MCBs, or Miniature Circuit Breakers, are electrical devices designed to protect an electrical circuit from damage caused by overcurrent. They serve as a crucial component in the electrical distribution system of buildings, homes, and industrial facilities. You can learn more in our MCB guide.

RS offer a comprehensive selection of high-quality Miniature Circuit Breakers from industry-leading brands including ABB, Siemens, Schneider Electric, Eaton, Rockwell Automation and Lovato.

How does a miniature circuit breaker work?

MCBs automatically disconnect the electrical circuit when they detect a current exceeding the rated capacity of the circuit. This action helps prevent overheating and potential damage to the wiring, appliances, or other connected devices.

What are the different types of circuit breakers?

MCBs come in different types, including Type B, C, and D, each designed to trip at different levels of overcurrent. The choice of MCB type depends on the specific characteristics of the electrical load it is protecting.

Type B: General purpose, suitable for domestic installations. Trips between 3 and 5 times the load current.
Type C: Designed for applications with higher inrush currents, such as motors and transformers. Trips between 5 and 10 times the full load current.
Type D: Intended for circuits with significant inrush currents, like those associated with high-powered equipment. Trips between 10 and 20 times the full load current.

What is the tripping mechanism of an MCB?

MCBs typically use thermal and magnetic tripping mechanisms. The thermal component responds to prolonged overcurrent conditions, while the magnetic component reacts to short-circuit currents.

Where are MCBs installed?

MCBs are installed in distribution boards or consumer units and are often used in conjunction with residual current devices (RCDs) for enhanced electrical safety.

Can I reset an MCB?

After tripping due to overcurrent, MCBs can usually be reset manually. However, it is crucial to investigate and address the cause of the overcurrent before resetting to avoid potential hazards.

MCBs play a vital role in electrical safety by preventing electrical fires and protecting equipment from damage caused by excessive current. They are an integral part of modern electrical installations, contributing to the overall reliability and safety of electrical systems.