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Square D QOB140 Miniature Circuit Breaker
- 40A
- 1 Pole
- Bolt-On
Square D
QOB140
Miniature Circuit Breaker
Brand
Square D
SKU
QOB140
Quantity
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Square D QOB140 - 40A 1 Pole Miniature Circuit Breaker
New
Quantity
Quantity
Square D QOB140 - 40A 1 Pole Miniature Circuit Breaker
New
Quantity
| Brand | Square D |
|---|---|
| Part Number | QOB140 |
| Series | QOB |
| Amperage | 40A |
| Poles | 1 |
| Mounting Style | Bolt-On |
| Voltage | 120/240VAC, 48VDC |
| Phase | 1 |
| AIC Rating | 10kA @ 120/240VAC, 5kA @ 48VDC |
| Frame Type | QOB |
|---|---|
| Terminal Type | Box Lugs |
| For Use With | NQ Panelboards, NQOD Panelboards |
| Wire Gauge | 8-2 AWG (Al/Cu) |
| Max Wire | 2 AWG |
| Min Wire | 8 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed |
| Available Options | Shunt Trip, Auxiliary Switch, Alarm Switch, Padlock Attachment |
|---|---|
| Accessories | Load Side Lugs Included |
| Standards | CSA C22.2 No. 5, UL 489, NEMA AB 1 |
| Approval | CSA, HACR, UL |
| Temp Rating | 40C |
| Construction Features | Visual Trip Indicator, HACR Rated |
Sold out
Quantity
Square D QOB140 - 40A 1 Pole Miniature Circuit Breaker
Re-Certified
Quantity
| Brand | Square D |
|---|---|
| Part Number | QOB140-R |
| Series | QOB |
| Amperage | 40A |
| Poles | 1 |
| Mounting Style | Bolt-On |
| Voltage | 120/240VAC, 48VDC |
| Phase | 1 |
| AIC Rating | 10kA @ 120/240VAC, 5kA @ 48VDC |
| Frame Type | QOB |
|---|---|
| Terminal Type | Box Lugs |
| For Use With | NQ Panelboards, NQOD Panelboards |
| Wire Gauge | 8-2 AWG (Al/Cu) |
| Max Wire | 2 AWG |
| Min Wire | 8 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed |
| Available Options | Shunt Trip, Auxiliary Switch, Alarm Switch, Padlock Attachment |
|---|---|
| Accessories | Load Side Lugs Included |
| Standards | CSA C22.2 No. 5, UL 489, NEMA AB 1 |
| Approval | CSA, HACR, UL |
| Temp Rating | 40C |
| Construction Features | Visual Trip Indicator, HACR Rated |
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Description
The QOB140 is a single-pole, 40A miniature circuit breaker from Square D. Built for commercial and industrial systems, it delivers dependable thermal-magnetic protection for branch circuits. This unit features a secure bolt-on mounting style, ensuring a stable connection. It is designed to install into Square D NQ and NQOD panelboards, accepting 8-2 AWG wiring. Rated at 10 kAIC at 120/240VAC, it includes the exclusive Visi-Trip indicator for clear visual identification of tripped circuits.Specifications
| Brand | Square D |
|---|---|
| Part Number | QOB140 |
| Series | QOB |
| Amperage | 40A |
| Poles | 1 |
| Mounting Style | Bolt-On |
| Voltage | 120/240VAC, 48VDC |
| Phase | 1 |
| AIC Rating | 10kA @ 120/240VAC, 5kA @ 48VDC |
| Frame Type | QOB |
|---|---|
| Terminal Type | Box Lugs |
| For Use With | NQ Panelboards, NQOD Panelboards |
| Wire Gauge | 8-2 AWG (Al/Cu) |
| Max Wire | 2 AWG |
| Min Wire | 8 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed |
| Available Options | Shunt Trip, Auxiliary Switch, Alarm Switch, Padlock Attachment |
|---|---|
| Accessories | Load Side Lugs Included |
| Standards | CSA C22.2 No. 5, UL 489, NEMA AB 1 |
| Approval | CSA, HACR, UL |
| Temp Rating | 40C |
| Construction Features | Visual Trip Indicator, HACR Rated |
Product FAQs
7 answersCan I install the QOB140 in a standard Square D QO load center?
No. The QOB140 features a bolt-on connection designed specifically for Square D NQ and NQOD panelboards. It will not fit in standard QO load centers, which require plug-on circuit breakers.
What is the recommended tightening torque for the terminals on the QOB140?
The box lugs on this breaker should be torqued to 44.3 lb-in (5 N.m) when securing 8-2 AWG copper or aluminum wire.
Is the QOB140 suitable for HVAC equipment?
Yes, this breaker is HACR rated, meaning it is approved for use with heating, air conditioning, and refrigeration equipment that requires this specific circuit protection designation.
Are there direct alternatives to the QOB140 with higher interrupting ratings?
Yes. If your panel requires a higher fault current rating, you can substitute the QOB140VH, which provides 22kAIC, or the QHB140, which is rated for 65kAIC at 120/240VAC.
How can I easily identify if the QOB140 has tripped in a crowded panel?
This breaker features the Square D Visi-Trip indicator. When the breaker trips due to an overcurrent or short circuit, the handle snaps to a center position and a highly visible red indicator flag appears.
Can the QOB140 be used for switching fluorescent lighting loads?
No. SWD (Switching Duty) ratings are only applied to 15A and 20A circuit breakers. A 40A breaker like the QOB140 is not SWD rated and should not be used as a switch for fluorescent lighting circuits.
Does this breaker support direct current (DC) applications?
Yes, alongside its AC ratings, the QOB140 is rated for 48VDC with a 5kA interrupting capacity, making it suitable for compatible low-voltage DC control and distribution circuits.
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Parcel shipments with item value over $99 qualify for free economy shipping within the continental US. Please call to confirm special handling instructions. We do not charge a handling fee or require a minimum amount on any order. SuperBreakers does not ship on customer accounts.
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Reviews
Review summary
Customers rate this product 4.9 out of 5 based on 205 reviews.
Reviews Summary
Generated by AI from 100 most recent customer reviews
Last updated 3/11/26
Customers say these electrical breakers arrive exactly as ordered and work perfectly for their intended applications. They consistently praise the competitive pricing, which many report is significantly lower than local suppliers. Fast shipping and prompt delivery are frequently highlighted, with many receiving orders within days or even next-day delivery for urgent needs. The breakers arrive well-packaged and in excellent condition. Many reviews emphasize the company's extensive inventory availability, particularly for hard-to-find breakers. One customer experienced difficulty with order cancellation and was charged a restocking fee, which caused dissatisfaction.
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Rating
205 reviews
- BLBOOSTIX L.Verified BuyerReviewingSquare D QOB220 - 20A 2 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars8/17/26QOB220
That's nice breakers!
- PHPaul H.Verified BuyerReviewingSquare D QOB330 - 30A 3 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars8/5/26Quick shipping and delivery
Shipped and delivered on time for installation at one of our projects. Thank you!
- RMRick M.Verified BuyerReviewingSquare D QOB220 - 20A 2 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars8/3/26Project Mgr
Just what I needed.
- DHDoug H.Verified BuyerReviewingSquare D QOB220 - 20A 2 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars8/3/26Square D QOB breakers
As always, our order arrived timely, and accurate. You can’t beat their prices that’s why we have used this company for years.
- RKRyan K.Verified BuyerReviewingSquare D QOB230VH - 30A 2 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars7/1/26Awesome
Worked great