Below is a summary of the main reference standards for the construction of electric motors:

IEC 72-1  Dimensions and output series for rotating electrical machines

IEC 34-1  Rating and performance

IEC 34-5  Classification of degrees of protection provided by enclosures of rotating electrical machine (IP Code)

IEC 34-6  Cooling methods

IEC 34-7  Classification of types of constructions and mounting arrangements

IEC 34-8  Terminal markings and direction of rotation of electrical machines

IEC 60034-30 Rotating electrical machines, energy-efficiency classes for single-speed, three-phase cage asynchronous motors (IE code)