Winding engineers and transformer manufacturers are looking for a magnet wire that retains its electrical insulating qualities during long-term exposure to high electrical stress and an elevated thermal load not one that fails after hundreds of running hours. The 5.5mm x 1.6mm heavy duty insulated enameled rectangular copper magnet wire provides high dielectic, thermally resilient winding conductor designed for the most strenuous electromagnetic environments. This guide includes all technological parameters, application advice and selection guidelines.
What Is Enameled Rectangular Copper Magnet Wire?
Rectangular enameled copper magnet wire is a solid copper conductor with a rectangular cross-section that is coated with a number of layers of thermally cured enamel. Magnet wire is used for the windings of transformers, motors, inductors and generators. The rectangular profile allows for a greater conductor packing density in winding slots leading to a higher slot fill factor than would be achieved using a round wire with the same cross-sectional area.
The specified 5.5mm x 1.6mm relates to bare conductor width and height before insulation. Heavy duty ( Grade 2 or double build) insulation refers to the enamel wall thickness when compared to Grade 1 build enamel being about 60–80% greater. This is to give the wire higher dielectric withstand voltage and improved mechanical protection when wound.
And this wire is the conductor of choice where power density is critical, where operation must be continuous at high temperature, and where a long life with minimal insulation deterioration is desired.
Key Specifications & Technical Parameters
| Parameter | Value / Range |
| Conductor material | Electrolytic tough-pitch (ETP) copper, ≥99.9% IACS |
| Nominal conductor width | 5.5 mm |
| Nominal conductor height | 1.6 mm |
| Insulation build | Heavy / Grade 2 (double build) |
| Insulation type | Polyesterimide / Polyamideimide (PAI) overcoat |
| Temperature index | 180°C, 200°C |
| Dielectric breakdown voltage | ≥6,000 V (per IEC 60317) (verify with LP Industry) |
| Conductor conductivity | ≥99.9% IACS |
| Elongation at break | ≥25% |
| Tensile strength | 200–280 MPa |
| Corner radius (bare) | Per IEC 60317-13 (typically 0.3–0.8 mm) |
| Standard spool weight | 30 kg, 60kg, 90kg, 110kg(verify with manufacturer) |
| Applicable standards | IEC 60317-13, NEMA MW 1000, GB/T 7672 |
Core Benefits of Heavy Duty Insulation Build
Dielectric withstand at high -> Grade 2 insulating wall provides breakdown voltage of 6,000 V allowing for decreased turn-to-turn failure risk in HV transformer windings.
If realize extended thermal endurance (from F grade to Class 200 temperature index support continuous operation at 200DC (compact design can be made with higher power density without derating.
Higher slot fill factor: Rectangular conductor profile results in 20-30% more copper fill in winding slots compared with equivalent-section round wire, which directly enhances efficiency.
Enhanced mechanical protection -> The slighter enamel wall has higher winding tension-withstand capability and lubricating flange wear-ability while no cracking of the insulation.
Chemical/ moisture resistant -> Cured polyamideimide top coat is resistant to ingress of transformer oil, coolants and moisture over the entire service life.
100% spark-tested continuity -> In-line dielectric testing at line speed assures that zero pinholes or voids make to the spool – thereby no post-winding insulation failures at installation.
Applications & Use Cases
The rectangular profile of 5.5mm x 1.6mm is designed to be appropriate for medium-to-large winding cross-sections, and can be used in any application where both high current capacity, small winding geometry and thermal stability are needed.
Typical applications include:
Power transformers (mainly for primary and secondary windings) LV and MV (up to 33 kV class) distribution transformers.
Traction Motor Stator Windings For electric vehicle (EV) and hybrid drivetrain motor applications that demand Class 200 thermal performance.
Field and armature windings of industrial motors Motors for use in motors, pumps, compressors, and fans high efficiency IE3/IE4 class motors
High-frequency inductors and chokes4.7.2.3 Power electronics filter inductors working at high ambient temperature.
Generator rotor and stator windings. Wind turbine generators and industrial alternators
Solenoid and electromagnetic coils Heavy duty industrial actuators with sustained duty cycles
Welding Transformer Windings High Current Secondary Windings for resistance and arc welding equipment.
Railway traction equipment Locomotive auxiliary transformers and traction motor armatures
Heavy Duty vs. Standard Build Insulation — Comparison
| Parameter | Standard Build (Grade 1) | Heavy Duty Build (Grade 2) |
| Insulation wall thickness | 1× (baseline) | ~1.6–1.8× baseline |
| Typical dielectric breakdown | ≥4,000 V | ≥6,000 V |
| Mechanical abrasion resistance | Good | Excellent |
| Max operating temperature | Class 155–180 (typ.) | Class 180–200 (typ.) |
| Winding tension tolerance | Moderate | High |
| Best use case | Low-voltage coils, gentle winding | HV transformers, EV motors, automated winding |
| Slot fill efficiency | Slightly higher | Slightly lower (thicker wall) |
| Unit cost | Lower | 5–12% higher |
Select Heavy Duty (Grade 2) if your design demands higher voltage dissipation, greater thermal endurance or machine winding with high tension and abrasion. Go for Standard (Grade 1) if problem is primarily slot fill and conditions are mild.
Compliance & Certifications
IEC 60317-13 enameled rectangular copper conductors (25mm2 and above) with a temperature index of 200 degreesC. Required standard for purchase in international trade.
NEMA MW 1000 North American standard specifying dimensional tolerances, dielectric strength and thermal endurance specs. Necessary for projects intended for shipment to the US and Canada.
GB/T 7672 Chinese national standard for enameled rectangual copper conductors. (Need for CFIUS compliant supply chains, and China-market products.)
RoHS 2 / REACH SVHC compliant – Confirms that the formulation of the enamel is not contaminated by any restricted hazardous substances. Mandatory on CE marked end products in the EU.
UL Recognized Component (check with manufacturer) UL recognized under the Magnet Wire category (OBJY2) facilitates the end product UL listing.
Frequently Asked Questions
Q: What temperature class is heavy duty enameled rectangular copper magnet wire?
A: Heavy duty, enameled, rectangular copper magnet wire is generally rated at Class 200. The Class 200 °C rating indicates that the wire can operate continuously at 200°C. This value is a measure of the overall thermal capability of the polyesterimide coating system, tested to IEC 60317 thermal aging tests. Verify the temperature index on the manufacturer‘s test certificate before specifying.
Q: What is the difference between grade 1 and grade 2 (heavy duty) building of insulation?
A: Grade 2 (heavy duty) insulation provides an enamel wall (about 60–80% thicker than Grade 1 (standard build)) offering a higher dielectric breakdown voltage (usually 6,000 V as opposed to 4,000 V) and effective mechanical abrasion resistance to winding during manufacture. It is recommended for high-voltage transformer windings and automated winding processes that impose additional mechanical forces on the conductor.
Q: How do I remove the enamel coating from 5.5mm x 1.6mm heavy duty rectangular wire?
A: For polyamideimide heavy duty coating, thermal stripping, a resistive contact stripping tool set at 400–450 degrees C is the preferred method of removal. Thermal stripping will remove the coating cleanly without scoring the surface of the copper. However mechanical blade stripping is also an option, although a properly adjusted blade must be used to prevent surface damage which can lead to fatigue cracking under vibratory loading.
Q: Is 5.5mm x 1.6mm rectangular magnet wire appropriate to use for an electric vehicle motor windings?
Yes, the 5.5mm x 1.6mm dimension range is ideal for EV and hybrid traction motor stator slot geometries. The Class 200 temperature rating enables high thermal loading for EV motors with integrated inverters. The rectangular shape is particularly optimized for high slot fill in EV hairpin wound stators.
Q: What is the MOQ of this rectangle magnet wire?
A: MOQ will depend on the supplier and will usually be given by weight. Standard production quantities usually range from 500 kg to 1,000 kg per size.
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With 30 years of experience, we specialize in manufacturing high-quality enameled rectangular copper wire with precise specifications.
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Our state-of-the-art production facilities ensure consistent quality, and we adhere to IEC, NEMA, and JIS standards to meet international requirements.
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