Overview
The Littelfuse FLNR25 is a Class RK5 dual-element time-delay fuse engineered for reliable circuit protection across industrial and commercial applications. The FLNR series sets the standard for general purpose fuses with a dual-element design that provides advanced short-circuit and overload protection. FLNR series fuses are the most widely used class of fuses and have been the superior UL Class RK5 dual-element time-delay fuses.
Key Features
- Dual-element design with current limiting capability
- Excellent protection for all types of circuits, especially those containing motors
- 25A ampere rating at 250VAC/125VDC with time-delay/slow-blow operation
- High interrupting rating for reliable fault clearance
- UL Listed and CSA Certified for industrial compliance
- Cartridge-style construction for standard fuse holders
Technical Specifications
- Ampere Rating: 25A
- Voltage Rating (AC): 250V
- Voltage Rating (DC): 125V
- Fuse Class: Class RK5
- Element Type: Dual-element design
- Operation: Time Delay / Slow Blow
- Interrupt Rating (AC): 200 kA rms symmetrical
- Interrupt Rating (DC): 20 kA
- Construction Style: Cartridge-style
- Certifications: UL Listed (File: E81895), CSA Certified (File: LR29862), Federal Specification WF-1814
- Quantity per Box: 9 fuses
Typical Applications
The FLNR Series fuse is ideal for use in service entrance switches, transformers, switchboard mains and feeders, motor control central mains and motor branch circuits, and all general purpose circuits. These fuses are particularly well-suited for:
- Motor branch circuits and motor control centers
- Transformer protection
- Switchboard and feeder protection
- Industrial machinery and equipment circuits
- HVAC and manufacturing facility electrical protection
Compatibility & Replacements
Compatible With
- Standard cartridge fuse holders rated for RK5 fuses
- Service entrance switches and panelboards
- Motor control centers and disconnect switches
- Transformer primary protection circuits
- Industrial electrical distribution systems
Replaces / Drop-In Replacement For
- Littelfuse FLNR025 (OEM equivalent designation)
- Other standard 25A RK5 time-delay fuses from equivalent manufacturers
- Verify compatibility with your system integrator before ordering.
Works With
- UL Class RK5 rated fuse holders and clips
- Standard 250VAC industrial electrical distribution systems
- 125VDC systems (battery backup and control circuits)
- Motor starter and contactor protection schemes
- Transformer protection systems












