What Is The Wire Square, And How Is The Square Number of The Wire Calculated

1. When we select wires and cables, there are several steps:

1. multiply the rated power of a single load by the required coefficient to get the calculated power, and then sum the calculated power of all the loads, and then multiply by the coefficient at the same time to calculate the current. The result of this calculated current is the basic parameters of matching wire or cable.

2. According to the calculation of the total current, check the table to get the cross-sectional area of the cable or wire.

3. Check the voltage loss according to the length of the cable or wire. In general, the voltage loss of the lighting load wire shall not exceed 10% of the system voltage, and the voltage loss of the motor load shall not exceed 8% of the system voltage. After checking, the start impact current of the maximum power load is replaced into the total calculated current to check again. If found to be not met, increase the cross-sectional area of the wire or cable.

4. Substitute the short circuit current on the power side and check the thermal stability calculation formula of the cable. If it does not meet the thermal stability requirements of the cable, the cross-sectional area of the wire or cable must be increased again.

5. There are overlapping modes when laying the cable, which is related to the heat dissipation of the cable. The installation method is also related to the cross-sectional area of the cable or wire.

2. How do the wires look at the square number?

1, A plate of new wire, the packaging surface will be wired label, need to clearly understand the wire brand, model, wire diameter (the square number of the wire);

2, The swimming ruler can be used to measure the diameter of the wire, and then find the section, the calculation formula of the section: S = RR π (R is the radius of the wire)

① If it is a single core wire, you can measure its diameter, and then get the radius, according to the area formula S= radius * radius * 3.14, the cross-section area of the wire can be calculated, such as the diameter of 1.4mm line, is (1.4÷2)*(1.4÷2)×3.14=1.5386 square 1.5 square (take approximate value)

② Multi-line core combination twisted together multi-core line, can not be used by single core method to calculate, can only be according to the wire of one of the lines to receive the core line, and then multiplied by the number of lines, the formula is S= radius * radius * 3.14 * N (N is the number of twisted into this wire).

3. The square calculation method of wire and cable

The square of the wire is the formula for the circular area: the wire square number (square millimeter) = PI (3.14) the square of the wire radius (millimeter).

Cable size is also square nominal, multiple strands is the sum of the cross-section area of each wire. Calculation formula of cable cross-sectional area: 0.7854 the number of square shares of wire radius (millimeter). For example, 48 strands (0.2 mm per wire radius) 1.5 square line: 0.7854 (0.20.2) 48=1.5 square

If you want to choose the size of the wire, it is generally based on the first according to the power of the electrical appliance to calculate the current (current I= power P / voltage U), and then choose the appropriate wire square according to the current. Conversion relation between square number and current of copper core wire (open assembly):

Safe load flow rate of 1.5 square millimeter copper power cable- -21A;

Safe load flow rate of 2.5 square millimeter copper power cable- -28A;

Safe carrying capacity of 4 square millimeter copper power cable- -35A;

Safe load rate of 6 square mm copper power cable- -48A;

Safe carrying capacity of 10 square mm copper power cable- -65A;