Eaton / Westinghouse NB31200 Molded Case Circuit Breaker
- 1200A
- 3 Pole
- Bolt-On
Eaton / Westinghouse
NB31200
Molded Case Circuit Breaker
Brand
Eaton / Westinghouse
SKU
NB31200
Quantity
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Eaton / Westinghouse NB31200 - 1200A 3 Pole Molded Case Circuit Breaker
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Description
Built to handle demanding electrical loads, this 1200A molded case circuit breaker offers fixed thermal and adjustable magnetic trip settings for commercial environments. It serves as a precise hardware match for vintage Westinghouse PRL4 panelboards, bypassing the complexity of modern adapter plates. Facility managers can use it to replace aging ND31200 or HNB31200 models.Specifications
| Brand | Eaton / Westinghouse |
|---|---|
| Series | NB |
| Amperage | 1200A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 600VAC, 250VDC |
| Phase | 3 |
| AIC Rating | 42kA @ 240VAC, 30kA @ 480VAC, 22kA @ 600VAC, 20kA @ 250VDC |
| Frame Type | NB |
|---|---|
| Terminal Type | Lugs |
| For Use With | Westinghouse PRL4 Panelboards, Switchboards |
| Wire Gauge | (4) 4/0 AWG - 500 kcmil |
| Max Wire | 500 kcmil |
| Min Wire | 4/0 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed Thermal, Adjustable Magnetic |
| Available Options | Shunt Trip, Auxiliary Switch, Undervoltage Release, Alarm Switch |
|---|---|
| Accessories | Lugs Not Included |
| Standards | NEMA AB-1, UL 489 |
| Approval | UL |
| Temp Rating | 40C |
| Construction Features | Interchangeable Trip Unit |
Product FAQs
6 answersWhat wire sizes do the factory lugs on the NB31200 accommodate?
The standard mechanical lugs accept four conductors per phase, supporting wire sizes from 4/0 AWG to 500 kcmil for both copper and aluminum cable.
How is the thermal-magnetic trip unit on the NB31200 configured?
This breaker features a fixed thermal element for long-time overload protection and an adjustable magnetic pickup, allowing installers to tune the instantaneous short-circuit response for proper system coordination.
Which panelboards are compatible with the NB31200 circuit breaker?
This bolt-on MCCB mounts in legacy Westinghouse, Cutler-Hammer, and Eaton PRL4 (Pow-R-Line 4) panelboards and switchboards equipped with mounting hardware for NB frame breakers.
What specific protection parameters does the LI trip function indicate?
The LI code means the trip unit provides Long-Time (L) overload protection to prevent cable overheating, paired with an Instantaneous (I) magnetic override to clear massive short-circuit faults without intentional delay.
Is there a higher interrupting capacity alternative for the NB31200?
Yes. If your short-circuit coordination study requires a higher AIC rating, the HNB31200 is the direct high-interrupting version that shares the same physical dimensions and mounting footprint.
What is the recommended practice for securing the primary wire connections?
Terminations must always be tightened using a calibrated torque wrench to the exact inch-pound specifications printed on the breaker label. Improperly torqued connections can lead to thermal runaway or arc flash hazards.
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Reviews
Review summary
Customers rate this product 5.0 out of 5 based on 18 reviews.
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Rating
18 reviews
- MMMike M.Verified BuyerReviewingFederal Pacific NB100 - 100A 2 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars7/2/26100amp federal pacific breaker
So far the breaker works as expected
Just good to know some of these old federal are still available.
Thank you
- SGscott g.Verified BuyerReviewingFederal Pacific NB111020 - 20A 1 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars6/26/26Hard to find breakers
Had a project at a school built in the 1960’s and thought we were up a creek when confronted with ancient FPE commercial panels. Luckily we found what we needed with Suoerbreakers.
- BFBarry F.Verified BuyerReviewingFederal Pacific NB100 - 100A 2 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars6/13/26Hard to find circuit breaker
Item was as described.
- WWWilliam W.Verified BuyerReviewingFederal Pacific NB100 - 100A 2 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars3/9/26Exactly what I needed.
Awesome! Packaging and delivery were good. Bolted in and worked perfectly!!)
- GHGary H.Verified BuyerReviewingFederal Pacific NB125 - 125A 2 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars3/3/26Federal Pacific NB125 2 Pole Circuit Breaker
Federal Pacific NB125 2 Pole Circuit Breaker
Great product and excellent price and warranty.