Cooper Bussmann FRS-R-4-1/2 Time Delay Fuse 4.5A RK5

Product Description

The COOPER BUSSMANN FRS-R-4-1/2 is a time delay cartridge fuse rated at 4.5 amps in the Class RK5 designation. It is designed for general-purpose overcurrent protection in electrical distribution systems where brief inrush currents must be tolerated without nuisance tripping. The fuse measures 5 inches in overall length and 20.6 millimeters in diameter, and features a dual-element construction that distinguishes between harmless transient surges and genuine fault conditions. Licensed electricians and electrical contractors install this fuse in fuse holders during panel work, motor circuit protection, and equipment branch circuit applications.

This fuse is suited for residential and light commercial electrical installations where Class RK5 time delay protection is specified. It is commonly installed in fuse holders serving motor loads, HVAC equipment, and general branch circuits that require a fuse capable of riding through startup inrush without opening. The non-indicating body provides no visual fault signal, so replacement follows standard continuity testing during troubleshooting.

Key Features

• Class RK5 time delay rating handles motor inrush and transient overloads without nuisance opening
• Dual-element construction separates overload response from short-circuit interruption
• 20 kA interrupting capacity at DC 200 volts RMS
• Non-indicating cartridge body — 5 inches long, 20.6 millimeters in diameter
• Mounts in standard Class RK5 fuse holders
• CE Certified, CSA Certified, and UL Listed to applicable overcurrent protection standards

Compatibility

Designed for use in standard fuse holders that accept Class RK5 cartridge fuses. Confirm holder sizing matches the 5-inch overall length and 20.6-millimeter diameter before installation.

Installation Notes

Installation must be performed by a qualified electrician in accordance with the National Electrical Code (NEC) and any applicable local codes. Always de-energize and lock out the circuit before removing or installing fuses. Use an appropriately rated fuse puller for cartridge fuse removal — do not pull live fuses by hand. Verify the replacement fuse amperage and class match the circuit protection requirements exactly before restoring power.