section of each cable, which will ultimately illuminate, heat and feed your loved ones.
Initial data for calculating the power cable
First of all, let's determine what power is involved. To the distributed electric power supply to your structure, there is no role here, in order to calculate the cross sections of the internal wiring wires, it is necessary to know the power consumption of all electrical appliances located in the house. For convenience, we divide them into three groups( which, by the way, makes sense to be planted on separate RCDs).
- Lighting. Energy consumption is unstable, therefore, to calculate the cross-section of the wires of this group in the frequent houses of permanent residence, it is better to take as a starting value the simultaneous consumption of all the lighting devices and 100W for one lamp.
- Household appliances. Calculate the total power for this group and the corresponding sections of the supply cable is not as simple as it seems at first glance. In the passport of each device, the minimum and maximum consumption are usually indicated. Washing machines, electric stoves and other equipment work in different modes, but you will have to take into account the maximum parameters adjusted for the peak start jump.
- Electrical equipment. Water heaters, systems of warm floors, electric heating boilers, electric radiators are the most energy consuming consumers, connected irregularly, but sometimes for a long time. Calculation of the cable cross section for them is better done by load.
