Industrial electric motors have been available for nearly a century. In that time there have been a great many changes. One of the most obvious has been the ability to pack more horsepower in a smaller physical size. Another important achievement has been the standardization of motors by the National Electrical Manufacturers Association (NEMA).
A key part of motor interchangeability has been the standardization of frame sizes. This means that the same horsepower, speed, and enclosure will normally have the same frame size from different motor manufacturers. Thus, a motor from one manufacturer can be replaced with a similar motor from another company provided they are both in standard frame sizes.
| Frame Size | U | D | E | 2F | V Min. |
|---|---|---|---|---|---|
| 42 | 3/8" | 2-5/8" | 1-1/4" | 1-11/16" | 1-1/8" |
| 48 | 1/2" | 3" | 2-1/8" | 2-3/8" | 1-1/2" |
| 56 56H | 5/8" | 3-1/2" | 2-7/16" | 3" 5" | 1-7/8" |
| 143T 145T | 7/8" | 3-1/2" | 2-3/4" | 4" 5" | 2-1/4" |
| 182 184 182T 184T | 7/8" 7/8" 1-1/8" 1-1/8" | 4-1/2" | 3-3/4" | 4-1/2" 5-1/2" 4-1/2" 5-1/2" | 2" 2" 2-1/2" 2-1/2" |
| 213 215 213T 215T | 1-1/8" 1-1/8" 1-3/8" 1-3/8" | 5-1/4" | 4-1/4" | 5-1/2" 7" 5-1/2" 7" | 2-3/4" 2-3/4" 3-1/8" 3-1/8" |
| 254 254U 256U 254T 256T | 1-1/8" 1-3/8" 1-3/8" 1-5/8" 1-5/8" | 6-1/4" | 5" | 8-1/4" 8-1/4" 10" 8-1/4" 10" | 3-1/8" 3-1/2" 3-1/2" 3-3/4" 3-3/4" |
| 284 284U 286U 284T 286T 284TS 286TS | 1-1/4" 1-5/8" 1-5/8" 1-7/8" 1-7/8" 1-5/8" 1-5/8" | 7" | 5-1/2" | 9-1/2" 9-1/2" 11" 9-1/2" 11" 9-1/2" 11" | 3-1/2" 4-5/8" 4-5/8" 4-5/8" 4-5/8" 3" 3" |
| 324 326 324U 326U 324T 326T 324TS 326TS | 1-5/8" 1-5/8" 1-7/8" 1-7/8" 2-1/8" 2-1/8" 1-7/8" 1-7/8" | 8" | 6-1/4" | 10-1/2" 12" 10-1/2" 12" 10-1/2" 12" 10-1/2" 12" | 4-5/8" 4-5/8" 5-3/8" 5-3/8" 5" 5" 3-1/2" 3-1/2" |
| 364 365 364U 365U 364T 365T 364TS 365TS | 1-7/8" 1-7/8" 2-1/8" 2-1/8" 2-3/8" 2-3/8" 1-7/8" 1-7/8" | 9" | 7" | 11-1/4" 12-1/4" 11-1/4" 12-1/4" 11-1/4" 12-1/4" 11-1/4" 12-1/4" | 5-3/8" 5-3/8" 6-1/8" 6-1/8" 5-5/8" 5-5/8" 3-1/2" 3-1/2" |
| 404 405 404U 405U 404T 405T 404TS 405TS | 2-1/8" 2-1/8" 2-3/8" 2-3/8" 2-7/8" 2-7/8" 2-1/8" 2-1/8" | 10" | 8" | 12-1/4" 13-3/4" 12-1/4" 13-3/4" 12-1/4" 13-3/4" 12-1/4" 13-3/4" | 6-1/8" 6-1/8" 6-7/8" 6-7/8" 7" 7" 4" 4" |
| 444 445 444U 445U 444T 445T 447T 449T 444TS 445TS 447TS 449TS | 2-3/8" 2-3/8" 2-7/8" 2-7/8" 3-3/8" 3-3/8" 3-3/8" 3-3/8" 2-3/8" 2-3/8" 2-3/8" 2-3/8" | 11" | 9" | 14-1/2" 16-1/2" 14-1/2" 16-1/2" 14-1/2" 16-1/2" 20" 25" 14-1/2" 16-1/2" 20" 25" | 6-7/8" 6-7/8" 8-3/8" 8-3/8" 8-1/4" 8-1/4" 8-1/4" 8-1/4" 4-1/2" 4-1/2" 4-1/2" 4-1/2" |
Download our handy NEMA Motor Frame Chart.