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Square D Q1B390 Molded Case Circuit Breaker
- 90A
- 3 Pole
- Bolt-On
Square D
Q1B390
Molded Case Circuit Breaker
Brand
Square D
SKU
Q1B390
Quantity
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Square D Q1B390 - 90A 3 Pole Molded Case Circuit Breaker
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Description
Built for commercial applications, this 90A three-pole breaker delivers standard 10kAIC protection at 240VAC. It features thermal-magnetic trip technology for consistent long-time and instantaneous response. This unit installs into legacy Square D NQO and NQOB panelboards. For modern upgrades, it is replaced by the QOB390, which requires an SK5668 mounting kit to fit the older bus structure. The Visi-Trip indicator provides clear visual confirmation during a fault, reducing downtime.Specifications
| Brand | Square D |
|---|---|
| Series | Q1B |
| Amperage | 90A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 240VAC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC |
| Frame Type | Q1B |
|---|---|
| Terminal Type | Box Lugs |
| For Use With | Square D NQO, NQOB Panelboards |
| Wire Gauge | #4-2/0 AWG |
| 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 Thermal, Fixed Magnetic |
| Available Options | Shunt Trip, Auxiliary Switch, Alarm Switch |
|---|---|
| Accessories | Load Side Lugs Included |
| Standards | CSA C22.2 No. 5, HACR Rated, UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | Visual Trip Indicator, Common Trip |
Product FAQs
4 answersWhat panelboards are compatible with the Square D Q1B390?
The Q1B390 is designed specifically for older Square D NQO and NQOB panelboards. It uses a bolt-on connection to secure directly to the panel busbar.
Can I replace a Q1B390 with a newer QOB circuit breaker?
Yes, but it requires additional hardware. The Q1B series is obsolete and has been replaced by the QOB series. However, installing a newer QOB breaker in place of a Q1B requires an SK5668 mounting bracket. Using an exact Q1B390 replacement is a simpler, drop-in solution for existing panels.
What wire gauge is required for the Q1B390 box lugs?
The terminal lugs on this breaker are designed to accept wire sizes ranging from #4 AWG to 2/0 AWG.
What does the LI trip function mean on the Q1B390?
The LI designation indicates that this thermal magnetic breaker includes both Long-Time and Instantaneous trip functions. The thermal element provides Long-Time protection against gradual overloads, while the magnetic element provides Instantaneous protection against short circuits.
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Reviews
Review summary
Customers rate this product 5.0 out of 5 based on 1 review.
Total 5 star reviews: 1 Total 4 star reviews: 0 Total 3 star reviews: 0 Total 2 star reviews: 0 Total 1 star reviews: 0
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1 review
- MCMichael C.ReviewingSquare D Q1B3100 - 100A 3 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars2/11/22Fast Service.
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