Littelfuse FLNR Series Class R...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$25.67
Littelfuse FLNR Series Class RK5 Dual-Element Time-Delay Fuse

Littelfuse FLNR Series Class RK5 Dual-Element Time-Delay Fuse

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Model: FLNR.800

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

$25.67
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Littelfuse FLNR Series Class RK5 Dual-Element Time-Delay Fuse

The Littelfuse FLNR Series is a UL Class RK5 dual-element time-delay fuse line, one of the most widely used fuse classes in the industry and a superior choice for protecting circuits that contain motors. Rated 125VDC and 250VAC with an interrupting rating of 20000A@125VDC, these Industrial Cartridge fuses deliver reliable interruption of overcurrents up to 200,000 amperes (A.I.R.), providing faster-acting short-circuit protection than any non-current-limiting mechanical protective device. Available across FLNR series models — FLNR.500, FLNR.600, FLNR.800, FLNR100, FLNR125, FLNR150, and FLNR300 — to match specific circuit amperage requirements, the series is UL Listed and CSA Certified for use in motor control centers, distribution panelboards, and industrial control panels, and is also well suited to all general-purpose circuits.

Key Features

  • Time-Delay Opening: Slo-Blo/Time Lag (T)/Time Delay opening characteristic rides through motor inrush current and temporary overloads without nuisance opening.
  • High Interrupting Rating: Interrupting rating of 20000A@125VDC with reliable interruption of overcurrents up to 200,000 amperes (A.I.R.), delivering faster-acting short-circuit protection than any non-current-limiting mechanical protective device.
  • Dual Voltage Rating: Rated 125VDC and 250VAC for flexible use across DC and AC control and distribution circuits.
  • UL Class RK5 Dual-Element Construction: Automated, precision-manufactured and assembled parts ensure accurate, consistent response to overloads and short circuits.
  • Industrial Cartridge Package: Sized to fit standard industrial cartridge fuse holders and clips for straightforward replacement.
  • Motor Circuit Protection: Purpose-built for motor control center mains, motor branch circuits, and individual fused combination motor controllers.
  • Broad Circuit Coverage: Suitable for service entrance switches, switchboard main and feeder switches, and all general-purpose circuits.
  • Series Range: Offered across FLNR.500, FLNR.600, FLNR.800, FLNR100, FLNR125, FLNR150, and FLNR300 models to cover a range of circuit amperage needs.

Certifications & Compliance

  • UL Listed (JDDZ E81895)
  • CSA Certified (1422-02 029862)

Technical Specifications

  • Voltage Rating: 125VDC / 250VAC
  • Standards: CSA

Typical Applications

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

Why Littelfuse?

Littelfuse FLNR series fuses combine UL Class RK5 dual-element construction with automated, precision-manufactured assembly for consistent, code-compliant overcurrent protection. With a 200,000 ampere interrupting rating plus UL Listed and CSA Certified performance, the FLNR series gives electrical professionals a dependable, time-delay fuse rated 125VDC/250VAC for demanding motor circuits, panelboards, and general-purpose distribution work.

Product Specs

Product Type:
Time-Delay Fuse
Series:
FLNR
Voltage Rating:
125VDC / 250VAC
Listing:
UL Listed
Standards:
CSA
Department:
Electrical
Product Group:
Circuit Protection
Product Subgroup:
Fuses

Littelfuse FLNR.800 – Frequently Asked Questions

1) Will a Littelfuse FLNR fuse hold up to motor inrush current without blowing on startup?
That is what the FLNR Series is built for. It is a dual-element time-delay (Slo-Blo / Time Lag) Class RK5 fuse, so it rides through motor starting inrush and temporary overloads without nuisance opening, while still clearing a short circuit. Littelfuse lists it for motor control center mains, motor branch circuits, and individual fused combination motor controllers. If you need fast-acting protection instead, for example on a non-motor load where you do not want any delay, a time-delay fuse is the wrong characteristic.
2) Does the FLNR fuse have a high enough interrupting rating for my 200kAIC panel?
Yes. The FLNR Series reliably interrupts overcurrents up to 200,000 amperes A.I.R., with an interrupting rating of 20,000A at 125VDC. Because it is current-limiting Class RK5, it clears a short circuit faster than any non-current-limiting mechanical protective device, which is what series-rating and available fault current calculations in switchboards and panelboards depend on.
3) Will a Class RK5 FLNR fuse fit the same fuse clips as my existing Class RK1 fuse?
The FLNR is an industrial cartridge fuse sized to standard industrial cartridge fuse holders and clips, so replacement is straightforward in a Class R rejection or standard clip of the same amp and voltage class. Class RK1 and RK5 share Class R dimensions at a given amp rating, but RK1 fuses such as the Mersen A2D-R or the A2K Series have different let-through performance, so match whatever the equipment nameplate or the engineer's spec calls for rather than swapping classes freely.
4) Is the Littelfuse FLNR fuse UL Listed and CSA approved for use in a panelboard?
The FLNR Series is UL Listed under JDDZ, file E81895, and CSA Certified under 1422-02 029862. Littelfuse lists it for distribution panelboards and loadcenters, service entrance switches, switchboard main and feeder switches, and industrial control panels. That covers most inspection requirements for Class RK5 branch and feeder fusing.
5) Is a Littelfuse FLNR fuse usable on a medium voltage circuit?
No. The FLNR series is rated 250VAC and 125VDC, which puts it in low voltage distribution and motor circuit service such as motor control centers, panelboards, and industrial control panels. For medium voltage protection you need a fuse built for it, such as the Mersen D0R0 series Amp-Trap E-rated medium voltage fuse with ferrule terminals. The two are not substitutes in either direction.
6) What is the closest time-delay equivalent to a Littelfuse FLNR fuse from another manufacturer?
The Mersen A2D-R is the nearest time-delay counterpart. The Littelfuse FLNR series is a UL Class RK5 dual-element time-delay fuse rated 250VAC and 125VDC, while the Mersen A2D-R is a Class RK1 time-delay fuse that adds SmartSpot blown-fuse indication. Both are time-delay designs intended to ride through motor inrush, so either will hold on a motor branch circuit; the difference is the class, RK5 versus RK1, and the visual indicator on the Mersen part. Check what the panel schedule or equipment label calls for before swapping classes.
7) What amp ratings does the Littelfuse FLNR series come in?
FLNR fuses are offered in 1/2 A (FLNR.500), 6/10 A (FLNR.600), 8/10 A (FLNR.800), 100 A (FLNR100), 125 A (FLNR125), 150 A (FLNR150), and 300 A (FLNR300). Size the fuse to the circuit and motor nameplate, not to the holder.
8) Can I use an FLNR fuse for fast-acting short circuit protection on a transformer or non-motor feeder?
Not if the design calls for a fast-acting fuse. Every FLNR is time-delay, so it intentionally tolerates short overloads. For a fast-acting Class RK1 alternative, ZenSupply carries the Mersen A2K Series 250V fast-acting fuse and the Mersen A6K-R Series. The FLNR does suit general-purpose circuits where a time delay is acceptable.
9) Which FLNR part number do I order for a 1/2 amp control circuit fuse?
Order FLNR.500 for 1/2 A (0.5 A). The next sizes up in the small end of the range are FLNR.600 at 6/10 A and FLNR.800 at 8/10 A. All three are the same 250VAC / 125VDC Class RK5 time-delay construction as the larger FLNR fuses. If you need a 600V half-amp fuse for metering instead, the Square D PowerLogic energy meter fuse pack is 0.5A 600V and ships as a set of three.
10) Can I standardize on one fuse type across motor branch circuits and general distribution in my facility?
The FLNR Series is a reasonable single standard for 250V and below. Littelfuse lists one family across motor control center mains, motor branch circuits, fused combination motor controllers, service entrance switches, distribution panelboards and loadcenters, industrial control panels, and switchboard main and feeder switches, plus general-purpose circuits. Class RK5 is one of the most widely used fuse classes in the industry, so stocking FLNR in the amp sizes your equipment uses keeps the spares shelf simple. Anything on a 480V system needs a different voltage class.
11) I need a 1/2 amp fuse for a metering circuit - is the FLNR.500 the right choice or something else?
The FLNR.500 is a 1/2 amp Class RK5 time-delay industrial cartridge fuse rated 250VAC and 125VDC, sized for standard industrial cartridge holders and clips. If the application is specifically a utility or submeter voltage input, the Square D PowerLogic energy meter fuse pack is a set of three 0.5A 600V fuses supplied for that metering duty. Match the fuse to the holder and the circuit voltage rating in the equipment, since a 250V fuse cannot stand in for a 600V requirement.
12) If a panel is specified for Class RK1 fuses, can I drop in a Littelfuse FLNR instead?
The FLNR is a Class RK5 fuse, and RK5 and RK1 share the same R-dimension body so they will physically fit the same clips, but they are different UL classes with different let-through performance. Where the equipment label or drawing calls out Class RK1, use an RK1 part such as the Mersen A2D-R time-delay fuse or, for fast-acting duty, the Mersen A2K. Reserve the FLNR for openings specified as Class RK5.
13) Which fuse should I stock if I want to see at a glance whether it has blown?
The Littelfuse FLNR series is a Class RK5 dual-element time-delay fuse without a visual indicator, so a blown unit is confirmed with a meter. If an at-a-glance check matters for your maintenance routine, the Mersen A2D-R is a Class RK1 time-delay fuse that carries SmartSpot blown-fuse indication. Confirm the equipment accepts the class you choose before standardizing a facility on one or the other.
How fast can I get the Littelfuse FLNR.800 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 FLNR.800 come with a warranty?
Absolutely. The Littelfuse FLNR.800 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 FLNR.800?
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
Why buy the Littelfuse FLNR.800 from ZenSupply?
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