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Home > News > How to choose cable size in mm² for house wiring application?

How to choose cable size in mm² for house wiring application?


To know what cross section area of the cable should be prepare for a household, we have to know the its maximum electricity demand cable`s max. current carrying capacity.

Current house-service entrance wire generally is 4mm².Therefore, the total amps of household appliances turned on at the same time are should not exceed 25A,which means it ups to 5500w.

Some electrical appliances cost more electricity consumption than others. See as follows:

3 sets Air Conditioner:3000w(estimate14A)

Water Heater:10A


Electric Rice Cooker:4A


Washing Machine with dryer:10A

Electric Switches:4A

Notel: Among fire caused by electrical power,90% is because of joint heat. So all joints need to bewelded. If not,they must be replaced in 5-10years.

copper conductor

For national standard, theoretical long-term working current please see below two as reference:

4mm²:25-32A(max power is 8000w)

6 mm²:32-40A(max power is 9000w)

To a household cable choice, we should take total power of all appliances into consideration. To get the suitable cable wire,we should also know its ma. Current capacity. The calculation to get its current carry capacity should base on below equation:I= w/uxk

IMax. Line Capacitance,its Unit is A

WTotal Domestic Electrical Power,its unit is w

URated Voltage,Unit is V

kSafety Index of Overvoltage,common range is from 1.2 to 1.3

You could calculate the max required electricity in total based on above equation. Then you could also know best option according to max. current capacity of each cross section area cable:

1.P is for Total load of the circuit,also known as total electrical power of endmost terminal set. The unit is KW.

2.U is for Voltage range,U0/U 220/380V.

3.Total current of the circuit, we call it I,I=P/U, its unit is A

4.cable type decision make(copper conductor/aluminum,single core/multicore)

5. X is for current capacity.

6.cross section area=IX

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Michael Huang

Mr. Michael Huang


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