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Square D QOB240 Miniature Circuit Breaker
- 40A
- 2 Pole
- Bolt-On
Square D
QOB240
Miniature Circuit Breaker
Brand
Square D
SKU
QOB240
Quantity
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Square D QOB240 - 40A 2 Pole Miniature Circuit Breaker
New
Quantity
Quantity
Square D QOB240 - 40A 2 Pole Miniature Circuit Breaker
New
Quantity
| Brand | Square D |
|---|---|
| Part Number | QOB240 |
| Series | QOB |
| Amperage | 40A |
| Poles | 2 |
| 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, HACR, UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | Visual Trip Indicator, HACR Rated |
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Quantity
Square D QOB240 - 40A 2 Pole Miniature Circuit Breaker
Re-Certified
Quantity
| Brand | Square D |
|---|---|
| Part Number | QOB240-R |
| Series | QOB |
| Amperage | 40A |
| Poles | 2 |
| 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, HACR, UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | Visual Trip Indicator, HACR Rated |
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Description
Part of the proven QO family, this 40A miniature circuit breaker is engineered for reliable performance in commercial and industrial power distribution. The 2-pole device features a bolt-on mounting configuration, ensuring a tight, vibration-resistant connection within Square D NQ and NQOD panelboards. Rated at 10kAIC for 120/240VAC systems, the QOB240 includes a Visi-Trip red indicator flag to simplify maintenance and reduce downtime during electrical faults.Specifications
| Brand | Square D |
|---|---|
| Part Number | QOB240 |
| Series | QOB |
| Amperage | 40A |
| Poles | 2 |
| 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, HACR, UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | Visual Trip Indicator, HACR Rated |
Product FAQs
6 answersWhat is the difference between the QO240 and QOB240 circuit breakers?
Both breakers share the same 40A capacity and trip characteristics, but they differ in their mounting style. The QO240 is a plug-on breaker for residential QO load centers, while the QOB240 features a bolt-on connection designed specifically for commercial NQ and NQOD panelboards.
How much panel space does the QOB240 require?
This 2-pole breaker requires two spaces in a compatible panelboard. Square D QO and QOB series breakers use a compact 3/4-inch width per pole, so the QOB240 has a total installed width of 1.5 inches.
What are the correct tightening torque specifications for the QOB240?
For this 40A breaker, the box lug wire terminals should be tightened to 45 lb-in of torque. Additionally, the bolt-on mounting screws that secure the breaker to the panelboard bus require a torque of 18 to 21 lb-in.
Is the QOB240 suitable for heating and cooling equipment?
Yes, the QOB240 is HACR rated. It has been tested and certified to handle the temporary inrush currents typical of heating, air conditioning, and refrigeration motor compressors without causing nuisance tripping.
Can the QOB240 be used in DC power circuits?
Yes, this breaker carries a tested DC interrupting rating of 5kA at 48VDC. This allows it to be used safely for specific low voltage direct current control circuits or battery applications, adding versatility beyond standard AC installations.
Does the QOB240 feature a tripped circuit indicator?
Yes, this breaker is equipped with the Square D Visi-Trip visual indicator. When the breaker trips due to an overcurrent or short circuit, a red flag appears in the window to help you quickly identify the faulted circuit during maintenance.
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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