how to determine the cable size and type of protection for a particular H.P of a motor?

Question

for example if i have a 30 H.P how will i determine the cable size and type of fuses which will be suitable for it and am talking about the motors used in industries. if posible please let me know the protection for both D.C and A.C motors.

Answer 1

On the data plate of the motor you will find its rated current. (tables are also available from motor manufacturers). Multiply the rated current by 1.25, and look up the wire size from NEC tables on conductors.Your fuses need to be FRS or FRN, depending on the voltage you are using, and are sized to match the wiring DC and single-phase AC motors have 2 current-carrying conductors, while 3-phase motors will have 3 conductors. (Don't forget to incllude a ground wire rated at 1/4 the ampacity of the motor.).The moror circuit must include a circuit-breaker or fusible disconnect at the source, a motor starter rated for the motor HP, and a locking disconnect located within reach or within sight of the motor.

All of this equiipment must be installed by a licensed electrician or under the supervision of a licensed electrician or Engineer.

Sorry to be so nebulous, but there are too many factors you haven't specified for a more specific answer.