Urgent: Cable size calculation

[Walid_Abid]

Good afternonn,​

these are the motor and circuit data:

Motor power: 0.37kW,
Nominal current: I= 0.8 A
voltage: 415 V,
cable length = 80m
ambiant temperature: 50°C
​

Maximum voltage drop percentage =415*4% =16.6V

According to the Bahraini Regulations:
- temprature factor= 0.89
- core factor (3core cable)= 0.7

This is the calculation I did:
- target current=I/(0.89*0.7)=1,29A ==> 1,5A
when I check the current rated table, the suitable cable section will be 1.5mm but our contractor us a 2.5mm cable (I must verify his choice and prove that it's correct and submit the calculation to our consultant at least tomorrow morning!!!!)

According to the current rated table, we get:
for the cable section: 2.5mm ==> current rating= 33A and Voltage drop /amp/m= 16

but when I calculate the Voltage drop /amp/m for my circuit, I find:
mV= dV*1000/(target current *L)= 16.6V*1000/(1,5A*80m) = 138,33mV >16 (from the table)

Now, what I have to do?
I don,t know how to proceed and finalize the calculation!!

I have to make the verification for 20 different equipments with power variying between 0.37 and 48A!
Would you please help me and show me how to continue with the remainder calculation?

Your help is extreamly needed, I'am really blocked.
Thank you

 

[trev]

Walid, you're in Bahrain unless one of us has experience of the wiring regulations in force there you'll be getting information based on the UK wiring regs which might not be much good to you. You'll be better off consulting an electrician nearby