Overview
The Bussmann 663-R fuse reducer is a non-indicating rejection adapter that enables smaller-gauge Class R fuses (1–30A at 600V) to install safely in 60A fuse block clips. This reducing adapter maintains both mechanical and electrical integrity at the connection point, preventing arcing and ensuring reliable circuit protection during equipment conversions or downsizing operations.
Key Features
- Non-indicating rejection design ensures compatibility with Class R fuse blocks only
- Rated for 600 Volts AC across all amperage configurations
- Strong mechanical and electrical contact between reducer and fuse
- Fits most dead-front and standard panel-mount fuse blocks
- Eliminates the need for fuse block replacement during equipment conversion
- UL listed and CSA certified for North American electrical code compliance
Technical Specifications
- Fuse Rating: 1–30 Amperes
- Fuse Block Clip Rating: 60 Amperes
- Voltage: 600 VAC
- Fuse Class: Class R (rejection type)
- Certifications: UL, CSA
- Material: Non-conductive (PVC-based construction)
- Mounting Type: Direct fit into 60A fuse holder clips
- Quantity per Order: Sold as individual or paired reducers
Typical Applications
The 663-R is commonly used in:
- Industrial control panels where circuit protection is being downrated
- Commercial switchgear and panelboards requiring Class R compliance
- Equipment conversion projects that retain existing fuse blocks
- Control circuits in manufacturing and process automation systems
- HVAC and electrical distribution systems requiring code-compliant protection
- Facilities performing load analysis that results in lower amp-hour requirements
Compatibility & Replacements
Compatible With
- Class R dimension fuse blocks and holders
- 60A fuse block clips (adapts to accept 30A and lower fuses)
- FRN-R, LPN-RK, FRS-R, LPS-RK, KTN-R, and KTS-R series Class R ferrule fuses
- All UL and CSA approved Class R fuse configurations at 600V
- Standard panelboards and dead-front switchgear installations
Replaces / Drop-In Replacement For
The NO.663-R is the standard Class R 60A-to-30A reducer. No direct “drop-in” replacement units exist for this specific model number, as it is the industry-standard part. Other class reducers (H, J) are not interchangeable due to dimensional and rejection rejection specifications.
Works With
- UL-listed electrical distribution systems
- CSA-approved panelboards and fuse blocks
- NFPA 70 (National Electrical Code) compliant installations
- Industrial control and automation systems using Class R protection
- Equipment rated for 600V three-phase or single-phase circuits
