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Square D QO340SWN Miniature Circuit Breaker
- 40A
- 3 Pole
- Plug-On
Square D
QO340SWN
Miniature Circuit Breaker
Brand
Square D
SKU
QO340SWN
Quantity
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Square D QO340SWN - 40A 3 Pole Miniature Circuit Breaker
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Description
Built for specialized applications requiring a disconnected neutral, the Square D QO340SWN delivers 40 amps of thermal-magnetic protection. This three-pole miniature circuit breaker is rated for 120/240VAC systems and is commonly utilized in commercial environments like gas pump assemblies. It mounts securely into standard Square D QO load centers and NQ panelboards using a convenient plug-on connection.Specifications
| Brand | Square D |
|---|---|
| Part Number | QO340SWN |
| Series | QO |
| Amperage | 40A |
| Poles | 3 |
| Mounting Style | Plug-On |
| Voltage | 120/240VAC |
| Phase | 1 |
| AIC Rating | 10kA @ 120/240VAC |
| Terminal Type | Box Lugs |
|---|---|
| For Use With | QO Load Centers, NQ 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 |
|---|---|
| Standards | CSA C22.2 No. 5, UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | Visual Trip Indicator, Switch Neutral |
| Special Features | Switching Neutral |
Product FAQs
6 answersWhat is the primary application for the QO340SWN circuit breaker?
The QO340SWN is a switched neutral breaker designed to disconnect all grounded and ungrounded conductors simultaneously. It is commonly used to protect gas pump assemblies and motor fuel dispensing facilities to comply with NEC Article 514 requirements.
Why is the QO340SWN listed as a 3-pole breaker for a single-phase circuit?
The QO340SWN features a Switched Neutral (SWN) design. While it physically occupies three spaces on the busbar like a standard 3-pole breaker, it is wired for a 2-pole, 3-wire 120/240V single-phase circuit. The third pole is dedicated to disconnecting the neutral conductor.
Can the QO340SWN be used for 3-phase equipment?
No. Despite having three poles, the QO340SWN is specifically engineered for single-phase 120/240V applications that require a switched neutral. It is not intended for 3-phase motor loads or standard 3-phase distribution.
How does the common trip mechanism function on the QO340SWN?
The internal common trip ensures that an overcurrent event on either of the ungrounded hot lines will trip all three poles simultaneously. This completely isolates the circuit by disconnecting both the hot lines and the neutral conductor at the same time.
Does this breaker include ground fault or arc fault protection?
No. The QO340SWN is a standard thermal-magnetic breaker with a switched neutral. It provides long-time and instantaneous (LI) trip functions for overload and short circuit protection, but it does not include GFCI or AFCI circuitry.
Which panels will accept the QO340SWN breaker?
This plug-on breaker is designed exclusively for Square D QO load centers and NQ panelboards. It requires three adjacent full-size spaces on the busbar for proper installation.
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Reviews
Review summary
Customers rate this product 4.9 out of 5 based on 286 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
286 reviews
- RBRobert B.Verified BuyerReviewingSquare D QO120 - 20A 1 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars10/5/26Square D Q0120-20A circuit breaker
This device was delivered on time as advertised and it was in excellent condition. The installation process was simple and straightforward, and the unit worked perfectly when connected to the electric circuit.
I am completely satisfied and will utilize this component resource for my future electrical needs.
- 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