Free Shipping Over $99
Free Shipping Over $99
Free Shipping Over $99
Free Shipping Over $99
Square D QO340-1021 QO3401021 - 40A 3 Pole Miniature Circuit Breaker
- 40A
- 3 Pole
- Plug-On
Square D
QO340-1021
QO3401021 - 40A 3 Pole Miniature Circuit Breaker
Brand
Square D
SKU
QO340-1021
Quantity
Shop with Confidence
Add an extra year of protection in your cart.
Square D QO3401021 - 40A 3 Pole Miniature Circuit Breaker
New
Quantity
Similar Items
QO3601021 - 60A 3 Pole Miniature Circuit Breaker
QO3201021 - 20A 3 Pole Miniature Circuit Breaker
70A 3 Pole Miniature Circuit Breaker
Description
Part of the QO series, the Square D QO340-1021 is a 40-amp, three-pole miniature circuit breaker designed for residential, commercial, and industrial use. It is engineered to mount into QO load centers, NQ panelboards, and legacy NQOD systems. This plug-on breaker features a 10kAIC rating at 240VAC and utilizes thermal-magnetic trip technology. The defining feature is the factory-installed 120/240V shunt trip accessory, which enables the breaker to be tripped remotely from a pilot device.Specifications
| Brand | Square D |
|---|---|
| Part Number | QO3401021 |
| Series | QO |
| Amperage | 40A |
| Poles | 3 |
| Mounting Style | Plug-On |
| Voltage | 240VAC, 120/240VAC, 48VDC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC, 10kA @ 120/240VAC, 5kA @ 48VDC |
| 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 | Auxiliary Switch, Alarm Switch, Padlock Attachment |
|---|---|
| Accessories | Shunt Trip |
| Standards | HACR, UL 489, CSA C22.2 No. 5 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Visual Trip Indicator, Common Trip |
Product FAQs
7 answersWhat does the -1021 suffix mean on the QO340-1021 catalog number?
The -1021 suffix denotes a factory-installed 120/240VAC shunt trip accessory. This allows the breaker to be tripped remotely via an external pilot device or control signal.
How many panel spaces does the QO3401021 require?
Because of the factory-installed shunt trip accessory, this 3-pole breaker requires four standard 3/4-inch pole spaces in your panel.
Can I install the QO3401021 in a Homeline load center?
No. Square D QO breakers are not interchangeable with Homeline breakers. The QO3401021 is specifically designed for QO load centers, NQ panelboards, and legacy NQOD panelboards.
Does the QO3401021 feature a Visi-Trip indicator?
Yes, it includes Square D's Visi-Trip indicator. When the breaker trips due to an overcurrent or a remote shunt trip signal, a red indicator appears in the window to help you quickly identify the tripped breaker in the panel.
What voltage is required to operate the shunt trip on the QO3401021?
The factory-installed shunt trip accessory requires a 120/240VAC control signal to remotely open the breaker contacts.
Can the QO3401021 be manually switched on and off?
Yes. Even though it includes a remote shunt trip accessory, it still functions as a standard thermal-magnetic breaker and can be manually toggled on or off at the panel.
Is the QO3401021 suitable for use with heating, air conditioning, and refrigeration equipment?
Yes, this breaker is HACR rated, making it suitable for protecting heating, air conditioning, and refrigeration motor loads.
SuperClub
Join free. Get 500 SuperPoints.
Earn points on eligible purchases and redeem them at checkout.
100 SuperPoints = $1 off.
Warranties
Add an extra year of protection
60-Day Warranty
Your purchase includes 60 days of SuperBreakers warranty coverage.
Add a 1-year warranty extension in your cart.
Get a Quote
Don’t see what you’re looking for?
We source obsolete and hard-to-find parts every day.
Shipping
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.
Same Day Shipping
We strive to ship out your items the same day the order is placed. In rare circumstances SuperBreakers may reserve up to 5 business days to consolidate orders for complete shipment.
Expedited Shipments
Orders being shipped via Next Day Air, 2 Day Shipping or 3 Day Shipping must be received by 3 PM EST to guarantee same-day shipments. Expedited orders only ship on normal business days. Shipments will NOT be sent out on Saturdays and Sundays.
International Shipping
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 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.
Search
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