NEMA (National Electrical Manufacturers Association) standards provide detailed specifications and guidance for the production and application of magnet wire.
Requirements for magnet wire in NEMA standards:
Thermal Class: NEMA standards specify the thermal ratings of insulated magnet wire, which are typically indicated by temperature indices such as 105°C, 130°C, 155°C, 180°C, 200°C, 220°C, and 240°C.
Types of Enamelled Wire: NEMA standards cover various types of enamelled wires, including straight solderable polyurethane enamelled wire, polyester enamelled wire, polyamide enamelled wire, polyvinyl butyral enamelled wire, polyimide enamelled wire, etc.
Insulation Layers: The insulation layer of magnet wire can be thin, thick, heavy, or extra thick, and can consist of a base coat/over coat/bond over coat.
Round and Flat Wire: NEMA standards include specifications for both round (Round Build) and flat and rectangular (Rect & Sq. – Build) wires.
Self-bonding Layer: Some magnet wire products have a self-bonding layer to facilitate fixing and shaping after winding.
Composite Enamelled Wire: NEMA also specifies the standards for composite enamelled wires, such as polyester (amide) (imide)/polyamide composite enamelled wires.
Special Purpose Enamelled Wire: NEMA standards also include specifications for special purpose enamelled wires, such as corona-resistant enamelled wires and self-bonding enamelled wires.
Safety and Performance: NEMA standards ensure the safety performance and electrical characteristics of magnet wire, including resistance to voltage, thermal shock, and mechanical strength.
Testing and Certification: NEMA standards also cover testing methods and certification procedures for magnet wire to ensure that products meet specified performance and safety requirements.
International Cooperation: NEMA participates in the development of international standards, such as IEC and ISO, and coordinates North American electrical standards through CANENA to facilitate the entry of members’ products into the international market.
| Thermal Class | Film Insulation, Coating, Covering, and Form | Aluminum | Copper |
| 105 | Polyvinyl Acetal | MW 15-A | MW 15-C |
| 105 | Polyvinyl Acetal and Self-bonding Overcoat | – | MW 19-C |
| 120 | Polyvinyl Acetal | MW 86-A | |
| 120 | Polyvinyl Acetal | MW 86-C | |
| 120 | Polyvinyl Acetal | MW 87-A | |
| 120 | Polyvinyl Acetal | MW 87-C | |
| 130 Solderable | Polyurethane Overcoated with Polyamide | MW 28-A | MW 28-C |
| 130 Solderable | Polyurethane | – | MW 75-C |
| 130 Solderable | Polyurethane with Self-bonding Overcoat | – | MW 130-C |
| 130 Solderable | Polyurethane Overcoated with Polyamide and Self-bonding Overcoat | – | MW 135-C |
| 155 | Polyester | – | MW 5-C |
| 155 | Polyester (amide)(imide) Overcoated with Polyamide | MW 24-A | MW 24-C |
| 155 Solderable | Polyurethane | – | MW 79-C |
| 155 Solderable | Polyurethane Overcoated with Polyamide | MW 80-A | MW 80-C |
| 155 Solderable | Polyurethane with Self-bonding Overcoat | – | MW 131-C |
| 155 Solderable | Polyurethane Overcoated with Polyamide and Self-bonding Overcoat | – | MW 136-C |
| 180 | Polyester (amide)(imide) | – | MW 30-C |
| 180 | Polyester (amide)(imide) Overcoated with Polyamide | MW 76-A | MW 76-C |
| 180 | Polyester (amide)(imide) Overcoated with Polyamideimide and Self-bonding Overcoat | MW 102-A | MW 102-C |
| 180 Solderable | Polyester (imide) | – | MW 77-C |
| 180 Solderable | Polyester (imide) Overcoated with Polyamide | – | MW 78-C |
| 180 Hermetic | Polyester (amide) (imide) | – | MW 72-C |
| 180 Solderable | Polyurethane | – | MW 82-C |
| 180 Solderable | Polyurethane Overcoated with Polyamide | – | MW 83-C |
| 180 Solderable | Polyurethane Fully Insulated FIW Zero-De- fect Insulated Round Copper Wire for Solder- able Applications | – | MW 85-C |
| 180 Solderable | Solderable Polyurethane with Self-bonding Overcoat | – | MW 132-C |
| 180 Solderable | Solderable Polyurethane Overcoated with Polyamide and Self-bonding Overcoat | – | MW 137-C |
| 200 | Polyester (amide) (imide) Overcoated with Polyamideimide | – | MW 35-C |
| 200 | Polyester (amide)(imide) | – | MW 74-C |
| 220 Hermetic | Polyester (amide)(imide) Overcoated with Polyamideimide | MW 73-A | – |
| 220 | Polyester (amide)(imide) Overcoated with Polyamideimide | – | MW 37-C |
| 220 | Polyester (amide)(imide) | MW 74-A | – |
| 220 | Polyamideimide | MW 81-C | |
| 240 Hermetic | Polyimide | – | MW 16-C |
| 105 | Polyvinyl Acetal | MW 18-A | MW 18-C |
| 200 | Polyester (amide)(imide) Overcoated with Polyamideimide | – | MW 36-C |
| 220 | Polyester (amide)(imide) Overcoated with Polyamideimide | MW 36-A | – |
| 220 | Polyester (amide)(imide) Overcoated with Polyamideimide | – | MW 38-C |
| 220 | Polyamideimide | MW 84-C | |
| 240 | Polyimide | – | MW 20-C |
| 90 or 105 | Paper Covered | MW 31-A | MW 31-C |
| 155 | Glass Fiber Covered | – | MW 41-C |
| 155 | Polyester Glass Fiber Covered | – | MW 45-C |
| 180 | Glass Fiber Covered, High-Temperature Organic Varnish Treated | – | MW 50-C |
| 180 | Polyester Glass Fiber Covered, High-Temper- ature Organic Varnish Treated | – | MW 51-C |
| 200 | Glass Fiber Covered, Silicone Treated | – | MW 44-C |
| 200 | Polyester Glass Fiber Covered, Silicone Treated | – | MW 47-C |
| 220 | Aromatic Polyamide Paper Covered | MW 61-A | MW 61-C |
| 240 | Aromatic Polyimide Tape Covered | MW 65-A | MW 65-C |
| 90 or 105 | Paper Covered | MW 33-A | MW 33-C |
| 155 | Glass Fiber Covered | – | MW 42-C |
| 155 | Polyester Glass Fiber Covered | – | MW 46-C |
| 180 | Glass Fiber Covered, High-Temperature Organic Varnish Treated | – | MW 52-C |
| 180 | Polyester Glass Fiber Covered, High-Temper- ature Organic Varnish Treated | – | MW 53-C |
| 155 | Dimensions for Double Polyester Glass Fiber Covered | MW 54-C | |
| 155 | Dimensions, Radii, and Cross-Sectional Area for Standard | MW 55-C | |
| 200 | Glass Fiber Covered, Silicone Treated | – | MW 43-C |
| 200 | Polyester Glass Fiber Covered, Silicone Treated | – | MW 48-C |
| 220 | Aromatic Polyamide Paper Covered | MW 60-A | MW 60-C |
| 240 | Aromatic Polyimide Tape Covered | MW 64-A | MW 64-C |