NB3900 - 900 Amp Circuit Breaker

NB3900 - 900 Amp Circuit Breaker

The NB3900 is a 900-amp, 3-pole thermal-magnetic circuit breaker for compatible Type NB electrical equipment. If you're replacing an existing breaker, the important thing is getting the specifications right. This model is rated for 40°C, uses an interchangeable trip unit, and includes load-side terminals. Interrupting ratings are 22k AIC at 600VAC, 30k AIC at 480VAC, and 42k AIC at 240VAC. The breaker measures 16 inches high, 8.25 inches wide, and 5.5 inches deep. Check those dimensions, along with the amperage, voltage, AIC rating, pole count, and trip configuration, against the equipment before installation. For older electrical systems already designed around Type NB equipment, the NB3900 can be a straightforward form-, fit-, and function-replacement when the specifications match. It's a practical, built-to-last breaker that maintains compatibility without changing the basic system configuration.

Key Features and Benefits

• 900 amp rating with a 3-pole configuration
• Thermal-magnetic protection
• Interchangeable trip unit
• 40°C rated
• 22 kAIC at 600VAC
• 30 kAIC at 480VAC
• 42 kAIC at 240VAC
• Load-side terminals included
• Sized for compatible Type NB applications
• Built to last when properly installed and used within its ratings

Technical Specifications

• Part Number: NB3900
  
• Type: NB
  
• Amperage: 900A
  
• Poles: 3
  
• Breaker Type: Thermal Magnetic
  
• A.I.C. @ 600VAC: 22k
  
• A.I.C. @ 480VAC: 30k
  
• A.I.C. @ 240VAC: 42k
  
• Temperature Rating: 40°C
  
• Trip Unit: Interchangeable
  
• Load-Side Terminals: Included
  
• Height: 16.0 in.
  
• Width: 8.25 in.
  
• Depth: 5.5 in.
  

Material Compliance and Certifications

• The available product specifications don't include specific material compliance information or certification/listing numbers. If your application requires a particular certification or compliance standard, check the markings on the breaker and the applicable equipment documentation before installation.

Where It Works Best

• The NB3900 is intended for compatible legacy electrical distribution equipment that calls for a Type NB, 900A, 3-pole thermal magnetic breaker with matching electrical and physical specifications.
• Before replacing an existing breaker, check more than the part number. Match the amperage, number of poles, voltage, AIC rating, dimensions, trip configuration, and terminal arrangement to the equipment you're working on. Qualified personnel should confirm electrical installation and compatibility.