Cooper Bussmann LPJ-400SPI Class J 400A Time Delay Fuse

Product Description

The COOPER BUSSMANN LPJ-400SPI is a Class J time delay cartridge fuse rated at 400 amps for use in industrial and commercial power distribution systems. It features a two-element design that allows short-term overloads without nuisance tripping while still providing fast response to damaging fault currents. The fuse carries an interrupting rating of 300 kA at AC (RMS) and 100 kA at DC, making it suitable for high-fault-current environments. The bolt-on mount style and 7.125-inch overall length with a 2-inch diameter body fit standard Class J fuse blocks and holders. An indicating feature signals when the fuse has operated, speeding up troubleshooting during service calls. Licensed electricians and industrial maintenance technicians are the primary installers.

This fuse is intended for general-purpose branch circuit and feeder protection in residential, commercial, and light industrial applications where Class J rejection-style fusing is specified. The bolt-on termination style suits panel and disconnect installations where vibration resistance and secure current paths are required. Its time delay characteristic makes it a common choice for protecting motor branch circuits, where inrush current at startup must be tolerated without sacrificing overload protection during run conditions.

Key Features

• 400-amp rating with Class J rejection body prevents installation in lower-rated holders
• Two-element time delay design tolerates motor inrush and transformer inrush without nuisance opening
• 300 kA AC (RMS) interrupting rating for high-fault-current systems
• 100 kA DC interrupting rating
• Indicating feature provides visual confirmation of fuse operation
• Bolt-on mount for secure, vibration-resistant termination
• RoHS compliant, UL Listed, CSA Certified, and CE Certified

Compatibility

Designed for use in Class J fuse holders and disconnect switches that accept a 7.125-inch by 2-inch cartridge body with bolt-on termination. Verify holder ampere rating and voltage rating 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. De-energize and lockout/tagout the circuit before removing or installing the fuse. Confirm that the fuse holder, disconnect, or panelboard is rated for Class J fuses and for the system voltage and fault-current level. Do not substitute a fuse of a different class, amperage, or interrupting rating.