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If you have a 100amp service to your disconnect and the new controller manufacturer is recommending 45 amp. What size should the disconnect fuses be ?

https://m.littelfuse.com/~/media/electrical/application-notes/littelfuse-motor-protection-guide.pdf

https://www.elliottelectric.com/Sta...otor-protection-using-horsepower-hp.aspx

https://www.elliottelectric.com/Sta...ection-using-full-load-amps-current.aspx

Thank you.

Usually the controller manufacturer will list the mainline disconnect size on the print. In your case they are probably calling out a 45 amp disconnect so 45 amp fuses. They should of calculated this load off of your survey of the equipment being modded. What equipment and controller are you going with?

Alpha Controller
Canton Power Unit.
480v
25 HP motor.
I think FLA was 33.9
75fpm