IP and insulation classes of electric motors
When selecting an electric motor for a specific application, the IP rating and insulation class are two critical technical characteristics. They determine how well a motor is protected against environmental factors and how resistant the electrical insulation is to heat. In this article, we explain what these classifications mean and what to consider when choosing a motor.
What is an IP rating?
The IP rating (International Protection, also known as Ingress Protection) indicates the degree of protection an electric motor offers against dust and moisture. The code is defined in international standard IEC 60034-5.
The IP code consists of two digits:
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The first digit refers to protection against solid objects and dust.
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The second digit refers to protection against water and moisture.
For example:
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IP55 = dust protection + protection against water jets
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IP69K = completely dust-tight + resistant to high-pressure/steam cleaning
IP69K is commonly used in food processing and other hygiene-critical environments.
| IP first digit | Protection against solid objects | IP second digit | Protection against liquids |
|---|---|---|---|
| 0 | No protection | 0 | No protection |
| 1 | Protected against solid objects > 50 mm | 1 | Protected against vertically falling drops |
| 2 | Protected against solid objects > 12 mm | 2 | Protected against drops falling at 15° angle |
| 3 | Protected against solid objects > 2.5 mm | 3 | Protected against water spray up to 60° angle |
| 4 | Protected against solid objects > 1 mm | 4 | Protected against splashing water from any direction |
| 5 | Dust protected | 5 | Protected against water jets from any direction |
| 6 | Dust-tight | 6 | Protected against temporary immersion |
| - | N/A | 7 | Protected against immersion (0.15–1 m deep) |
| - | N/A | 8 | Protected against immersion under defined pressure and time |
What is an insulation class?
The insulation class of an electric motor indicates the thermal resistance of the winding insulation. This classification is defined in IEC 60085. Each insulation class defines a maximum operating temperature at which the motor can safely function without degrading the insulation.
Common classes include:
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Class B: 130°C
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Class F: 155°C
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Class H: 180°C
A motor with a higher insulation class is often more suitable for heavy-duty applications, frequent cycling, or environments with elevated ambient temperatures.
Do you have specific protection or insulation requirements? Feel free to contact us to discuss the options.
| Insulation class ► IEC | A | E | B | F | H |
|---|---|---|---|---|---|
| Temperature limit | 105°C | 120°C | 130°C | 155°C | 180°C |
| Max winding temperature | 100°C | 115°C | 120°C | 140°C | 165°C |
| Ambient temperature for land-based installations | 40°C | 40°C | 40°C | 40°C | 40°C |
| Max stator winding delta T (K) | 60K | 75K | 80K | 100K | 125K |
IP and insulation classes in practice
When selecting a motor, always consider the operating environment. Is it installed in a dusty production hall, a parking garage, or outdoors? Then a higher IP rating is essential. Will the motor be heavily loaded or exposed to high ambient temperatures? Then a higher insulation class is recommended.
Legal and regulatory requirements also come into play. In many cases, electric motors must comply with ErP directives, which focus on energy efficiency and sustainability.
Read more in our knowledge base article on ErP directives for fans and motors.
Additionally, accessories and enclosures can affect the motor’s IP protection level — such as motor hoods, control boxes, or ventilation covers
Need advice? Get in touch!
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Frequently asked questions about IP and insulation classes of electric motors
What does the IP code of an electric motor mean?
The IP code defines the degree of protection against intrusion of solid objects and liquids. The first digit refers to protection against solids, the second to protection against liquids.
When should I choose a motor with IP69K classification?
IP69K motors are suitable for environments where high-pressure and high-temperature cleaning is required, such as in the food and beverage industry.
What is the difference between insulation class F and H?
Class F is rated up to 155°C, while Class H is rated up to 180°C. Class H is used in applications with higher thermal loads.
Are there new standards in effect in 2025?
Yes, IEC 60034-5:2020 was updated in 2024 with technical corrections. It’s important to always consult the latest standards when selecting electric motors.