Overview
The Cooper Bussmann FNM-20 is a dual-element time-delay supplemental midget fuse engineered for industrial circuits requiring overcurrent protection. Rated at 20A, 250VAC, this fuse is color-coded green and delivers a 10 kA interrupting rating. Supplied in a box of 10 units, the FNM-20 is ideal for machine controls, motor circuits, and transformer-fed equipment where temporary overloads must be tolerated before circuit protection acts.
Key Features
- Dual-element time-delay design: Allows temporary overloads to pass without nuisance tripping, protecting high-inrush circuits from unnecessary interruptions.
- Class CC supplemental protection: Provides coordination with larger branch circuit protection in AC power distribution at 125V and 250V.
- Melamine tube construction: Enclosure with nickel-plated ferrule endcaps ensures durability and reliable contact in standard fuse holders.
- Green color coding: Clearly identifies 250VAC maximum voltage rating for rapid field identification.
- Compact midget form factor: 13/32″ diameter × 1-1/2″ length fits standard midget fuse holders and cartridge blocks.
Technical Specifications
Voltage Rating: 250VAC
Amperage: 20A
Interrupting Rating: 10 kA at 125VAC; 35A at 250VAC
Fuse Class: CC (Midget Supplemental)
Time Delay: Dual-element, slow-blow characteristic
Body Material: Melamine tube with nickel-plated endcaps
Dimensions: 13/32″ (10.3mm) diameter × 1-1/2″ (38.1mm) length
Ferrule Terminal: Standard clip or holder mounting
Quantity per Package: 10 fuses
Agency Certifications: UL Listed (File E19180, Std. 248-14, Guide JDYX); CSA Certified (Class 1422-01, File 53787); CE Compliant; RoHS Compliant
Typical Applications
- AC motor control circuits with high starting inrush currents.
- Transformer primary and secondary circuits requiring supplemental protection.
- Inductive load circuits up to 250VAC (relays, solenoids, contactors).
- Lighting and distribution circuits in industrial control panels.
- Meter circuits and upgrading legacy supplemental fuse installations.
Compatibility & Replacements
Compatible With
- Bussmann BMM modular fuse blocks (1-, 2-, and 3-pole configurations).
- Standard midget cartridge fuse holders and clip-based mounting blocks.
- 125VAC and 250VAC industrial control circuits rated for Class CC supplemental protection.
- Control panels and electrical enclosures using 10.3 × 38.1mm fuse form factor.
Replaces / Drop-In Replacement For
- Bussmann FNM-20 (original part number and equivalent designations: FNM20, FNM-20A, FNM 20A).
- Littelfuse FLM-20 (similar time-delay midget fuse; verify application compatibility before substitution).
Works With
- UL, CSA, and CE-certified power distribution and industrial control systems.
- IEC-compliant electrical installations in North America and international markets.
- Both DIN-style and British Standard fuse enclosures supporting the 13/32″ × 1-1/2″ cartridge form.
