ABB Explains MCB - Twice as hot as the sun

Imagine a flash, so hot that molecules are torn apart. Imagine a temperature of 12,000 Kelvins - twice as hot as the sun’s surface. And this in a place near you.

news

3min

2026-02-26

This is not a scenario from a horror movie. It is what happens in a controlled way inside an MCB (miniature circuit breaker). In fact, the electricity you use in your home or at has comes through such breakers. They ensure your safety and that of the building and everything inside it.

What happens when an MCB trips?

When an MCB trips, it must interrupt the current as quickly as possible. As the contacts move apart, an electrical arc forms between them. The arc is formed by molecules being ripped into fragments that we call ions. These ions conduct the electrical current, and in doing so, generate the heat that sustains the further tearing apart of molecules. The goal of the MCB is to stop the arc, but this does not happen instantaneously. During these critical milliseconds, the MCB must safely contain and manage the arc, which can be burning at an intensity of up to 20kW, that is 20 microwaves at full blast. The MCB ingeniously uses the arc’s own magnetic field to guide it into a chamber where it grows in length and becomes easier to cool.

MCBs are heroes that takes the heat to keep you safe. Discover more about MCBs and ABB’s other contributions to power distribution and safety. 

Discover more about MCBs

Low Voltage Products and Systems

ABB provides a full range of low voltage solutions to connect, protect, control and measure a wide range of electrical installations, enclosures, switchboards, electronics and electromechanical devices. The business improves the reliability and efficiency of its customers’ activities across all major industries including the residential sector

Circuit breakers

The world of electrical power distribution is evolving rapidly, driven by digitalization, energy efficiency, and the growing need for resilient infrastructure. ABB’s low-voltage circuit breakers are engineered to meet these demands with precision, reliability, and adaptability.

Building and Home Automation

Our goal is to enhance comfort, security, and productivity with forward-thinking technology, ensuring everyone feels at home wherever they are—in modern family dwellings, exclusive luxury hotels, or workplaces worldwide.

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