Overview
The Littelfuse FLNR45 Class RK5 time delay fuse delivers reliable overcurrent protection in industrial, commercial, and general-purpose electrical systems. This dual-element fuse is designed for applications requiring both short-circuit and overload protection without nuisance tripping. The FLNR series sets the standard for general-purpose fuses and is widely used in service entrance switches, transformers, switchboards, motor control circuits, and distribution panelboards.
Key Features
- Dual-Element Design: Advanced short-circuit and overload protection in a single cartridge
- Current-Limiting Technology: Reduces fault current to protect equipment and downstream conductors
- Time-Delay Construction: Eliminates nuisance opening on harmless transients and inrush currents
- Compact Cartridge Form: Standard 0.8125″ diameter, 3.0″ length for easy installation in RK5 blocks
- UL Listed & CSA Certified: Meets UL Standard 248-12 and Federal Specification WF-1814 (QPL)
- Box of 10: Convenient quantity for maintenance stocking and emergency replacement
Technical Specifications
- Ampere Rating: 45A
- Voltage Rating AC: 250V
- Voltage Rating DC: 125V
- Fuse Class: RK5
- Type: Time Delay (Dual-Element)
- Cartridge Diameter: 0.8125 inches
- Cartridge Length: 3.0 inches
- Interrupting Rating AC: 200 kA rms symmetrical (300 kA rms symmetrical Littelfuse self-certified)
- Interrupting Rating DC: 20 kA
- Current Limiting: Yes
- Certifications: UL Listed (File E81895), CSA Certified (File LR29862), Federal Specification WF-1814
- Quantity per Box: 10 units
Typical Applications
The Littelfuse FLNR45 is ideal for protecting circuits in:
- Service entrance and main disconnect switches
- Power transformers and distribution transformers
- Switchboard mains and feeder circuits
- Motor control centers and motor branch circuits
- General-purpose AC and DC distribution circuits
- Fluorescent lighting systems and other equipment requiring surge tolerance
Compatibility & Replacements
Compatible With
- Standard Class RK5 fuse blocks and holders rated for 250V AC service
- NEMA-compliant electrical distribution equipment
- Industrial control panels and switchboards
- Motor control centers with 45A Class RK5 fuse provisions
Replaces / Drop-In Replacement For
- Littelfuse FLNR-45 (original cartridge version)
- Littelfuse FLNR045 (alternate part numbering)
- Other equivalent 45A 250V Class RK5 dual-element time-delay fuses meeting UL Standard 248-12
Works With
- Class RK5 fuse blocks and cartridge holders (Littelfuse, Bussman, Eaton, and equivalent manufacturers)
- 250V AC/125V DC electrical distribution systems
- UL-listed switchgear and panelboards designed for Class RK5 cartridge fuses
- Transformer protection circuits and feeder protection applications
