Mersen AJT250/600 Reducer Fuse AJT - Class J - Time-delay 600VAC 500VDC 250A Blade

AJT Reducer Fuses provide a safe, permanent solution for decreasing current rating without needing a separate Fuse Reducer accessory, which is designed for temporary use.

These fuses are rated for 600VAC and 500VDC. Amperage ratings range from 125 to 200A in a 400A body, and 250 to 400A in a 600A body.

For 125-200A fuses, dimension A is 7-1/8 in, B is 2-1/8 in, C is 1/4 in, D is 1-5/8 in, E is 1-7/8 in, F is 5-1/4 in, G is 17/32 in, and H is 13/32 in.

For 250-400A fuses, dimension A is 8 in, B is 2-1/2 in, C is 3/8 in, D is 2 in, E is 2-1/8 in, F is 6 in, G is 11/16 in, and H is 17/32 in.

The interrupting rating is 200kA I.R. AC and 100kA I.R. DC. It is self-certified for 600VAC at 300kA I.R., UL witnessed.

They are suitable for motor circuits, mains, feeders, branch circuits, lighting, heating, general loads, transformers, control panels, circuit breaker back-up, and bus duct.

Yes, AJT Reducer Fuses are recommended for Arc Flash energy reduction.

They offer extremely low peak let-thru current, making them the most current-limiting UL class fuse available.

Yes, they feature a time-delay function suitable for motor starting and transformer inrush.

Yes, an optional EI indicator/switch is available for these fuses.

Mersen products are used across diverse industrial sectors including solar power, electric vehicles, buildings/construction, industrial automation, power distribution, HVAC, elevators, telecommunications, and specialty manufacturing. Key application areas include circuit protection, surge protection, battery module protection, electrical safety systems, and power management for residential, commercial, and utility-scale installations.

Mersen offers five primary electrical power product lines: IEC and UL/CSA Fuses and Fusegear, Surge Protection, Low Voltage Disconnect Switches, Power Distribution Blocks, and Engineered Solutions. Their comprehensive range includes specialized components like high-speed fuses, modular fuse holders, surge arresters, and custom-engineered electrical protection systems for industrial and power management applications.

Mersen products feature advanced electrical protection and power management solutions with key characteristics including finger-safe design, compact modularity, and high-performance safety features. Their product lines span electrical power components like fuses, surge protection, power distribution blocks, and specialized solutions for industrial, solar, and building applications. Critical features include UL/CSA approvals, high short-circuit current ratings, and innovative technologies like the Fuse Control™ program that minimize electrical risks and optimize system performance.

Mersen products meet rigorous environmental ratings across multiple standards, including UL 508A Type 1, 2, 3, 4, 4X, 12, and 13, CSA Type 1, 2, 3, 4, 4X, 12, and 13, and NEMA Type 1, 2, 3, 4, 4X, 12, and 13. They feature IEC 60529 IP66 protection, with enhanced UV inhibitors for outdoor weathering and operating temperatures ranging from -40°C to 130°C (-40°F to 266°F). These ratings ensure superior protection in wet, corrosive, and challenging industrial environments.

Mersen offers multiple accessories for their fuse blocks and systems, including safety pullers (DFC3M and DFC3LP), DIN-rail adapters (DRM), bus bars, auxiliary contacts, and specialized mounting hardware. Key accessories include the DFC3M safety puller for 1-1/2" x 13/32" midget or Class CC fuses, the DRM adapter for mounting 303 series fuse blocks on DIN-rail, and UltraSafe fuse module accessories like bus bars and auxiliary contacts that enable module interconnection and monitoring.

Mersen products are typically installed in electrical distribution systems, control panels, and industrial automation environments using multiple mounting options. These include service entrance panel mounting, distribution panel installation, control panel DIN rail mounting, and custom engineered solutions like Fused Coordination Panelboards. Installation depends on the specific product type, such as fuses, surge protective devices, or switches, and is designed to provide electrical protection and circuit safety in various industrial and commercial applications.

Mersen products are certified to multiple international standards, including UL (Underwriters Laboratories), CSA (Canadian Standards Association), CCC (China Compulsory Certification), and EAC (Eurasian Conformity). Our products meet rigorous safety and performance standards for industrial applications across North America, China, Russia, and other global markets, ensuring compliance and reliability in electrical power and advanced materials solutions.

Mersen provides comprehensive technical support through multiple channels, including technical experts located in your time zone who can assist with product selection, application guidance, and troubleshooting. Their Fuse Control™ program offers a free Fuse Inventory Audit & Analysis, and customers can access technical resources through their sales representatives and online platform ep.mersen.com.