IEC motor frame sizes and mounting codes.
Frame and mounting codes are some of the most useful cross-brand clues on a replacement motor. They narrow physical fit quickly — but they do not replace a dimensional drawing.
How to read an IEC frame code
A code such as 132M contains two different pieces of information. The number identifies the frame's nominal shaft centre-height family; the suffix identifies a length variant within that family.
- 132 — nominal shaft centre height of 132 mm for the standard foot-mounted geometry.
- S — short frame-length variant.
- M — medium frame-length variant.
- L — long frame-length variant.
That means a 132S, 132M and 132L share the same centre-height family but are not the same physical package. Overall length and mounting-hole spacing can differ between the suffix variants.
Why frame size matters in motor replacement
IEC frame standardisation is what makes many cross-brand motor replacements possible. Once power, poles, voltage and other electrical requirements have been narrowed, the frame code helps answer a practical question: can a different manufacturer's motor occupy the same general mounting envelope?
BecSpec treats frame as a compatibility input rather than a cosmetic specification. A motor in a different frame is not promoted above a same-frame candidate merely because it has slightly better efficiency.
Common frame searches
Users often search directly from a nameplate, so frame codes themselves become useful replacement queries. You can jump straight into the Australian motor finder with a frame preselected:
- 80 frame motors
- 90S frame motors
- 90L frame motors
- 100L frame motors
- 112M frame motors
- 132S frame motors
- 132M frame motors
- 132L frame motors
- 160M frame motors
- 160L frame motors
- 180M frame motors
- 180L frame motors
These links are filters into the live finder rather than claims that every frame is present in every power or pole combination. The actual registration corpus determines what results appear.
IEC mounting codes
The mounting code describes how the motor is supported and attached to the driven equipment. It is frequently missing from a nameplate, so a photograph of the installed motor is often as useful as the plate itself.
| Code | Typical arrangement | Replacement implication |
|---|---|---|
| B3 | Foot mounted | Motor sits on feet and bolts to a base or bedplate. |
| B5 | Large flange, no feet | Flange geometry and driven-machine interface must match. |
| B14 | Face flange, no feet | Smaller face-mounted arrangement; not interchangeable with B5 by code alone. |
| B35 | Feet plus B5 flange | Both the foot and flange interfaces may matter. |
| V1 | Vertical shaft, flange mounted | Orientation, thrust and application details need explicit confirmation. |
What a matching frame does not prove
Even when two motors carry the same IEC frame designation, a replacement still needs the details that are specific to the actual machine and installation. Depending on the application, verify:
- shaft diameter and shaft extension length;
- key and keyway dimensions;
- exact flange or face dimensions where applicable;
- terminal-box position and cable-entry arrangement;
- full-load speed and driven-machine speed tolerance;
- duty, starting torque and number of starts;
- IP rating and environmental constraints;
- VSD, brake, encoder or special accessory requirements.
Frame matching narrows; it does not certify interchangeability
BecSpec uses the frame and mounting evidence carried in registration data to narrow candidates. Where the source cannot establish a shaft or installation detail, the result remains marked for verification.
B3 motor mounting
B3 is the most familiar industrial arrangement: a horizontal shaft and feet on the motor base. If an existing motor is B3, matching B3 is a useful first fitment constraint because a flange-only B5 or B14 motor is not a like-for-like mounting arrangement.
Browse B3 three-phase motors →
B5 vs B14
B5 and B14 are both flange or face-mounted configurations, but they describe different mechanical interfaces. Treating them as interchangeable because both lack feet is unsafe. The actual driven-machine interface and dimensional drawing should be checked before ordering.
Use frame as one part of the selection
A sound replacement search normally combines frame with rated output, pole count or speed, supply voltage and mounting. Enclosure, duty and other application details can then be checked as required.
Read the three-phase motor selection guide →