Cable cross-sectional area
- What is a cross sectional area?
It should be common-sense knowledge that liquids flow through large-diameter pipes easier than they do through small-diameter pipes (if you would like a practical illustration, try drinking a liquid through straws of different diameters). The same general principle holds for the flow of electrons through conductors: the broader the cross-sectional area (thickness) of the conductor, the more room for electrons to flow, and consequently, the easier it is for flow to occur (less resistance).
It is the cross-sectional area of the wire determines its ability to conduct the maximum allowable current, preventing from overheating and causing a fire.
- How to define the cross-section area of the wire?
If you have a bite through of the wire and look at it from the end face, you will see the core of the wire, here is the area of the end face of this core, that is, the area of the circle is the cross section area of the wire. The larger the diameter of the circle, the larger the cross-section of the wire and, therefore, the wire is capable of transmitting a larger current when heated to an acceptable temperature.
As you can see from the formula, by its diameter it’s easy to define the wire cross-section area (circle area). It’s enough to multiply the diameter size upon itself and multiply 0,785.
Calculation example. There is a wire, which diameter is 1.78 mm. Define its cross-section area. 1.78 mm × 1.78 mm × 0,785 = 2,49 mm2 . The diameter of the wire can be defined by slide gauge accurate up to 0.1 mm or by
micrometer calliper accurate up to 0.01 mm.
In multi-wire cords, to calculate the cross-section of a cord, it is necessary to measure the diameter of one cord, calculate its cross section and multiply by the number of wires of the cord.
Calculation example. There is a wire with cords 47*0.26, that is 47 cords, the diameter of each is 0,26 mm. Define its cross-section: 0,26 mm × 0,26 mm × 0,785 × 47 = 2,49 mm2