Fractional HP AC Motors Wire Size

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Are you wanting to use smaller conductors or larger conductors?

For NEC covered installations in general 14 AWG is the smallest you can use. You may find same size motor as part of listed equipment that does have smaller conductors - but it is tested and listed and is not subject to NEC.

310.106 tells us the minimum size conductor for 0-2000 volts is 14 AWG copper and 12 AWG aluminum, except where elsewhere permitted in the code.

430.21 supports what I mentioned above on listed equipment where it says:

The provisions of Articles 250, 300, and 310 shall not apply to conductors that form an integral part of equipment, such as motors, motor controllers, motor control centers, or other factory-assembled control equipment.
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Then there is 430.22(G) that does allow less then 14 AWG with some conditions:

(G) Conductors for Small Motors.
Conductors for small motors shall not be smaller than 14 AWG unless otherwise permitted in 430.22(G)(1) or (G)(2).

(1) 18 AWG Copper.

Where installed in a cabinet or enclosure, 18 AWG individual copper conductors, copper conductors that are part of a jacketed multiconductor cable assembly, or copper conductors in a flexible cord shall be permitted, under either of the following sets of conditions:
The circuit supplies a motor with a full-load current rating, as determined by 430.6(A)(1), of greater than 3.5 amperes, and less than or equal to 5 amperes, and all the following conditions are met:
The circuit is protected in accordance with 430.52.
The circuit is provided with maximum Class 10 or Class 10A overload protection in accordance with 430.32.
Overcurrent protection is provided in accordance with 240.4(D)(1)(2).
The circuit supplies a motor with a full-load current rating, as determined by 430.6(A)(1), of 3.5 amperes or less, and all the following conditions are met:
The circuit is protected in accordance with 430.52.
The circuit is provided with maximum Class 20 overload protection in accordance with 430.32.
Overcurrent protection is provided in accordance with 240.4(D)(1)(2).

(2) 16 AWG Copper.


Where installed in a cabinet or enclosure, 16 AWG individual copper conductors, copper conductors that are part of a jacketed multiconductor cable assembly, or copper conductors in a flexible cord shall be permitted under either of the following sets of conditions:
The circuit supplies a motor with a full-load current rating, as determined by 430.6(A)(1), of greater than 5.5 amperes, and less than or equal to 8 amperes, and all the following conditions are met:
The circuit is protected in accordance with 430.52.
The circuit is provided with maximum Class 10 or Class 10A overload protection in accordance with 430.32.
Overcurrent protection is provided in accordance with 240.4(D)(2)(2).
The circuit supplies a motor with a full-load current rating, as determined by 430.6(A)(1),^ of 5.5 amperes or less, and all the following conditions are met:
The circuit is protected in accordance with 430.52.
The circuit is provided with maximum Class 20 overload protection in accordance with 430.32.
Overcurrent protection is provided in accordance with 240.4(D)(2)(2).
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Also, 430.22(G) mentions the conductors in a cabinet or enclosure, I'm really wanting to use the 16AWG wire from the motor to the enclosure(field wiring) on my food packaging machine. Any mention of that?

Thanks!
 
Hi, I'm not sure if my last post submitted? I'm looking to use 16AWG wire from the motor to the electrical enclosure, is there an exception for that? Please let me know if my reply went through.

Thanks,
Kilowatt76
 
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Kilowatt76 said:
Also, 430.22(G) mentions the conductors in a cabinet or enclosure, I'm really wanting to use the 16AWG wire from the motor to the enclosure(field wiring) on my food packaging machine. Any mention of that?

Thanks!
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I honestly don't know what they intend with that section.

It says "Where installed in a cabinet or enclosure..." but never clarifies if that is supposed to mean where the conductors are in the cabinet or enclosure (which I am leaning towards based on title of section/subsections) or if it supposed to mean the motor is in the cabinet or enclosure. Based on it meaning the conductors are in the cabinet - I'd say that means motor conductors in a field constructed control cabinet can be 16 AWG but conductors that leave the cabinet to go to the motor still need to be 14AWG minimum. A listed control cabinet would follow listing requirements instead of NEC.
 
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