Mersen RL Class H Fast-Acting ...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$4.51
Mersen RL Class H Fast-Acting Renewable Fuse, 250V AC

Mersen RL Class H Fast-Acting Renewable Fuse, 250V AC

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Model: RL20

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

$4.51
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Mersen RL Class H Fast-Acting Renewable Fuse

The Mersen RL Class H Fast-Acting Renewable Fuse is a general purpose fuse designed for applications where available short-circuit currents do not exceed 10,000 amperes. This Class H fuse line is rated 250V AC (UL), built for 50/60 Hz AC systems, and is available in Motor FLA amperage ratings ranging from 3A to 400A across 21 options, allowing electricians and maintenance crews to size protection precisely to the branch-circuit or equipment load. Each fuse uses a fast-acting renewable link, meaning the fuse body itself can be reused with a fresh RL series die-cut zinc replacement link rather than discarded after every operation, and RL series replacement links are available from 2 to 600 amperes across 31 ratings for fast restoration of protection.

Key Features

  • Amperage Range: Available in Motor FLA ratings from 3A to 400A (21 options) to match specific branch-circuit and motor protection requirements.
  • Fuse Class: Class H general purpose fuse construction for standard branch-circuit and equipment protection.
  • Speed/Characteristic: Fast-Acting link responds quickly to overcurrent conditions for reliable circuit protection.
  • Rated Voltage: 250V AC (UL) rated for standard commercial and industrial AC distribution systems.
  • Frequency: Rated for 50/60 Hz AC power, suitable for standard North American electrical systems.
  • Renewable Link Design: Accepts RL series die-cut zinc replacement links from 2 to 600 amperes in 31 ratings, allowing the fuse holder to be reloaded instead of fully replaced after an operation.
  • Short-Circuit Application Range: Suitable for applications where available short-circuit currents do not exceed 10,000 amperes.
  • AC or DC: AC-rated fuse for alternating current circuits.

Technical Specifications

  • AC or DC: AC
  • Frequency: 50/60 Hz
  • Rated Voltage AC (UL): 250 V
  • Speed/Characteristic: Fast-Acting
  • Fuse Class: Class H
  • Motor FLA Range: 3A to 400A (21 options)

Typical Applications

  • General Purpose Branch-Circuit Overcurrent Protection
  • Commercial and Industrial Electrical Panels
  • Motor and Equipment Circuit Protection
  • Renewable Fuse Holder Systems Requiring Periodic Link Replacement
  • Systems with Available Short-Circuit Currents Up to 10,000 Amperes

Why Mersen?

Mersen builds the RL Class H fuse around a renewable link design, letting facilities restore fast-acting overcurrent protection with an RL series die-cut zinc replacement link instead of sourcing a whole new fuse for every operation. With a 250V AC (UL) rating, 50/60 Hz compatibility, Motor FLA ratings spanning 3A to 400A, and Class H construction sized for short-circuit currents up to 10,000 amperes, this fuse line supports dependable, code-compliant protection across a wide range of commercial and industrial electrical applications.

Manufacturer Resources

Mersen Product Catalog

Product Specs

AC or DC:
AC
Frequency (Hz):
50/60 Hz
Rated voltage AC UL:
250 V
Speed/Characteristic:
Fast-Acting
Fuse Class:
Class H
list_batch:
MERSEN-20260825
Department:
Electrical
Product Group:
Circuit Protection
Product Type:
Renewable Fuse
Voltage Rating:
250V
Amperage Rating:
3A - 400A
Product Subgroup:
Fuses

Mersen RL20 – Frequently Asked Questions

1) Can I use a Mersen RL Class H renewable fuse on a 480V circuit?
No. The Mersen RL Class H renewable fuse is rated 250V AC (UL) only, for 50/60 Hz alternating current. Applying it on a 480V system is outside its rating, and it is an AC-rated fuse so it isn't intended for DC service either. For 480V protection you need a 600V class fuse instead.
2) Is a Class H fuse good enough for my panel's available fault current?
Only up to 10,000 amperes. The RL Class H line is a general purpose fuse built for applications where available short-circuit current does not exceed 10,000 A. If your service study shows more available fault current at that panel, a Class H fuse is the wrong choice and you need a current-limiting class (such as Class J, RK, or CC) rated for the higher interrupting duty.
3) What does "renewable" mean on the Mersen RL fuse, and do I throw it away after it blows?
You keep the body. The RL fuse is built around a die-cut zinc link that you replace after the fuse operates, so the fuse shell is reloaded rather than discarded. That is the whole point of the design for maintenance crews: stock links, not complete fuses, and restore protection on the spot.
4) What amperage replacement links fit the Mersen RL renewable fuse?
RL series die-cut zinc links are offered from 2 through 600 amperes across 31 ratings. Note the fuse bodies themselves are sold in Motor FLA ratings from 3A to 400A (21 options, RL3 through RL400), so the link range is broader than the body range. Match the link to the body size and the circuit load, not just to the link you happen to have on the truck.
5) Will a fast-acting Class H fuse hold through my motor's starting inrush?
Probably not if you size it at nameplate FLA. The RL is a fast-acting characteristic, so it reacts quickly to overcurrent and does not have the intentional delay a motor start draws through. For motor branch circuits where inrush is trips you, a time-delay fuse is the better fit, for example the Littelfuse CCMR Series Class CC time-delay fuse (CCMR040 in 40A). Use the RL where general purpose, fast-acting protection suits the load.
6) If a panel needs a Class CC time-delay fuse instead of a Class H fast-acting fuse, what should be ordered?
The Mersen RL is a Class H fast-acting fuse rated 250V AC (UL), so it does not satisfy a circuit specified for a Class CC time-delay fuse. For that requirement, the Littelfuse CCMR040 is a CCMR series Class CC time-delay fuse rated 40A. Class CC and Class H fuses use different dimensions and clip or holder prep, so the two are not interchangeable in the same fuse block.
7) What is the closest fast-acting 250V alternative to a Mersen RL fuse for a midget fuse holder?
The Mersen RL is a Class H renewable fuse rated 250V AC (UL) with a fast-acting characteristic, sized for Class H fuse clips. For a midget-size holder, the Littelfuse BLF series is a midget fast-acting fuse rated 250V in a laminated tube body. Both share the fast-acting characteristic and 250V class, but the BLF is a midget-dimension cartridge, while the RL is a renewable Class H body that accepts replacement links.
8) Which Mersen RL part number do I order for a 60 amp disconnect?
RL60 is the 60A Motor FLA body. The line is ordered by amp rating with the number following the RL prefix, so RL15 for 15A, RL25 for 25A, RL100 for 100A, up to RL400. Available steps are 3, 5, 10, 15, 20, 25, 35, 40, 45, 50, 60, 70, 100, 125, 150, 175, 200, 225, 250, 300 and 400 amps.
9) Is the Mersen RL the same thing as a midget or glass tube fuse?
No, those are different animals. The RL is a Class H renewable fuse rated 250V AC with a replaceable zinc link, used in branch circuit and equipment disconnects. A midget fuse such as the Littelfuse BLF Series is a 250V fast-acting laminated tube fuse in a much smaller body, and glass tube types like the Littelfuse AGA and AGU series are for small electronics and automotive style holders. They are not interchangeable with a Class H fuse block.
10) Can I keep using RL renewable fuses in an older industrial plant, or do I have to upgrade?
For facilities already running renewable fuse holders, the RL line is the direct way to keep them in service: the body reloads with an RL series zinc link and protection is restored without re-engineering the disconnect. The limits to respect are 250V AC maximum and available short-circuit current no higher than 10,000 A at that point in the system. Within those limits it stays a valid general purpose branch circuit and equipment fuse.
11) Can a glass tube fuse be used in place of a Mersen RL Class H fuse?
No. The Mersen RL is a Class H fuse rated 250V AC (UL) with Motor FLA ratings from 3A to 400A, intended for branch-circuit and equipment protection in commercial and industrial panels. Littelfuse AG-style glass fuses such as the AGA series and the AGU series are small glass tube fuses for low-current device and accessory circuits, and they do not carry Class H branch-circuit construction or fit Class H fuse clips.
12) What should be used for a metering circuit rather than a Mersen RL fuse?
The Mersen RL covers Motor FLA ratings from 3A to 400A at 250V AC (UL), so it does not reach the sub-amp, higher-voltage range metering taps call for. For energy meter inputs, the Square D PowerLogic energy meter fuse pack supplies three 0.5A 600V fuses matched to that duty.
13) Which option avoids replacing the whole fuse after every operation?
The Mersen RL is built as a renewable fuse: the body is reloaded with an RL series die-cut zinc replacement link rather than discarded, with links offered from 2 to 600 amperes. Cartridge alternatives such as the Littelfuse BLF midget fast-acting fuse and the CCMR040 Class CC time-delay fuse are one-time fuses that are replaced as complete units.
How fast can I get the Mersen RL20 delivered?
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Can I return it if it doesn’t work for me?
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Does the Mersen RL20 come with a warranty?
Absolutely. The Mersen RL20 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 Mersen RL20?
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