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Double checking Air Comp wiring

76carguy

New member
Joined
Jan 11, 2015
Messages
2
Location
St. Paul, MN
Hi everyone! This is my first post, but I've spent loads of time as a viewer.

Recently picked up an older SpeedAir cast iron air compressor off CL. I think I have my wiring figured out, but thought I would ask for a peer review.

I installed 100 amp service last fall and ran 12/2 in the wall. I have a dedicated run for my air compressor outlet that has never been hooked up.

My new comp is 230v single phase. The motor tag says HP=2.98kw. FLA=15.0. SF=1.0. I checked the NEC tables and confirmed using the Motor Branch-Circuit and Voltage Drop Calculator on http://www.electrician2.com/. I should be good to go with my 12/2 and a 20 amp double poke breaker....right? If a 20 amp breaker is not enough at startup can I go bigger with the 12/2 already in the wall? I know there are max % upgrades allowed to cover a motor just not sure I fully understand. Also, the motor says Thermally Protected Manual. Can you help me understand that? The word manual is throwing me off.

In hindsight I wish I'd have run 10/2 for this circuit, but the reality is this comp is bigger than I will ever need. So fingers crossed you agree I'm ok with 12/2!

Thanks everyone!

Anthony
 
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JohnKal

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Mar 24, 2014
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1,801
Location
New York State
I believe Thermally Protected Manual means if it goes off on overload, you must manually reset it. Usually a red button on the side of the motor frame.
 
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sberry

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Jun 18, 2005
Messages
35,747
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Brethren, Michigan
Its thermal so it has its own on board protection. These are often installed on larger circuits with larger breakers and the thermal protects its own internals as well as the incoming cord. It would allow for a 30A breaker on a 12 wire for this unit if needed.
 

sberry

Banned
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Jun 18, 2005
Messages
35,747
Location
Brethren, Michigan
The breaker become an off/n switch and to protect or open during faults (short circuit) The thermal protects it the incoming wire as it will open before it overheats it.
 
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