Littelfuse JTD Series POWR-PRO...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$14.79
Littelfuse JTD Series POWR-PRO Class J Time-Delay Fuse with Blown-Fuse Indicator, 600V

Littelfuse JTD Series POWR-PRO Class J Time-Delay Fuse with Blown-Fuse Indicator, 600V

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Model: JTD1.25

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

$14.79
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Littelfuse JTD Series POWR-PRO Class J Time-Delay Fuse with Blown-Fuse Indicator, 600V

The Littelfuse JTD Series POWR-PRO® Class J time-delay fuse delivers true dual-element protection with permanent blown-fuse indication in a compact Industrial Cartridge package. Rated 600VAC/300VDC and UL Listed, this JTD_ID Indicator fuse family is available in ampere ratings from 1.25A to 70A (1.25A, 3A, 4A, 8A, 30A, 60A, and 70A), making it easy to match the right time-delay protection to circuits with high inrush currents. The permanently darkened indicator window pinpoints an open fuse at a glance, reducing troubleshooting time and exposure to live circuits.

Key Features

  • Ampere Rating Range: Available in 1.25A, 3A, 4A, 8A, 30A, 60A, and 70A ratings for reliable, code-compliant overcurrent protection across a wide range of circuits.
  • Voltage Rating: 600VAC / 300VDC for use across a wide range of industrial power systems.
  • Time-Delay Opening: Slo-Blo/Time Lag (T) true dual-element design reduces nuisance fuse opening in circuits with high inrush currents.
  • Blown-Fuse Indication: The indicator window darkens permanently once the fuse opens, regardless of power state, for immediate visual troubleshooting without exposure to live circuits.
  • Compact Package: Industrial Cartridge package size is designed specifically for Class J circuits where space is at a premium.
  • IEC Type II Protection: Delivers IEC Type II "No Damage" protection to IEC and NEMA type motor starters and fused combination motor controllers.
  • Reduced Downtime: A glance at the indicating window pinpoints an open fuse immediately, eliminating fuse testing so maintenance personnel can bring the correct replacement without delay.
  • Reduced Fuse Inventory: A single JTD Series family spanning 1.25A to 70A lets electrical teams standardize on fewer fuse types while covering a wide range of applications.

Certifications & Compliance

  • UL Listed (JDDZ E81895)
  • CSA Certified (1422-02 029862)

Technical Specifications

  • Series: JTD

Typical Applications

  • UL Listed Series-Rated Molded Case Circuit Breaker Panels
  • Fused Combination Motor Controllers for IEC Type II Branch-Circuit and Ground-Fault Protection
  • Motor Control Centers
  • General Purpose Mains, Feeders, and Branch Circuits
  • Transformer Protection

Why Littelfuse?

Littelfuse POWR-PRO JTD Series fuses pair a patented true dual-element design with permanent blown-fuse indication, giving electrical professionals fast fault identification and dependable current-limiting protection across ampere ratings from 1.25A to 70A. Backed by UL and CSA certification, the JTD Class J fuse family delivers the safety and reliability that industrial and commercial power distribution systems demand. Its compact Industrial Cartridge construction and permanent blown-fuse indicator help maintenance teams cut troubleshooting time and minimize exposure to live circuits, making it a dependable choice for professional electrical work.

Product Specs

Series:
JTD
Listing:
UL Listed
Product Type:
Time-Delay Fuse
Voltage Rating:
600VAC / 300VDC
Amperage Rating:
1.25A - 70A
Standards:
UL-CSA
Department:
Electrical
Product Group:
Circuit Protection
Product Subgroup:
Fuses

Littelfuse JTD1.25 – Frequently Asked Questions

1) Will a Littelfuse JTD fuse fit a Class R or Class RK1 fuse holder?
No. The JTD is a Class J fuse, and Class J bodies and ferrules are dimensionally unique to Class J blocks and holders. They won't drop into a Class R holder. If your holder is Class RK1, look at the Mersen A2D-R Class RK1 time-delay fuse (which also carries SmartSpot blown-fuse indication) or, for fast-acting RK1, the Mersen A2K Series at 250V or the A6K-R Series.
2) Will a time-delay Class J fuse hold through motor inrush without nuisance blowing?
That is what it's built for. The JTD uses a true dual-element, Slo-Blo (time lag) design that rides through the high inrush of motor starting and transformer energization while still clearing a real fault. It also provides IEC Type II "no damage" protection to IEC and NEMA motor starters and fused combination motor controllers. For a straight feeder or a circuit with no inrush, a fast-acting fuse is the better fit.
3) Is the Littelfuse JTD fuse UL Listed and CSA certified for inspected commercial work?
Both. The JTD carries UL Listing under JDDZ, file E81895, and CSA certification under 1422-02 029862. For an inspector or a facility spec that calls for UL and CSA marked Class J overcurrent protection, those are the file references to cite.
4) Can a Littelfuse JTD fuse be used for medium voltage transformer or feeder protection?
No. The JTD POWR-PRO Class J fuse is rated 600VAC / 300VDC and is intended for low-voltage mains, feeders, branch circuits, motor control centers, and transformer protection on 600V class systems. Medium voltage distribution calls for a different fuse class entirely - for example the Mersen D0R0 Series Amp-Trap E-rated medium voltage fuse with ferrule terminals. The two are not interchangeable in either direction.
5) Is the Mersen A2D-R a drop-in replacement for a Littelfuse JTD Class J fuse?
No. The Littelfuse JTD POWR-PRO is a Class J time-delay fuse, while the Mersen A2D-R is a Class RK1 time-delay fuse. Class J and Class RK1 bodies are dimensionally different and use different mounting, so a JTD fuseblock will not accept an RK1 fuse and vice versa. Both are time-delay designs with blown-fuse indication - the JTD uses a permanently darkening indicator window and the A2D-R uses Mersen SmartSpot indication - so if you need a time-delay indicating fuse in RK1 clips rather than Class J, the A2D-R is the one to specify.
6) I need a fast-acting fuse instead of time-delay - what should I use in place of the Littelfuse JTD?
The JTD POWR-PRO is a true dual-element time-delay (Slo-Blo) fuse, built to ride through motor and transformer inrush rather than clear it quickly. For fast-acting protection of circuits without inrush, Mersen offers the Amp-Trap A2K Series, a fast-acting Class RK1 fuse rated 250V, and the A6K-R Series fast-acting Class RK1 such as the A2K12R. Note that both are Class RK1 rather than Class J, so the fuseholder is not interchangeable with a JTD, and the A2K Series 250V rating is below the JTD's 600VAC / 300VDC rating.
7) How does the blown-fuse indicator on the Littelfuse JTD work, and does it need power to show?
The indicator window darkens permanently the moment the fuse element opens, and it stays dark whether or not the circuit is energized. No power is needed to read it and no meter test is required, so a tech can identify the open fuse by sight, know the amp rating to bring, and stay out of a live enclosure.
8) Why would I spec a Class J fuse instead of a Class R in a tight motor control center?
Space and current limiting. Class J fuses use a smaller industrial cartridge body than an equivalent Class R, which matters in a crowded MCC bucket or combination starter, and the JTD is a current-limiting device suitable for series-rated molded case breaker panels, motor control centers, mains, feeders, branch circuits and transformer protection. Class J blocks are also non-interchangeable with Class R, which prevents someone dropping in a lower-interrupting replacement later.
9) Is the 1.25A JTD the right choice for protecting a small control transformer?
A 1.25A time-delay Class J is a common pick for control transformer primaries, because the time-delay element tolerates the transformer's magnetizing inrush instead of opening on it. The JTD1.25 is the lowest rating in the family and transformer protection is one of the listed applications. Size it to the transformer manufacturer's recommendation and your NEC calculation. If you only need a small panel meter fuse, the Square D PowerLogic 0.5A 600V energy meter fuse pack is the purpose-built item instead.
10) What fuse do I use for a PowerLogic energy meter instead of a Littelfuse JTD?
Use the metering fuse pack built for it. The Square D PowerLogic Energy Meter Fuse Pack is a set of three 0.5A 600V fuses sized for meter voltage-sensing leads. The Littelfuse JTD POWR-PRO family starts at 1.25A and runs to 70A, so even its smallest rating is above a typical 0.5A metering circuit, and the JTD is a Class J dual-element time-delay fuse intended for motor, feeder, and transformer branch protection rather than instrument leads.
11) Which indicating time-delay fuse should I standardize on across a motor control center - Littelfuse JTD or Mersen A2D-R?
It comes down to the fuse class your blocks and switches are prepped for. The Littelfuse JTD POWR-PRO is Class J, UL Listed and CSA Certified, rated 600VAC / 300VDC, available from 1.25A to 70A, and uses a compact industrial cartridge body with a permanently darkened indicator window that reads an open fuse whether or not the circuit is energized. The Mersen A2D-R is a Class RK1 time-delay fuse with SmartSpot indication. Class J holders are physically smaller and will not take an RK1 fuse, so standardize on whichever class your existing gear is rejection-fitted for rather than mixing the two in one lineup.
How fast can I get the Littelfuse JTD1.25 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 JTD1.25 come with a warranty?
Absolutely. The Littelfuse JTD1.25 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 JTD1.25?
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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