Littelfuse FLSR400 - FLSR400 is a Class RK5 fuse with an ampere rating of 400 and knife-blade-style construction.
Littelfuse

FLSR400

Alternate Item Number: FLSR400.X

UPC: 079458170931

Documents & Media
BrochureTechnical BulletinTechnical DrawingSpecification Sheet

Contact for Pricing

Overview

The **Littelfuse FLSR400** is a high-performance **Class RK5 fuse** engineered for demanding industrial applications where reliable overcurrent protection is critical. With a **400A current rating** and **knife-blade-style construction**, this fuse is designed to deliver superior performance in power distribution systems, motor control circuits, and industrial machinery. As part of Littelfuse’s trusted Class RK5 series, the FLSR400 combines robust interrupting ratings with precise fault detection, ensuring optimal circuit safety and operational continuity in harsh environments. Class RK5 fuses are widely recognized in industrial settings for their ability to handle high fault currents while providing fast, consistent response to overcurrent conditions. The FLSR400 is specifically optimized for applications requiring **high interrupting capacity (HIC)** and **superior current limitation**, making it an ideal choice for protecting sensitive equipment from damage caused by short circuits or overloads. Its **knife-blade connection design** ensures secure, low-resistance contact in panelboards, switchgear, and other industrial enclosures, reducing the risk of arcing or loose connections that could compromise system reliability. Industries such as **manufacturing, mining, oil & gas, utilities, and heavy machinery** rely on Class RK5 fuses like the FLSR400 to safeguard critical infrastructure. These fuses are particularly well-suited for: - **Motor control centers (MCCs)** where high inrush currents are common. - **Power distribution panels** requiring high fault current protection. - **Industrial machinery** with variable loads and frequent start-stop cycles. - **Renewable energy systems** where grid stability and fault protection are paramount. Littelfuse, a global leader in circuit protection solutions, has built a reputation for engineering fuses that meet or exceed stringent industry standards, including **UL, CSA, and IEC certifications**. The FLSR400 is no exception—it is designed to perform reliably in extreme temperatures, vibration-prone environments, and areas with high electrical noise, ensuring long-term durability and minimal maintenance. Professionals in electrical engineering, maintenance, and safety compliance trust Littelfuse fuses for their **consistent performance, ease of installation, and compliance with safety regulations**. When selecting a fuse for industrial applications, key considerations include **interrupting rating, response time, physical dimensions, and compatibility with protective devices**. The FLSR400 excels in all these areas, offering a **superior balance of protection and longevity**. Its **compact knife-blade design** allows for easy insertion into standard fuse holders, while its **high-quality materials** resist corrosion and mechanical stress, further extending service life. For facilities prioritizing **downtime reduction and equipment longevity**, the FLSR400 is a proven solution that delivers both immediate and long-term value. Whether you’re upgrading an existing system or designing a new industrial installation, the **Littelfuse FLSR400 Class RK5 fuse** provides the performance and reliability needed to protect your most critical assets. Backed by Littelfuse’s decades of expertise in circuit protection, this fuse is a smart investment in safety, efficiency, and operational resilience.
  • 400A current rating for high-demand industrial applications
  • Class RK5 classification ensures superior interrupting ratings and fast fault response
  • Knife-blade-style construction for secure, low-resistance connections
  • UL, CSA, and IEC certified for global compliance and safety
  • Ideal for motor control centers, power distribution, and heavy machinery

Specifications

Application
General Purpose
Brand Name
Littelfuse
Special Features
Time-Delay
Standard
Standard 248-12 UL Listed/CSA
Sub Brand
POWR-GARD FLSR Series
Type
Class RK5
Package Weight (Imperial)
3.498 L
Package Weight (Metric)
1590.000 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 Modulostar® Size 10x38 IEC 690VAC 690VDC 3-Pole IP20

E1062696

Fuse Holder Modulostar® Size 10x38 IEC 690VAC 690VDC 3-Pole IP20
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
9F61 Size B Clips 1.6in

9F61BWW460

9F61 Size B Clips 1.6in
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.

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.