Conductor ampacity for overhead crane circuit.

steve61

licensed Electrical Contractor
Location
Nebraska
Occupation
Electrician
I have an overhead crane that I need to run a 460 volt 3 phase circuit to. After doing the amperage calculations and coming up with 46.375 amps ( # 8 thhn in the 75 degree column) I got an actual picture of the crane nameplate showing a required circuit ampacity of 115 amps. With the value of 115 amps, do I need to multiply 115 by 1.25 getting 143.75 amps needing # 1/0 wire or go just with the name plate rating of 115 amps and # 2 wire ? (all amperages from the 75 degree column).
 
crane nameplate showing a required circuit ampacity of 115 amps. With the value of 115 amps, do I need to multiply 115 by 1.25 getting 143.75 amps
I think you need to know how the nameplate required ampacity was calculated. The 125% may already be included like it is for the AC minimum circuit ampacity.
 
See 610.14. I don't think it is that simple.

The nameplate rating at 100% but the wire size might require you to have the duty rating.

Is this just the feeder circuit to a industrial control panel (409.20) or is this to the crane itself?
 
I haven't dealt with Art 610 to be anywhere close to proficient but it certainly appears a #2would more than adequate.
 
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