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Electrical and electronic products depend on their insulating materials to function correctly. If the magnet wire within an electric motor touches any of the metal housing, it will ground the motor, and the motor will become inoperable. However, the extra bulk of insulation material can be a determining factor in your product's size. The earliest computers took up whole rooms, partially because of all the insulation material needed to keep the heat they produced from damaging the systems. When choosing insulation for a specific project, you must consider many factors. The first factor is usually temperature rating, but other essential characteristics include voltage and mechanical strength.

Motor Breakdown


In the electrical and electronic industry, the materials' heat is a real danger to the system. Improperly selected insulation will break down in the heat. So, it is essential to choose insulation material that has an appropriate temperature rating. The National Electrical Manufacturers Association has set standard classes for temperature ratings in electrical insulation material to help with this. (See Table below). Each class rating has specific materials that work best in those ranges.

Insulation Rating Insulation Class Average Winding
Temperature Rise
Hot Spot
Temperature Rise
Winding Temperature
Class 105 A 55°C 65°C 105°C
Class 130 B 80°C 110°C 150°C
Class 155 F 115°C 145°C 180°C
Class 180 H 130°C 160°C 200°C
Class 200 N 150°C 180°C 220°C
Class 220 N 170°C 200°C 200°C


Within your selected temperature class, insulation materials differentiate by voltage capacity. The standard voltage supplied to households is 125V, while household clothes dryers run on 220V. However, electrical apparatuses can run on many different voltages. Some common ones are 12v, 24v, 125v, 208v, 220v, 460v, 575v, 950v, 2300v, 4160v, 7.5kv, and 13.8kv. Insulation products are only effective within certain voltage brackets, which is why it is important to select the proper insulation for your project.


Now that you have selected the appropriate temperature rating and voltage, the next most important thing to consider is mechanical strength. Mechanical strength is most important to consider for flexible insulation products such as tape products. In electrical motors, the tape holds the magnet wire away from the metal stator core. If the magnet wire current were higher than could be managed by the strength of the insulation, then the insulation would fail and allow the magnet wire to come in contact with the core. This would ground the motor, and it would have to be stripped and rebuilt before using it again. Having the correct mechanical strength selected for your insulation is crucial because it will make the insulation adequately resistant to the weight of the wire and any abrasion that may happen. All fabricating processes must be correct to that specific insulation, or it will degrade the insulation's mechanical strength. Insulating varnishes and resins are also in motors. They help bond magnet wires together in the correct shape, as well as provide insulation. When selecting insulation for your system, the combination of insulations you choose must meet your electric apparatus's class rating. It is important to have this tested for each combination of insulations you choose, as the combination of certain materials can either raise or lower the class rating. Each built electrical apparatus needs to be tested in a complete UL or IEEE system to ensure it meets testing and safety requirements.