A4BY1200 - 1200Amp Fuse

A4BY1200 - 1200Amp Fuse

Looking for a high-performance fuse that won’t let you down when the stakes are high? The Mersen A4BY1200 Amp-Trap® Class L Time-Delay Fuse is built for professionals who need reliable overcurrent protection in demanding industrial and commercial electrical systems. Rated for 600VAC and 300VDC, this 1200 amp powerhouse is perfect for protecting service entrance equipment, feeder circuits, and circuit breakers. Its smart time-delay design lets normal current surges pass without tripping, while still delivering fast protection during serious fault conditions.

With 4-second minimum time delay at 500% rating, the A4BY1200 coordinates seamlessly with ground fault relays, ensuring your system stays safe without unnecessary interruptions. Designed with silver-plated copper blade terminals and a durable insulating body, it guarantees consistent performance and conductivity in even the toughest environments. And with a massive 200 kA interrupting rating, this fuse can handle high fault currents to keep your equipment protected.

Key Features and Benefits

• 1200 Amp Class L fuse for heavy-duty electrical systems
• Time-delay design that handles startup surges without nuisance trips
• 600VAC / 300VDC rating works for AC and DC applications
• 200 kA interrupting rating protects against high fault currents
• 100% rated device – safe at continuous full load
• Coordinates with ground fault relays thanks to 4-second minimum time delay at 500%
• Silver-plated copper blade terminals for reliable conductivity
• Bolted mounting design ensures a secure, stable installation
• Ideal for service entrance, feeder circuits, and switchgear protection

Technical Specifications

• Manufacturer: Mersen
  
• Catalog Number: A4BY1200
  
• Product Type: Class L Time-Delay Fuse
  
• Series: A4BY
  
• Ampere Rating: 1200A
  
• Fuse Class: Class L
  
• Voltage Rating AC: 600VAC
  
• Voltage Rating DC: 300VDC
  
• Frequency: 50/60 Hz
  
• Interrupting Rating: 200 kA
  
• Characteristic: Time Delay
  
• Mounting Type: Bolted
  
• Terminal Type: Blade
  
• Terminal Material: Silver-Plated Copper
  
• Insulating Material: GMG
  
• Product Length: 273 mm
  
• Product Diameter: 63.5 mm
  
• Product Weight: 1.9414 kg
  

Material Compliance and Certifications

• UL and CSA approved for low-voltage fuse applications
• Rated for 600VAC UL and 300VDC UL operation
• Made with industrial-grade insulating materials and high-quality conductive components
  

Where It Works Best

• Industrial plants and factories
• Commercial power distribution
• Service entrance and feeder circuits
• Switchgear and switchboard protection
• Large motor control systems
• Utility and critical infrastructure projects
• Backup power and mission-critical distribution