Mersen A4BY250 - Fuse A4BY - Class L - Time-Delay 600VAC 300VDC 250A Blade Amp-Trap®
Mersen

A4BY250

Alternate Item Number: A4BY250

UPC: 782001939014


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Overview

The Mersen A4BY250 is a Class L time-delay fuse, engineered for robust protection of service entrance equipment, feeder circuits, and circuit breakers. This 100% rated device from Mersen (SKU: A4BY250) allows continuous current application up to its 250A ampere rating. Its key feature is a minimum 4-second time delay at 500% of its rating, enabling it to safely pass normal current surges and effectively coordinate with ground fault relays. The A4BY series boasts a high interrupting rating of 200kA I.R. AC and 100kA I.R. DC, ensuring safety under fault conditions. Constructed with a glass melamine body and plated terminals, these fuses offer superior reliability, even in harsh industrial environments. Unique dimensions prevent incorrect substitution by other fuse classes, and blade-stamped catalog numbers provide permanent identification. This fuse is UL listed to standard 248-10 and CSA certified to standard C22.2 No. 248.10, with self-certification for DC applications per UL248. Applications include mains, feeders, load centers, panelboards, switchboards, and metering centers. The A4BY250 is a current-limiting fuse designed for uniform characteristics across all ampere ratings within its class.
  • Class L Time-Delay Fuse
  • 250A Ampere Rating
  • 600VAC / 300VDC Voltage Rating
  • 200kA IR AC / 100kA IR DC Interrupting Rating
  • 4-second minimum time delay at 500% rating

Specifications

AC Voltage Rating
600 V
Amperage Rating
250 A
Application
Mains Feeders Circuit Breakers Load centers Panelboards Switchboards Metering Centers
Body Material
GMG
Brand Name
Mersen
Class
Class L
Connection
Blade
Connection Material
Silver-Plated Copper
DC Voltage Rating
300 V
Fuse Class
L
Interrupt Rating
200 kA
Mounting
Bolted
Size
8.63 x 2 in
Size
219.202 x 50.8 mm
Special Features
Unique dimensions prevent replacement by other fuse classes Blade-stamped catalog numbers for permanent identification Glass melamine body and plated terminals provide superior reliability in harsh environments
Standard
Mersen Self-Certification, UL Listed to Standard 248-10, File E2137 CSA Certified to Standard C22.2, No. 248.10 IEC 269-2-1 DC Tested to UL 248 limits (Mersen Self-Certified)
Sub Brand
Amp-Trap®
Type
Class L
Voltage Rating
600 VAC
Package Dimensions (L x W x H)
8.63 in x 2 in x 2 in
Package Dimensions (L x W x H)
219.202 mm x 50.8 mm x 50.8 mm
Package Weight (Imperial)
2.380 lb
Package Weight (Metric)
1.080 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.