Bay Power NewsIdentifying the right breaker for your electrical project is not only critical to your success but also prevents safety hazards and damage in the event of an overload. To choose the right one, you need to know the specifications and requirements unique to that application.

Not sure where to start? Having a basic knowledge of circuit breaker sizes and categories will help you sort through your options. 

A Basic Intro to Circuit Breaker Sizes

Because of their broad range of applications and frame sizes, it’s not always easy to choose circuit breakers based on simple specifications like size, amperage, or voltage. Within residential, commercial, or industrial applications, breakers can be rated for any amperage or voltage. However, the breaker you choose will be dictated by what panel you have. The key is to find the breaker that has the correct specifications and rating for your application.

Let’s take a look at the three most common categories of circuit breakers:

circuit breaker sizes

Molded Case Circuit Breakers

Molded case circuit breakers (MCCBs) are widely used for applications of all kinds, from residential to industrial settings. They get their name from the molded case that encloses all of the components. MCCBs can be rated for very low currents or for larger loads, and they protect against short circuits, ground faults, and overload situations using electromagnetic or thermomagnetic tripping mechanisms. Frame sizes range from 30 to 2000A.

Insulated Case Circuit Breakers

Insulated case circuit breakers contain a two-step stored energy mechanism that turns the breaker on and off and differentiates them from MCCBs. They are primarily used in commercial and industrial applications, with a frame size of 800 to 5000A.

Air Circuit Breakers

Air breakers are not as widely used as molded case or insulated case circuit breakers, but we do see them in older infrastructures. In newer infrastructures, air circuit breakers are largely being replaced by ICCBs. Air circuit breakers are more easily adjustable since they are completely open. These tend to be large circuit breakers, with a frame size of 800 to 5000A.

Finding the Right Circuit Breaker

When you need to install a new circuit breaker or replace an old one, start by considering the existing panel, the voltage ratings and the environment in which it will be used. Look for a breaker with the lowest voltage rating possible to meet the needs of the application. Keep in mind that the National Electric Code (NEC) stipulates that breakers carry only 80% of the maximum continuous current they have been rated for unless they have been specifically designed for 100% usage.

If you need help finding the right breaker or replacing an old breaker, call Bay Power at 866-543-1231. We’re always ready to answer your questions or provide a quote!

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