What is the cross section – Troubleinthepeace

In the construction and electrical industry, cross-section is one of the parameters that builders need to pay attention to. However, many people do not know what a cross section is, its formula and units of measurement. To learn more about this issue, let’s find out through the article right below!

What is section?

A section is a plane shape obtained when we cut a cube with a plane. The cross-section of that cube is usually about a certain magnitude or a face with a shape.


What is section?

What is the cross-section of an electrical conductor?

The main wire cross-section is a flat shape we get after cutting perpendicular to the core of the conductor. For example: aluminum, copper or aluminum phase copper (excluding wire core).

If you cut directly and perpendicular to the width of the wire, when looking at the end of the wire it will look like a circle. That circular cross-section will be the cross-sectional area. A large cross-sectional area will result in a lower resistance per mm2 even with the same wire type. But this only applies to single-core electrical conductors. In the case of a multi-strand cable, you need to calculate the cross-section of 1 fiber and then multiply it by the number of remaining fibers. The larger the surface area and thickness, the better the cable will conduct electricity.


Speaker wire cross-section

A basic power cable consists of the following three parts:

Conductive part: Made of aluminum or copper, as these are the best conductors of electricity. Insulating part: This part is located in the middle, usually made of natural rubber or PVC synthetic resin. Mechanical protection layer: As for this part, depending on each special working environment such as being submerged in water, alkaline or subject to great impact, there are corresponding materials for this mechanical protection layer.

Currently, on the market, there are many different types of electrical conductors such as: double conductor, single conductor, bare conductor, flexible conductor. And now this is the standard method to compare the conductivity of different cables on the market today. After knowing the cross-section of the conductor, we can easily choose the cross-section of the conduit for cables and wires.

The formula for calculating the conductor cross-section

The cross-section of the conductor is calculated according to the following formula:

S = I/J

In there:

S: Cross-section of conductor (mm2) I: Current flowing through the square section (A) J: Density of allowable current (A/mm2)

The allowable density (J) of copper wire is approximately 6A/mm2.

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The allowable density (J) of aluminum wire is approximately 4.5A/mm2.

The formula for calculating the 3-phase wire cross section, the motor winding cross section or the transformer winding cross section is similar to the above.

For example: How to calculate the electrical wire cross-section for an induction cooker with a capacity of 6KW using 1-phase electricity as follows:

I = 6000 / (220×0.8) = 34.2A

Thus, when I = 34.2, we should choose copper wire with a cross section of S = 34.2 / 6 = 5.7 mm².

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Thus, with an induction cooker with a capacity of 6KW, using single-phase electricity, we should choose a conductor with a core of 6mm as the safest. You can choose Cadivi 6.0 cable, Cadivi wire cross-section is 6mm2, capable of operating at a voltage of 450/750V.

Application of cross section in construction


To calculate the area of ​​columns, beams, foundations, etc., the cross section formula . is applied

In construction, cross-sections are used to calculate diameters for iron and steel or to select preliminary cross-sections of columns and foundations for works.

Different sections will need to use different steel cross-sections. For example, when making windows, you only need to use steel with a small cross section, and when building columns, you should use box steel, and box steel with a cross section of 6 × 6 or 12 × 12. Or when making piles for the foundation of the house, you can use I-shaped steel. Currently, I-steel cross-sections have many types: I steel section 100 x 55 x 4.5 x 6000, 148 x 100 x 6 x 9 x 12000, 150 x 75 x 5 x 7 x 12000,…

In addition, when building a house, depending on the number of floors, people choose appropriate columns, iron and steel. For example, the column cross section of a 3-storey house, the cross-section of a column of a 5-storey house will be different from the cross-section of a column of a 7-storey house.

Selection table of conductor cross-section by current


Table of wire cross-section by current

In addition, you can choose the conductor cross-section according to each work item by basing on the experience or load capacity of each branch in the electrical diagram.

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Conductor cross-sectional lookup table by capacity


Table to select the cross-section of electrical conductors by capacity

Above is information about electricity saving and electricity saving of wires. Hopefully, through this, readers have understood better What is electricity? and apply it effectively in life as well as in work.

Category: FAQ

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