Wire and cable manufacturers reveal the basic knowledge of wire and cable construction, how much current can the maximum 1mm2 power line pass, how much power? For example, 2.5 square wire, how to calculate the size of the wire to be used in engineering construction?

① For 1.5, 2.5, 4, 6, 10mm2 wires can be multiplied by 5 times its cross section.

② For 16, 25mm2 wire can be multiplied by 4 times its cross section.

③ For 35, 50mm2 wire can be multiplied by 3 times its cross section.

④ For 70, 95mm2 wires can be multiplied by 2.5 times its cross section.

⑤ For 120, 150, 185mm2 wires can be multiplied by 2 times its cross section.

The operating temperature is 30℃, and the carrying capacity under long-term continuous 90% load is as follows:

1.5 square millimeters -- 18A

2.5 sq. mm -- 26A)

4 square millimeters -- 26A

6 square millimeters -- 47A

10 square millimeters -- 66A

16 square millimeters -- 92A

25 square millimeters -- 120A

35 square millimeters -- 150A

Power P= Voltage U x current I=220 volts x 18 amps =3960 watts

National standard GB4706.1-1992/1998 wire load current value (part)

Copper wire: Copper wire cross-sectional area... Allowable long-term current

2.5 square mm (16A ~ 25A)

4 square mm (25A ~ 32A)

6 square mm (32A ~ 40A)

Aluminum core wire: aluminum core wire cross-sectional area... Allowable long-term current

2.5 square mm (13A ~ 20A)

4 sq. mm (20A ~ 25A)

6 square mm (25A ~ 32A)

〖 illustration 〗

1, each computer power consumption is about 200 ~ 300W(about 1 ~ 1.5A), then 10 computers need a 2.5 square mm copper core wire power supply, otherwise there may be a fire.

2, the power consumption of 3 air conditioners is about 3000W(about 14A), then 1 air conditioner needs a separate 2.5 square mm copper core wire power supply.

3, the current housing wire is generally 4 square millimeters of copper wire, so the household appliances opened at the same time should not exceed 25A(that is, 5500 watts), someone will replace the wires in the house into 6 square millimeters of copper wire is useless, because the wire into the meter is 4 square millimeters.

4, the early housing (15 years ago) wire is generally 2.5 square millimeters of aluminum wire, so the household appliances opened at the same time should not exceed 13A(that is, 2800 watts).

5. Household appliances with large power consumption are: Air conditioning 5A(1.2 pieces), electric water heater 10A, microwave oven 4A, rice cooker 4A, dishwasher 8A, washing machine with drying function 10A, electric water boiler 4A In the fire caused by the power supply, 90% is caused by the joint heat, so all the joints should be welded. Contact devices that cannot be welded must be replaced in 5 to 10 years (such as sockets, air switches, etc.).

Long-term current allowed by national standard

4 squared is 25 minus 32A

6 squared is 32 minus 40A

In fact, these are theoretical safety values, the limit value is greater than these.

The maximum power allowed for 2,5 square copper wire is :5500W; 8000W of 4 square, 69000W will be fine.

40A digital meter is normal 9000W is absolutely fine. The 12000W of the machine won't burn.

Copper wire and cable carrying capacity standard cable carrying capacity port:

Estimation formula:

Two and a half times nine, minus one straight up.

Thirty-five times three and a half. Pairs minus five.

Conditions change and convert, high temperature 10% discount copper upgrade.

Through the pipe number two, three, four, eighty-six fold full load flow.

Instructions:

In this section, the current carrying capacity (safety current) of various insulated wires (rubber and plastic insulated wires) is not directly pointed out, but is expressed by "cross section multiplied by a certain multiple" and obtained by mental calculation.

"Two and a half times down to nine, minus one line up" said is 2.5mm and below a variety of cross-section aluminum core insulated wire, its carrying capacity is about 9 times the number of sections.

For example, 2.5mm 'wire, the carrying capacity is 2.5×9=22.5(A).

The multiple relationship between the carrying capacity and the number of sections of the wires from 4mm 'and above is arranged upward along the line number, and the multiple is successively reduced by l, that is, 4×8, 6×7, 10×6, 16×5, 25×4.

"Fifteen times three and A half, double group minus point five", that is, 35mm "wire carrying capacity is 3.5 times the number of sections, that is, 35×3.5=122.5(A).

For conductors 50mm 'and above, the multiple relationship between the carrying capacity and the number of sections becomes two two line numbers into a group, and the multiple is reduced by 0.5 in turn. That is, the carrying capacity of 50, 70mm 'wire is 3 times the number of sections; 95, 120mm "wire carrying capacity is 2.5 times the number of its section, and so on.

"The conditions are changed and converted, and the high temperature copper is upgraded by 10%." The above formula is an aluminum-core insulated wire, and it is arranged at an ambient temperature of 25 ° C.

If the aluminum core insulated wire is placed in the area where the ambient temperature is higher than 25 ° C for a long time, the conductor carrying capacity can be calculated according to the above formula calculation method, and then discounted by 10%; When the use is not aluminum wire but copper core insulated wire, its carrying capacity is slightly larger than the same specification aluminum wire, can be calculated according to the above formula method to increase the carrying capacity of a line number than aluminum wire. For example, the carrying capacity of 16mm 'copper wire can be calculated according to 25mm2 aluminum wire.

Calculate cable carrying capacity Select cable (Select cable according to current) :

The current carrying capacity of the conductor is related to the cross section of the conductor, as well as the material, model, laying method and ambient temperature of the conductor. There are many influencing factors and the calculation is more complicated. The carrying capacity of various conductors can usually be found in the manual. However, with the use of the formula and some simple mental calculation, you can calculate directly, without looking up the table.

1. Formula aluminum core insulated wire carrying capacity and cross section multiple relationship

Ten down five, 100 up two,

25, 35, four, three

70, 95, two and a half times.

Through the tube, temperature, 20%, 10% discount.

Add half of the bare wire.

Copper wire upgrades count.

The current carrying capacity (ampere) of various sections is not directly pointed out, but is expressed by multiplying the section by a certain multiple.

To this end, the nominal cross section (square mm) of commonly used wires in China is arranged as follows:

1, 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185......)

(1) The first formula points out that the aluminum core insulated wire carrying capacity (ampere) can be calculated according to the multiple of the section.

The Arabic digit in the formula indicates the cross section of the conductor (square millimeter), and the Chinese digit indicates the multiple. Arrange the cross section and multiple relation of the formula as follows:

1 to 10 16, 2535, 50, 70, 95120 or more

Five times four times three times two and a half times two times

Now it is more clear to compare with the formula, the formula "10 under five" means that the section is below 10, and the carrying capacity is five times the section value. "100 on two" (read 100 on two) means that the carrying capacity of more than 100 is twice the value of the section. The cross-section of 25 and 35 is four times and three times the boundary. This is the mantra "25, 35, four and three realms". Sections 70 and 95 are 2.5 times as large. It can be seen from the above arrangement that, except for less than 10 and more than 100, the cross section of the middle wire is the same multiple for each of the two specifications.

For example, calculation of carrying capacity of aluminum core insulated wire when the ambient temperature is not more than 25℃ :

When the cross section is 6 square millimeters, the carrying capacity is 30 amps;

When the cross-section is 150 square millimeters, the carrying capacity is 300 amps;

When the cross section is 70 square millimeters, it is calculated as 175 amperage.

It can also be seen from the above arrangement that the multiple decreases with the increase of the cross-section, and the error is slightly larger at the junction of the multiple transformation. For example, section 25 and 35 are four times and three times the boundary, 25 is four times the range, it is calculated as 100 AMps according to the formula, but according to the manual is 97 amps; 35, on the other hand, is 105 AMps according to the formula, but 117 amps according to the table. But it doesn't have much effect on usage. Of course, if you can "have a few things in your mind", when selecting the cross section of the wire, 25 does not let it be full to 100 amps, and 35 can slightly exceed 105 amps, which is more accurate. Similarly, the position of the 2.5 square millimeter wire is five times the beginning end, which is actually more than five times (the maximum can reach more than 20 amps), but in order to reduce the power loss in the wire, the current is usually not so large, and the manual is generally only 12 amps.

(2) The last three phrases are the treatment of condition changes.

"Through the pipe, temperature, 80%, 10% discount" means: if the pipe is laid (including groove plate and other laying, that is, the wire with a protective sleeve layer, unknown exposure), after calculation, then 20% discount; If the ambient temperature exceeds 25 ° C, a 10% discount will be given after calculation. If the temperature exceeds 25 ° C after pipe installation, a 20% discount will be given after 10% discount, or simply a 30% discount will be given once.

As for ambient temperature, it refers to the average maximum temperature of the hottest month in summer. In fact, the temperature is variable, and in general, it does not affect the current carrying of the wire very much. Therefore, only for some temperature workshops or hotter areas more than 25 ° C, consider the discount.

For example, the calculation of the download flow of the aluminum-core insulated wire under different conditions:

When the cross section is 10 square mm, the carrying current is 10×5×0.8═40 a; If the temperature is high, the carrying current is 10×5×0.9═45 a; If the pipe is pierced and the temperature is high, the carrying current is 10×5×0.7═35 A.

(3) For the carrying capacity of the bare aluminum wire, the formula points out that "bare wire plus half" is to add half after calculation. This means that the same section of bare aluminum wire and aluminum core insulated wire compared, the carrying capacity can be increased by half.

For example, the calculation of the carrying capacity of the bare aluminum wire:

When the cross-section is 16 square mm, the carrying capacity is 16×4×1.5═96 amps, if at high temperature, the carrying capacity is 16×4×1.5×0.9=86.4 amps.

(4) For the carrying capacity of the copper wire, the formula points out that "copper wire upgrade calculation", that is, the cross section arrangement of the copper wire is upgraded one level, and then calculated according to the corresponding aluminum wire conditions.

For example, the ambient temperature of the bare copper wire with a cross-section of 35 square mm is 25 ° C, and the calculation of the carrying capacity is: 50 x 3 x 1.5=225 AMps when upgraded to 50 square mm bare aluminum wire.

For cables, there is no introduction in the formula. Generally, directly buried high-voltage cables can be calculated directly using the relevant multiples in the first sentence. For example, the carrying capacity of 35 square mm high-voltage armored aluminum core cable buried in the ground is 35×3=105 AMPs. 95 square mm is about 95×2.5≈238 amps.

The zero line section in the three-phase four-wire system is usually selected as about 1/2 of the phase line section. Of course, it must not be less than the minimum section allowed by the mechanical strength requirements. In a single-phase line, because the neutral line and the phase line pass the same load current, the neutral line section should be the same as the phase line section.

Qingdao Tianxing Cable Co., Ltd. specializes in the production of customized wire and cable manufacturers, exports to more than 40 countries and regions around the world, the annual production capacity of 1 billion yuan. 6000 square meters of storage, standing hundreds of millions of inventory, order demand for rapid distribution and delivery, large prices more favorable. Hotline: 16678668090/ 16678668098