Select the wire list, how do I select the wire type?

The wire selection table does not have a wire selection formula.

In the installation of electrical distribution equipment, often encounter the problem of wire selection, the correct selection of wire is a very important work, if the cross-sectional area of the wire is small, the electrical load is easy to cause the consequences of electrical fire; If the cross-sectional area of the wire is large, the cost will be high and the material will be wasted. The wire selection formula is introduced for reference when using.

Multiply by nine at 2.5 and subtract one by one straight up. Thirty-five times 3.5, double in a group minus five. The conditions are changed and converted, the high-temperature plus converted copper is upgraded, and the number of pipe threads is two, three, four, eight, seven, and six folds are fully loaded.

This formula does not directly indicate the current carrying capacity (safety current) of various insulation, but "the cross-section is expressed by multiplying it by a certain multiple, and it is obtained by calculation." That is, the multiplier decreases as the cross-section increases.

2.5 times by nine, up minus one in order" means that the current carrying capacity of the following various cross-sectional aluminum core insulated wires is about 9 times the number of cross-sections. For example, the current carrying capacity of the wire is a multiple of the cross-sectional area of the wire of 4mm2 and above, and the relationship is to go up along the wire number, and the multiple gradually decreases by 1, that is, 4 8, 6 7, 10 6, 16 5, 25 4.

Thirty-five times three .five, double and double into a group minus five" is said to be 35mm2 wire current carrying capacity is a multiple of the cross-section, that is, 35 from 50 mm2 more than the wire, the relationship between the current carrying capacity and the number of cross-sections becomes two wire numbers into a group, and the multiples are reduced in turn. That is, the current carrying capacity of 50 70 mm2 wire is 3 times the number of cross-sections; 95 120 mm2 wire current carrying capacity is a multiple of the cross-sectional area; And so on.

The conditions are variable and converted, and the high temperature is converted by nine. It means that if the aluminum core insulation is applied to the area where the ambient temperature is higher than 25 for a long time, the current carrying capacity of the wire can be calculated according to the above formula, and then it will be discounted. If the copper core wire, its current carrying capacity is larger than that of the aluminum core, such as 16mm2 copper wire can be calculated as 25mm2 aluminum wire.

The principle of cable selection is [simple algorithm]:

For wires below 10mm2 (including 10mm2), multiply the cross-sectional area of the wire by 5 is the current carrying capacity of the cross-sectional wire.

The corresponding cross-sectional area of 100mm2 or more is multiplied by 2

16mm mm2 times 4

35mm mm2 times 3

70mm mm2 multiplied.

If the wire is multiplied by the coefficient of the pipe, the total cross-sectional area of the wire is not more than 40% of the cross-sectional area of the pipe) used in high-temperature places within the coefficient of Celsius).

The cross-sectional area of bare wire (such as overhead bare wire) is multiplied by the corresponding magnification and then multiplied by 2 (e.g., 16mm2 wire: 16*4*2).

The above is calculated based on the cross-sectional area of the aluminum wire.

Copper wire upgrade calculation means that the current carrying capacity of copper wire is equal to the current carrying capacity of aluminum wire, and so on.

At present, rubber insulated wires and plastic insulated wires are generally used for indoor wiring; Bare aluminum stranded wire, bare copper stranded wire and steel core aluminum stranded wire for outdoor use; Cables are used where there are special requirements. In order to avoid improper selection, the use of wires must be carefully selected according to the different places of use. Table 6-1 shows the slippery models and places of use of commonly used wires.

3 Marks] The model and place of use of the wire for Changxiang pants Table 6-1 <>