Wiring a compressor

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  #1  
Old 03-03-16, 09:44 AM
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Wiring a compressor

This is my first electrical project. I wanted to confirm that what I'm doing is ok, before I do it.

The info plate on the compressor says its 17.2 amps.

The circuit breaker is 220v, 30 amps

The outlet / receptacle is rated for 20 amps.

The compressor didn't come with a power cable, I bought a 6' length of 12 Gauge wire and a 250v 20 amp plug.

My questions are :
Is 17.2 amps the max amps of the compressor, or is that an average? i.e. Will it go higher at some point, under load, etc?

Is the 20 amp outlet and plug enough to handle 17.2 amps or should I go up to 30 amps?

Thanks
 
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Old 03-03-16, 11:25 AM
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Welcome to the forums.

17 amps would suggest that you have a 3HP 240v motor there. The 17 amps would be the full load amps so running it on #12 and a 20A breaker should be fine.
 
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Old 03-03-16, 01:54 PM
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What does the mfg. recommend for sire size and Max over current protection?
 
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Old 03-03-16, 02:42 PM
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If the compressor motor has a listed HP you need to wire it according to the HP rating of the motor unless the manufacture has provided the circuit size and breaker size. So to get a correct answer you need to see what the listed HP is on the motor data plate. Right off using 17.2 amps X 1.25 = 21.5 amp supply conductor requirement, so that's #10 on a 25A or 30A breaker. And you can't use a 20A plug on a 25A or 30A circuit. Also if the motor happens to be more than 3HP you cannot use a plug and outlet and be NEC compliant, it needs to be hardwired.
 
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Old 03-03-16, 05:37 PM
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At this point... the listed HP would need to be known.

I used table 430.148 which according to the chart.... #12 is ok.
schneider-electric/US/Motor Protection Selection Tables.pdf
 
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Old 03-03-16, 08:00 PM
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430.148 is old. Current table is 430.248. If you are going with 17A then to use #12 the wire needs to be THHN in pipe. If using NM-b it needs to be #10.
 
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