Littelfuse LLSRK020 - RK1 fuses are extremely current-limiting fuses meaning they greatly reduce or eliminate damage to circuits and equipment under short-circuit conditions. Replacing existing Class H, K and RK5 fuses with RK1 fuses is one of the easiest ways to immediately improve the protection of plant workers and equipment.
Littelfuse

LLSRK020

Alternate Item Number: LSRK020.T

UPC: 079458350715

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Overview

Littelfuse RK1 fuses (SKU: LLSRK020) are high-performance, current-limiting fuses engineered to deliver superior protection against short-circuit conditions in industrial and commercial electrical systems. Designed as a direct replacement for Class H, K, and RK5 fuses, these fuses significantly reduce or eliminate damage to circuits, equipment, and infrastructure during fault events. By integrating RK1 fuses into your electrical distribution system, you can achieve immediate improvements in safety, reliability, and equipment longevity while ensuring compliance with stringent industry standards. The RK1 series from Littelfuse is a trusted solution for professionals seeking to enhance the protective capabilities of their electrical systems. These fuses are particularly well-suited for demanding environments where equipment protection and worker safety are critical priorities. Whether installed in manufacturing plants, data centers, commercial buildings, or utility substations, RK1 fuses provide a robust defense against the devastating effects of short circuits, including arc flash hazards and equipment burnout. One of the standout features of Littelfuse RK1 fuses is their extreme current-limiting capability. Unlike standard fuses, which may allow high fault currents to persist briefly, RK1 fuses react almost instantaneously to fault conditions, interrupting the current flow before it can reach damaging levels. This rapid response not only protects sensitive equipment but also minimizes the risk of fire and electrical hazards, making RK1 fuses an essential component in modern electrical safety strategies. The fuses are designed to meet or exceed the requirements of UL 248-14, ensuring they provide reliable performance in a wide range of applications. Installation of RK1 fuses is straightforward, making them an ideal upgrade for facilities looking to enhance their existing fuse protection without significant downtime or reconfiguration. The fuses are available in a variety of ampere ratings to accommodate different system requirements, and their compact design allows for easy integration into standard fuse blocks and panels. Professionals in the electrical industry often choose RK1 fuses for their consistent performance, long service life, and compatibility with a broad spectrum of industrial equipment. Littelfuse, a global leader in circuit protection solutions, has built a reputation for innovation and reliability in the electrical industry. With decades of experience and a commitment to quality, Littelfuse RK1 fuses are trusted by engineers, electricians, and facility managers worldwide. By selecting RK1 fuses for your electrical system, you are investing in a solution that not only meets the highest safety standards but also delivers long-term value through reduced maintenance costs and minimized downtime. Key applications for Littelfuse RK1 fuses include motor control centers, panelboards, switchgear, transformers, and other critical electrical infrastructure. They are particularly effective in systems where high fault currents are a concern, such as in industrial plants with large motors, generators, or extensive distribution networks. Additionally, RK1 fuses are often specified in new construction projects where code compliance and safety are top priorities. For professionals responsible for electrical system design, maintenance, or safety compliance, Littelfuse RK1 fuses (LLSRK020) represent a smart choice. Their superior current-limiting performance, ease of installation, and compatibility with existing systems make them a versatile solution for a wide range of industrial and commercial applications. By upgrading to RK1 fuses, you can enhance the safety, reliability, and efficiency of your electrical infrastructure while protecting your most valuable assets—your equipment and your workforce.
  • Extreme current-limiting protection reduces or eliminates damage during short-circuit conditions
  • Direct replacement for Class H, K, and RK5 fuses for easy upgrades
  • Meets UL 248-14 standards for reliable performance and safety compliance
  • Compact design for easy integration into existing fuse blocks and panels
  • Trusted by professionals for motor control, switchgear, and industrial applications

Specifications

Amperage Rating
20 AMP
Application
All general purpose circuits
Brand Name
Littelfuse
Special Features
Time-Delay
Standard
Standard 248-12 UL Listed/CSA
Sub Brand
LLSRK Series
Type
Class RK1
Package Weight (Imperial)
0.185 L
Package Weight (Metric)
84.000 g
Fuse Block 600VAC 600VDC Class CC 30A 1/4in Quick Connect / Solder 90 angle screw Knob Panel Mount

GPM-SRR90

Fuse Block 600VAC 600VDC Class CC 30A 1/4in Quick Connect / Solder 90 angle screw Knob Panel Mount
Fuse Holder UltraSafe™ 800VAC 1000VDC UL Fuse size 14x51 1-Pole Visual Indicator Microswitch Pressure Plate IP20

C331156

Fuse Holder UltraSafe™ 800VAC 1000VDC UL Fuse size 14x51 1-Pole Visual Indicator Microswitch Pressure Plate IP20
Fuse Block 1500VAC 1500VDC 400A 1-Pole Stud M8

1SCM8

Fuse Block 1500VAC 1500VDC 400A 1-Pole Stud M8
Fuse Holder Modulostar® Size 10x38 IEC 690VAC 690VDC 3-Pole IP20

E1062696

Fuse Holder Modulostar® Size 10x38 IEC 690VAC 690VDC 3-Pole IP20
POWR-JAW clamps improve the contact between fuse and clip. The unnecessary heat from poor contact due to the loss of spring force in the clips can cause nuisance fuse opening and premature aging of surrounding components. High temperature phenolic resin knob designed for the most severe environments 7 sizes to provide effective coverage. Simple design makes installation easy.

LCC5

POWR-JAW clamps improve the contact between fuse and clip. The unnecessary heat from poor contact due to the loss of spring force in the clips can cause nuisance fuse opening and premature aging of surrounding components. High temperature phenolic resin knob designed for the most severe environments 7 sizes to provide effective coverage. Simple design makes installation easy.
9F61 Size B Clips 1.6in

9F61BWW460

9F61 Size B Clips 1.6in

Frequently Asked Questions about Littelfuse

What certifications and standards do Littelfuse products comply with?

Littelfuse products are certified to multiple international standards, including UL (Underwriters Laboratories), CSA (Canadian Standards Association), CCC (China Compulsory Certification), and EAC (Eurasian Conformity). Customers can verify specific product certifications by consulting individual product datasheets on Littelfuse.com, which provide comprehensive details about standards compliance for each component.

What industries and applications are Littelfuse products used for?

Littelfuse products are critical for electrical protection and safety across multiple industrial sectors, including manufacturing, automation, power distribution, and electrical control systems. Their comprehensive product portfolio serves industries that require robust electrical protection, including motor and pump applications, solar installations, programmable logic controllers (PLCs), electrical switch panels, and critical infrastructure environments. Key product lines protect against overcurrent, voltage transients, ground faults, and temperature-related electrical risks, ensuring equipment safety and operational reliability.

What technical support does Littelfuse offer?

Littelfuse offers comprehensive technical support through multiple channels. Their Technical Hotline (800-TEC-FUSE) provides direct access to engineers who can help identify issues and recommend solutions. Additionally, Littelfuse offers extensive online Technical Resources at Littelfuse.com, including datasheets, product manuals, whitepapers, application guides, and online design tools. Their experienced product and application engineers also provide step-by-step support from design to installation.

What are the main product lines offered by Littelfuse?

Littelfuse offers comprehensive industrial protection and control product lines, including fuses, fuse holders, protection relays, temperature sensors, and electrical safety components. Their key product categories span surge protective devices, custom OEM products, electrical switch panels, medium voltage fuses, ground-fault protection relays, motor and pump protection devices, and temperature sensors. These products are designed to minimize electrical safety hazards, limit equipment damage, improve productivity, and safeguard personnel from electrical faults.

What are the key features of Littelfuse products?

Littelfuse products feature exceptional circuit protection technologies with key characteristics including UL/IEC safety standard compliance, low internal resistance, and advanced protective capabilities across multiple product lines. Their components provide critical protection for industrial systems, offering features like overcurrent protection, voltage transient suppression, and resettable protection devices with ultra-low resistance and compact designs. Key product lines include fuses, metal oxide varistors (MOVs), TVS diodes, PolySwitch devices, and specialized electronic protection components that enhance system reliability and safety.

What environmental ratings do Littelfuse products have?

Littelfuse products feature comprehensive environmental ratings, including NEMA Type 1, 2, 3, 3R, 4/4X, 12, and 13 certifications, as well as IP65 protection. These ratings ensure superior protection in diverse industrial environments, with an operating temperature range of -40°F to +131°F (-40°C to +55°C). Many products also include UV-stabilized materials and neoprene gaskets for enhanced durability in outdoor and challenging conditions.

What accessories are available for Littelfuse products?

Littelfuse offers several key accessories across their product lines, including fuse holders, voltage monitoring modules, and terminal connectors. Specific accessories include the LPSM003ZXID (indicating) and LPSM003Z (non-indicating) POWR-SAFE Dead Front fuse holders for Class CC and Midget-Style fuses, the VRM6048 voltage monitor accessory module, and female quick connect terminals (P1015 series) in various wire gauge sizes. These accessories are designed to enhance protection, monitoring, and connectivity for Littelfuse electrical components.

What is Littelfuse's warranty policy?

Littelfuse provides comprehensive warranty details on their official website at www.littelfuse.com/warranty. Customers should visit this page to review the specific warranty terms and conditions for their specific product lines. For direct warranty support or questions, customers can contact Littelfuse Technical Support at 1-800-TEC-FUSE or email [email protected].

What communication protocols do Littelfuse products support?

Littelfuse supports a comprehensive range of industrial communication protocols, including PROFIBUS, PROFINET, EtherNet/IP, DeviceNet, Modbus RTU, and CANopen. Our products provide flexible connectivity solutions across multiple industrial automation platforms, enabling seamless integration with various control systems and network architectures.

How are Littelfuse products typically installed?

Littelfuse products are typically installed using specialized mounting hardware like fuse holders, blocks, and panels designed for specific industrial applications. The POWR-SAFE Dead Front holders, for example, provide optimum protection for Class CC and Midget-Style fuses, supporting installations up to 600 VAC/DC. Installation often involves using precision terminals with strain relief, such as 0.25 in. female quick connect terminals, to ensure secure and safe electrical connections in industrial control systems.