Nema vs IEC Motor Starters
Nema is an acronymn for National Electrical Manufacturers Association. Nema is the accepted standard in the United States pretaining to ratings and frame sizes of Motor Starters. Nema frame starters are recognized as being robust and able to withstand electrical short circuits exceptional well. Nema also exceeds in Motor HP ratings, meaning fewer sizes cover a broader range of horse powers. Open sytle Nema starters are also advantageous as they are serviceable. Coils and contacts can usually be easily replaced.
IEC stands for International Electro-technical Commission. Until recently, this standard was primarily used in Asia and Europe. By far the greatest advantage of IEC motor starters is cost and second is size. Additionally, IEC starters are always enclosed type which makes them safer. Another very important aspect compared to Nema is there are many more IEC sizes available. This has some benefits and some drawbacks. With Nema sizing there is very little that needs to be known about the application. IEC on the otherhand, the designer needs to know the application and whether the service exceeds the starter's capability.
The IEC motor starters we use and sell are dual rated both Nema and IEC. This allows our control panels and starters to be used on projects where specifications require Nema standards.
Example of this is our Nema size 2/IEC size 40 contactor. The contactor is labeled with both Nema and IEC ratings and is an acceptable substitute for either requirement.
In our control panel and starter listings, we give the buyer information to help in sizing. Most listings indicate one of three application "loadings". We may indicate a particular set up is sized for a Lightly loaded, Normal loaded, or Heavy loaded application. By this we mean how often or how much a motor runs at or near the full load Amps.