Things to Look for Before Buying a Circuit Breaker

There are several things you should consider before you buy a circuit breaker. Discussed below are some of the things you should look for before you buy one.


A circuit breaker with an amp of up to 600 can be applied to frequencies between 50Hz and 120Hz. A breaker will have to derate when it is applied to a frequency that is higher than 120Hz. Iron losses and eddy currents often cause great heating in the components of the thermal trip in higher frequency projects hence why the breaker has to be specifically calibrated or derated.

The current frequency, frame size, and amp rating will determine the overall deration quantity. The general rule of thumb is the higher the rating of the amp in a particular frame size, the greater the derating required.

Circuit breakers above 600 amps have a bimetal that is transformer heated, and they are usually best for 60 Hz AC maximum. It would be best to consult your electrician beforehand to ensure that all the calibration measures are taken care of before proceeding with a 50Hz project.

Voltage rating

It is essential to get a circuit breaker that has sufficient voltage capacity to meet a specific application. Generally, the voltage rating is often calculated by how a circuit breaker can be integrated into a system, the distribution type, and the highest voltage applicable across all end ports.

Maximum interrupting capacity

Generally, the interrupting capacity is accepted as the maximum amount of fault a current breaker can interrupt without system failure. The maximum amount of fault current that a system supplies can be determined by doing the calculation at any time. The rule to follow when applying the appropriate breaker is the interrupting capacity of the circuit breaker has to be greater or equal to the amount of fault current, which can be delivered at the point in a system that the breaker is applied to. The breaker will be damaged if the incorrect amount of interrupting capacity is applied to it.

When you choose a circuit breaker, you must consider the end-user location. All breakers are different, and some are designed for use in more unforgiving environments. Some of the scenarios you should consider include resting position, altitude, high shock probability, corrosion and moisture, and high ambient temperatures. You will also have to decide whether you want to purchase one that is UL tested or not. It would be best if you get a UL-tested circuit breaker.

Contact CLF Services if you need any help with choosing the correct circuit breaker for your project.