Littelfuse FLNR350 350A 250V RK5 Time Delay Fuse

Product Description

The LITTELFUSE FLNR350 is a 350-amp, 250-volt, Class RK5 time-delay fuse designed for overcurrent protection in demanding electrical distribution applications. The time-delay characteristic allows the fuse to absorb short-duration inrush currents common during motor startup without nuisance opening, while still providing reliable short-circuit and overload protection. It is installed in fused disconnect switches, motor control panels, and branch-circuit protection equipment. Electricians and maintenance technicians working on commercial and industrial systems specify this fuse type where motor loads and transformer inrush are a factor.

The FLNR350 fits standard Class RK5 fuse holders and fusible disconnect switches rated for 250 volts AC or less. It is suited for motor branch circuits, feeder circuits, and service entrance protection in commercial and light industrial installations. The RK5 rejection feature prevents substitution of lower-interrupt-rating fuses, supporting code-compliant installations under NEC Article 430 for motor circuits and Article 240 for overcurrent protection.

Key Features

• 350-amp continuous current rating for high-capacity motor and feeder circuits
• 250-volt AC maximum voltage rating
• Class RK5 rejection blade construction prevents installation of non-listed substitutes
• Time-delay design tolerates motor inrush and transformer magnetizing currents without nuisance opening
• Dual-element construction provides independent response to overloads and short-circuit faults

Compatibility

Designed as an OEM-style replacement for Class RK5 fuse holders and fusible disconnect switches rated at 250 volts AC, commonly used in motor branch-circuit and feeder-circuit protection applications.

Installation Notes

Installation must be performed by a licensed electrician in accordance with the NEC and applicable local codes. De-energize and lock out the circuit at the upstream overcurrent device before removing or installing fuses. Verify that the fuse holder is rated for Class RK5 fuses and that the circuit voltage and ampacity do not exceed the fuse ratings. Never replace a time-delay fuse with a fast-acting fuse in motor-circuit applications without engineering review.

Technical Specifications

• Current Rating: 350 amps
• Voltage Rating: 250 volts AC
• Fuse Class: RK5
• Response Type: Time Delay
• UPC: 07945815092

Standard Information

• Brand: LITTELFUSE
• Manufacturer Part Number: FLNR350