A friend asked about the current carrying capacity of the cable. We mentioned it before. Everyone thinks that it is troublesome through calculation. So this is a decision. Let's summarize it together.
First, the current situation
A square millimeter of copper wire has different amperages under different currents. In theory, the maximum value is 15A, which can be calculated as 9A-13A in normal use.
1 mm2 copper wire:
The overhead line 15A is applied to the wall 11-12A, around the sheath line 9A, and passed through the tube 5-7A.
In other words, there is no problem with a square copper wire with a stable ampacity of 6A.
Therefore, in terms of the current carrying capacity of electric wires, it is relatively easy to cause controversy. It is difficult to calculate a very specific current carrying capacity. Because the environment is different, we generally estimate it for reference. Let us have a bottom in the actual project application center.
Second, the estimation
The current carrying capacity of the cable is determined, and the estimated formula is:
Multiplied by nine and five,
Go up one minus.
Thirty five by three five,
Both groups reduce points by five.
Conditions are subject to change and conversion.
High temperature 10% copper upgrade.
The number of pipes is two, three, four,
It is full of current carrying capacity.
The multiple decreases as the cross section increases.
"Multiplying by two and five times nine and subtracting one from the other" means that aluminum core insulated wires of various cross sections of 2.5 mm 'and below have a current carrying capacity of about nine times the number of cross sections. Such as 2.5mm 'wire, the ampacity is 2.5 × 9 = 22.5 (A). The multiple relationship between the current carrying capacity and the cross section of the conductors from 4mm 'and above is to line up along the line number, and the multiple is decreased by 1, which is 4 × 8, 6 × 7, 10 × 6, 16 × 5, 25 × 4.
"Thirty-five times three point five, both points are reduced by five points," said 35mm.
From 50mm 'and above wires, the multiple relationship between the current carrying capacity and the number of sections becomes two groups of two wire numbers, and the multiple is reduced by 0.5 in order. That is, the current carrying capacity of a 50mm wire is three times the number of sections, that is, 50 × 3 = 150A; the current carrying capacity of a 70, 95, 120mm "wire is 2.5 times its cross-sectional area, and so on.
"Conditions are subject to change and discounts, and high-temperature 10% copper upgrades." The above formula is determined by the aluminum core insulated wire, exposed to the environment temperature of 25 ℃. If the aluminum core insulated wire is applied in an 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 calculation method, and then a 10% discount can be used;
When not using aluminum wire but copper core insulated wire, its current carrying capacity is slightly larger than that of the same specification aluminum wire. You can calculate the current carrying capacity by one wire number larger than that of aluminum wire according to the above-mentioned method. For example, the current carrying capacity of 16mm 'copper wire can be calculated as 25mm2 aluminum wire.
"The number of pipes through which two or three pipes pass is two-three, eighty-six percent full," that is, when two pipes are worn, the current carrying capacity is calculated as eighty percent, three seven percent, and four six percent.
General copper wire ** current estimates are:
The maximum current carrying capacity of a 2.5mm2 copper power cable is about 28A.
The current carrying capacity of the 4mm2 copper power cord is about 35A.
The maximum current carrying capacity of 6 square millimeter copper power cord is about 48A.
The maximum current carrying capacity of a 10mm2 copper power cord is about 65A.
The maximum current carrying capacity of a 16mm2 copper power cord is about 91A.
The maximum current carrying capacity of 25 square millimeter copper power cord is about 120A.
For aluminum wire, the same current carrying capacity, the wire diameter should be 1.5 times that of copper wire.
The general applications are as follows:
1.1.5mm2 --- spot light;
2.2.5mm2 --- sockets, such as air conditioners (1.0p or 1.5P air conditioners), main lighting fixtures, electric water heaters, etc .;
3, 4.0mm2 --- particularly large appliances, household lines, or special occasions, such as cabinet air conditioners. air conditioning. 2.5mm2 wire ** power is at least 3.2KW.
If the on-hook air conditioner is 1.5p, the number of horses refers to the power consumption of the appliance, 1 horse = 1 horsepower = 735W, the total power = 1.5 * 735 = 1102W. Some friends mentioned that using 2.5mm2 wires is also sufficient, but we still recommend using 4.0mm2 wires.
The other is a kitchen, which can be used simultaneously: lighting, range hoods, gas water heaters, disinfection cabinets, refrigerators, and microwave ovens.
If the home bathroom uses an electric water heater, it is also recommended to use a separate 4.0mm2 circuit for the bathroom, which can meet the needs of the bathroom: electric water heater, bath heater, heater, and lighting.
The summary is this picture