Answer / abid

Normally for the circuit breaker calculation we multiply our motor's current into 125% for example if a motor 5HP operates in 8amps we multiply8*125%(10) so the breaker size will be 8+10 18amps or 20 amps.
and for the cable size we multiply breakers amp*1.5
=27
so for 5hp 3ph motor suitable breaker is 20amps
and the suitable cable 4sqmm

Answer / naresh

1sqmm will withstand upto 4amps.

(i.e) 1sqmm = 4amps

Answer / sibu

One has to consider the distance of the motor and power supply sources too. In short if the motor distance is let say 400 meters from the power supply then voltage drop will be more and in that case u need to consider bigger size cable then what u find in calculation

Answer / k.l.lim

ex 10kw 3 phase ac motor,
10kw x 1.74 = 17.4 amp
MCB using 25 amp/30 amp 3 pole(C)
Motor using star-delta/overload setting 0.58 = 10.1 amp
cable size = 6x2.5mm2/1c pvc copper cable

if using soft starter
MCB using 25amp/30amp 3 pole MCB(C)
cable size = 3x4mm2/1c pvc copper cable

cable size :calculate include starter overload setting
(right or wrong,thank's)L

Answer / pedro

what's wrong with you guys. You dont even know how to spell
correctly. Please improve on that. Its not only about idea
but also on how you convey it. Damn!

Answer / raja

THE ABOVE SAID IS WRONG , ITS A THUMB RULE I USE TO FALLOW
1 sqmm = 5A & endangering amps withstand is 8A for alu
(sqmm * 1.87A)for cu sqmm *2

Answer / ibrahim

for cooper 2.5 mm for 1 amp
for aluminum 1.5 mm for 1 amp

Answer / hemant

Normally copper has more conductivity than aluminium. So it
is actually reverse. 1.5 mmsqr for copper and 2.5 mm sqr
for alu

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