Re: 3 phase 208 motor
I agree with Bob. We usually like to see your attempt at figuring out the answer. Tell us what you have tried to do, and we'll let you know if you're on the right track.
By the way, is there a fused disconnect or other overcurrent device at the motor end of that 150 foot run? If not, if there is just a disconnect device, then you are talking about a "branch circuit," not a "feeder."