3VA5212-5EF31-0AA0 - MFAS 125 Amp Circuit Breaker

3VA5212-5EF31-0AA0 - MFAS 125 Amp Circuit Breaker

If you’re working with a three-phase system and need something you can install and not worry about later, the Siemens 3VA5212-5EF31-0AA0 is a solid pick. It’s a 125 amp, 3-pole circuit breaker from the 3VA5 series—built for everyday use in commercial and industrial setups where reliability matters more than bells and whistles. This one keeps things simple. It uses a thermal magnetic trip unit, so you’re covered on both overloads and short circuits without adding complexity. The overload protection is fixed at 125 amps, which means no field adjustments and no guesswork. For short circuits, it trips instantly at 10 times the rated current, helping shut things down fast before damage spreads. With a 35kA interrupting rating at 480V, it’s ready for higher fault conditions you’d expect in real-world systems. And since it’s built on the 3VA52 frame, it fits neatly into most panel layouts without forcing you to rearrange everything just to make it work. In short—it does what you need it to do, and it does it consistently.

Key Features and Benefits

• 125 amp rating for common commercial and industrial applications
• 35kA interrupting capacity at 480V for higher fault levels
• Thermal magnetic trip unit for both overload and short-circuit protection
• Fixed overload setting (125A) keeps performance consistent
• Instantaneous trip at 10x rated current for quick fault response
• 3-pole design for standard three-phase systems
• 3VA52 frame fits well in most panel configurations

Technical Specifications

• Part Number: 3VA5212-5EF31-0AA0
• Series: Siemens 3VA5
• Frame: 3VA52 (UL Frame 250)
• Poles: 3
• Amperage: 125A
• Interrupting Rating: 35kA @ 480V
• Trip Unit: TM240 Thermal Magnetic
• Overload Protection (Ir): 125A (fixed)
• Short-Circuit Protection (Ii): 10 × In (fixed)
• Dimensions: 9.65" H × 6.3" W × 5.9" D

Material Compliance and Certifications

• UL Listed for use in the U.S.
• Supports NEC-compliant installations when applied correctly
• Built to meet standard commercial and industrial requirements

Where It Works Best

• You’ll typically find this breaker in commercial buildings, industrial facilities, OEM equipment, and control panels. It’s a practical fit for HVAC systems, manufacturing lines, and general power distribution—anywhere you need dependable protection without overcomplicating the setup.