How to choose the section of wires and cables

If the section of wire is chosen less demanded, when passing of current on it it will heat up considerably. Too strong heating threatens with melting of isolation and short circuit. It, in turn, can cause stronger heating and ignition.

Instruction

1. Before choosing the section of the conductor depending on the current passing on it, calculate this current, being guided by the total power of the loadings fed through it. For this purpose in the beginning put capacities of all in parallel of the connected loadings receiving power supply through this conductor, and then divide result into tension. Do not forget to transfer before it if necessary kilowatts to watts, and kilovolts - to volts. Then current will turn out in amperes.

2. Divide the received current intensity into 10 if copper wire, or on 8 if wire aluminum. The result will turn out in square millimeters.

3. If the wire is laid not on the wall, and in pipe, cable box or in wall, increase the received result by the safety factor equal 1.25.

4. Before choosing the section of the conductor depending on the current passing on it, calculate this current, being guided by the total power of the loadings fed through it. For this purpose in the beginning put capacities of all in parallel of the connected loadings receiving power supply through this conductor, and then divide result into tension. Do not forget to transfer before it if necessary kilowatts to watts, and kilovolts - to volts. Then current will turn out in amperes.

5. Remember that to apply wire of bigger section, than it is necessary, it is always possible, and smaller - it is always impossible. If the value of section has turned out too small that the wire was mechanically strong, choose bigger section. But do not do it too big needlessly, otherwise the wire can not be located in box or come off wall under the influence of curb weight.

6. If nearby from two to nine wires are laid, increase result by 1.8 if from ten to twenty - on 2.16.

7. In difficult cases, in particular, at operation of cables in the conditions of the increased external temperatures, use the special tables provided according to the following ссылкам:http://www.radiofan.ru/faq/s2.htmhttp://www.denvo.ru/pub/manual/wire-section.htmlhttp://os-info.ru/montaj/spravochnye-tablicy.html

Author: «MirrorInfo» Dream Team