Cooper Bussmann FRS-R-4 RK5 Time Delay Fuse 4A 5 in

Product Description

The COOPER BUSSMANN FRS-R-4 is a cartridge-style, time-delay fuse rated at 4 amps and classified as RK5. It measures 5 inches in overall length with a body diameter of 0.81 inches and is designed for general-purpose overcurrent protection in industrial and commercial electrical systems. The dual-element, time-delay construction allows it to ride through brief inrush currents without nuisance tripping while still responding decisively to sustained overloads and short-circuit faults. Licensed electricians and maintenance technicians install this fuse in fuse holders where RK5-class protection is required. Certifications include CE, CSA C22.2 No. 248.12, and UL Listed 248-12 Class RK5.

The FRS-R-4 is suited for residential, commercial, and light industrial electrical panels and equipment where RK5 cartridge fuses are specified. Common applications include motor branch circuits, transformer secondaries, and control circuits that experience normal startup inrush. It mounts in standard fuse holders sized for 5-inch cartridge fuses and is used wherever a non-indicating, dual-element time-delay fuse at 4 amps is called for by the system design or equipment nameplate.

Key Features

• Time-delay dual-element design tolerates motor and transformer inrush without nuisance tripping
• RK5 class rating for general-purpose overcurrent protection
• 20 kA interrupting rating at DC 200 V RMS for reliable fault clearing
• Non-indicating body keeps installation compact with no added indicator components
• CE Certified, CSA C22.2 No. 248.12 Certified, and UL Listed 248-12 Class RK5
• Mounts in standard cartridge fuse holders — no special tooling required

Compatibility

Designed as an OEM-style replacement for RK5-class cartridge fuse positions requiring a 4-amp, 5-inch time-delay fuse in standard fuse holders.

Installation Notes

Installation should be performed by a qualified electrician in accordance with the NEC and applicable local codes. Always de-energize and lock out the circuit before removing or installing fuses. Use an insulated fuse puller rated for the voltage of the circuit — never pull a fuse from a live holder with bare hands or unrated tools. Verify the replacement fuse class, amperage, and voltage rating match the circuit and equipment nameplate before restoring power.