Motor Breaker Sizing...

[cfordyce]

Quick question. Can I put a 40A Breaker on a 20HP rated Inverter driving a 20HP fan motor??? The Inverter is an Allen Bradely 1336 Plus 2 model.

Also, is RWU90 #10 wire OK?

 

[dpc]

What voltage?

(#10 AWG cannot be used with a 40A breaker)

 

[cfordyce]

OK sorry. you're right. #10 is only good for 30 A. I have 32.5 FLA. so I need #8 wire. I will fuse at 30A (TD) and my breaker can be sized up to 60 A according to CE Code. I think I figured it out... I asked question before trying to find answer myself.

 

[jbartos]

Suggestion:
1. The circuit length is normally given a consideration for allowable voltage drop.
2. 32.5 FLA x 1.25 = 40.625 A. Therefore, the conductor next size is appropriate, e.g. #6AWG @60°C, 55A.
3. Check with the manufacturer for the recommended protection for the drive.