I have a 2hp compressor which is labeled Volts 230/115; PH1. The compressor is not going to be used that often. I would like to plug the compressor into an outlet which was used for a clothes dryer at one time. The outlet has a 10/3 conductor connecting it to double breakers which are labeled 30amps each.
What kind of receptacle should I use? And how should I wire it?

What is the amps??

7 amp?

Amps listed on the compressor motor are 11/22

The 11 is for 230v, the 22 is for 115. If you wire for 230 (240) you should use a dble. Pole 15 amp breaker... with a minimum of 14 ga wire. You can use the 10 ga. but you MUST reduce the breaker size for proper protection of the compressor.

The 11 is for 230v, the 22 is for 115. If you wire for 230 (240) you should use a dble. pole 15 amp breaker...with a minimum of 14 ga wire. You can use the 10 ga., but you MUST reduce the breaker size for proper protection of the compressor.

Why must he reduce the breaker size?

So I can use the existing 10 gauge wire, but I would have to change the
Breaker size from 30 amp to 15 amp. Can you tell me how to connect the wires (red, black, white & ground) to the receptacle? I have a receptacle that is rated 20A, 250V. - it has 2 brass screws and 1 green screw. Can I use that?

You can use both the 30A breaker, and #10AWG. In your case, you would cap the white conductor, and use the black, red, and bare copper conductor. Use a device as required per manufacture.

Can you clarify "Use a device as required per manufacture". Is the device the receptacle? And are you referring to the manufacture of the compressor?
Also, does the ground wire connect to the green screw on the receptacle?
And wouldn't I have to lower the breaker size to 15amps to protect the compressor which is rated for 11 amps (as previously mentioned by Missouri Bound)?

Wash,

I thought that you cannot use a 30 amp CB to protect a 15 amp circuit.

Is this a situation where you are allowed to do that because this is a motor circuit?

Wash,

I thought that you cannot use a 30 amp CB to protect a 15 amp circuit.

Is this a situation where you are allowed to do that because this is a motor circuit?


The breaker protects the circuit conductors, NOT the load. So with #10cu a 30A breaker is fine.

If the 15 amp circuit has a fault, how will a 30 amp breaker react in time to prevent damage, fire or explosion on the devices attached to the 30 amp circuit?

If the 15 amp circuit has a fault, how will a 30 amp breaker react in time to prevent damage, fire or explosion on the devices attached to the 30 amp circuit?It is NOT a 15A circuit. It is a 30A circuit.

The motor should have built-in protection. If it does not then it is likely that it would be required, OR it be required to be on a circuit of limited size. This is all based on the motor, not code.

This is NO different than plugging in a .5A desk fan into a 20A general use circuit.

The breaker protects the circuit conductors, NOT the load. Sow with #10cu a 30A breaker is fine.
Stanfortyman,

If I connect a 250v, 20A receptacle to the #10cu should I connect the ground to the green screw, the red & black wires to the brass screws, and then cap the white wire?

Stanfortyman,

If I connect a 250v, 20A receptacle to the #10cu should I connect the ground to the green screw, the red & black wires to the brass screws, and then cap the white wire?Yes, exactly... BUT, if you use a 20A receptacle you MUST then replace the breaker with a 20.

Stan, Thanks for the clarification -

Harris... let me add to the confusion. Your compressor should have a nameplate somewhere on the motor. Voltage, phase, amperage... etc. There should be a FLA number on that plate which will help you determine what size breaker / overcurrent protection the motor requires. When you use a motor starter, often the protection is on the contactor which starts the motor, in the form of an amperage setting. If you are using a 20 amp receptacle with a 20 amp breaker, you will accomplish the same thing. Is there a pressure switch on the compressor or do you have to add one?

Missouri Bound,
There is no FLA number on the nameplate. There is a pressure swithch on the compressor.
Would it make more sense to use a 30 amp receptacle and just leave the 30 amp breaker as is?

The breaker protects the circuit conductors, NOT the load. Sow with #10cu a 30A breaker is fine.

Sorry, I've been busy. Seems stan answered the questions you had of me. Thanks stan!