Gearing Solutions Blog

Electric Motors, NEMA vs IEC

When measuring anything, some use the metric system, and others use the imperial system. The metric system is used in most parts of the world, while the imperial system is used in the U.S. These two standards of measurement can be applied to anything we use. Likewise, we have two standards for electric motors: the National Electrical Manufacturers Association (NEMA motors) and the International Electrotechnical Commission (IEC motors).

NEMA is the North American standard for electric motors. NEMA is the publisher of NEMA MG 1-2014, a book that defines the manufacturing standards for alternating-current (AC) and direct-current (DC) motors in North America. The IEC is the standard for electric motors for the rest of the world. Similar to NEMA, IEC publishes Standard 60034-1:2010, the standard outside North America.

NEMA and IEC motors are similar in size, efficiency and output power. Both also have standards in place to designate various frame sizes, in only one case will you find both systems using the same nomenclature, that is for the 56 frame, but actually that has different meanings. IEC’s 56 frame is what we’d call a subfractional motor, while NEMA’s 56 frame is our most common, covering ¼ to 1 ½ HP. To add to the confusion IEC uses kilowatts and NEMA uses horsepower. IEC uses millimeters and NEMA uses inches.

The best way to convert one to the other is by using the following: To obtain equivalent HP multiply the KW rating by 1.358. To obtain equivalent KW multiply the HP rating by 0.7457. To convert millimeters to inches multiply by 0.03937. To convert inches to millimeters multiply by 25.4.

We can help you with adapters that can fit both configurations. Our Flexframe Motor Adapters have a replaceable motor faceplate mount, face flange mounts are available for vertical configurations. Interchangeable with NEMA and IEC motors, add GS shaft adapters to accommodate a wide range of shaft sizes. We can resolve the majority of problems faced when trying to interface NEMA and IEC components. Just fill out our web questionnaire at or call us at 440-498-9538.

Experience the Gearing Solutions MaxaMin System, visit our website or call us today at 440-498-9538


5905A Harper Road
Solon, OH 44139

+1 440-498-9538
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