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Square D QO140 Miniature Circuit Breaker
- 40A
- 1 Pole
- Plug-On
Square D
QO140
Miniature Circuit Breaker
Brand
Square D
SKU
QO140
Quantity
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Square D QO140 - 40A 1 Pole Miniature Circuit Breaker
New
Quantity
Quantity
Square D QO140 - 40A 1 Pole Miniature Circuit Breaker
New
Quantity
| Brand | Square D |
|---|---|
| Part Number | QO140 |
| Series | QO |
| Amperage | 40A |
| Poles | 1 |
| Mounting Style | Plug-On |
| Voltage | 120/240VAC, 48VDC |
| Phase | 1 |
| AIC Rating | 10kA @ 120/240VAC, 5kA @ 48VDC |
| Frame Type | QO |
|---|---|
| Terminal Type | Box Lugs |
| For Use With | QO Load Centers, 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 | Padlock Attachment |
|---|---|
| Standards | CSA C22.2 No. 5, UL 489, HACR, NEMA AB 1 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | Visual Trip Indicator, HACR Rated |
Sold out
Quantity
Square D QO140 - 40A 1 Pole Miniature Circuit Breaker
Re-Certified
Quantity
| Brand | Square D |
|---|---|
| Part Number | QO140-R |
| Series | QO |
| Amperage | 40A |
| Poles | 1 |
| Mounting Style | Plug-On |
| Voltage | 120/240VAC, 48VDC |
| Phase | 1 |
| AIC Rating | 10kA @ 120/240VAC, 5kA @ 48VDC |
| Frame Type | QO |
|---|---|
| Terminal Type | Box Lugs |
| For Use With | QO Load Centers, 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 | Padlock Attachment |
|---|---|
| Standards | CSA C22.2 No. 5, UL 489, HACR, NEMA AB 1 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | Visual Trip Indicator, HACR Rated |
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Description
Providing reliable overcurrent protection, the Square D QO140 is a 40-amp, single-pole miniature circuit breaker. It is engineered for systems requiring standard thermal-magnetic trip functions. This unit installs into Square D QO load centers, NQ panelboards, and NQOD enclosures. The plug-on mounting style allows for rapid deployment, accommodating 8-2 AWG wire. With a 10 kAIC rating, it includes the signature Visi-Trip window to instantly identify tripped circuits.Specifications
| Brand | Square D |
|---|---|
| Part Number | QO140 |
| Series | QO |
| Amperage | 40A |
| Poles | 1 |
| Mounting Style | Plug-On |
| Voltage | 120/240VAC, 48VDC |
| Phase | 1 |
| AIC Rating | 10kA @ 120/240VAC, 5kA @ 48VDC |
| Frame Type | QO |
|---|---|
| Terminal Type | Box Lugs |
| For Use With | QO Load Centers, 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 | Padlock Attachment |
|---|---|
| Standards | CSA C22.2 No. 5, UL 489, HACR, NEMA AB 1 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | Visual Trip Indicator, HACR Rated |
Product FAQs
8 answersCan I install a QO140 circuit breaker in a Square D Homeline load center?
No. Square D QO and Homeline series breakers are not interchangeable. The QO140 is designed exclusively for QO load centers, NQ panelboards, and legacy NQOD panelboards. It will not physically attach to the bus bar in a Homeline panel.
What is the physical width of the QO140 in a load center?
As a standard QO single pole breaker, it occupies exactly one panel space and measures 0.75 inches, or 3/4 inch, in width.
What is the recommended tightening torque for the box lug on the QO140?
The factory recommended tightening torque for the box lug terminal is 44.25 lb-in (5 N.m) when securing 8 AWG to 2 AWG copper or aluminum wire.
Is the Square D QO140 HACR rated?
Yes, this circuit breaker is HACR rated, making it suitable for use with group motor applications in heating, air conditioning, and refrigeration equipment.
How does the Visi-Trip indicator work on this breaker?
The QO140 includes the standard Square D Visi-Trip feature. When the breaker trips due to an overload or short circuit, the handle snaps to a midpoint position and a highly visible red flag appears in a small window, allowing you to easily identify the tripped breaker in a crowded panel.
Is there a bolt-on alternative for commercial panels?
Yes. If your panelboard requires a bolt-on connection instead of the standard plug-on mounting, you will need the Square D QOB140. Bolt-on breakers are often used in commercial NQ and legacy NQOB panelboards.
Is there a 22 kAIC rated version of the QO140?
Yes. If your electrical system fault current analysis requires an interrupting rating higher than the standard 10 kA, you can use the Square D QO140VH. It is the same physical size but provides a 22 kAIC rating at 120/240 VAC.
What is the ambient operating temperature rating for the QO140?
This circuit breaker is calibrated for a standard ambient operating temperature of 104 degrees Fahrenheit (40 degrees Celsius).
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Free Shipping Policy
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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All International orders require a $1,000 minimum order threshold. Due to the special nature of these shipments, we require that these be placed with a SuperBreakers representative. Additional shipping and instructions will apply. All International Orders are Non-Cancel and Non-Refundable.
Reviews
Review summary
Customers rate this product 4.9 out of 5 based on 285 reviews.
Reviews Summary
Generated by AI from 100 most recent customer reviews
Last updated 6/13/26
Customers say these circuit breakers arrive quickly and work as described. Fast shipping and competitive pricing are frequently mentioned, with many noting same-day or next-day delivery. Users appreciate the wide inventory, particularly for hard-to-find older-style models unavailable locally. The products function reliably and arrive in good condition. Most customers report straightforward ordering and positive interactions. However, some experienced delivery delays or received incorrect items requiring reordering. A few noted concerns about condition upon arrival or customer service responsiveness.
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Rating
285 reviews
- GCGerard C.Verified BuyerReviewingSquare D QO130GFI - 30A GFCI Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars9/21/26Great !
I could not find the breaker in hardwood stores. Superbreakers took car of it in a week.
- RHRoy H.Verified BuyerReviewingSquare D QO280 - 80A 2 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars9/17/26Square D QO280 - 80A 2 Pole Miniature Circuit Breaker
Exactly as described
- KWKevin W.Verified BuyerReviewingSquare D QO120 - 20A 1 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars9/15/26Great Price
Brand spanking new!
- CEchristopher e.Verified BuyerReviewingSquare D QO115PDF - 15A Dual Function Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars9/11/26My breakers
Had a hard time locating these breakers locally, when I did find 1 they wanted to charge me triple what superbreakers charged. Items delivered exactly when they said they would, were exactly what I ordered. Appreciated the ease of ordering, definitely my go to from this point on
- JCJerry C.Verified BuyerReviewingSquare D QO250 - 50A 2 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars9/8/26Great quality
No issues