Built for commercial and industrial applications, the Eaton BAB2040S is a 40A, two-pole miniature circuit breaker. It integrates standard thermal-magnetic protection with a factory-installed shunt trip mechanism, allowing the breaker to be tripped remotely via a 120/208/240VAC signal. The bolt-on configuration is engineered for Eaton Pow-R-Line, Cutler-Hammer, Westinghouse, Bryant, and Challenger panelboards. It effectively replaces older QNBL2040S and QB2040S models.
What panelboards are compatible with the BAB2040S circuit breaker?
This bolt-on breaker is designed for commercial and industrial Eaton Pow-R-Line panelboards. It is also backward compatible with legacy Cutler-Hammer, Westinghouse, Bryant, and Challenger panelboards that accept Quicklag BAB frame breakers.
Can I install the BAB2040S in a standard residential load center?
No. The BAB2040S features a bolt-on connection designed specifically for commercial and industrial panelboards. It will not fit in standard plug-on residential load centers.
What does the 'S' suffix indicate on the BAB2040S catalog number?
The 'S' suffix indicates that this breaker includes a factory-installed 120/240VAC shunt trip mechanism. This allows the breaker to be tripped remotely, which is commonly required for emergency stop systems or automated power cutoff.
What is the difference between the standard BAB2040 and the BAB2040S?
The standard BAB2040 provides standard thermal-magnetic overcurrent protection. The BAB2040S adds an integrated shunt trip accessory, allowing the breaker contacts to be opened remotely via an external voltage signal.
How does the shunt trip function operate on the BAB2040S?
The integrated shunt trip requires an external voltage control signal. When voltage is applied to the shunt trip leads, it energizes a coil that mechanically trips the breaker, opening the circuit. The breaker must then be manually reset at the panel.
What type of wire is approved for the BAB2040S box lugs?
The terminal box lugs are rated for both aluminum and copper (Al/Cu) conductors. They accept wire gauges ranging from 14 AWG to 4 AWG, allowing flexibility for various 40A branch circuit installations.
What does the LI trip function code mean on the BAB2040S?
The LI designation stands for Long-Time and Instantaneous trip functions. The Long-Time function provides delayed tripping for sustained overloads, while the Instantaneous function trips the breaker immediately in the event of a severe short circuit.
Does the BAB2040S provide arc fault or ground fault protection?
No. The BAB2040S is a standard thermal-magnetic circuit breaker with a shunt trip accessory. It provides overload and short-circuit protection but does not include GFCI or AFCI circuitry.
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Reviews
Review summary
Customers rate this product 4.9 out of 5 based on 164 reviews.
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Rated 4.9 out of 5 stars
Based on 164 reviews
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Reviews Summary
Generated by AI from 100 most recent customer reviews
Last updated 6/19/26
Customers say these breakers function as intended and arrive quickly. Fast shipping is consistently mentioned across reviews, with many noting timely delivery and secure packaging. Customers appreciate competitive pricing and the availability of items in stock. Products arrive in good condition, well-packaged, and work properly upon installation. Common feedback addresses responsive customer service and reliable order fulfillment. Most customers report smooth purchasing experiences and indicate they will return for future orders.
We placed our first order with superbreakers.com recently for a breaker we weren't able to acquire locally. I ordered the breaker way ahead of time because I've had issues with shipping for products purchased online in the past. The estimate for the item when I initially ordered was 3 days. Without adding an expedited shipping options, the breaker arrived the next day. We installed it this week, and so far so good. In my opinion, they sell quality parts and have excellent turn around time. Very impressed.