What is the minimum size overload protection required for a 480 volt 3 phase 15hp continuous duty motor
The actual thermal overload heater elements I am using are 21 amps with a Service Factor rating of 1.15. For Service Factor of 1.0 (100% Full Load Current) you can go as low as 18 amps. Use a 30 up to 50 Amp Moulded Case Breaker with Magnetic Overload Protection. Hope this helps.
About 25 amps. If it were me, I would bump it up to 30 amps for a safety margin. You don't want a motor on a hair trigger for over load fault if you can help it.
