Mersen A4BY Class L Time-Delay...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$1,881.67
Mersen A4BY Class L Time-Delay Fuse, Blade Terminal, 600VAC/300VDC

Mersen A4BY Class L Time-Delay Fuse, Blade Terminal, 600VAC/300VDC

(No reviews yet) Write a Review

Model: A4BY1000

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

$1,881.67
Adding to cart… The item has been added
Free Shipping on orders over $199
We price match and offer bulk discounts! Click Add to Quote. It's quick and easy.
✨
Earn points with this purchase! You can redeem points for giftcards, iPads, XBox's and more. View Rewards
Free Keying on all locks
You may also like

Mersen A4BY Class L Time-Delay Fuse, Blade Terminal, 600VAC/300VDC

The Mersen A4BY Class L Time-Delay Fuse delivers reliable circuit protection for high-amperage applications, rated 3000A with dual 600VAC/300VDC capability for both AC and DC systems. This blade terminal fuse features GMG body insulating material and silver-plated copper terminals, backed by a 200kA breaking capacity for high-fault current environments. The time-delay characteristic provides enhanced protection against temporary overloads while ensuring fast clearing of fault conditions.

Key Features

  • 3000A High-Amperage Rating: Handles substantial electrical loads for demanding commercial and industrial applications requiring maximum current capacity.
  • Class L Time-Delay Design: Provides selective coordination and enhanced protection against temporary overloads while ensuring rapid fault clearing.
  • Dual Voltage Capability: Supports both 600VAC and 300VDC systems for versatile installation flexibility across diverse electrical configurations.
  • 200kA Breaking Capacity: Delivers exceptional fault interruption capability for high-fault current environments and critical system protection.
  • Silver-Plated Copper Terminals: Ensures optimal electrical conductivity and corrosion resistance for long-term reliable connections.
  • GMG Body Construction: Features advanced insulating material for superior arc quenching and thermal performance under extreme conditions.
  • Blade Terminal Configuration: Provides secure bolted mounting for industrial-grade installations requiring robust mechanical connections.

Certifications & Compliance

  • RoHS Compliant

Technical Specifications

  • Ac Max I R Breaking Capacity I1: 200 kA
  • Ac Or Dc: AC/DC
  • Ampere Rating: 3000 A
  • Body Insulating Material: GMG
  • Connection Terminal Material: Silver-Plated Copper
  • Connection Terminal Type: Blade
  • Frequency Hz: 50/60 Hz
  • Fuse Class: Class L
  • Mounting Method: Bolted
  • Product Length: 10.75 in
  • Product Weight: 19.3 lb
  • Rated Voltage Ac Ul: 600 V
  • Rated Voltage Dc Ul: 300 V
  • Rohs Compliant: Yes
  • Speed Characteristic: Time Delay

Typical Applications

  • Industrial Manufacturing Facilities
  • Commercial Power Distribution Systems
  • Data Centers and Critical Infrastructure
  • Heavy Equipment and Motor Protection
  • Utility and Substation Applications
  • Large Commercial Buildings
  • Process Control and Automation Systems

Why Mersen?

Mersen delivers proven reliability in high-amperage circuit protection with RoHS compliant construction and professional-grade materials. The combination of GMG insulating material, silver-plated copper terminals, and Class L time-delay characteristics ensures dependable performance in the most demanding electrical environments where circuit protection integrity is critical.

Manufacturer Resources

Product Specs

Product Type:
Fuse
Series:
A4BY
Voltage Rating:
600VAC/300VDC
Amperage Rating:
3000A
Product Material:
GMG
Connection Type:
Blade
Standards:
RoHS Compliant
Department:
Electrical
Product Group:
Wiring Devices

Mersen A4BY1000 – Frequently Asked Questions

1) What amp ratings does the Mersen A4BY Class L fuse come in?
The A4BY Class L time-delay fuse is stocked in six amp ratings: 600A (A4BY600), 800A (A4BY800), 1000A (A4BY1000), 1200A (A4BY1200), 1600A (A4BY1600) and 3000A (A4BY3000). Amperage is the only thing that changes across them, so pick the rating off your switchgear or panel schedule and order the matching part number. Class L fuses are current-limiting bolt-in fuses used in the large service and feeder range, which is why the family starts at 600A rather than down in the branch-circuit sizes.
2) Can I use a Class L fuse like the A4BY to protect a small control circuit or branch circuit?
No. The A4BY starts at 600A and runs to 3000A, which is main service and large feeder territory, not branch or control work. For a control transformer or a small branch circuit you want a midget or Class CC fuse instead, such as the Littelfuse CCMR Series Class CC time-delay fuse (CCMR040 is the 40A) or the Littelfuse BLF Series midget fast-acting fuse rated 250V. For automotive style glass tube work, the Littelfuse AGU and AGA Series glass fuses are the small format.
3) I need a replacement fuse for my main switch, how do I confirm the A4BY is the right one?
Match four things off the fuse you are pulling: the class, the amp rating, the voltage and the speed. The A4BY is Class L, time delay, 600VAC/300VDC, in 600 through 3000 amps. Class L is what fixes the physical fit, since Class L bodies and blade centers are standardized by amp rating so any Class L fuse of the same amperage bolts into the same holder. If the old fuse says Class L and matches on amps, the A4BY of that rating drops in. If the old one is Class J, RK1, RK5 or T, it is a different body and will not fit.
4) Can a Littelfuse CCMR040 be used in place of a Mersen A4BY?
No. The Littelfuse CCMR040 is a Class CC time-delay fuse rated 40A, a small ferrule-style branch-circuit fuse. The Mersen A4BY is a Class L bolted blade-terminal fuse covering 600A through 3000A at 600VAC/300VDC. The two share only the time-delay characteristic; Class CC and Class L fuses use entirely different holders and mounting, and the CCMR040 current rating is far below anything the A4BY range covers. Use a Class CC fuse where a Class CC fuseblock is installed, and the A4BY where the switchgear has bolted Class L mounting pads.
5) My meter cabinet calls for fuses on the potential transformer taps. Is a Class L fuse the right part?
No. Metering potential taps are protected by small low-current fuses; the Square D PowerLogic energy meter fuse pack supplies a set of three 0.5A 600V fuses for exactly that duty. The Mersen A4BY is a 600A to 3000A Class L fuse for the power path itself, not for the metering circuit. A switchboard commonly carries both: A4BY fuses on the main and 0.5A metering fuses on the instrument taps.
6) Is the A4BY a bolt-in fuse, and what do the terminals mount to?
Bolted mounting, with blade terminals in silver-plated copper. Class L fuses do not drop into a clip holder; the blades bolt directly to the bus or fuse block, so you need clear access to torque both ends. The silver plating on the copper is there for conductivity and corrosion resistance at the joint, which matters on a 3000A connection where a poor contact means heat.
7) Why choose a time-delay Class L fuse instead of a fast-acting one for a motor or transformer feeder?
Time delay is the point of the A4BY. A large motor or transformer pulls heavy inrush on start, and a fast-acting fuse of the same amp rating will see that inrush as a fault and open. The time-delay characteristic rides through the temporary overload while still clearing a real short circuit quickly, which is also what lets you coordinate selectively with the downstream devices so only the faulted branch drops. If your load has no inrush and you want the fastest possible let-through, a fast-acting fuse is the better choice.
8) What is the difference between a midget fast-acting fuse like the Littelfuse BLF and the Mersen A4BY?
Speed characteristic and scale. The Littelfuse BLF is a midget fast-acting fuse rated 250V in a laminated tube body. The Mersen A4BY is a time-delay fuse rated 600VAC/300VDC with silver-plated copper blade terminals for bolted mounting. Fast-acting midget fuses are chosen to protect control circuits and semiconductors that cannot tolerate let-through energy; the A4BY time-delay curve is chosen so that motor inrush and transformer magnetizing current do not open the fuse, while the main service fault is still cleared. They are not interchangeable in either direction.
9) I need a fuse for a 240V accessory circuit, not a main feeder. Should I order the A4BY?
No. The A4BY series starts at 600A and runs to 3000A, sized for service entrance, switchboard mains, and large motor circuits. For a small accessory or in-line circuit, a glass tube fuse such as the Littelfuse AGU series or the AGA series 5A glass fuse suits the load and the holder types used on that kind of circuit. Order the A4BY only where the equipment has bolted Class L mounting and the circuit is rated in the hundreds or thousands of amps.
10) Does the Mersen A4BY cover DC circuits, or do I need a separate DC-rated fuse?
The A4BY carries a dual rating of 600VAC and 300VDC, so one part number serves both AC distribution and DC bus protection within those limits. The comparable small-format fuses are AC-oriented parts - the Littelfuse BLF is rated 250V and the Square D PowerLogic meter fuses are 600V - and none of them approaches the A4BY current range. For a DC bus drawing 600A or more within 300VDC, the A4BY is the part to specify rather than adding a separate DC fuse type.
11) Is the Mersen A4BY RoHS compliant for a spec job?
Yes, the A4BY is RoHS compliant. That is the compliance statement carried on the fuse, and it is usually what an institutional or government submittal is asking for when it queries hazardous substance content on electrical components.
12) What frequency and body material does the A4BY use, and will it hold up in a hot switchgear room?
Rated for 50/60 Hz, so it works on both North American and international line frequencies. The body is GMG insulating material, chosen for arc quenching and thermal performance, which is what a Class L fuse needs when it interrupts a high fault inside a tightly packed switchgear lineup.
How fast can I get the Mersen A4BY1000 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 Mersen A4BY1000 come with a warranty?
Absolutely. The Mersen A4BY1000 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 A4BY1000?
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 Mersen A4BY1000 from ZenSupply?
ZenSupply makes it easy to get the commercial door hardware you need—fast shipping, expert support, and rewards on every order. Our team is always ready to help you choose the right product for your project.
!