Square D / Schneider MasterPact NT / NW Catalog Number Decoder
Decode Square D / Schneider MasterPact NT and NW catalog numbers. Identifies frame construction (T/W/Y), ampere rating, interrupting class, device type, sensor plugs, and Micrologic trip unit. The decoder is free, needs no login, and runs entirely in your browser — paste a catalog number such as WA4ECR43A9SXXXWXJA and it returns every field it can resolve, plus a position-by-position map showing which character carried which value.
- Manufacturer
- Square D
- Frames
- NT (T-frame) · NW (W / Y-frame)
- Ratings
- 800A – 6,300A
What this decoder identifies
- Frame construction — NT T-frame, NW W-frame or Y-frame
- Frame ampere rating, 800A through 6,300A
- Interrupting class
- Device type — drawout, fixed, or switch-only
- Sensor and long-time rating plug
- Micrologic trip unit family and feature set
- Padlocking and factory accessory positions
Also sold or stamped as
The same breaker family appears under several names depending on the era of the nameplate. This decoder covers numbers labelled:
- Schneider MasterPact
- MasterPact NT
- MasterPact NW
- Square D universal power circuit breaker
Square D / Schneider MasterPact NT / NW — common questions
Is a Square D MasterPact the same as a Schneider MasterPact?
Yes — Square D is Schneider Electric’s North American brand, so the same MasterPact NT and NW breakers are sold and stamped under both names. One decoder covers both nameplates.
Why is the trip unit ordered separately from the breaker?
MasterPact NT and NW use a modular ordering system: the frame carries its own number and the Micrologic trip unit carries another. That is why the decoder accepts the frame number and the trip unit designation as separate inputs.
Related resources
Free manuals for this equipment
Square D MasterPact manuals and catalogs
All breaker decoders
Siemens, Eaton / Cutler-Hammer, GE and Square D catalog-number tools
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