Square D Q1L390 Molded Case Circuit Breaker
- 90A
- 3 Pole
- Unit Mount
Quantity
Square D Q1L390 - 90A 3 Pole Molded Case Circuit Breaker
Re-Certified
Quantity
Description
Operating at 240VAC with a 10kAIC rating, the Square D Q1L390 is a 3-pole, 90A unit-mount circuit breaker. It provides essential long-time and instantaneous protection for commercial and industrial electrical systems. This legacy component mounts into OEM panels and Q1L enclosures using standard feed-thru lugs, accepting 4-2/0 AWG wire. Facilities looking for a modern equivalent can cross-reference this unit to the current QOU390 series.Specifications
| Brand | Square D |
|---|---|
| Series | Q1L |
| Amperage | 90A |
| Poles | 3 |
| Mounting Style | Unit Mount |
| Voltage | 240VAC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC |
| Frame Type | Q1L |
|---|---|
| Terminal Type | Lugs |
| For Use With | Square D Q1L Enclosures, OEM Panels |
| Wire Gauge | 4-2/0 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 Thermal, Fixed Magnetic |
| Available Options | Padlock Attachment |
|---|---|
| Accessories | Lugs (Factory Installed) |
| Standards | UL 489, CSA C22.2 No. 5 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | Visual Trip Indicator, HACR Rated, Common Trip |
Product FAQs
5 answersWhat is the modern replacement for the legacy Square D Q1L390?
The Square D QOU390 is the direct modern equivalent. It shares the same 90A, 3-pole, 240VAC electrical ratings and unit-mount, feed-thru design as the legacy Q1L series.
Can the Q1L390 be installed in a standard Square D QO load center?
No. The Q1L390 is a unit-mount, feed-thru breaker designed specifically for legacy Q1L enclosures and OEM panels. It does not have the plug-on or bolt-on connections required for QO or QOB load centers.
How is the Q1L390 mounted and connected?
This breaker uses a unit-mount, feed-thru design. It mounts directly to the panel or enclosure backpan and features factory-installed lugs on both the line and load sides, rather than plugging into a busbar.
What wire gauges are compatible with the Q1L390 terminals?
The factory-installed lugs accept aluminum or copper wiring ranging from 4 AWG up to 2/0 AWG. Proper torque specifications must be followed during installation to ensure a secure connection.
How does the trip mechanism operate on the Q1L390?
The breaker utilizes a fixed thermal-magnetic trip unit. The thermal element responds to sustained overloads, while the magnetic element provides instantaneous tripping during short-circuit faults.
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