Steamdonkey2011
Member
- Location
- Boise, Id
I'm working on a project where the owner wants to use a spare VFD (rated 150HP 480V 180A) to replace an FVNR starter that controls a well pump (100HP 460V 127FLA). The feeder conductors to the motor starter are #3/0 copper and the upstream overcurrent protection is a 200A fused disconnect. Using the 75 deg. ampacity table and no adjustment factors it appears the #3/0 conductors are rated for 200A, which is short of the 225A (125% of 180A) required by NEC 430.122(A). So the question is.... Do I have to replace the #3/0 feeder conductors with #4/0 even though they're protected by 200A fuses?