j_braddock
Member
NEC 2002
from another thread i read about 430.52(B) - the motor branch circuit short circuit and ground fault protective device shall be capable of carrying the starting current of the motor.
Where would one find the starting torque of motors or would you use table 430.52 to compute this current?
table 430.151(B) gives the locked rotor current for motors when determining the disconnecting means.
does 430.52(b) and table 430.151(B) imply the wire to the motor also carry this current?
for example, a 3 hp motor at 460 volts is 4.6 amps and 50 ft from the starter. i have seen #14 wire used to power the motor. table 430.151(B) says the locked rotor current is 36.5 amps. i know that #14 is only rated for 15 amps.
we have a wide range of motors at the plant and i would like some guideance on this topic so i may reduce our inventory and assist maintenance with the disconnect sizing and wire size required.
thank you in advance
from another thread i read about 430.52(B) - the motor branch circuit short circuit and ground fault protective device shall be capable of carrying the starting current of the motor.
Where would one find the starting torque of motors or would you use table 430.52 to compute this current?
table 430.151(B) gives the locked rotor current for motors when determining the disconnecting means.
does 430.52(b) and table 430.151(B) imply the wire to the motor also carry this current?
for example, a 3 hp motor at 460 volts is 4.6 amps and 50 ft from the starter. i have seen #14 wire used to power the motor. table 430.151(B) says the locked rotor current is 36.5 amps. i know that #14 is only rated for 15 amps.
we have a wide range of motors at the plant and i would like some guideance on this topic so i may reduce our inventory and assist maintenance with the disconnect sizing and wire size required.
thank you in advance