Reusing starter bucket for new motor feed sizing question.

[MidwestJest141]

I have an existing bucket that supposedly feeds a 3 hp motor. System is 3ph 480v. I want to reuse the bucket to feed a 2hp motor. The magnetic trip breaker currently is a 2 amp mag trip only breaker "ITE ED63A002" the starter is a size 1 Furnas "14DP32AF" I understand that this breaker has an adjustable trip and can be set up for different horsepower's to protect for short circuit. What is the proper way to determine if the mag breaker is suitable for what horsepower's?

 

[MidwestJest141]

My understanding is i need to identify the continuous rating of the breaker along with my max allowable trip rating. For a 2 hp motor at 480 that would be 3.4 amps x 800% = 27.2 amps per 430.52(C)(1). As long as the trip settings allow up to that range and the continuous rating is enough for the fla of the motor, i should be good to use this breaker for a 2 hp motor setup?

 

[ptonsparky]

My understanding is i need to identify the continuous rating of the breaker along with my max allowable trip rating. For a 2 hp motor at 480 that would be 3.4 amps x 800% = 27.2 amps per 430.52(C)(1). As long as the trip settings allow up to that range and the continuous rating is enough for the fla of the motor, i should be good to use this breaker for a 2 hp motor setup?

You don't have to use the max settings. It can be less.

 

[MidwestJest141]

You don't have to use the max settings. It can be less.

Yeah that is my understanding. the documentation for the breaker calls out a range for the fla at .53-2.0 amps so in my opinion it is not capable of the 3.4 amps fla continuous rating for the 2hp motor. It may work but not the best set up for the situation.

 

[topgone]

800% is too much for an inverse time breaker (250%) or a non-time delay fuse (300%), IMO. If it's an instantaneous trip breaker, that setting is fine. It's better to know the inrush current and the possible short circuit current on that motor location and decide the proper protection setting/ breaker size from there.

 

[ptonsparky]

A 2 HP certainly should be able operate if it is replacing a 3.

You need to investigate past what you're told. Trust but verify.