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Square D QOB390 Miniature Circuit Breaker
- 90A
- 3 Pole
- Bolt-On
Square D
QOB390
Miniature Circuit Breaker
Brand
Square D
SKU
QOB390
Quantity
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Square D QOB390 - 90A 3 Pole Miniature Circuit Breaker
New
Quantity
Quantity
Square D QOB390 - 90A 3 Pole Miniature Circuit Breaker
New
Quantity
| Brand | Square D |
|---|---|
| Part Number | QOB390 |
| Series | QOB |
| Amperage | 90A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 240VAC, 120/240VAC, 48VDC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC, 10kA @ 120/240VAC, 5kA @ 48VDC |
| Frame Type | QOB |
|---|---|
| Terminal Type | Box Lugs |
| For Use With | NQ Panelboards, NQOD Panelboards |
| Wire Gauge | 4 AWG-2/0 AWG (Al/Cu) |
| Max Wire | 2/0 AWG |
| Min Wire | 4 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, Handle Tie, Handle Lock |
|---|---|
| Accessories | Load Side Lugs Included |
| Standards | CSA C22.2 No. 5, HACR, UL 489 |
| Approval | CSA, HACR, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Visual Trip Indicator, Common Trip, Trip-Free Mechanism, Quick-Make/Quick-Break |
Sold out
Quantity
Square D QOB390 - 90A 3 Pole Miniature Circuit Breaker
Re-Certified
Quantity
| Brand | Square D |
|---|---|
| Part Number | QOB390-R |
| Series | QOB |
| Amperage | 90A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 240VAC, 120/240VAC, 48VDC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC, 10kA @ 120/240VAC, 5kA @ 48VDC |
| Frame Type | QOB |
|---|---|
| Terminal Type | Box Lugs |
| For Use With | NQ Panelboards, NQOD Panelboards |
| Wire Gauge | 4 AWG-2/0 AWG (Al/Cu) |
| Max Wire | 2/0 AWG |
| Min Wire | 4 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, Handle Tie, Handle Lock |
|---|---|
| Accessories | Load Side Lugs Included |
| Standards | CSA C22.2 No. 5, HACR, UL 489 |
| Approval | CSA, HACR, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Visual Trip Indicator, Common Trip, Trip-Free Mechanism, Quick-Make/Quick-Break |
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Description
Part of the QO family, this 90A miniature circuit breaker provides thermal-magnetic overcurrent protection for commercial and industrial applications. It is rated for 10kAIC at 240VAC. The three-pole unit mounts into Square D NQ and NQOD panelboards using a secure bolt-on connection. It accepts 4 AWG to 2/0 AWG aluminum or copper wiring via standard box lugs. A built-in Visi-Trip indicator provides immediate visual confirmation of a tripped circuit. The breaker is also HACR rated.Specifications
| Brand | Square D |
|---|---|
| Part Number | QOB390 |
| Series | QOB |
| Amperage | 90A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 240VAC, 120/240VAC, 48VDC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC, 10kA @ 120/240VAC, 5kA @ 48VDC |
| Frame Type | QOB |
|---|---|
| Terminal Type | Box Lugs |
| For Use With | NQ Panelboards, NQOD Panelboards |
| Wire Gauge | 4 AWG-2/0 AWG (Al/Cu) |
| Max Wire | 2/0 AWG |
| Min Wire | 4 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, Handle Tie, Handle Lock |
|---|---|
| Accessories | Load Side Lugs Included |
| Standards | CSA C22.2 No. 5, HACR, UL 489 |
| Approval | CSA, HACR, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Visual Trip Indicator, Common Trip, Trip-Free Mechanism, Quick-Make/Quick-Break |
Product FAQs
4 answersWhat panelboards are compatible with the QOB390?
This breaker bolts into Square D NQ and NQOD panelboards. Because it utilizes a bolted bus connection, it will not fit in standard QO residential load centers that require plug-on breakers.
How much panel space does this circuit breaker occupy?
It requires three standard 3/4-inch spaces within your panelboard chassis.
Is there a version of this breaker with a higher interrupting rating?
Yes. If your fault current calculations exceed 10kA at 240VAC, the QOB390VH is the direct upgrade that provides a 22kAIC rating in the same footprint.
Is the QOB390 HACR rated?
Yes, it is HACR rated, meaning it is certified for safely supplying power to heating, air conditioning, and refrigeration equipment motor loads.
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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 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