Welcome to the home of NEMA MW 1000, Magnet Wire, a standards publication of the National Electrical Manufacturers Association (NEMA). This site tells you about MW 1000, how to use it, and gives updates on revisions as they are approved and published.

About NEMA MW 1000

NEMA members that manufacture magnet wire

NEMA contacts

How to Use

Download a copy of ANSI/NEMA MW 1000-2003

Comparisons to international standards

End user information

Revisions to MW 1000-2003

MW 1000-2008

About NEMA MW 1000

MW 1000 is the premier standards publication for general requirements, product specifications and test procedures for the manufacture and packaging of magnet wire.  The first edition was published in 1965.  MW 1000 is a dynamic document that is continually developed and maintained by the NEMA Magnet Wire Section Technical Committee, to ensure that specifications and test procedures reflect evolving magnet wire end user requirements and state-of-the-art magnet wire manufacturing technologies.

MW 1000 is designed to present, in concise and convenient form, all existing NEMA Standards for magnet wire, including standards for round, rectangular, and square film insulated and/or fibrous covered copper and aluminum magnet wire for use in electrical apparatus.  MW 1000 contains the definitions, type designations, dimensions, constructions, performance, and test methods for magnet wire generally used in the winding of coils for electrical apparatus.

MW 1000 is approved as an American National Standard through an accredited canvass of the American National Standards Institute (ANSI), and is endorsed by Electro-Federation Canada (EFC) for use in Canada and by La Asociación de Normalización y Certificación del Sector Eléctrico (Association of Standardization and Certification of the Electrical Sector (ANCE) for use in Mexico.

What is magnet wire?

Magnet wire (also known internationally as winding wire) is an insulated electrical conductor, usually copper or aluminum that when wound into a coil and energized, creates a useful electromagnetic field. Without magnet wire, electricity is essentially useless. Around 90% of all electrical energy requires modification using magnet wire to be of any use.

- top -

NEMA members that manufacture magnet wire

For 2008, the following magnet wire manufacturers are NEMA members:

Condumex–México D.F., México

Bridgeport Insulated Wire Company–Bridgeport, CT

Elektrisola, Inc.–Boscawen, NH

Essex Group, Inc.–Fort Wayne, IN

Magnekon–San Nicolás, NL México

MWS Wire Industries–Westlake Village, CA

Rea Magnet Wire Company–Fort Wayne, IN

- top -

NEMA Contacts

How to Use Your Hard Copy of MW 1000

The white pages make up the Table of Contents for Parts 1, 2, and 3 and the Appendices. The Part 2 specifications are first listed in order according to MW specification number, then by Thermal Class for easy reference to a particular type of magnet wire.

Part 1, in blue deals with general information common to all types of magnet wire found in Part 2, including reference documents, definitions, general material requirements, manufacturing information, test conditions and parameters, thermal class information and ordering information.  Part 1 also includes dimensions in both AWG and equivalent metric sizes (in mm) for bare wire, minimum insulation increase, and overall dimensions for all MW specifications in Part 2.  The only exception to this is MW 16-C, a standalone specification that includes dimensional and other requirements particular to polyimide constructions.

Part 2, in yellow has all of the NEMA specifications for the particular types of magnet wire listed in the Table of Contents, identified and ordered by “MW” number.  The MW number is followed by a “-C” or “-A” to identify the conductor type, copper or aluminum.  These specifications provide all of the performance requirements for magnet wire for various types of coatings and/or coverings. Insofar as possible, the product specifications are complete on one sheet since they are arranged to include only one insulation or covering per sheet. The title identifies the product, for example, MW 15-C, Polyvinyl Acetal Round Copper Magnet Wire, while MW 15-A covers the aluminum version of the same generic product.

Part 3, in green contains the test procedures to be followed and the corresponding tables of specific test values to be attained in determining compliance with the requirements given in Part 2.  The requirements are consolidated with the test procedures and testing parameters for a given property. The Table of Contents provides a useful index of the main test paragraphs, beginning on page viii.

Appendix A, in tan provides a cross-reference between MW 1000 test procedures and those published by the American Society for Testing and Materials (ASTM International).

Appendix B, in tan consists of definitions, requirements, and recommended test procedures for reusable magnet wire packaging, standardized dimensions for spools and reels, and standard formatting for the labeling of magnet wire products.

Appendix C, in tan provides a cross-reference of MW specifications with those published by the International Electrotechnical Commission (IEC), and the J-W-1177 series of Federal Specifications canceled in 1995.

To properly use MW 1000, first, review Part 1 for general information, then locate the specification in Part 2 for the particular type of insulation and conductor of interest.  Part 2 is arranged in MW number order as shown beginning on page ii.  The dimensions for each Part 2 MW type are provided in Part 1 beginning with Table 1-1. The specification in Part 2 will indicate the performance requirements to be met and references the test procedures and corresponding test values to be attained in Part 3.

- top -

Download a copy of ANSI/NEMA MW 1000-2003 with the latest 2008

NEMA offers MW 1000 for download free of charge in a limited use pdf format.  Go here for your copy.

Adobe Acrobat reader is required.  Download the latest version of the reader here if you need one.

This free version of MW 1000 has no navigational enhancements, so we recommend that you also order a hard copy for easier navigation between the various parts of the standard.

- top -

Comparison to international standards

NEMA specifications and test methods differ from those published by the IEC. The following is a general summary of these differences:

Dimensions: NEMA dimensional requirements apply American Wire Gauge (AWG) wire sizing, while dimensional requirements in IEC standards apply metric sizing in mm.  Therefore the requirements are not exactly the same, but some overlap occurs between the standards.

Specifications: Appendix C of NEMA MW 1000 cross-references NEMA and IEC magnet wire specifications.  Not all NEMA specifications have a corresponding IEC specification number and vice versa.

Test Procedures: There is an ongoing effort to harmonize IEC, NEMA and Japanese Industrial Standard (JIS) test procedures.  The following summarizes notable differences in these procedures:

Determination of Dimensions: IEC 60851-2, for determining dimensions, does not recognize the laser micrometer measurement method however this is being proposed in the present amendment cycle for this standard.

Heat Shock: Differences exist between the degree of pre-elongation of wire specimens and the diameter of the test mandrels used for wrapping wire specimens.  However, a resolution to these differences has been proposed within IEC/TC 55 and is being considered at the working group level.

Dielectric Breakdown (for rectangular wire): MW 1000 does not recognize the IEC 60851-5 shot box methodology for determining breakdown of rectangular and large round wires, however such a method is under investigation.

Thermoplastic Flow (Cut Through): The next edition of IEC 60851-6, for thermal properties, will adopt a single-point method of evaluation.  This could be adopted in MW 1000 in the future as a routine test, however for now MW 1000 recognizes a rising-point method as a qualification test.

- top -

End user information

This section contains information applicable to the magnet wire end user

Table of recommended winding wire tensions

Companion NEMA publications:
MW 750, Dynamic Coefficient of Friction of Film Insulated Magnet Wire
MW 765, Reclaiming of Magnet Wire Packaging
MW 785, Simulated Insertion Force Test for Film Insulated Magnet Wire

- top -

Revisions to MW 1000-2003

The following are the revisions to MW 1000-2003 that have been approved, or are pending. Click on the "rationale" link for a summary of why the revision was made.

Revision 1 (publication date June 16, 2005)

Note to clause 1.6.7.1 Rationale

Addition of notes to specifications for paper or tape wrapped magnet wire Rationale

Revision to clause 1.5.1 Rationale

Expansion of MW 15-A and MW 15-C specifications Rationale

Revision to Solubility test procedure Rationale

New MW 37-C and MW 38-C specifications for Polyamideimide over Polyester (amide)(imide) wire Rationale

Obsolete specifications Rationale

Revision to MW 16-C specifications and test procedures with refrigerant R-22 Rationale

Addition of half-AWG wire sizes Rationale

Revision to Adherence and Flexibility and Heat Shock specimen preparation procedures Rationale

Revisions to Completeness of Cure test Rationale

Renamed and reclassified Toluene-Ethanol Compatibility test procedure Rationale

Addition of Quad Build wire requirements for MW 15-C, MW 35-C and MW 73-C specifications Rationale

Modified definition of “self-bonding” Rationale

New MW 130-C, MW 131-C, MW 135-C and MW 136-C specifications Rationale

New Appendix C: NEMA, Canceled Federal J-W-1177, and IEC Magnet Wire Specifications Rationale

Revision 2 (publication date December 12, 2006)

Test requirements for half-AWG size wire Rationale

Revision 3 (publication date August 28. 2007)

Revision to Adherence and Flexibility and Heat Shock specimen preparation procedures Rationale

Specifications for fibrous covered wire Rationale

Addition of note to MW 33-C specification Rationale

New MW 64-C and MW 65-C specifications Rationale

Clarified scrape resistance requirements for Quad Build wire Rationale

Expanded half-AWG dimensions and requirements for 2.5 - 3.5 AWG and 30.5 - 44.5 AWG, to be published in 2008 Rationale

Expansion of MW 15-C and MW 35-C specifications Rationale

Expansion of MW 80-C specification Rationale

Revised Solderbility requirements for MW 29-C, MW 79-C and MW 80-C Rationale

- top -

NEMA MW 1000-2008

MW 1000-2008 will be published around December 20 incorporating all revisions to MW 1000-2003, and in addition, the following amendments:

Clause 1.3, Definitions - addition of terms "thickness" and "width" Rationale

View File

Clause 1.7, Units of Measure - clarification on conversion of dimensional values from inch to millimeter Rationale

View File

Revised Table 1-1 Max ODs for certain full-AWG wire sizes in the 30-46 AWG range Rationale

View File

Part 2 specifications for Polyvinyl Acetal - revised insulation material description Rationale

View File

Clause 3.5.1, Heat Shock - revised specimen preparation procedures Rationale

View File

Clause 3.8.5, Dielectric Breakdown - deletion of Layer Method Rationale

View File

Clause 3.50.2, Thermoplastic Flow - correction to rate of temperature increase Rationale

View File

Clause 3.58, Thermal Endurance - expansion of wire specimen size range from 18 AWG to 10-29 AWG (18 AWG preferred) Rationale

View File

New Appendix D - Formulas for dimensional and performance requirements Rationale

View File