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Motor nameplate letter code designations

Pumps & Systems
Publication date: 
May 2013
Tom Bishop, P.E., EASA Senior Technical Support Specialist

The nameplates of alternating current (AC) motors built to National Electrical Manufacturers Association (NEMA) standards reference a system of alphabetical letters that designate the principal characteristics of each motor—code, design and insulation class. Though critical to proper motor selection, these designations are easy to misinterpret.