Mersen HSJ Class J High-Speed ...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$150.66
Mersen HSJ Class J High-Speed Fuse

Mersen HSJ Class J High-Speed Fuse

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Model: HSJ15

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

$150.66
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Mersen HSJ50 Class J High-Speed Ferrule Fuse, 50A 600VAC/500VDC

The Mersen HSJ50 is a Class J, high-speed Amp-Trap ferrule fuse engineered for demanding overcurrent protection applications. Rated 50A at 600VAC and 500VDC, this fuse features a GMG body insulating material and a compact 2.38 in. length, making it a reliable choice for protecting sensitive semiconductor loads, drives, and other equipment requiring fast-acting current-limiting protection. With a 200 kA AC maximum interrupting rating and tin-plated copper connection terminals, the HSJ50 delivers dependable performance across 50/60 Hz systems while meeting RoHS compliance standards.

Key Features

  • Ampere Rating: 50A rating provides precise overcurrent protection for the connected circuit.
  • Speed Characteristic: High-speed operation delivers fast current-limiting response for sensitive equipment and semiconductor protection.
  • Voltage Rating: Rated 600VAC and 500VDC (UL), suitable for both AC and DC applications.
  • Interrupting Capacity: 200 kA AC maximum RMS breaking capacity (I1) ensures safe operation under high fault-current conditions.
  • Durable Construction: GMG body insulating material provides robust mechanical and dielectric performance.
  • Connection Terminals: Tin-plated copper terminals support reliable, low-resistance clip-mount connections.
  • Mounting Method: Ferrule-style fuse designed for clip mounting in standard Class J fuse holders and blocks.
  • Frequency: Rated for 50/60 Hz electrical systems.

Certifications & Compliance

  • RoHS Compliant

Technical Specifications

  • Ac Max I R Breaking Capacity I1: 200 kA
  • Ac Or Dc: AC/DC
  • Ampere Rating: 50 A
  • Body Insulating Material: GMG
  • Connection Terminal Material: Tin-Plated Copper
  • Frequency Hz: 50/60 Hz
  • Mounting Method: Clip
  • Product Length: 2.38 in
  • Product Weight: 0.157 lb
  • Rated Voltage Ac Ul: 600 V
  • Rated Voltage Dc Ul: 500 V
  • Rohs Compliant: Yes
  • Speed Characteristic: High Speed

Typical Applications

  • Industrial and Commercial Power Distribution
  • Motor and Branch Circuit Overcurrent Protection
  • Semiconductor and Drive Equipment Protection
  • Panelboard and Switchgear Fuse Blocks
  • Renovation and New Construction Electrical Systems

Why Mersen?

Mersen fuses like the HSJ50 combine a durable GMG-insulated body, tin-plated copper terminals, and a high 200 kA interrupting rating to deliver dependable, code-compliant overcurrent protection. The high-speed Class J Amp-Trap design and RoHS-compliant construction make it a trusted choice for professionals specifying fast-acting, reliable fuse protection in commercial and industrial electrical systems.

Manufacturer Resources

Mersen Product Catalog

Product Specs

Product Group:
Wiring Devices
Rohs Compliant:
Yes
Body Insulating Material:
GMG
Frequency Hz:
50/60 Hz
Ac Max I R Breaking Capacity I1:
200 kA
Rated Voltage Dc Ul:
500 V
Fuse Class:
Class J
Speed Characteristic:
High Speed
Ac Or Dc:
AC/DC
Rated Voltage Ac Ul:
600 V
Department:
Electrical
Mounting Method:
Clip
Product Type:
Fuse

Mersen HSJ15 – Frequently Asked Questions

1) Will a Mersen HSJ fuse fit a standard Class J fuse block?
Yes. The HSJ is a Class J ferrule fuse with clip mounting, so it drops into standard Class J fuse holders and blocks. Class J has its own rejection dimensions, so an HSJ will not seat in a Class RK5, RK1, or CC holder, and a Class J block will not accept those fuses either. If the block on the panel is stamped Class J, the HSJ ampere you order will seat in it.
2) Can I use a Mersen HSJ fuse on a DC circuit, like a drive DC bus or a battery system?
Yes, the HSJ is rated AC/DC, 600V AC and 500V DC on its UL ratings. So it works on a DC bus up to 500 volts. On AC it is good to 600 volts at 50/60 Hz. Do not apply it above the DC figure just because the AC figure is higher, a fuse interrupting DC has no current zero to help it and the 500V number is the limit that matters there.
3) What is the difference between a high-speed Class J fuse and a regular time-delay Class J fuse?
Speed is the whole difference, and it decides what you can protect. The HSJ is a high-speed Class J, it clears fast enough to protect semiconductors, so it suits VFDs, soft starters, rectifiers, and SCR or IGBT power sections where the silicon fails faster than a standard fuse opens. A time-delay Class J is the opposite, it rides through motor inrush so a full-load-current-sized fuse does not blow on every across-the-line start. Use high-speed for the drive and its power electronics, time-delay for a plain motor branch circuit that starts hard.
4) Is the Mersen HSJ rated for a 200,000 amp available fault current service?
Yes. The HSJ carries a 200 kA AC maximum RMS breaking capacity, which covers services engineered to a 200,000 AIC available fault current. It is also current-limiting, so it can be used in a series-rated combination where the equipment label calls for a current-limiting Class J upstream. Match the label on the gear to the class and rating, not just the amperage.
5) I need to replace a blown Class J fuse in a VFD, how do I pick the right HSJ?
Read the ampere and voltage off the fuse you pulled, or off the drive nameplate, and order the HSJ with the matching ampere. Part numbers run HSJ15 through HSJ225 with the ampere in the number. Two things to confirm before you order: the old fuse must be Class J, because an HSJ will not seat in an RK or CC block, and the circuit voltage must be within 600V AC or 500V DC. If the drive manual calls for a semiconductor or high-speed Class J specifically, the HSJ is that type, not a time-delay.
6) Can a Square D PowerLogic energy meter fuse pack be used in place of a Mersen HSJ high-speed Class J fuse?
No. The Mersen HSJ is a Class J, high-speed fuse rated 600 VAC and 500 VDC that clip-mounts into Class J fuse holders and blocks, with a 200 kA AC maximum breaking capacity, and it is offered from 15A up to 225A for protecting motor branch circuits, drives and semiconductor loads. The Square D PowerLogic energy meter fuse pack is a set of three 0.5A 600V fuses intended for the metering circuit of a PowerLogic energy meter, not for the load circuit itself. At 0.5A it protects instrument voltage-sensing leads; it will not carry the current of a branch or feeder circuit, so the two are not interchangeable even though both are 600V parts.
7) What amp ratings does the Mersen HSJ Class J fuse come in?
Thirteen ratings: 15, 25, 30, 35, 40, 45, 50, 60, 80, 90, 100, 125, and 225 amps, ordered by the part number that matches the ampere, so a 60 amp is HSJ60 and a 225 amp is HSJ225. The ampere is the only thing that changes between them, the voltage, class, and speed characteristic are the same across the range.
8) Can I use an HSJ fuse to protect the metering circuit on a power meter?
No, that is the wrong part for it. Metering potential circuits are fused at a fraction of an amp, and the smallest HSJ is 15 amps, far too large to protect meter inputs. For that, use a purpose-built meter fuse pack such as the Square D PowerLogic Energy Meter Fuse Pack, a set of three rated 0.5A at 600V. Keep the HSJ for the power circuit feeding the equipment.
9) Does the HSJ need a special fuse block, or will it work in a panelboard fuse holder?
Clip mounting is all the HSJ needs, it is a ferrule fuse that snaps into the clips of a Class J block or holder, no bolting and no adapters. Panelboard and switchgear fuse blocks are a listed application for it. What you cannot do is put it in a plain non-rejection holder and call it Class J protection, the rejection feature only works if the block is a Class J block.
10) What fuse protects the metering leads on a PowerLogic energy meter if the panel already uses Mersen HSJ fuses on the feeder?
Those are two separate jobs. The Mersen HSJ handles the power circuit: Class J, high speed, 600 VAC and 500 VDC, clip-mounted, in ampere ratings including 30A, 60A and 100A. The voltage-sensing leads running to a PowerLogic energy meter are protected by the Square D PowerLogic energy meter fuse pack, a set of three 0.5A 600V fuses sized for instrument current only. A panel doing both metering and feeder protection uses the HSJ on the feeder and the 0.5A metering fuses on the sensing leads.
11) Are Mersen HSJ fuses RoHS compliant for a spec that requires it?
Yes, HSJ fuses are RoHS compliant. The connection terminals are tin-plated copper, which is what keeps the lead out of the plating and gives a low-resistance clip contact at the same time. For institutional and government jobs carrying a RoHS line item in the spec, this one meets it.
How fast can I get the Mersen HSJ15 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 HSJ15 come with a warranty?
Absolutely. The Mersen HSJ15 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 HSJ15?
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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