Electricity has become such an integral part of our lives that with a sudden power outage, our life seems to freeze, and we look forward to it being restored. We are surrounded by a huge number of different electrical appliances that are connected to the home network either directly through sockets or through
extension cords or carriers.
Sometimes it is necessary to lead the light to the garage or to another outbuilding, replace the wire or make a homemade extension cord. Or you need to calculate the maximum number of devices that can be simultaneously connected to one tee so that the wire does not heat up in it and a fire does not occur due to a short circuit. In such cases, you should first calculate the cross-section of the wires in order to be sure of the safety of the installed wiring.
Which wire to choose?
It's no secret that copper has less resistance than aluminum, and therefore if we compare copper and aluminum wires, which have the same wire cross section, then in the first case the allowable load will be slightly larger. Copper wire is stronger, softer and won't breakin places of inflection. In addition, copper is less susceptible to oxidation and corrosion. The only advantage of aluminum wire is its cost, which is three or four times less than copper.
Calculation of the wire section by power
Any electrical wiring must be suitable for the load connected to it. The cross section of the wire is calculated based on the maximum allowable heating of the current-carrying core. The amount of heating depends on the power of the connected electrical appliances. Thus, by calculating the maximum possible total power of devices in the room, you can determine what the wire cross section should be. In practice, it is convenient to use an online calculator or special tables that contain information about the permissible current load on the cable.
Wire section, sq.mm |
Copper wire (cable, core) |
|||
| Chain voltage, 220 V | Chain voltage, 380 V | |||
| power, kW | current strength, A | power, kW | current strength, A | |
1.5 |
4.1 | 19 | 10.5 | 16 |
2.5 |
5.9 | 27 | 16.5 | 25 |
4 |
8.3 | 38 | 19.8 | 30 |
6 |
10.1 | 46 | 26.4 | 40 |
10 |
15.4 | 70 | 33.0 | 50 |
16 |
18.7 | 85 | 49.5 | 75 |
25 |
25.3 | 115 | 59.4 | 90 |
35 |
29.7 |
135 | 75.9 | 115 |
50 |
38.5 | 175 | 95.7 | 145 |
70 |
47.3 | 215 | 118.8 | 180 |
95 |
57.2 | 260 | 145.2 | 220 |
120 |
66.0 | 300 | 171.6 | 260 |
Wire section, sq.mm |
Aluminum wire (cable, core) |
|||
| Chain voltage, 220 V | Chain voltage, 380 V | |||
| power. kW | current strength. A | power. kW | current strength. A | |
2.5 |
4.4 | 20 | 12.5 | 19 |
4 |
6.1 | 28 | 15.1 | 23 |
6 |
7.9 | 36 | 19.8 | 30 |
10 |
11.0 | 50 | 25.7 | 39 |
16 |
13.2 | 60 | 36.3 | 55 |
25 |
18.7 | 85 | 46.2 | 70 |
35 |
22.0 | 100 | 56.1 | 85 |
50 |
29.7 | 135 | 72.6 | 110 |
70 |
36.3 | 165 |
92.4 |
140 |
95 |
44.0 | 200 | 112.2 | 170 |
120 |
50.6 | 230 | 132.0 | 200 |
How to check wire size?
Since the wires most often have a round cross-sectional shape, the cut area is calculated by the formula:
S=π x d²/4 or S=0.8 x d², where
S is the cross-sectional area of the core in mm.sq.;
π - 3, 14; d - core diameter in mm.
Assume, for example, that the wire diameter is 1.3 mm., Then S=0.8 • 1. 3²=0.8 • 1. 3 x 1. 3=1.352 mm2
If the wire consists of several cores, then the cross section of one core is considered and multiplied by their total number in the bundle. The diameter is usually measured with a caliper, but if it is not available, then a regular ruler will do. In this case, approximately 10-15 turns are tightly wound on a pencil, the winding length is measured with a ruler and the resulting value is divided by the number of turns.
In any electrical work, you need to remember that electricity does not tolerate negligent handling and does not forgive mistakes. Electrical safety and reliability - this is what you should always strive for when doing any work with electrical wiring in an apartment, in a country house or in a house.
