Cooper Bussmann ECNR20 Fuse

The Bussmann ECNR20 is a high-performance Class RK5 fuse engineered for industrial and commercial motor protection where space and heat management are critical. This 20 amp dual element fuse features a 2-inch length and 9/16-inch diameter, making it a standard fit for 250V applications requiring time-delay-rated circuit protection. Unlike standard fast-acting components, the ECNR20 utilizes a specialized dual-element design that allows for temporary motor starting surges without nuisance tripping, while still providing rapid response to short-circuit events up to a 200,000 RMS symmetrical amperage interrupting rating.

For technicians in the field, the ECNR20 is a preferred current-limiting fuse because it operates significantly cooler than comparable Class K5 or older cartridge fuses. This thermal efficiency prevents localized heat damage to fuse blocks and reduces the risk of "needless blows" in high-ambient HVACR environments. As a rejection type fuse, its physical dimensions ensure it cannot be replaced by lower-rated or non-current-limiting fuses, maintaining the safety integrity of the branch circuit. It is highly recommended for inductive loads including motors, transformers, and solenoid-operated equipment commonly found in refrigeration and air conditioning systems.

• Enhanced Motor Protection: True dual-element construction allows for sizing closer to full-load amps (FLA) to prevent motor burnout while overriding initial startup inrush currents.
• Superior Thermal Management: Engineered to run cooler than standard fuses, extending the life of clips and holders while preventing thermal-related failure.
• High Interrupting Capacity: Provides reliable circuit protection in systems with available fault currents up to 200kA RMS Symmetrical.
• Standard RK5 Compatibility: Direct replacement for any 250V Class RK5 application, ensuring wide compatibility with existing fuse blocks and disconnects.

• Can I use an ECNR20 in a non-rejection fuse holder? No, this is a rejection-type fuse designed specifically for Class R fuse clips to ensure current-limiting safety standards are maintained.
• What is the typical time-delay for this fuse? The ECNR20 provides a minimum 10-second opening delay at 500% of its rated current (8 seconds at 500% specifically for 250V ratings 30A and below).
• Is this fuse suitable for DC circuits? Yes, it is rated for up to 125 Vdc, making it versatile for both AC and DC power distribution systems.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.