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    What is a QO Breaker?

    A QO Breaker is a “Qwik-Open” breaker from Square D. They are the fastest opening breakers in the industry and will open within one complete 60 Hz power cycle (1/60th of a second). In addition, they have a visual trip indicator, making it easy to tell when it is tripped. 


    Square D was founded in 1902 and is well known for its electrical breakers and safety switches. Keep reading this detailed guide to learn more about QO breakers, how they work, and what they do. 


    Qwik-Open Breakers Explained

    As we now know, QO breakers are short for Qwik-Open breakers from Square D. They have the following features:

    • Fast opening– 1/60th of a second or one 60 Hz AC power cycle
    • Visual trip indication
    • Rated for commercial use
    • Available in single, double, and triple-pole options


    Square D offers two main types of QO breakers, which we cover below. 

    Qwik-Open Miniature Circuit Breakers

    QO miniature circuit breakers are the most common type of breakers from Square D and fit QO load centers, NQO, NQOD, NQ, and QOB panelboards. 

    Qwik-Open Bolted Circuit Breaker

    Qwik-Open-Bolted or QOB breakers are similar to the QO miniature breakers but have screws that secure them to the panel’s bus. So, it is nearly impossible to pop one out by accident when changing breakers. In addition, they fit NQOB, NQOD, and NQ panelboards. 


    In Need of QO Breakers?

    At Bay Power, we offer various circuit breakers and panels. Click here to shop our Square D breakers, including QO and QOB models. Contact us today if you need additional support, and a team member will be happy to help.