How to choose the cable size for a home electrical network

When constructing a home transaction, in addition to the type of cable or wire, particular attention should be paid to the correctness of the choice of its cross section.

2015-11-24 09:05:34 44

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Why it's so important the value of the cable cross-sections

As is known, the electric current flowing through a conductor increases its internal energy or, more simply, it heats. The amount of energy emitted by the heated conductor, in accordance with the Joule-Lenz law (Q = I2Rt) is proportional to its resistance. Therefore, the larger the resistance value of the conductor, the higher temperature it will heat up. In turn, the resistance of a conductor is inversely proportional to the square of its cross section. It follows a simple and logical conclusion – the smaller cross-sectional area of the conductor, the more heat it will emit when passing through it an electric current. The thickness of current-carrying lived transactions, which is a building of old construction, was designed for lamp lighting and a small number of appliances (TV, fridge, washing machine and iron). Following the emergence of new household electrical appliances and increase their numbers, increased power consumption, which naturally led to an increase in power supply current. Old wiring, consisting of cables of small cross-section, due to the increase of the load on it running in emergency mode, overheating, peregory and even causing fires. This caused mass replacement of old wiring segments or even new construction using larger size cable.

Calculation of cable cross-sections

How to calculate the cable section should be used for decorating your home network? Not to tire readers with complex calculations, just here is a table of the calculation of cable section, flush mounted, made of copper and aluminum wires. In the case of the arrangement of wiring you can use wire with the cross sectional area of less than 20%, but it is better not to skimp on reliability and security, and to use the same values as for the wiring hidden. Data are shown for electric network with voltage of 220 V. Cable cross-section мм2Диаметр conductor, mm Copper Aluminum Current, And Power, kW Current, And Power, kW 1,5 1,38 15 3,3 10 2,2 2,0 1,60 19 4,2 14 3,1 2,5 1,78 21 4,6 16 3,5 4,0 2,26 27 5,9 21 4,6 6,0 2,76 34 7,5 26 5,7 10,0 3,57 50 11,0 38 8,4 16,0 4,51 80 17,6 55 12,1 25,0 5,64 100 22,0 65 14,3 35,0 6,68 135 29,7 75 16,5 50,0 7,98 175 38,5 105 23,1 How to use the table? Here is the calculation of the required cross section of the cable line, in which there are 5 electrical outlets. Assuming that all of them can be simultaneously supplied with 5 appliances with total power consumption of about 5 kW, the table shows that the recommended cable cross section for the arrangement of this line is 2.5 mm2. Based on the same reasons, to connect the chandeliers and other lighting devices will be sufficient cable cross-section 1.5 mm2. Good luck to you! Let you will succeed!


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