Overview
The Bussmann Fusetron FNA-4 is a dual-element, time-delay cartridge fuse designed for overcurrent protection in control circuits, inductive loads, and electronic equipment. Each fuse is rated for 4 amperes at 250 volts AC, with superior time-delay characteristics that allow temporary overloads to pass without unnecessary nuisance trips. The Fusetron series is engineered for consistent performance and minimal circuit downtime in industrial and commercial applications.
Key Features
- Dual-element construction provides extended time-delay response ideal for transformer and relay circuits
- Ferrule end terminals (13/32 inch diameter) ensure secure, reliable connections
- Silver-plated pins reduce contact resistance and improve conductivity
- Pin indicator design provides visual identification of blown fuses, reducing troubleshooting time
- Compact 1-1/2 inch length fits standard cartridge fuse holders
- UL Listed to Standard 248-14; CSA and CE approved for global compliance
Technical Specifications
- Current Rating: 4 amperes
- Voltage Rating: 250V AC (10 kAIC at 125V, 200 kAIC at 250V)
- Fuse Type: Dual-element time-delay cartridge
- Terminal Style: Ferrule end × ferrule end
- Terminal Diameter: 13/32 inch (0.406 inch)
- Length: 1-1/2 inches
- Interrupting Rating: 10,000 amperes (125V AC)
- Interrupting Rating: 200,000 amperes (250V AC)
- Pin Indicator: Yes, non-indicating standard configuration
- Conductor Material: Silver-plated copper pins
Typical Applications
Fusetron FNA-4 fuses are widely used in:
- Control transformers and low-voltage power circuits
- Motor control circuits and soft-starter protection
- Electronic equipment with inductive loads (relays, contactors, solenoids)
- Process control systems and instrumentation circuits
- HVAC and refrigeration control panels
- Industrial automation and machinery startup circuits
Compatibility & Replacements
Compatible With
- Standard cartridge fuse holders rated for 13/32 inch ferrule terminals
- Control circuits up to 250V AC
- Inductive load circuits requiring time-delay protection
- Electrical panels and switchgear with FNA-series fuse blocks
Replaces / Drop-In Replacement For
- Original Bussmann Fusetron FNA-4 fuses
- Cooper Bussmann FNA-4 (successor branding)
- Verify compatibility with your specific fuse holder before ordering to ensure proper fit and performance
Works With
- Allen-Bradley control systems and PLCs
- Siemens SIMATIC control circuits
- General Electric (GE) industrial control panels
- Schneider Electric automation platforms
- Standard industrial power distribution systems














