Cooper Bussmann FRS-R-250 RK5 250A Time Delay Fuse

Product Description

The COOPER BUSSMANN FRS-R-250 is a cartridge-style, time delay fuse rated at 250 amps and classified under Class RK5. It is designed for general-purpose overcurrent protection in branch circuits, feeder circuits, and motor load applications where a time delay is required to ride through harmless inrush currents without nuisance opening. The fuse measures 11-5/8 inches in overall length and uses a bolt-on mount. With a dual-element construction and a DC interrupting rating of 20 kA at 200 volts RMS, this fuse provides reliable protection in demanding electrical distribution systems. Licensed electricians and industrial maintenance technicians are the primary installers.

The FRS-R-250 is suited for residential, commercial, and light industrial electrical panels and disconnect switches where Class RK5 fusing is specified. It is commonly installed in fusible disconnect switches protecting motors, HVAC equipment, and other inductive loads that draw high starting current. The time delay characteristic allows motor inrush to pass without opening the fuse, while still providing fast response to sustained overloads and short-circuit faults. Any application requiring a 250-amp, cartridge-style Class RK5 fuse with bolt-on mounting is a typical use case for this part.

Key Features

• Class RK5 time delay rating allows safe ride-through of motor inrush and transformer magnetizing currents
• Dual-element construction provides both overload and short-circuit protection in a single fuse body
• 250-amp continuous current rating suitable for heavy motor and HVAC branch circuit protection
• Bolt-on mount for secure installation in fusible disconnect switches and panel fuse blocks
• 20 kA interrupting capacity at DC 200 volts RMS for reliable fault clearing
• CE Certified, CSA Certified, and UL Listed to applicable Class RK5 standards

Compatibility

Designed as an OEM-style replacement Class RK5 cartridge fuse for fusible disconnect switches and fuse blocks that accept 250-amp bolt-on cartridge fuses with an 11-5/8 inch overall length.

Installation Notes

Installation and replacement of branch-circuit fuses must be performed by a qualified, licensed electrician in accordance with the National Electrical Code (NEC) and all applicable local codes. De-energize and lock out or tag out the circuit and verify absence of voltage before handling or replacing any fuse. Use properly rated fuse pullers and insulated tools sized for cartridge fuses of this class. Never replace a fuse with a unit of a higher amperage rating or a different fuse class than what is specified for the circuit.