Molded Case vs Miniature Circuit Breakers — What's the Difference?
The terms 'molded case circuit breaker' (MCCB) and 'miniature circuit breaker' (MCB) are often used interchangeably, but they refer to different products with different applications. Understanding the distinction helps you specify the right device for your project.
Miniature Circuit Breakers (MCB)
Miniature circuit breakers are the small, DIN-rail-mounted breakers commonly used in residential panels, small commercial panels, and control panels. They are typically rated from 0.5A to 125A and are designed for final distribution circuits.
Key characteristics: DIN rail or panel board mounting Compact size Fixed trip characteristics (not adjustable) Thermal-magnetic trip mechanism Common in residential and light commercial applications Examples: Square D QO series, Eaton BR series, Siemens QP series
Molded Case Circuit Breakers (MCCB)
Molded case circuit breakers are larger, more robust devices used in commercial and industrial distribution systems. They are rated from 15A to 2,500A and are designed for feeder and service entrance applications.
Key characteristics: Bolt-on or plug-in mounting in distribution panels Larger physical size May have adjustable trip settings (on electronic trip units) Available with thermal-magnetic or electronic trip Higher interrupt ratings (up to 200kA) Examples: Square D PowerPact H/J/L frames, Eaton HFD/HJD/HKD series
Key Differences at a Glance
| Feature | MCB | MCCB | |---|---|---| | Current range | 0.5–125A | 15–2,500A | | Mounting | DIN rail | Bolt-on/plug-in | | Trip adjustment | Fixed | Fixed or adjustable | | Interrupt rating | Up to 25kA | Up to 200kA | | Applications | Residential, final circuits | Commercial, industrial, feeders |
Which One Do You Need?
Use an MCB for: residential panels, small commercial panels, branch circuits in control panels, final distribution circuits up to 125A.
Use an MCCB for: main service entrance breakers, feeder breakers in distribution panels, motor feeders, commercial and industrial applications, any application requiring currents above 125A or interrupt ratings above 25kA.
Related Circuit Breaker Resources
- Circuit Breaker Frame Sizes Explained
- Thermal-Magnetic vs Electronic Trip Circuit Breakers
- What Is Interrupt Rating (kA) on a Circuit Breaker?
Need an MCB or MCCB? The AllBreakerSales.com catalog includes both types in all brands. Request a written quote to confirm the required catalog number and current availability. Call (951) 903-9804.