Square D FJA140503 Molded Case Circuit Breaker
- 50A
- 1 Pole
- I-Line
Quantity
Square D FJA140503 - 50A 1 Pole Molded Case Circuit Breaker
New
Quantity
Description
Designed to handle 65 kAIC at 277VAC, this 50-amp molded case circuit breaker delivers essential long-time and instantaneous (LI) protection. The FJA140503 is engineered with a factory-configured Phase B connection and mounts into Square D I-Line switchboards using a secure plug-on design. As part of the legacy F-Frame family, it provides high interrupting capacity for industrial applications. When replacing this unit, the HJA260503 serves as the substitute but requires two pole spaces.Specifications
| Brand | Square D |
|---|---|
| Part Number | FJA140503 |
| Series | FJA |
| Amperage | 50A |
| Poles | 1 |
| Mounting Style | I-Line |
| Voltage | 240VAC, 277VAC, 125VDC |
| Phase | 1 |
| AIC Rating | 65kA @ 240VAC, 65kA @ 277VAC, 10kA @ 125VDC |
| Frame Type | FJA |
|---|---|
| Terminal Type | Lugs |
| For Use With | Square D I-Line Panelboards and Switchboards |
| Wire Gauge | 14-1/0 AWG (Cu/Al) |
| Max Wire | 1/0 AWG |
| Min Wire | 14 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, Undervoltage Release, Padlock Attachment |
|---|---|
| Accessories | Phase B Connection (Factory Configured) |
| Standards | UL 489, CSA C22.2 No. 5, NEMA AB 1, IEC 60947-2 |
| Approval | CSA, HACR, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, High Interrupting Capacity |
Product FAQs
5 answersCan I install the FJA140503 in a standard Square D NQ or NF panel?
No, this breaker is designed exclusively for Square D I-Line panelboards and switchboards. It utilizes a specialized plug-in mounting jaw that connects directly to the I-Line busbar system.
What wire sizes and materials are compatible with the FJA140503 lugs?
The factory-installed lugs accept 14 AWG to 1/0 AWG wire. Both copper and aluminum conductors are supported.
Is the FJA140503 suitable for direct current applications?
Yes, in addition to its 65kAIC rating at 240VAC and 277VAC, this breaker is DC-rated. It provides a 10kAIC interrupting capacity at 125VDC.
What is the recommended replacement for the legacy FJA140503?
When replacing this legacy 1-pole F-frame breaker, the PowerPact H-frame HJA260503 serves as the modern substitute. Because the HJA replacement is a 2-pole breaker, it will require two pole spaces in your I-Line panel.
How does the trip unit on the FJA140503 operate?
It features a fixed thermal magnetic trip mechanism. This provides dual protection, utilizing a thermal element for long-time overload conditions and a magnetic element for instantaneous short-circuit protection.
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