Mersen Amp-Trap 2000® AJT Seri...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$71.34
Mersen Amp-Trap 2000® AJT Series Class J Time-Delay Ferrule Fuse, 600VAC

Mersen Amp-Trap 2000® AJT Series Class J Time-Delay Ferrule Fuse, 600VAC

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Model: AJT12N

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

$71.34
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Mersen Amp-Trap 2000® AJT Series Class J Time-Delay Ferrule Fuse, 600VAC

The Mersen Amp-Trap 2000® AJT fuse is a Class J, time-delay, ferrule-terminal fuse rated 600VAC / 500VDC with a 200 kA AC breaking capacity, engineered to protect main, feeder, and branch circuits across a wide range of loads. This family is available across a Motor FLA range from 1.25A up to 12A, letting engineers and electricians select the precise current rating needed for a given motor or branch-circuit application while relying on the same proven Class J platform. Built with advanced material technology, the AJT delivers IEC Type 2 No Damage protection while requiring only half the mounting space of comparable 600VAC Class RK fuses. Its time-delay characteristic is ideal for handling typical motor and transformer inrush currents while providing superior current-limiting performance, and the SmartSpot visual open-fuse indicator supports fast field diagnosis.

Key Features

  • Amp Rating Range: Available across Motor FLA ratings from 1.25A to 12A to match specific motor and branch-circuit load requirements.
  • Connection/Terminal Type: Ferrule terminals constructed of tin-plated copper for a reliable, low-resistance connection.
  • Mounting: Clip-mount design for standard fuse block and holder compatibility.
  • Rated Voltage: 600VAC and 500VDC (UL), supporting both AC and DC circuit applications.
  • Breaking Capacity: 200 kA AC interrupt rating (I1) for high fault-current environments.
  • Fuse Class: Class J for compact, current-limiting overcurrent protection.
  • Speed/Characteristic: Time-delay operation suited to motor and transformer inrush currents.
  • Body/Insulating Material: GMG construction for durable, high-temperature performance.
  • Frequency: Rated 50/60 Hz for standard AC power systems.

Certifications & Compliance

  • RoHS Compliant
  • UL Rated Voltage: 600VAC / 500VDC

Technical Specifications

  • ROHS Compliant: Yes
  • Rated voltage AC UL: 600 V
  • Rated voltage DC UL: 500 V
  • Speed/Characteristic: Time Delay
  • AC or DC: AC/DC
  • Body/Insulating Material: GMG

Typical Applications

  • Main, Feeder, and Branch Circuit Protection
  • Motor and Transformer Inrush Current Protection
  • Industrial and Commercial Electrical Panels
  • Current-Limiting Overcurrent Protection
  • Panelboard and Switchgear Fuse Replacement

Why Mersen?

Mersen's Amp-Trap 2000® AJT fuses combine advanced GMG body construction with tin-plated copper ferrule terminals to deliver dependable, code-compliant overcurrent protection across the full 1.25A-12A Motor FLA range. With IEC Type 2 No Damage performance, a 200 kA breaking capacity, and RoHS-compliant materials, these Class J fuses are built for demanding motor, transformer, and branch-circuit applications where reliability and compact mounting matter, giving electrical contractors and panel builders a single trusted platform across their full range of current ratings.

Manufacturer Resources

Mersen Product Catalog

Product Specs

Connection Terminal Type:
Ferrule
Mounting Method:
Clip
Connection/Terminal Material:
Tin-Plated Copper
AC Max I.R./Breaking Capacity: I1:
200 kA
ROHS Compliant:
Yes
Frequency (Hz):
50/60 Hz
Rated voltage AC UL:
600 V
Speed/Characteristic:
Time Delay
AC or DC:
AC/DC
Rated voltage DC UL:
500 V
Fuse Class:
Class J
Body/Insulating Material:
GMG
list_batch:
MERSEN-20260825
Department:
Electrical
Product Group:
Circuit Protection
Product Type:
Time-Delay Fuse
Product Material:
GMG
Voltage Rating:
600VAC
Connection Type:
Ferrule Terminal
Amperage Rating:
1.25A - 12A
Standards:
RoHS Compliant
Product Subgroup:
Fuses

Mersen AJT12N – Frequently Asked Questions

1) Will a Mersen AJT Class J fuse fit my existing Class RK60 fuse block?
No. Class J and Class RK fuses use different dimensions and mounting, so the AJT needs a Class J block or holder. The AJT is a clip-mount ferrule fuse, and Mersen states it takes only half the mounting space of comparable 600VAC Class RK fuses, which is why it cannot drop into RK clips. If you're replacing RK fuses, change the block to a Class J block rated 600V.
2) Can I use the Mersen AJT fuse on a 500VDC circuit, or is it AC only?
Both. The AJT carries a UL rated voltage of 600VAC and 500VDC, and the AC side is rated 50/60 Hz. The published 200 kA interrupting rating is the AC breaking capacity, so for DC applications size the circuit to the DC rating and check the available DC fault current against Mersen's DC interrupting data.
3) Which AJT amp rating do I order for a motor starter?
The AJT ferrule family covers Motor FLA ratings from 1.25A to 12A, ordered as individual amp ratings: AJT1-1/4N (1.25A), AJT1-1/2N (1.5A), AJT1-8/10N (1.8A), AJT2N (2A), AJT2-1/4N (2.25A), AJT4-1/2N (4.5A), and AJT12N (12A). Pick the rating against the motor's full load amps and the overcurrent sizing rules in your application, not against the breaker size you removed.
4) Will a time-delay Class J fuse nuisance trip on motor inrush?
That's exactly what the time-delay characteristic is for. The AJT is a time-delay Class J fuse built to ride through typical motor and transformer inrush while still current-limiting on a fault, and Mersen rates it for IEC Type 2 No Damage protection of the starter. A fast-acting fuse of the same amp rating would open on starting current.
5) Is 200 kA enough interrupting rating for a service panel with high available fault current?
The AJT is rated 200 kA AC breaking capacity, which is the highest commonly specified interrupting rating for branch and feeder fuses and covers essentially any available fault current you will see downstream of a utility transformer in commercial or industrial service. It is used on main, feeder, and branch circuits at 600VAC.
6) How do I tell if an AJT fuse has blown without pulling it out of the clips?
The Amp-Trap 2000 AJT carries Mersen's SmartSpot visual open-fuse indicator, so a blown fuse can be identified by sight in the block instead of being pulled and metered. Useful on panel troubleshooting calls where you are checking a bank of three.
7) Can I substitute a Class CC fuse like the Littelfuse CCMR for a Mersen AJT Class J?
Not directly. The Littelfuse CCMR is a Class CC time-delay fuse, and Class CC bodies are rejection-style and physically smaller than Class J, so they will not seat in a Class J block. Both are time-delay and suit motor circuits, but you have to match the holder to the class. Stay with an AJT if your block is Class J.
8) I need a small glass fuse for a control circuit, not a Class J fuse. What should I look at?
Class J fuses like the Mersen AJT are 600V power-circuit fuses for mains, feeders, and motor branch circuits, not small electronics protection. For low-voltage control and accessory circuits, ZenSupply carries Littelfuse AGA and AGU glass tube fuses, and the Littelfuse BLF Series midget fast-acting fuse rated 250V. For metering, Square D sells a PowerLogic energy meter fuse pack of three, 0.5A 600V.
9) Is a Littelfuse AGU or AGA glass tube fuse an equivalent to the Mersen AJT?
No, they serve different circuits. The Littelfuse AGU is an AG glass tube fuse and the Littelfuse AGA5 is a 5A AGA series glass fuse; glass-tube AG fuses are small electronic and automotive-style fuses. The Mersen Amp-Trap 2000 AJT is a Class J, current-limiting fuse with a GMG body, tin-plated copper ferrule terminals, and a 200 kA AC breaking capacity at 600VAC, intended for main, feeder, and branch circuit protection in panels and switchgear. Matching on amperage alone is not enough here - the interrupting rating and fuse class have to match the equipment.
10) My meter has a Square D PowerLogic fuse pack in it - would I order the Mersen AJT instead?
No. The Square D PowerLogic energy meter fuse pack is a set of three 0.5A 600V fuses supplied for metering voltage-sense leads, so it is matched to the meter rather than to a load. The Mersen Amp-Trap 2000 AJT is a Class J time-delay fuse covering Motor FLA ratings from 1.25A to 12A for motor, transformer, and branch-circuit protection. The two share a 600V class but not the application or the holder.
11) I need DC protection as well as AC - which of these fuses covers both?
The Mersen Amp-Trap 2000 AJT is rated AC/DC, at 600VAC and 500VDC UL, so it can be applied on either. Among the comparable fuses, the Littelfuse BLF is a 250V midget fast-acting fuse and the Square D PowerLogic pack is a 0.5A 600V metering set, both matched to narrower applications. If the circuit is DC at up to 500V, the AJT is the one to specify.
How fast can I get the Mersen AJT12N 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 AJT12N come with a warranty?
Absolutely. The Mersen AJT12N 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 AJT12N?
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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