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What is a Main Line Circuit Breaker (MLCB)?

Safety is important and the main line circuit breaker (MLCB) plays a key role in protecting people and equipment. This main breaker is placed between the generator end and the load. All of the electrical current goes through this breaker. If there is too much load it will trip and interrupt the current to help and prevent damage or overload.

Many of our products have multiple receptacles. The MLCB serves as the main safety gate and feeds additional circuit breakers that protect the individual receptacles. The picture below shows a WL18000VE and how the smaller circuit breakers (CB) and receptacles all wire through the MLCB. The MLCB is normally rated at 100-125% of the generator output.


In some applications it makes sense to have dual breaker systems. For example, the WL22000VE panel below has two breakers that provide the main line protection for half of the receptacle panel. The ratings of both breakers are specified to be equal to 100-125% of the total generator output.

WL22000VE W/ Dual Breakers
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2 thoughts on “What is a Main Line Circuit Breaker (MLCB)?

  1. I found it interesting when you said that the electrical equipment in your home is protected by the circuit breaker because of proper electrical management. My best buddy told me a few nights ago that he and his spouse were looking for a circuit breaker panel installation service to help provide the appropriate electrical management for their landscaping lighting installation. He asked if I had opinions on the best panel installation approach. I’m thankful for this enlightening electrical knowledge article. I’ll tell him they can consult a well-known electrical contracting business as they can help provide facts about their electrical services.

  2. I recently had the opportunity to read your informative article titled “What Is a Main Line Circuit Breaker (MLCB)?” on the Winco blog, and I wanted to express my gratitude for shedding light on this important electrical component. Your article provides a clear and concise explanation of the main line circuit breaker (MLCB), its purpose, and its significance in electrical systems.

    Your introductory section effectively sets the stage by highlighting the crucial role of MLCBs in electrical distribution systems. By explaining how MLCBs serve as the first line of defense in protecting electrical circuits from overcurrents, you establish their importance in maintaining the safety and functionality of electrical systems.

    I appreciate the detailed breakdown of the components and functionality of MLCBs. Your explanation of their trip mechanisms, current ratings, and the distinction between single-pole and double-pole MLCBs offer readers a comprehensive understanding of these devices. The inclusion of relevant diagrams further aids in visualizing the concepts and enhances clarity.

    Furthermore, your discussion on the significance of proper installation and maintenance of MLCBs is vital. By emphasizing the need for periodic inspections and the consequences of neglecting these important tasks, you underscore the importance of ensuring the reliability and safety of electrical systems.

    One suggestion for improvement would be to provide some practical examples or scenarios where MLCBs are commonly used. This could help readers relate the information to real-world applications and enhance their understanding of MLCBs’ role in different settings.

    In conclusion, your article effectively educates readers on the purpose and functionality of mainline circuit breakers (MLCBs). The clear explanations, detailed breakdowns, and emphasis on safety considerations contribute to a comprehensive understanding of these essential electrical components.

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