Why Frame Size Matters With Molded Case Circuit Breakers

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Molded case circuit breakers (MCCBs) are the critical building blocks for many electrical panels. But panel builders could be excused for treating these devices as a commodity at times. However, the physical design of these products can make a big difference in how efficiently panel builders are able to do their jobs, because when it comes to MCCBs, smaller can be better.

Starting with the basics, MCCBs are circuit breakers that incorporate all current-carrying parts, mechanisms and trip devices into a molded case manufactured from insulating material. Designed to protect connected circuits in low-voltage distribution systems, MCCBs are comprised of two main components:

  • Frame – This is considered the body of the circuit breaker. It is the molded, insulated housing, fabricated from a glass-polyester, thermoset composite resin, or thermo-plastic glass fiber material.
  • Trip unit – this is considered the brain of a circuit breaker. It activates an operating mechanism when a short circuit or prolonged current overload occurs. Today’s most advanced trip units are electronic and offer flexible mounting configurations depending on the application.

Building power distribution systems incorporate multiple MCCBs into centralized electrical panels. Assembling these panels is a complicated process. Ensuring long-lasting electrical connections, addressing the possible need for auxiliary circuits, meeting earth-leakage requirements and enabling the option for future upgrades all can be part of the same assignment.

These challenges are multiplied when one considers the critical element of space to consider. In industrial and small commercial settings, especially, wall space can be valuable real estate, so minimizing panel dimensions also can be a customer goal. But wiring a smaller panel can mean a greater time commitment for builders, as adjustments become more difficult to make.

For example, ComPact NSX MCCBs, address panel board real estate issues by incorporating earth leakage protection into the breakers, themselves. The trip units in these breakers are interchangeable, so they can be upgraded over time to include more advanced metering and alarming functions. Even with their reduced footprint, these MCCBs feature breaking capacities of up to 100 kA at 690 V. Watch the video below to learn more!

Now, the smaller ComPact NSXm MCCBs can make panel building even easier. These devices are designed for breaking capacities up to 70 kA at 415 V and also incorporate earth leakage protection. Additionally, panel builders benefit from:

  • EverLink™ connectors, which enable easy cable connections using a patented spring-loaded mechanism that also maintains constant pressure on connected cables over time.
  • One-click auxiliaries that simply snap into place and are both field-installable and externally visible.
  • Built-in DIN rails, so these breakers simply click into place.

To further learn about to ensure power protection, download our white paper, “How to ensure a secure, long-lasting power connection for your electrical installation.” Also, be sure to register for our Panel Builder Portal to find even more ways to make panel builders’ work easier and more efficient.

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