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Square D QOB340GFI GFCI Miniature Circuit Breaker
- 40A
- 3 Pole
- Bolt-On
Square D
QOB340GFI
GFCI Miniature Circuit Breaker
Brand
Square D
SKU
QOB340GFI
Quantity
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Square D QOB340GFI - 40A GFCI Miniature Circuit Breaker
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Description
Part of the renowned QO series, this 40-amp, three-pole GFCI breaker provides essential 6mA ground fault protection for commercial electrical systems. Rated for 10kAIC at 208Y/120VAC, the Square D QOB340GFI features a robust bolt-on mounting style that ensures a secure mechanical and electrical connection in NQ and NQOD panelboards. It comes equipped with a pigtail neutral and a Visi-Trip visual indicator to help electricians rapidly locate faults during routine maintenance or outages.Specifications
| Brand | Square D |
|---|---|
| Part Number | QOB340GFI |
| Series | QOB |
| Amperage | 40A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 208Y/120VAC |
| Phase | 3 |
| AIC Rating | 10kA @ 208Y/120VAC |
| Terminal Type | Box Lugs |
|---|---|
| For Use With | NQ Panelboards, NQOD Panelboards |
| Wire Gauge | 12-4 AWG (Al), 14-6 AWG (Cu) |
| Max Wire | 4 AWG (Al), 6 AWG (Cu) |
| Min Wire | 12 AWG (Al), 14 AWG (Cu) |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LIG |
| Trip Function | Long-Time, Instantaneous, Ground Fault |
| Trip Adjustability | Fixed |
| Special Classification | GFCI |
|---|---|
| Available Options | Shunt Trip, Auxiliary Switch, Alarm Switch, Padlock Attachment |
| Accessories | Load Side Lugs Included, Pigtail Neutral |
| Standards | CSA C22.2 No. 5, RoHS, UL 489, UL 943 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | Visual Trip Indicator |
Product FAQs
6 answersWill the QOB340GFI bolt-on breaker fit in a standard Square D QO load center?
No. While it shares the same internal mechanism as the QO series, this QOB breaker features bolt-on brackets specifically designed for NQ and legacy NQOD commercial panelboards. Standard residential QO load centers require plug-on style breakers.
Is the QOB340GFI rated for equipment protection or personnel protection?
It provides Class A personnel protection. The ground-fault circuitry is designed to trip when leakage current reaches the 4 to 6 milliamp range, unlike equipment protection devices (EPD) which typically trip at a much higher 30 milliamp threshold.
How does the pigtail neutral on the QOB340GFI connect during installation?
The coiled white pigtail wire must be routed and secured directly to the panelboard neutral bar. This connection provides the return path necessary to power the breaker's internal ground-fault monitoring electronics.
Can the QOB340GFI be used on a straight 240V or delta 3-phase system?
No. This GFCI breaker is rated strictly for 208Y/120V AC wye systems. Its internal ground-fault sensors require a solidly grounded 120V reference to function correctly, rendering it incompatible with ungrounded or corner-grounded delta configurations.
Can I substitute the QO340GFI for this breaker if they share the same electrical ratings?
Only if your panelboard bus accepts plug-on connections. The QO340GFI is a plug-on variant, whereas the QOB340GFI requires bolt-on mounting. They cannot be interchanged between bolt-on NQ panelboards and plug-on QO load centers.
Does the QOB340GFI feature a visual trip indicator?
Yes. It includes the Square D Visi-Trip indicator. When the breaker trips due to an overcurrent or ground-fault condition, the handle moves to a midpoint position and a highly visible red indicator appears in the window, making it easy to identify the tripped circuit in a busy panel.
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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