Teach you three minutes to learn how to estimate the current carrying capacity of wires.

Release time: 2023-10-25

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

1.5 mm²-13A

2.5 mm²-26A 4 mm²-32A

6 mm²-47A 16 mm²-92A

25 mm²-120a

35 mm²-150a

Current conversion power:

1A = 220W,10A = 2200W, and so on.

for example, if the current carrying capacity is 14A copper wire, it is: 220W & times;14=3080W, then the power of 1.5 square copper wire is 3.08 kW.

The long-term current allowed by the national standard:4 square is 25-32A

6 squared is 32-40A

In fact, these are all theoretical safety values, and the limit values are even greater than these.

The maximum power allowed for 2,5 square copper wire is: 5500W.

4 square 8000W,6 square 9000W is no problem.

40A digital meter is normal 9000W, absolutely no problem. The 12000W of machinery will not burn.

Copper core wire allows long-term current:

2.5 mm² (16A to 25A) 4 mm² (25A to 32A)6 mm² (32A to 40A)

Example:

1. each computer consumes about 200~300W (about 1~1.5A), so 10 computers need a 2.5 mm² copper core wire to supply power, otherwise a fire may occur.

2. the power consumption of 3 large air conditioners is about 3000W (about 14A), so one air conditioner needs a separate 2.5 mm² copper core wire to supply power.

3, the current housing into the line is generally 4 mm² copper wire, therefore, at the same time open household appliances should not exceed 25A (I. e. 5500 watts), someone will be replaced with 6 mm² copper wire inside the house is useless, because the wire into the meter is 4 mm².

4, early housing (15 years ago) into the line is generally 2.5 mm² aluminum wire, therefore, at the same time open household appliances should not exceed 13A (that is, 2800 watts).

5. household appliances with relatively large power consumption are: air conditioner 5A(1.2 pieces), electric water heater 10A, microwave oven 4A, rice cooker 4A, dishwasher 8A, washing machine 10A with drying function and electric water boiler 4A.

90% of the fires caused by the power supply are caused by the heating of the joints, so all joints must be welded, and the contact parts that cannot be welded must be replaced in 5 to 10 years (such as sockets, air switches, etc.).

copper wire and cable ampacity standard cable ampacity estimation formula:

multiply 2.5 by nine and go up minus one. Thirty-five times 3.5, both in groups minus 5. Conditions have changed plus conversion, high temperature 10% copper upgrade.

the number of pipes passing through 2 3 4, and the full load current is folded by 87%.

Description:

this formula does not directly point out the current carrying capacity (safe current) of various insulated wires (rubber and plastic insulated wires), but & rdquo; The cross section is multiplied by a certain multiple & rdquo; To express it, it is obtained by mental calculation.

& ldquo; Multiply 2.5 by nine, and go up minus one number & rdquo; What we are talking about is aluminum core insulated wires with various cross sections of 2.5mm2 and below, and their current carrying capacity is about 9 times of the number of cross sections. For example, for 2.5mm2 conductor, the current carrying capacity is 2.5 & times;9=22.5(A). The multiple relationship between the current carrying capacity and the number of cross-sections of 4mm2 and above is arranged upward along the line number, and the multiple is successively reduced by 1, I .e. 4 & times; 8,6 & times; 7,10 & times; 6,16 & times; 5,25 & times;4.

& ldquo; Thirty-five times 3.5, double-group reduction point 5 & rdquo; It is said that the current carrying capacity of 35mm2 conductor is 3.5 times of the number of sections, I .e. 35 & times;3.5=122.5(A). From 50mm2 and above, the multiple relationship between the current carrying capacity and the number of cross sections becomes a group of two wire numbers, and the multiple is reduced by 0.5 in turn. That is, the current carrying capacity of 50,70mm2 conductors is 3 times the number of sections; The current carrying capacity of 95 and 120mm2 conductors is 2.5 times the number of their cross-sectional areas, and so on.

& ldquo; Conditions change plus conversion, high temperature 10% copper upgrade & rdquo;. The above formula is a copper core insulated wire, exposed to the ambient temperature of 25 degrees Celsius under the conditions. If the aluminum core insulating wire is exposed 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 formula calculation method, and then 10% discount can be made. When not aluminum wire but copper core insulated wire is used, its current carrying capacity is slightly larger than that of aluminum wire of the same specification, and the current carrying capacity of one wire number can be calculated according to the above formula method. For example, the current carrying capacity of 16mm2 copper wire can be calculated by 25mm2 aluminum wire.

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