Littelfuse FLNR Series UL Clas...
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Littelfuse FLNR Series UL Class RK5 Dual-Element Time-Delay Fuse, 250VAC/125VDC

Littelfuse FLNR Series UL Class RK5 Dual-Element Time-Delay Fuse, 250VAC/125VDC

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Model: FLNR010

In Stock (leaves warehouse same day if ordered before 3pm ET)

$4.47
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Littelfuse FLNR Series UL Class RK5 Dual-Element Time-Delay Fuse, 250VAC/125VDC

The Littelfuse FLNR Series is a line of UL Class RK5 dual-element time-delay fuses engineered for accurate, consistent response to overloads and short circuits across industrial and commercial power distribution systems. Rated 250VAC and 125VDC in an industrial cartridge package, FLNR Series fuses are available in ampere ratings from 1.5A to 350A across 25 ratings, giving specifiers the flexibility to match protection precisely to circuit and motor-load requirements. FLNR fuses deliver faster-acting short-circuit protection than any non-current-limiting mechanical protective device, making the series a widely specified choice for distribution panelboards, motor control centers, and industrial control equipment. Specifiers evaluating the FLNR Series should also consider the additional benefits offered by Littelfuse Indicator fuses for applications where visible blown-fuse indication is desired.

Key Features

  • Ampere Rating: Available from 1.5A to 350A across 25 ratings for precise, reliable overcurrent protection in general-purpose and motor circuits.
  • Dual Voltage Rating: Rated 250VAC and 125VDC for flexible use across AC and DC systems.
  • Time-Delay Operation: Slo-Blo/Time Lag (T)/Time Delay opening characteristic tolerates momentary overloads like motor starting while still responding quickly to short circuits.
  • Industrial Cartridge Construction: Automated, precision-manufactured and assembled parts ensure accurate, consistent response to overloads and short circuits.
  • Package Size: Industrial Cartridge configuration for compatibility with standard fuse holders and clips.
  • Interrupting Rating: Rated 20,000A@125VDC, with the FLNR Series capable of reliably interrupting overcurrents up to 200,000 amperes (A.I.R.).
  • UL Class RK5: One of the most widely used dual-element time-delay fuse classes for demanding industrial and commercial circuits.

Certifications & Compliance

  • UL Recognized (File E81895)
  • CSA Certified (1422-02 029862)

Technical Specifications

  • Refer to manufacturer documentation for complete technical specifications.

Typical Applications

  • Distribution Panelboards
  • Motor Control Center Mains and Motor Branch Circuits
  • Individual Fused Combination Motor Controllers
  • Service Entrance Switches
  • Industrial Control Panels
  • Switchboard Main and Feeder Switches

Why Littelfuse?

Littelfuse FLNR Series fuses combine automated, precision manufacturing with UL Class RK5 performance to deliver dependable, code-compliant overcurrent protection for motors, panelboards, and industrial control equipment across a full 1.5A to 350A ampere range. Backed by UL recognition and CSA certification, the FLNR Series gives electrical professionals a trusted dual-element time-delay fuse that responds accurately and consistently to both overload and short-circuit conditions, supporting safe, reliable operation across general purpose and motor-driven circuits.

Product Specs

Product Type:
Fuse
Series:
FLNR
Voltage Rating:
250VAC/125VDC
Listing:
UL Recognized
Standards:
UL Class RK5
Department:
Electrical
Product Group:
Wiring Devices

Littelfuse FLNR010 – Frequently Asked Questions

1) Will a Littelfuse FLNR fuse work on a 480V circuit?
No. The FLNR Series is rated 250VAC and 125VDC, so it can only be applied where circuit voltage is at or below those figures. On a 480V system you need a 600V-rated Class RK5 fuse instead, not an FLNR.
2) Is the FLNR Series a time-delay fuse suitable for motor starting inrush?
Yes. FLNR fuses are dual-element time-delay (Slo-Blo / Time Lag T) devices, so they ride through the momentary overload of a motor start while still clearing short circuits quickly. That is why they get specified for motor control center mains, motor branch circuits, and individually fused combination motor controllers.
3) Does the FLNR fuse have a high enough interrupting rating for my industrial panel?
The FLNR Series interrupts up to 200,000 amperes A.I.R., and is rated 20,000A at 125VDC. That covers the available fault current on essentially any 250V industrial distribution panel or service entrance switch.
4) Will an FLNR fuse fit my existing Class R fuse block and rejection clips?
FLNR fuses are UL Class RK5 in an industrial cartridge package, so they carry the Class R rejection feature and drop into standard Class R fuse holders and clips. Class R blocks accept both RK5 and RK1 fuses, so an FLNR will seat in a block currently holding a Class RK1 fuse.
5) Should I buy a Class RK5 or a Class RK1 time-delay fuse?
Both are Class R and mount in the same holders, but RK1 is the more current-limiting class, so it is the one specified when you need lower let-through energy for equipment short-circuit current ratings or series-rated assemblies. The Littelfuse FLNR is the RK5 choice for general distribution and motor branch protection. If the drawing calls for RK1, the Mersen A2D-R Amp-Trap 2000 fuses are the RK1 equivalents, including the A2D60R at 60A and the A2D400R at 400A.
6) What is the difference between a Littelfuse FLNR fuse and a Mersen A2D-R fuse?
Both are dual-element time-delay cartridge fuses, but they belong to different UL fuse classes. The Littelfuse FLNR Series is UL Class RK5, rated 250VAC/125VDC, in ampere ratings from 1.5A to 350A. The Mersen A2D-R is a Class RK1 time-delay fuse rated 250VAC/250VDC and carries SmartSpot blown-fuse indication. Class RK1 and Class RK5 fuses share the same rejection-style dimensions and will fit the same Class R clips, but RK1 has tighter current-limiting let-through characteristics, so equipment short-circuit current ratings and series-rating tables that specify RK1 should not be satisfied with an RK5 fuse without checking the equipment label.
7) I need a 60A time-delay fuse for a motor branch circuit but the panel label calls for Class RK1 - what should I order instead of the FLNR?
For a 60A Class RK1 requirement, the Mersen A2D60R is a 60A Class RK1 time-delay fuse rated 250VAC/250VDC with SmartSpot indication. The Littelfuse FLNR060 is a 60A dual-element time-delay fuse in the same amperage but is UL Class RK5, so it does not meet an RK1 call-out on an equipment label. If the label permits either class, the FLNR060 covers the same 250VAC circuit at 125VDC.
8) I need more than 350 amps in a 250V time-delay fuse - what covers that?
The Littelfuse FLNR Series tops out at 350A, with FLNR350 as the largest rating. Above that, the Mersen A2D400R is a 400A Class RK1 time-delay fuse with SmartSpot indication. Note the class change: A2D400R is Class RK1 rather than the FLNR's Class RK5, so confirm the equipment short-circuit current rating accepts it.
9) What amp ratings can I get in the Littelfuse FLNR fuse?
The FLNR line spans 1.5A to 350A across 25 ratings. Small-control ratings include 1.5A, 1.8A, 2A, 2.5A, 3A, 3.5A, 4A, 4.5A, 5A, 6A, 6.25A, 8A and 10A; larger ratings run 20A, 40A, 50A, 60A, 70A, 75A, 80A, 90A, 175A, 225A, 250A and 350A. Part numbers follow the rating, for example FLNR060 for 60A and FLNR250 for 250A.
10) Are Littelfuse FLNR fuses UL and CSA approved for Canadian jobs?
Yes. The FLNR Series is UL Recognized under file E81895 and CSA Certified under 1422-02 029862, so it is acceptable for use on both US and Canadian installations.
11) Can I use the FLNR on a 125V DC control or battery circuit?
Yes. Unlike many fuses that carry an AC rating only, the FLNR Series is rated for 125VDC as well as 250VAC, with a 20,000A interrupting rating at 125VDC. That makes it usable on DC control and battery-backed circuits within that voltage.
12) Is there a version of this fuse that shows when it has blown?
The Littelfuse FLNR Series is a standard industrial cartridge fuse without integral indication; Littelfuse Indicator fuses are the option where visible blown-fuse indication is wanted. Among other brands, the Mersen Amp-Trap 2000 A2D-R carries SmartSpot indication built into the fuse, though it is a Class RK1 device rather than Class RK5. Choose based on whether the equipment call-out is RK1 or RK5 first, then on whether you want the indicator.
13) Can I use a Square D PowerLogic meter fuse pack in place of a small-amp FLNR fuse?
No. The Square D PowerLogic Energy Meter Fuse Pack is a set of three 0.5A 600V fuses intended for metering circuits on PowerLogic energy meters. The Littelfuse FLNR Series is a UL Class RK5 dual-element time-delay fuse rated 250VAC/125VDC for branch and feeder overcurrent protection, starting at 1.5A. The voltage rating, class, and application are all different, so the meter fuse pack is not a substitute even at the low end of the FLNR range.
14) I need a 30A, 100A, or 400A fuse in this series. Is it available?
The FLNR ratings stocked run 1.5A through 350A. Between 90A and 175A and above 250A the steps are wide, so the available large ratings are 175A, 225A, 250A and 350A. For a 400A Class R time-delay fuse, the Mersen A2D400R covers that rating in Class RK1.
15) What is the FLNR fuse typically used for in a building's electrical system?
Distribution panelboards, switchboard main and feeder switches, service entrance switches, industrial control panels, motor control center mains and motor branch circuits, and individually fused combination motor controllers. It is a general workhorse for 250V and below overcurrent protection in commercial and industrial gear.
How fast can I get the Littelfuse FLNR010 delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Littelfuse FLNR010 come with a warranty?
Absolutely. The Littelfuse FLNR010 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Littelfuse FLNR010?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
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