Motor wire size calc

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I have a 150 HP motor @ 460V 177A. Sizing the wire between the controller and the motor I come up with 2/0. Is this correct?
I used 125% X FLC X 58% and multiplied that by 80% derating factor for having 6 current carrying conductors. Did I miss anything or do this right?
 
So this is a Wye start, Delta run ?

I don't think that 430.22(A) applies, so you can discard the 125%. Your circuit conductors on the line side are based on full load current of the motor as determined from 430.6(A)(1). The conductors between the controller and motor are sized at 58% as you indicated. I believe you do have to derate for the 6 current carrying conductors.

I get 104 amps. # 2 THHN is rated at 130 in the 90 deg. column. 80% of that is exactly 104.

Sounds like a good test question.
 
Thanks for the quick response! Yes it is a wye start, delta run. i'll read through section 430 again. Could you tell me why 430.22 (A) doesn't apply?
 
430.22(A) is a general provision. The more specific provision of 430.22(C) would take precedence in this case.

That's my interpretation only. Others may disagree.
 
I've been reading section 430 most of the morning. ( my head hurts!) I still think I need to use the 125% as well. Any other interpretations out there?
 
When you are running in delta, you have two wires connected to each corner of the delta where as in a standard motor you would only have one. This effectively gives you 116%.
Don
 
bdarnell said:
So this is a Wye start, Delta run ? I don't think that 430.22(A) applies, so you can discard the 125%.
Click to expand...
Brad is correct. Brad, that was amazing! How could you tell that was Wye start, Delta run?
 
Thanks for your expert help! I'm going with your interpretation. One thing that I didn't mention is that this is a renovation job, the equipment is already there just being rearranged and the original contractor used 4/0 so I've been trying to figure out why. I'm moving the motor further away and it's still only a 50' run.
Thanks again for your lesson!
 
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