Changes to NEMA MG 1-2016 - Motors and Generators


NEMA MG 1-2016 - Motors and Generators


The electric motor is an essential component of many products used in daily life. For example, in the common household kitchen alone, motors are found in microwave ovens, refrigerators, blenders, and even the clocks on ovens. However, as devices providing usable mechanical energy converted from electrical energy, motors can face many challenges. While most motors found in everyday appliances are highly reliable, some have been known to fail due to a variety of reasons, such as over-current, low resistance, overheating, dirt, moisture, and vibrations.

There is no method of completely ensuring that these incidents will never occur, but motors can be correctly assembled and fabricated during the manufacturing stage to reduce the possibility for failure. However, with the plentiful variety of motor types with a wide range of uses, NEMA MG 1-2016  - Motors and Generators has long been a necessity.

NEMA MG 1-2016  - Motors and Generators is intended to assist users in the selection and application of motors and generators. This comprehensive document not only compiles general information on the different types of motors, either by their size, electrical type, application, variability of speed, or methods of cooling, but also covers specifications on electrical current and related components.

Furthermore, this standard covers testing procedures to determine the exact capabilities of fabricated motors. These are expressed through the rating of a machine, which consists of the output (or input, for machines that are designed for absorbing power) power together with any other characteristics, such as speed, voltage, and current.

As a standard for an incredibly important yet varied product, NEMA MG 1-2016  - Motors and Generators has undergone many revisions, with the 2016 edition being the latest edition. And, like the also recently released ANSI/NEMA MW 1-2016 standard, the changes to the 2016 version of the motor standard are identified in the beginning of the document. Broken down by section, these include:

Section II, Part 10


  • 10.40.2: Addition/Revision of Superscripts
  • 10.40.2: Revision of Superscripts from 2 to 1 in items d, and e

Section II, Part 12


  • 12.0: Corrected Hp rating from 120 to 125
  • 12.35.1: Table Revised table to include an additional column (and footnote) for Locked –Rotor kVA Code
  • Table 12-1: Revised to including ½ Hp and by adding additional column (and Footnote) for Locked-Rotor kVA Code
  • 12.42.2 Added notes referencing air-cooling
  • 12.43 Added notes referencing air-cooling
  • 12.58.1 Deleted Superscripts
  • 12.58.2 Revised to accommodate 50Hz efficiency ratings. Addition/Revision of Superscripts
  • 12.60 Revision of title to denote Premium Efficiency
  • 12.60.1 Added Rating to title and deleted paragraph as not applicable
  • 12.60.1.4 Revised paragraph to include 60Hz and included reference to Table 12-16
  • 12.60.2 Revised paragraph for clarity and changed premium efficient to premium efficiency
  • 12.60.3 Revised paragraph for clarity purposes.
  • 12.61 Relocated to follow table 12-21
  • Table 12-14 Corrected table by removing strikeouts in 6 pole efficiency column
  • Section II, Part 14
  • 14.3 Addition of items 9 and 10 under letter a


Section II, Part 18


  • Table 2 of 18.250 Correction of frame designations

Section III, Part 20


  • 20.8 Addition/Revision of notes
  • 20.21.1 Addition/Revision of notes
  • 20.21. A Revision of section for inclusion of 50Hz efficiency and clarification purposes
  • 20.21. C.1 Revised to change premium efficient to premium efficiency
  • 20.21. C.2 Revised to change premium efficient to premium efficiency
  • 20.21. C.3 Revised paragraph for clarity and changed premium efficient to premium efficiency.
  • 20.21. C.4 Deleted paragraph as information is already covered in 20.21.C.1
  • 20.25. C.1 Addition of Superscript 3 and associated note

Section III, Part 21


  • 21.10 Addition of notes related to cooling air
  • 21.28.3 Addition of items 9 and 10 under letter a

Section III, Part 23


  • 23.25.3 Addition of items 9 and 10 under letter a

Section III, Part 24


  • 24.80.3 Addition of items 9 and 10 under letter a

Section IV, Part 31


  • 31.1.3 Addition of items 9 and 10 under letter a
  • 31.4.4.2 Revision/addition of Paragraphs, notes and tables

Section IV, Part 32


  • 32.33.3 Addition of items 9 and 10 under letter a

Section IV, Part 32


  • 33.4.1.2 Addition of items 9 and 10 under letter a

Users should also note that NEMA MG 1-2016  - Motors and Generators also lists the changes made to past revisions of the standard document. To assist compliant users who have either used or are actively using these outdated versions, the standard contains particular markings to identify the specific revision in which a change was made, the symbols for which are clarified in the beginning of the document itself.

NEMA MG 1-2016  - Motors and Generators is now available on the ANSI Webstore.
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