The Bullet ECNR400 is an industrial-grade, Class RK5 dual-element time-delay fuse engineered for demanding electrical protection applications. Rated at 400 amperes and 250 volts AC (125V DC), this current-limiting fuse delivers reliable motor overload, ground fault, and short-circuit protection in factory automation, control systems, and machinery circuits.
Overview
The ECNR400 combines proven dual-element construction with time-delay characteristics, allowing it to tolerate brief inrush currents from motor startup while instantly disconnecting during true fault conditions. This balance makes it ideal for protecting three-phase motors, compressors, pumps, and other equipment prone to transient overcurrent. The non-indicating blade-end design integrates seamlessly into cartridge fuse holders and modern switchgear assemblies.
Key Features
- Dual-element, time-delay design tolerates motor inrush without nuisance trips
- Class RK5 current-limiting technology reduces stress on downstream equipment
- 200 kAIC (kiloampere) interrupting rating at 250V AC; 20 kAIC at 125V DC
- 10-second delay at 500% rated current ensures coordination with motor starters
- Blade-end construction fits standard cartridge holders
- UL 248-12, CSA C22.2, and CE certified for global standards compliance
Technical Specifications
- Current Rating: 400 amperes
- Voltage: 250V AC / 125V DC
- Fuse Class: RK5 (dual-element, time-delay)
- Interrupting Rating: 200 kA symmetrical (250V AC), 20 kA (125V DC)
- Time Delay: 10 seconds minimum at 500% rated current
- Terminal Type: Blade end x blade end
- Case Diameter: 2.38 inches
- Element Type: Dual-element, non-indicating
- Certifications: UL 248-12, CSA C22.2, CE
Typical Applications
The ECNR400 serves as the backbone of electrical safety in:
- Three-phase motor protection (200–400 HP range)
- Industrial compressors and pump circuits
- Manufacturing and packaging equipment
- HVAC and refrigeration systems
- Mining, oil & gas, and process automation
- Distribution panels and switchgear assemblies
Compatibility & Replacements
Compatible With
- Standard Class RK5 cartridge fuse holders (all manufacturers)
- Industrial motor starter and contactor assemblies
- Medium-voltage switchgear with dual-element fuse cavities
- Eaton, Siemens, ABB, and Schneider distribution equipment
- Any 250V AC / 125V DC system requiring 400A protection
Replaces / Drop-In Replacement For
- Eaton Bussmann ECNR400 (original manufacturer)
- Bussmann FRN-R-400 (ferrule terminal equivalent)
- Edison ECNR400 variants
- Verify your fuse holder terminal type (blade vs. ferrule) before ordering
Works With
- Class RK5 fuse cartridge holders from all major manufacturers
- IEC and NEMA-compliant motor control centers
- Single-pole and three-pole disconnect switches
- Industrial PLC and automation control systems
- Standard circuit coordination and arc-flash studies
