NEMA & IEC Mounting Positions
Proper motor installation and mounting position is essential in obtaining top-quality operation, efficient performance, and maximum reliability. Sometimes, however, there is confusion about the many different ways a motor can be installed.
There are currently two different standards—NEMA and IEC— regarding electric motor mounting positions. While comparable, there are some slight differences between the two standards.
The NEMA standard mounting position is F1, whereby the junction/conduit box is located on the left side of the motor facing the output shaft. This is the most popular configuration, and is the standard for the majority of motors sold on the US marketplace. Another typical mounting position is a right-side location (facing the output shaft) indicated as F2. This mounting position is typical of design D oil well pump motors used on pump-jacks. On the other hand, the standard IEC mounting position places the junction box on the top of the motor, known as the IM B3 mounting position in IEC frame (or F3 in NEMA frames).
The design of motors is such that they can usually be operated in many mounting positions, unless indicated otherwise. Some mounting positions, however, may require additional construction modifications to achieve optimal performance. For example, shaft-up or shaft-down outdoor applications may require drilling of additional drain holes, drip covers and stronger bearings to support heavy loads. When in doubt, don’t hesitate to consult with an Elektrim engineer for mounting position requirements.
For your convenience, we have created a visual reference of all the typical NEMA and IEC electric motor mounting positions, different IEC flanges and junction box positions. Whether you're an installer, engineer, or maintainer, this handy quick reference is a must-have.
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Posted on: October 21, 2014
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