Cooper Bussmann JKS-400 Class J Cartridge Fuse 400A 600V

Product Description

The COOPER BUSSMANN JKS-400 is a Class J fast-acting cartridge fuse rated at 400 amps and 600 volts with a 200 kA RMS interrupting capacity. Designed for general-purpose overcurrent protection in industrial and commercial power distribution systems, this fuse provides reliable short-circuit protection where high fault-current capacity is required. The bolt-on mount design allows secure installation in Class J fuse holders and disconnect switches. At 7.125 inches overall length and 2 inches in diameter, it meets the dimensional standards required for Class J fuse block installations. Licensed electricians and industrial maintenance technicians are the primary installers.

This fuse is suited for use in commercial and industrial electrical distribution panels, motor branch circuits, and disconnect switches where Class J fuse protection is specified. Its fast-acting characteristics make it appropriate for loads that do not require time-delay protection, such as resistive and light inductive loads. The 200 kA interrupting rating supports high fault-current environments common in larger commercial facilities and industrial plants.

Key Features

• 400A continuous current rating at 600 volts AC
• 200 kA RMS symmetrical interrupting capacity for high fault-current environments
• Fast-acting fuse timing for immediate response to overload and short-circuit conditions
• Bolt-on mount type for secure, vibration-resistant installation
• Class J form factor: 7.125 inches OAL, 2 inches diameter
• CE Certified, CSA Certified (Class 1422-02 File 53787), and UL Listed (Guide JDDZ File E4273)

Compatibility

Designed as a Class J cartridge fuse replacement for use in UL-listed Class J fuse holders, fusible disconnects, and combination motor controllers requiring 400A, 600V fast-acting overcurrent protection.

Installation Notes

Installation must be performed by a licensed electrician in accordance with the National Electrical Code (NEC) and applicable local codes. De-energize and lock out the circuit at the upstream disconnect before removing or installing any fuse. Verify the fuse holder is rated for Class J fuses and confirm the fuse amperage and voltage ratings match the circuit requirements before installation. Do not substitute a different fuse class or a higher amperage rating to restore power after a fault without first identifying and clearing the fault condition.