What are iec standards?

In short: the International Electrotechnical Commission (IEC) standards are the uniform standards indicating the efficiency classes for electric motors.


In 1999, the European Commission established different efficiency classes for electric motors. They did this to reduce energy consumption and to create awareness of the importance of a more sustainable environment among various industries. These efficiency classes were called the EFF standards. However, the US established the NEMA standards for electric motors, which differed a lot from the EU standards. To overcome the international inconsistencies in regulations, the EFF standards changed to the current IEC standards for electric motors.

In the table below, you can see how the IEC correspond with some of the previous international standards.

IEC efficiency classes

Since 2014, the power range was extended for electric motors and was set between 0,12 kW and 1000 kW. Moreover, electric motors with a rated output of 0,75-375 kW must meet either IE3 efficiency or IE2 if fitted with VSD’s since 2017.

Electric motors included by the iec standards:

  • Single speed electric motors (single and three phase), 50 and 60 Hz
  • Line-start permanent magnet motors
  • 2, 4, 6 or 8 poles – Rated output PN from 0.12 kW to 1000 kW
  • Rated voltage UN above 50 V up to 1 kV
  • Motors, capable of continuous operation at their rated power with a temperature rise within the specified insulation temperature class

electric motors excluded by the iec standards:

  • Motors designed to operate wholly immersed in a liquid
  • Brake motors, when the brake cannot be dismantled or separately fed.
  • Single-speed motors with 10 or more poles or multi-speed motors
  • Motors completely integrated into a machine (for example, pump, fan or compressor) that cannot be tested separately from the machine.
  • Motors specifically designed to operate:
    • At altitudes exceeding 4000 meters (over 13.000 feet)
    • Where ambient air temperatures exceed 60°C
    • In maximum operating temperatures above 400°C.
    • Where ambient air temperatures are less than –30°C (any motor) or less than 0°C (water-cooled motors)
    • Where the water coolant temperature at the inlet to a product is less than 0°C or exceeds 32°C
    • In potentially explosive atmospheres as defined in Directive 94/9/EC


The torque motors designed and manufactured by Magnetic Innovations already fall within the IE4 super premium efficiency class. This can result in enormous energy savings for your operations. Please contact us for more info.

IEC specifications