Circuit Breakers

Miniature Circuit Breakers from 1 to 63 AMP in B, C and D trip curves

When deciding which miniature circuit breaker is best for any application, it is important to determine what type of protection is necessary.  For these MCB's, there are two important factors to consider when choosing which breaker is appropriate:

  1. Supplementary or Branch Circuit Protection
    1. Supplementary protectors are the most common type, but since branch circuit protection is not required, a separate device such as a fuse or molded case circuit breaker must be used upstream
    2. Branch Circuit protectors  are listed as a primary protection device and can be used alone without the need for an additional protection device

Determining the trip curve needed for your miniature circuit breaker

Miniature circuit breakers can come in 7 different trip curve ratings, with B, C and D being the most common.  It is imperative that the correct trip curve is chosen the effectively protect the equipment that is downstream from this device.  Listed below are the three most common trip curves along with a brief description of suitable applications:

  1. B-curve : Suitable for applications where protection against low level short circuit faults in control wiring is desired.  Instantaneous trip is 3 to 5 x continuous rating of device (In). Applications include PLC wiring, business equipment,
    lighting, appliances and some motors. Low magnetic trip point.
  2. C-Curve : Suitable for applications where medium levels of inrush current are expected. Instantaneous trip is 5 to 10 x rating of device (In). Applications include small transformers, lighting, pilot devices, control circuits, and coils. Medium magnetic trip point.
  3. D-curve : Suitable for applications where high levels of inrush current are expected. Instantaneous trip is 10 to 20 x rating of device (In). The high magnetic trip point prevents nuisance tripping in high inductive applications such as motors, transformers, and power supplies.
  • Sprecher and Schuh L8-8/1/C miniature circuit breaker Sprecher and Schuh L8-8/1/C side view

    L8-8/1/C

    Sprecher + Schuh L8-8/1/C single pole 8 AMP miniature supplementary circuit breaker with C trip curve rating. This trip rating is effective where medium levels on inrush are expected, most times in applications that include lighting, transformers, pilot...

    MSRP: $52.17
    $33.48
    Add to Cart
  • Eaton/Moeller NZMB1-A125-NA circuit breaker

    NZMB1-A125-NA

    Eaton/Moeller NZMB1-A125-NA 3-pole circuit breaker with basic switching capacity and a thermo-magnetic release. This 125 AMP molded case circuit breaker has a 750A-1250A short-circuit release and an adjustable overload release from 100A-125A. Line and...

    MSRP: $907.00
    $831.29
    Add to Cart
  • Eaton/Moeller NZMB1-A20-NA circuit breaker

    NZMB1-A20-NA

    Eaton/Moeller NZMB1-A20-NA 3-pole circuit breaker with basic switching capacity and a thermo-magnetic release. This 20 AMP molded case circuit breaker has a 350A short-circuit release and an adjustable overload release from 15A-20A. Line and load side...

    MSRP: $433.00
    $395.85
    Add to Cart
  • Eaton/Moeller NZMB1-A32-NA circuit breaker

    NZMB1-A32-NA

    Eaton/Moeller NZMB1-A32-NA 3-pole circuit breaker with basic switching capacity and a thermo-magnetic release. This 32 AMP molded case circuit breaker has a 600A-1000A short-circuit release and an adjustable overload release from 25A-32A. Line and load...

    MSRP: $433.00
    $395.85
    Add to Cart
  • Eaton/Moeller NZMB1-A40-NA circuit breaker

    NZMB1-A40-NA

    Eaton/Moeller NZMB1-A40-NA 3-pole circuit breaker with basic switching capacity and a thermo-magnetic release. This 40 AMP molded case circuit breaker has a 320A-400A short-circuit release and an adjustable overload release from 32A-40A. Line and load...

    MSRP: $433.00
    $395.85
    Add to Cart
  • Eaton/Moeller NZMB1-A50-NA circuit breaker

    NZMB1-A50-NA

    Eaton/Moeller NZMB1-A50-NA 3-pole circuit breaker with basic switching capacity and a thermo-magnetic release. This 50 AMP molded case circuit breaker has a 300A-500A short-circuit release and an adjustable overload release from 40A-50A. Line and load...

    MSRP: $433.00
    $395.85
    Add to Cart
  • Eaton/Moeller NZMB1-A63-NA circuit breaker

    NZMB1-A63-NA

    Eaton/Moeller NZMB1-A63-NA 3-pole circuit breaker with basic switching capacity and a thermo-magnetic release. This 63 AMP molded case circuit breaker has a 380A-630A short-circuit release and an adjustable overload release from 50A-63A. Line and load...

    MSRP: $433.00
    $395.85
    Add to Cart
  • Eaton/Moeller NZMB1-A80-NA circuit breaker

    NZMB1-A80-NA

    Eaton/Moeller NZMB1-A80-NA 3-pole circuit breaker with basic switching capacity and a thermo-magnetic release. This 100 AMP molded case circuit breaker has a 480A-800A short-circuit release and an adjustable overload release from 63A-80A. Line and load...

    MSRP: $470.00
    $430.69
    Add to Cart