# Sizing Breaker for Air Compressor



## CES (Jan 18, 2013)

I have a single phase 240volt 3.5 hp air compressor that is thermally protected is a 50amp breaker the correct size for fault protection.


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## HARRY304E (Sep 15, 2010)

CES said:


> I have a single phase 240volt 3.5 hp air compressor that is thermally protected is a 50amp breaker the correct size for fault protection.


Does it have the amp rating on the name plate?

I'm pretty sure a 20 amp circuit is all you need.


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## papaotis (Jun 8, 2013)

HARRY304E said:


> Does it have the amp rating on the name plate?
> 
> I'm pretty sure a 20 amp circuit is all you need.


 that sounds right to me, also


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## ponyboy (Nov 18, 2012)

yeah but he can go 250% over FLC. there are a lot of right answers to this question


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## varmit (Apr 19, 2009)

A 50 amp breaker sounds about right to me. That would be close to 200% FLA.


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## CES (Jan 18, 2013)

Going by the NEC table it lists 3 and 5 hp. I believe the flc for 3hp was 17amps @ 250 percent came out to 42 amps, allowing for the other 1/2 hp I was hoping a 50 would do it,


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## ponyboy (Nov 18, 2012)

CES said:


> Going by the NEC table it lists 3 and 5 hp. I believe the flc for 3hp was 17amps @ 250 percent came out to 42 amps, allowing for the other 1/2 hp I was hoping a 50 would do it,


you can actually size inverse time breakers up to 400% if the FLC is less than 100 amps. this is done when the 250% isn't enough to withstand the inrush current. probably not going to apply to your application but it's good information to have


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## Pete m. (Nov 19, 2011)

ponyboy said:


> you can actually size inverse time breakers up to 400% if the FLC is less than 100 amps. this is done when the 250% isn't enough to withstand the inrush current. probably not going to apply to your application but it's good information to have


Show off!.. :thumbup:

Pete


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## don_resqcapt19 (Jul 18, 2010)

Is that the actual horsepower on the motor factory nameplate or is it the inflated horsepower marked on the compressor and used for advertising purposes?


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## John Valdes (May 17, 2007)

ponyboy said:


> you can actually size inverse time breakers up to 400% if the FLC is less than 100 amps. this is done when the 250% isn't enough to withstand the inrush current. probably not going to apply to your application but it's good information to have


Code reference please.


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## ponyboy (Nov 18, 2012)

John Valdes said:


> Code reference please.


430.52(A)(1) exception 2(c)


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