Mersen 21005 - Fuse Block 250VAC 250VDC Class H/K 100A Adder Box with Reinforced Clip
Mersen

21005

Alternate Item Number: 21005

UPC: 782001753252

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Overview

The Mersen 21005 Class H/K/R fuse block is a 100A-rated, 250VAC/250VDC adder box fuse block designed for Class H, K, and R power fuses. This UL-recognized component features reinforced spring clips made of high-conductivity tin-plated copper, ensuring reliable electrical contact and thermal stability. The 21005 accommodates copper wire sizes from 2/0 AWG to 12 AWG, with a torque rating of 50 in-lb for secure connections. Its glass-filled polycarbonate (GFPC) insulator provides dielectric strength exceeding 2500V, meeting stringent safety standards. The adder box design allows snap-on extension to form multipole segmented blocks (1-, 2-, or 3-pole configurations), ideal for panelboard and switchgear applications. Compatible with stranded or solid copper wiring, the 21005 is engineered for heat cycling durability and OEM compliance. Recommended mounting screws are 1/4" (0.250" diameter) for secure installation. Trust Mersen’s US-manufactured solution for industrial power distribution reliability.
  • 100A rating, 250VAC/250VDC Class H/K/R fuse compatibility
  • Reinforced spring clips for reliable electrical contact
  • Accommodates copper wire sizes 2/0 AWG to 12 AWG
  • Adder box design for multipole segmented blocks (1-, 2-, or 3-pole)
  • GFPC insulator with dielectric strength >2500V

Specifications

AC Voltage Rating
250 V
Amperage Rating
100 A
Brand Name
Mersen
Class
Class H/K
Connection
Box with Reinforced Clip
DC Voltage Rating
250 V
Material
Glass Filled Polycarbonate
Maximum Operating Temperature
80 C
Mounting
Direct Screw Mount
Number Of Poles
1
Phase
1
Size
8.33 x 1.52 x 2.28 in
Size
211.582 x 38.608 x 57.912 mm
Standard
All fuse blocks meet the requirements of UL 4248 UL listed, guide IZLT, File E52283 UL recognized component guide IZLT2, file E52283 CSA certified class 6225, File 32169
Type
UL/CSA Fuse Bases
Voltage Rating
250 VAC
Package Dimensions (L x W x H)
8.33 in x 1.52 in x 2.28 in
Package Dimensions (L x W x H)
211.582 mm x 38.608 mm x 57.912 mm
Package Weight (Imperial)
0.700 lb
Package Weight (Metric)
0.318 kg
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Frequently Asked Questions about Mersen

What industries and applications are Mersen products used for?

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.

What are the main product lines offered by Mersen?

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.

What are the key features of Mersen products?

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.

What environmental ratings do Mersen products have?

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.

What accessories are available for Mersen products?

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.

How are Mersen products typically installed?

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.

What certifications and standards do Mersen products comply with?

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.

What technical support does Mersen offer?

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.