ANSI/NEMA MG 1-2021 Motors and Generators

For over 90 years the NEMA MG-1 Motors and Generators standard has been one of the most commonly used and well-respected standards in the electric motor industry. The big change impacting everyone for 2024 is that you can now download the NEMA MG-1 standard in its entirety for FREE. Prior to this unexpected decision, the most recent update of the NEMA MG-1 occurred in 2021. Many sections and parts of the MG-1 directly apply to electric motor technicians, analysts, and owners.  Some of these include:

  • Section II Part 12 Tests and Performance (Insulation Testing, Locked Rotor, Temperature Rise, Number of Starts, etc.)
  • Section II Part 14 Application Data (Effects of Variation in Voltage on…)

Following are some of the changes from the 2021 revision that may indirectly affect you:

  • Section II, Part 18, “Definite Purpose Machines,” was revised in its entirety, with updated electrical ratings for all applicable special purpose motors and manufacturing requirements for hermetic motors. Its clauses were also renumbered according to specific use motor type.
  • Section IV, Part 30, Revision was made to Voltage Stress requirements.

To download your free copy of NEMA MG-1 2021 go to