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Square D QOU340-1021 QOU3401021 - 40A 3 Pole Miniature Circuit Breaker
- 40A
- 3 Pole
- Unit Mount
Square D
QOU340-1021
QOU3401021 - 40A 3 Pole Miniature Circuit Breaker
Brand
Square D
SKU
QOU340-1021
Quantity
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Square D QOU3401021 - 40A 3 Pole Miniature Circuit Breaker
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Description
Designed for advanced control, the QOU340-1021 is a 3-pole, 40A miniature circuit breaker. It is engineered for OEM panels requiring remote shutdown capabilities. This model features a factory-installed 120V AC shunt trip accessory. The unit mount design easily integrates into DIN rail systems and includes box lugs for 14-2 AWG wiring. Providing 10 kAIC at 240VAC, it delivers dependable thermal-magnetic protection. The unit is HACR rated and includes a Visi-Trip visual indicator.Specifications
| Brand | Square D |
|---|---|
| Part Number | QOU340-1021 |
| Series | QOU |
| Amperage | 40A |
| Poles | 3 |
| Mounting Style | Unit Mount |
| Voltage | 240VAC, 120/240VAC, 48VDC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC, 10kA @ 120/240VAC, 5kA @ 48VDC |
| Frame Type | QOU |
|---|---|
| Terminal Type | Box Lugs |
| For Use With | DIN Rail Systems, OEM Panels, Control Panels, Enclosures |
| Wire Gauge | 14-2 AWG (Al/Cu) |
| Max Wire | 2 AWG |
| Min Wire | 14 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed |
| Available Options | Mounting Feet, Padlock Attachment, Auxiliary Switch, Alarm Switch |
|---|---|
| Accessories | Shunt Trip |
| Standards | CSA C22.2 No. 5, HACR, IEC 60947-2, UL 489 |
| Approval | CE, CSA, HACR, IEC, UL |
| Temp Rating | 40C |
Product FAQs
6 answersWhat does the 1021 suffix indicate on the QOU3401021 circuit breaker?
The 1021 suffix designates that this breaker includes a factory-installed 120V AC shunt trip. This allows the breaker to be tripped remotely by an external control signal.
How is the QOU3401021 installed in a panel?
This is a unit-mount breaker with a bolt-on connection. It is designed for standalone mounting in DIN rail systems, OEM panels, and control enclosures, rather than snapping onto a standard load center bus.
Are line and load lugs included with the QOU3401021?
Yes, this breaker features slotted box lugs on both the line and load sides. These terminals accept 14 AWG to 2 AWG aluminum or copper wire.
Can this breaker be used in DC control circuits?
Yes, while primarily used for AC systems up to 240V, this breaker is also rated for DC applications, providing a 5kA interrupting capacity at 48V DC.
Is QOU340-1021 the exact same part as QOU3401021?
Yes, QOU340-1021 is simply an alternate catalog formatting for the exact same Square D 40A, 3-pole breaker with a 120V shunt trip.
What type of protection does this breaker provide?
It utilizes a fixed thermal magnetic trip unit with Long-Time and Instantaneous (LI) functions to protect against standard overloads and short circuits, alongside the remote shunt trip capability.
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Reviews
Review summary
Customers rate this product 5.0 out of 5 based on 107 reviews.
Reviews Summary
Generated by AI from 99 most recent customer reviews
Last updated 5/14/26
Customers say these circuit breakers function properly and arrive quickly. Many reviews highlight fast shipping, competitive pricing, and reliable product condition upon arrival. Users appreciate the wide selection, including hard-to-find models, and note the breakers work as expected for various applications. Common feedback addresses quick order processing and easy website navigation. Most customers report satisfaction with value and delivery speed, with many indicating they will purchase again.
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Rating
107 reviews
- VBVictor B.Verified BuyerReviewingSquare D QOU280 - 80A 2 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars10/6/26Square D QOU280
As advertised, works great under normal load conditions. We Recomend this product. Service and shipping was great and easy. Pleasure to deal with.
- HLHOMETIGO L.Verified BuyerReviewingSquare D QOU260 - 60A 2 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars9/7/26Good thing
i recommend this for you
- RGRobert G.Verified BuyerReviewingSquare D QOU340 - 40A 3 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars9/3/26Circuit breakers
I appreciate the fact that you had these in stock. my Square D distributor does not seem to stock these anymore and it takes a couple weeks to get. your pricing is inline with theirs.
- THTiffany H.Verified BuyerReviewingSquare D QOU115 - 15A 1 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars8/28/26Will use Super Breakers again
Arrived in a timely manner. Exactly what we needed for a job.
- CSCary S.Verified BuyerReviewingSquare D QOU250 - 50A 2 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars8/12/26Just what I ordered
Just what I needed for dock pedestal