IEC Standards vs. NEMA Standards for Electrical Performance
Around the world, two organizations set standards for the design of electric motors: The International Electrotechnical Commission (IEC) and the National Electrical Manufacturers Association (NEMA). While some similarities exist between the two groups of standards, when you compare IEC vs. NEMA standards, you will find differences in what the motors look like, efficiency levels, and more.
What is IEC?
IEC is also known as the International Electrotechnical Commission. IEC is a European based organization that sets and publishes standards for mechanical and electrical equipment worldwide.What is NEMA?
NEMA is also known as the National Electrical Manufacturers Association. NEMA is a North American based organization that sets and publishes standards for mechanical and electrical equipment throughout North America.
What’s the takeaway? Although they are standards defined for different locations, IEC and NEMA motors have similar output power, efficiency ratings, and size.
Dimensional & Frame Comparison
IEC standards are expressed in metric units while NEMA frame standards are expressed in imperial units. Additionally, each group has different standards when it comes to motor construction. IEC motors are commonly made with cast aluminum or cast iron frames whereas NEMA motors are commonly made with rolled steel or cast iron frames.
NEMA Motors are made with the conduit box mounted on the side of the motor frame (F1 or F2 position) while IEC motors are made with the conduit box mounted on top the motor frame (F3 position) as seen in the below in Figure 1. NEMA motors are compatible with a C face kit and a D flange whereas the IEC frames are compatible with a B14 face and a B5 Flange.
Figure 1: NEMA vs. IEC Mount
Figure 2: NEMA vs IEC Dimension and HP Comparison
IEC/NEMA COMPARISON
| DIMENSION IN MILLIMETERS | KW/HP~ FRAME ASSIGNMENTS 3 Phase-TEFC |
||||||||||
| ICE | NEMA | D | E | F | H | U | BA | N-W | 2 Pole | 4 Pole | 6 Pole |
| 56 | NA | 56 - |
45 - |
35.5 - |
5.8 - |
9 - |
36 - |
20 - |
- - |
- - |
- - |
| 63 | NA | 63 - |
50 - |
40 - |
7 - |
11 - |
23 - |
.25KW 1/3HP |
.18KW 1/4HP |
- - |
- - |
| 71 | 42 | 71 66.7 |
56 44.5 |
45 21.4 |
7 7.1 |
14 9.5 |
45 52.4 |
30 - |
.55 3/4 |
.37 1/2 |
- - |
| 80 | 48 | 80 76.2 |
62.5 54 |
50 34.9 |
10 8.7 |
19 12.7 |
50 63.5 |
40 38.1 |
1.1 1-1/2 |
.75 1 |
.55KW 3/4HP |
| 90S | 56 | 90 88.9 |
70 61.9 |
50 38.1 |
10 8.7 |
24 15.9 |
56 69.9 |
50 46.6 |
1.5 2 |
1.1 1-1/2 |
.75 1 |
| 90L | 56 | 90 88.9 |
70 69.8 |
62.5 50.8 |
10 8.7 |
24 22.2 |
56 57.2 |
50 57.2 |
2.2 3 |
1.5 2 |
1.1 1-1/2 |
| 100L | 145T | 100 88.9 |
80 69.8 |
70 63.5 |
12 8.7 |
28 22.2 |
63 57.2 |
60 57.2 |
3 4 |
2.2 3 |
1.5 2 |
| 112L | 182T | 112 114.3 |
95 95.2 |
57 57.2 |
12 10.7 |
28 28 |
70 70 |
60 69.9 |
3.7 5 |
2.2 3 |
1.5 2 |
| 112M | 184T | 112 114.3 |
95 95.2 |
70 68.2 |
12 10.7 |
28 28 |
70 70 |
60 69.9 |
3.7 5 |
4 5-4/5 |
2.2 - |
| 132S | 213T | 132 133.4 |
108 108 |
70 69.8 |
12 10.7 |
38 34.9 |
89 89 |
80 85.7 |
7.5 10 |
5.5 7-1/2 |
3 - |
| 132M | 215T | 132 133.4 |
108 108 |
89 88.8 |
12 10.7 |
38 34.9 |
89 89 |
80 85.7 |
- - |
7.5 10 |
5.5 7-1/2 |
| 160M* | 254T | 160 158.8 |
127 127 |
105 104.8 |
15 13.5 |
42 41.3 |
108 108 |
110 101.6 |
15 20 |
11 15 |
7.5 10 |
| 160L* | 256T | 160 158.8 |
127 127 |
127 127 |
15 13.5 |
42 41.3 |
108 108 |
110 101.5 |
18.5 25 |
15 20 |
11 15 |
| 180M* | 284T | 180 177.8 |
139.5 139.8 |
120.5 120.2 |
15 13.5 |
48 47.6 |
121 121 |
110 117.5 |
22 - |
18.5 25 |
- - |
| 180L* | 286T | 180 177.8 |
139.5 139.8 |
139.5 139.8 |
15 13.5 |
48 47.6 |
121 121 |
110 117.5 |
22 - |
18.5 25 |
- - |
| 200M* | 324T | 180 203.3 |
159 158.8 |
133.5 133.4 |
19 16.7 |
55 54 |
133 133 |
110 133.4 |
30 40 |
30 40 |
- - |
| 200L* | 326T | 200 203.2 |
159 158.8 |
152.5 152.4 |
19 16.7 |
55 54 |
133 133 |
110 133.4 |
37 50 |
37 50 |
22 30 |
| 225S* | 364T | 225 228,6 |
178 117.8 |
143 142.8 |
19 16.7 |
60 60.3 |
149 149 |
140 149,2 |
- - |
37 50/75 |
30 40 |
| 225M* | 365 | 225 228.6 |
178 177.8 |
155.5 155.6 |
19 16.7 |
60 60.3 |
149 149 |
140 149.2 |
45 60/75 |
45 60/75 |
37 50 |
| 250M* | 405T | 250 254 |
203 203.2 |
174.5 174.6 |
24 20.6 |
65 73 |
168 168 |
140 182.2 |
55 75/100 |
55 75/100 |
- - |
| 280S* | 444T | 280 279.4 |
228.5 228.6 |
184 184.2 |
24 20.6 |
75 85.7 |
190 190 |
140 215.9 |
- - |
- - |
45 60/100 |
| 280M* | 445T | 280 279.4 |
228.5 228,6 |
209.5 209.6 |
24 20.6 |
75 85.7 |
190 190 |
140 215.9 |
- - |
- - |
55 75/125 |
Cooling and Insulation Duty Cycle Index
IEC motors have additional designations indicating how the motor is cooled which is represented by a two-digit IC code. On the other hand, a NEMA enclosure designation indicates how the motor is cooled.
| IEC | NEMA |
|---|---|
| IC 01 | Open Design |
| IC 40 | TENV |
| IC 41 | TEFC |
| IC 48 | TEAO |
NEMA Classes
NEMA motors commonly have four winding insulation classes: A, B, F and H, based on the max temperature ratings with a reference to a 40°C ambient temperature.
NEMA also specifies the allowable temperature rises for motors operating under full load at certain service factors.
Example: For a Class B insulated, 1.15 SF motor, if we add the NEMA allowable rise of 80°C to the reference ambient temperature of 40°C: the result is a motor with an operating temperature of 120°C.
| Class: A | 105° C |
| Class: B | 130° C |
| Class: F | 155° C |
| Class: H | 180° C |
| |
1.0 SF | 1.15 SF |
|---|---|---|
| Class: A | 60°C | 70°C |
| Class: B | 80°C | 90°C |
| Class: F | 105°C | 115°C |
| Class: H | 125°C |
IEC Classes
IEC motors identify multiple thermal classes based on the maximum allowable temperature.Note: Duty cycles are different. Where NEMA commonly designates either continuous, intermittent, or special duty (typically expressed in minutes), IEC uses eight duty cycle designations.
| IEC Thermal Class Designation | Letter Designation |
|---|---|
| 90 | Y |
| 105 | A |
| 120 | E |
| 130 | B |
| 155 | F |
| 180 | H |
| 200 | N |
| 220 | R |
IEC Duty Cycle Designations Guide
| S1 | Continuous duty. The motor works at a constant load for enough time to reach temperature equilibrium. |
| S2 | Short-time duty. The motor works at a constant load, but not long enough to reach temperature equilibrium, and the rest periods are long enough for the motor to reach ambient temperature. |
| S3 | Intermittent periodic duty. Sequential, identical run and rest cycles with constant load. Temperature equilibrium is never reached. Starting current has little effect on temperature rise. |
| S4 | Intermittent periodic duty with starting. Sequential, identical start, run and rest cycles with constant load. Temperature equilibrium is not reached, but starting current affects temperature rise. |
| S5 | Intermittent periodic duty with electric braking. Sequential, identical cycles of starting, running at constant load, electric braking, and rest. Temperature equilibrium is not reached. |
| S6 | Continuous operation with intermittent load. Sequential, identical cycles of running with constant load and running with no load. No rest periods. |
| S7 | Continuous operation with electric braking. Sequential identical cycles of starting, running at constant load and electric braking. No rest periods. |
| S8 | Continuous operation with periodic changes in load and speed. Sequential, identical duty cycles of start, run at constant load and given speed, then run at other constant loads and speeds. No rest periods. |
NEMA motor efficiencies have two standard levels defined as “Energy Efficient” and “Premium Efficient” in the NEMA standards. NEMA Premium is trademarked and the term should only be used by manufacturers who are part of NEMA’s premium motor program. IEC 60034-30-1 defines the efficiency classes for motors. IEC IE2 is equivalent to energy efficient and IE3 is mostly equivalent to premium efficiency.
| Efficiency Levels for 60 Hz Motor Designs | |
|---|---|
| NEMA | IEC |
| N/A | IE1 |
| Energy Efficient | IE2 |
| Premium Efficient | IE3 |
IEC and NEMA designs have a wide range of electric motors available. Understanding the differences and similarities between these two design standards will help you select the right motor for your application.
To find the right motor for you, visit the Regal Rexnord NEMA Motors Catalog or the IEC Motors Catalog.
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