Cable Size for 7.5 KW motor

By applying derating factor as 0.7 to 0.75 to 3Cx4Sq.mm, u may get derated cable ampacity of 30 to 35 amps withstand capacity from the rated value of 40 to 44 amps.

7.5kW rated current is 18 to 20A & starting may be 105 to 112 amps based on yr area rated voltage & starter timing.

So u want to run 1ly for 40M, if it is in air 3Cx4Sq.mm is more than sufficient to run the motor sucessfully, note that u can go upto 120M long there won't be any pbm with the 3Cx4Sq.mm.

Then whatever the cable size u r mentioned as 4Cx10Sq.mm is suitable for 22kW Motor with 40M distance.

Rgds,

Karthick...

Follow a simple rule

"KW and Cable size should be same for a distance up to 300 Feet"

" KW = Size of conductor in mm "

If motor is of 10 KW use cable of size 10mm

If motor is of 5 KW use cable of 6 mm.(5 mm cable is not available so use 6 mm cable)

If motor is 15 KW use cable of 16 mm (15 mm cable is not available)

If motor is of 30 Kw use cable of 35 mm

For one thing, it depends on the voltage of the motor, which was not specified. Half voltage = twice amperage, so rules of thumb that ignore voltage cannot be accurate. Another problem is failing to distinguish between mm and mm².

This is not a mere calculation, anyway. It is more like a decision tree (multicore cable, separate wires in air, in conduit, underground, in company with other conductors, etc.) and looking up in a code table.

you can download a size calculator from the general cable website.

→ British Standard 7671.