Information About Electricity
How To Determine The Right Cable Size For 1-Phase!
22 December 2021

The topic of determining the right cable size to use is still a rather unknown subject a lot of people question. If the size is less than the determined capacity, the cable may overheat and end up burning. Whereas, cable sizes that are too large are deemed unsafe and more expensive. To decide the right size of cables to use, here are some tips you may follow.


Tips for Determining the Right Cable Size for 1 Phase!


  1. Find Out The Required Power Capacity

On every electric appliances, you may see its power capacity attached on a name plate. For example, you may see the following image of a name plate attached on a 1-phase motor pump below:


 know the power capacity used


On the name plate, it is written the following: A capacity of 0,75 kW, 230 volt and 5.21 ampere.


  1. Calculating Power To Ampere

The following is an explanation on calculating power to ampere if there is no information regarding ampere capacity on the name plate.


Let’s say we know that the 1-phase motor pump has 0.75 kW.



I = Ampere

P = Power (Watt)

V = Voltage (220 V)


Cos Ø = 0.8

I = 4.26 A

From the following ampere, we are required to use a cable with the conducting capabilities larger by around 125% as a safety factor.


I x 125%

4.26 x 125% = 5.32 A


  1. Deciding The Cable Size

After finding out the ampere with the safety factor, we may now decide the cable size based on the table below:


NO       Cross Section mm²                 Ampere Used 

1          0.75 mm²                                 12 A                 

2          1 mm²                                      15 A                 

3          1.5 mm²                                   18 A                 

4          2.5 mm²                                   26 A                 

5          4 mm²                                      34 A                 

6          6 mm²                                      44 A                 

7          10 mm²                                    61 A                 

8          16 mm²                                    82 A                 

9          25 mm²                                    108 A              

10        35 mm²                                    135 A              

11        50 mm²                                    168 A              

12        70 mm²                                    207 A              

13        95 mm²                                    250 A              

14        120 mm²                                  292 A              


We can now pick a cable that has the capability to conduct a current of 5.35 A, which is a cable with the cross section of 0.75 mm2. Below is a table to calculate a 1-phase motor pump with the known kW:


NO         KW                        Voltage                  Ampere                 Safety Factor 125 %           Cable Cross Section  

1             0.75KW                 220V                      4.26A                     5.33A                                    0.75 mm²                              

2             1.1KW                   220V                      6.25A                     7.81A                                    0.75 mm²                              

3             2.2KW                   220V                      12.50A                   15.63A                                  1 mm²                    

4             2.7KW                   220V                      15.34A                   19.18A                                  2.5 mm²                 

5             3KW                      220V                      17.05A                   21.31A                                  2.5 mm²                 

6             4KW                      220V                      22.73A                   28.41A                                  4 mm²                    

7             5.5KW                   220V                      31.25A                   39.06A                                  6 mm²                    

8             7.5KW                   220V                      42.61A                   53.27A                                  10 mm²                  

9             15KW                    220V                      85.23A                   106.53A                                25 mm²                  

10           18.5KW                 220V                      105.11A                 131.39A                                35 mm²                


This concludes the steps on deciding a cable size to use and how to apply it to daily life. Don’t forget to also pick the right type of cables in accordance to your needs and required capacity. For cable products, make sure you choose Wilson Cables with our range of benefits such as a faster extinguishing rate when burning, 99% pure copper, easy application, and usage of digital printing marking on our products.


Other Interesting Information:

1. Understanding The Function of MCBs and Its Types
2. Understanding The Different Colors of Car Cables And Their Functions
3. Understanding the Difference Between Medium Voltage and Low Voltage
4. How to Calculate KVA to Watts
5. Benefits of Electrical Grounding at Home and How to Install It

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