How to determine how much wire and cable to use
The current carrying capacity (safety current) of various insulated wires (rubber and plastic insulated wire) is not directly indicated in this section, but is “multiplied by a certain factor” to indicate that it is calculated by mental arithmetic. It can be seen that the multiple decreases as the cross section increases.
"Twenty-five times down to nine, go up one minus one" is said to be 2.5mm' and below various cross-section aluminum core insulated wires, the current carrying capacity is about 9 times the number of sections. For example, a 2.5 mm' wire has a current carrying capacity of 2.5 x 9 = 22.5 (A). The relationship between the current carrying capacity of the wires of 4 mm' and above and the multiple of the number of sections is the upper row along the line number, and the multiple is successively decreased by 1, that is, 4 × 8, 6 × 7, 10 × 6, 16 × 5, 25 × 4.
"Thirty-five times three-five-five, double-group reduction of five points," said that the 35mm" wire current carrying capacity is 3.5 times the number of sections, that is, 35 × 3.5 = 122.5 (A). For wires of 50mm' and above, the multiple of the current carrying capacity and the number of sections becomes a set of two two line numbers, and the multiples are successively reduced by 0.5. That is, the current carrying capacity of the 50, 70mm' wire is 3 of the number of sections. Double; 95, 120mm" wire current carrying capacity is 2.5 times the number of its cross-sectional area, and so on.
"The conditions have been changed and converted, and the high temperature is 90% copper." The above-mentioned port is determined by the aluminum core insulated wire and the bright coating at an ambient temperature of 25 ° C. If the aluminum core insulated wire is applied to the area where the ambient temperature is higher than 25 °C for a long time, the current carrying capacity of the wire can be calculated according to the above-mentioned oral calculation method, and then 10% discount can be used; when the aluminum wire is used, the copper core insulated wire is used. Its carrying capacity is slightly larger than that of the standard aluminum wire. The above-mentioned port method can be used to calculate the current carrying capacity of one line number than the aluminum wire. For example, the current carrying capacity of a 16mm' copper wire can be calculated by 25mm2 aluminum wire.
What does the color of the wire mean?