Electricity has become so firmly entrenched in our lives that when the power is suddenly turned off, our life seems to freeze, and we look forward to being restored. We are surrounded by a huge number of different electrical appliances that connect to the home network either directly through outlets or through
extension cords or carrying.
Sometimes it is necessary to conduct light in a garage or in another outbuilding, replace the wire or make a homemade extension cord. Or you need to calculate what maximum number of devices can be simultaneously included in one tee so that the wire does not get warm in it and there is no fire due to a short circuit. In such cases, you should first make a calculation of the cross section of the wires to be sure of the safety of the installed wiring.
Which wire to choose?
It is no secret that copper has lower resistance compared to aluminum, and therefore, if we compare copper and aluminum wiring, in which the wire cross section is the same, then in the first case the permissible load will be slightly higher. The copper wire is stronger, softer and does not break in places of inflection. In addition, copper is less susceptible to oxidation and corrosion. The only advantage of an aluminum wire is its cost, which is three or four times less than copper.
Calculation of the wire cross section for power
Any wiring must match the load connected to it. The wire cross section 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 the devices in the room, you can determine what the cross-section of the wire 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 cross section, sq. Mm | Copper wire (cable, core) |
Circuit Voltage 220 V | Circuit Voltage 380 V |
power, kWt | current strength, A | power, kWt | 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 | thirty |
6 | 10.1 | 46 | 26.4 | 40 |
10 | 15.4 | 70 | 33.0 | fifty |
16 | 18.7 | 85 | 49.5 | 75 |
25 | 25.3 | 115 | 59.4 | 90 |
35 | 29.7 | 135 | 75.9 | 115 |
fifty | 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 cross section, sq. Mm | Aluminum wire (cable, core) |
Circuit Voltage 220 V | Circuit 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 | thirty |
10 | 11.0 | fifty | 25.7 | 39 |
16 | 13.2 | 60 | 36.3 | 55 |
25 | 18.7 | 85 | 46.2 | 70 |
35 | 22.0 | 100 | 56.1 | 85 |
fifty | 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 the wire cross section?
Since the wires most often have a round cross-sectional shape, the shear 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 is the core diameter in mm.
Suppose, for example, that the diameter of the wire 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 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, 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.
For any electrical work, you need to remember that electricity does not tolerate neglect and does not forgive mistakes. Electrical safety and reliability - this is what you should always strive for in any work with electrical wiring in an apartment, in a country house or in a house.