Littelfuse LITRLS RLS Series C...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$30.17
Littelfuse LITRLS RLS Series Class H Fast-Acting Fuse, 600VAC

Littelfuse LITRLS RLS Series Class H Fast-Acting Fuse, 600VAC

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Model: LITRLS100

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

$30.17
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Littelfuse RLS Series Class H Fast-Acting Fuse, 600VAC

The Littelfuse RLS Series is a Class H fast-acting fuse engineered for reliable overcurrent protection in industrial and commercial power circuits, available in amp ratings from 100A to 110A to match a range of feeder and branch-circuit loads. Rated 600VAC with a 10000A interrupting rating, this knife-blade fuse delivers fast-acting (F) time-current response to protect equipment, feeders, and branch circuits from short-circuit and overload conditions. The RLS Series cross-references directly to Littelfuse's modern Class RK5 (FLSR/FLSR_ID) and Class RK1 (LLSRK/LLSRK_ID) fuse families, giving electrical contractors and maintenance teams a clear, verified upgrade path when servicing or replacing fuses in existing panels and fuse blocks.

Key Features

  • Ampere Rating: Available in 100A and 110A ratings, sized for demanding industrial and commercial loads.
  • Voltage Rating: 600VAC rating supports use across higher-voltage industrial power distribution circuits.
  • Fast-Acting Opening: Fast-Acting (F) time-current response interrupts overcurrent conditions quickly to help limit equipment damage.
  • Interrupting Rating: 10000A@600VAC interrupting rating delivers the fault-clearing capacity required for demanding industrial and commercial circuits.
  • Knife-Blade Package: Knife-Blade terminal configuration seats securely in compatible fuse blocks and disconnect switches for a reliable connection.
  • Class H Cross-Reference: Cross-references to Littelfuse Class RK5 (FLSR/FLSR_ID) and Class RK1 (LLSRK/LLSRK_ID) fuses, simplifying replacement or upgrade sourcing.
  • Series Designation: Identified within Littelfuse's RLS Series fuse lineup, alongside related RLN, LKS, and LKN part types sharing the same cross-reference family.

Certifications & Compliance

  • UL Listed
  • CSA Certified

Technical Specifications

  • Series: RLS

Typical Applications

  • Industrial Motor and Equipment Circuit Protection
  • Panelboard and Switchboard Overcurrent Protection
  • Commercial and Industrial Power Distribution Systems
  • Fuse Block and Disconnect Switch Installations
  • Replacement or Upgrade for Legacy Class H Fuse Installations

Why Littelfuse?

Littelfuse builds the RLS Series to established Class H fuse performance benchmarks, backed by UL Listing and CSA Certification for code-compliant circuit protection. With a 10000A interrupting rating at 600VAC and Fast-Acting time-current response across the 100A-110A range, this fuse is engineered to deliver dependable protection for professional electrical installations. Its documented cross-reference to Littelfuse's current Class RK5 and Class RK1 fuse families gives contractors and facility teams a trusted path to sourcing verified replacements and long-term serviceability.

Product Specs

Series:
RLS
Listing:
UL Listed
Product Type:
Fast-Acting Fuse
Voltage Rating:
600VAC
Amperage Rating:
100A-110A
Configuration:
Knife-Blade Terminal
Standards:
CSA Certified
Department:
Electrical
Product Group:
Circuit Protection
Product Subgroup:
Fuses

Littelfuse LITRLS100 – Frequently Asked Questions

1) Can a Littelfuse RLS Class H fuse be used on a 480V or 600V industrial circuit?
The RLS Series is rated 600VAC, so it covers 480V and 600V distribution circuits as well as lower-voltage systems. Its interrupting rating is 10,000A at 600VAC, which is the Class H limit. If your available fault current at the fuse location exceeds 10,000A, a Class H fuse is the wrong choice and you need an RK5 or RK1 current-limiting fuse instead.
2) Will the RLS fuse fit my existing fuse block or fused disconnect?
The RLS uses a knife-blade terminal, so it drops into blades-style clips in Class H fuse blocks and fused disconnect switches. It will not fit ferrule-clip holders, which are used for smaller-amp cartridge fuses. At 100A and 110A, knife-blade is the standard termination.
3) Should I use a fast-acting Class H fuse or a time-delay fuse for a motor circuit?
The RLS has a fast-acting (F) time-current response, which clears overcurrent quickly and suits circuits without heavy inrush, such as feeders and resistive or non-motor equipment loads. Motor circuits draw locked-rotor inrush at startup and normally call for a time-delay fuse. For that, a time-delay Class RK1 like the Mersen A2D-R with SmartSpot indication is the type to look at instead.
4) What is the current Littelfuse replacement for an RLS100 or RLS110 fuse?
Littelfuse cross-references the RLS Series directly to its Class RK5 families (FLSR and FLSR_ID) and Class RK1 families (LLSRK and LLSRK_ID). Those are the modern upgrade paths when you are re-fusing an older Class H panel, and they bring a higher interrupting rating than the 10,000A of a Class H fuse. Related Littelfuse part types RLN, LKS and LKN share the same cross-reference family.
5) Will a Mersen A2K fuse substitute for a Littelfuse RLS on a 600V circuit?
No. The Mersen Amp-Trap A2K Series is a 250V fast-acting Class RK1 fuse, so it cannot be applied on a 600V circuit where the RLS is rated 600VAC. For 600V work stay with the RLS or move up to a 600V-rated Class R fuse.
6) What is the difference between the Littelfuse RLS fuse and a Mersen A2K Series fuse?
Both are fast-acting fuses, but they are built to different fuse classes and voltage ratings. The Littelfuse RLS is a Class H fast-acting fuse rated 600VAC with a knife-blade terminal, offered in 100A and 110A. The Mersen Amp-Trap A2K Series is a fast-acting Class RK1 fuse rated 250V. If the circuit is a 600V system, the RLS matches the voltage; if you are protecting a 250V circuit and want Class RK1 performance, the A2K is the family to look at.
7) I need a Class RK1 fast-acting fuse rather than a Class H. What should I look at instead of the Littelfuse RLS?
The Littelfuse RLS is a Class H fast-acting fuse at 600VAC. For Class RK1 fast-acting protection, the Mersen A2K12R in the A6K-R Series is a Class RK1 fast-acting fuse. Class RK1 fuses are rejection-style, so confirm your fuse block or disconnect accepts the rejection feature before switching from a Class H holder.
8) My motor circuit is nuisance-tripping the Littelfuse RLS on inrush. Is there a time-delay alternative?
The RLS Series uses a fast-acting time-current response, which clears quickly and is not intended to ride through motor starting inrush. For a time-delay characteristic, the Mersen A2D-R is a Class RK1 time-delay fuse with SmartSpot blown-fuse indication. Verify the amp rating and that the holder accepts a Class RK1 rejection fuse before you change over.
9) What amp ratings does the Littelfuse RLS Series come in?
Two ratings are offered: 100A (RLS100) and 110A (RLS110). Both are 600VAC knife-blade Class H fast-acting fuses, sized for feeder and branch-circuit loads in that range.
10) Is the Littelfuse RLS fuse UL Listed and CSA certified for code work?
Both. The RLS Series is UL Listed and CSA Certified, which is what inspectors and facility MRO buyers look for when documenting overcurrent protection in panelboards and switchboards.
11) Can I drop a Class RK1 fuse into the same holder as a Class H RLS fuse?
Not interchangeably in both directions. Class R fuses have a rejection notch in the blade and fit either a standard Class H block or an R-rejection block, while a Class H fuse like the RLS will not seat in an R-rejection holder. So upgrading an existing Class H installation to RK5 or RK1 works, but once a rejection block is installed you cannot go back to a plain Class H fuse. Fast-acting Class RK1 options include the Mersen A6K-R series fuse A2K12R.
12) Is the Square D PowerLogic meter fuse pack a substitute for the Littelfuse RLS?
No, despite both being 600V-class parts. The Square D PowerLogic Energy Meter Fuse Pack is a set of three 0.5A 600V fuses for metering circuits. The Littelfuse RLS is a 100A to 110A knife-blade power fuse for feeder and branch-circuit protection. They serve entirely different duties and the amp ratings are orders of magnitude apart.
13) If I am replacing legacy Class H fuses, do I stay with the Littelfuse RLS or move to a different class?
The RLS Series is the direct Class H fast-acting part, 600VAC, in 100A and 110A, and it cross-references to Littelfuse Class RK5 (FLSR/FLSR_ID) and Class RK1 (LLSRK/LLSRK_ID) families if you want to upgrade the class. On the Mersen side, Class RK1 options include the A2K12R fast-acting and the A2D-R time-delay with SmartSpot indication. Staying with the RLS keeps the existing Class H blocks as-is; moving to Class RK1 raises interrupting capability but requires a holder that accepts the rejection style.
14) Does the Littelfuse RLS have a blown-fuse indicator?
No indication feature is part of the RLS Series; it is a plain knife-blade Class H fast-acting fuse. If you want visual blown-fuse indication for faster troubleshooting in a crowded switchgear room, look at an indicating Class R fuse such as Littelfuse FLSR_ID or LLSRK_ID, or the Mersen A2D-R with SmartSpot indication.
15) Is the RLS a medium-voltage fuse?
No. The RLS Series is a low-voltage distribution fuse rated 600VAC. Medium-voltage protection uses an entirely different fuse, for example the Mersen D0R0 Series Amp-Trap E-rated medium voltage fuse with ferrule terminals.
How fast can I get the Littelfuse LITRLS100 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 LITRLS100 come with a warranty?
Absolutely. The Littelfuse LITRLS100 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 LITRLS100?
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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