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Legrand DNX3 Circuit Breaker, 1+N, 4A Curve C, 230V AC, 6 kA Breaking Capacity

Legrand Vistop MCB, 4P, 160A, 400V AC, 15 kA Breaking Capacity

Legrand DX3 Circuit Breaker, 3P, 25A Curve D, 400V AC, 10 kA Breaking Capacity

Legrand Circuit Breaker, 3P, 100A, 690V AC

Legrand Vistop MCB, 4P, 63A, 400V AC, 15 kA Breaking Capacity

Legrand DX3 Circuit Breaker, 230V AC

Legrand DX3 Circuit Breaker, 2P, 8A Curve C, 230V AC, 10 kA Breaking Capacity

Legrand MPX Circuit Breaker, 3P, 1.6A, 220 → 690V AC, 100 kA Breaking Capacity

Legrand DX Range DX3 MCB, 1P, 16A Curve C, 250V AC, 12V DC, 4.5 kA Breaking Capacity

Legrand MCB, 3+N, 500V AC, 100 kA Breaking Capacity


Miniature circuit breakers (MCBs) are essential safety devices that are designed to protect an electrical circuit from damage caused by overcurrent. These compact and reliable devices act as automatic switches, interrupting the flow of electricity when the current exceeds a safe level. Similar to [RCBOs](https://my.rs-online.com/web/c/fuses-circuit-breakers/circuit-breakers/rcbos/), they serve as a crucial component in the electrical distribution system of buildings, homes, and industrial facilities. Miniature circuit breakers are installed in distribution boards or consumer units and are often used in conjunction with residual current devices (RCDs) for enhanced electrical safety.

## **How Does a Miniature Circuit Breaker Work?**

Miniature circuit breakers automatically disconnect the electrical circuit when they detect a current exceeding the rated capacity of the circuit. This action [ensures machine safety](https://my.rs-online.com/web/content/discovery/ideas-and-advice/machine-safety-guide) and employee safety by helping to prevent overheating and potential damage to the wiring, appliances, or other connected devices. Along with equipment such as [safety relays](https://my.rs-online.com/web/c/relays-signal-conditioning/relays/safety-relays/) and [non-contact safety door switches](https://my.rs-online.com/web/c/switches/safety-interlock-switches-components/non-contact-safety-switches/), they are an integral part of modern electrical installations, contributing to the overall reliability and safety of electrical systems.

Mini circuit breakers typically use thermal and magnetic tripping mechanisms.

- **Thermal Tripping**: For overload protection, the bimetallic strip heats up and bends when continuous overcurrent flows. This deflection releases a mechanical latch, opening the MCB contacts and stopping current flow.
- **Magnetic Tripping**: For short-circuit protection, a sudden current rise causes electromechanical displacement of a plunger associated with a tripping coil or solenoid. The plunger strikes the trip lever, immediately releasing the latch mechanism and opening the circuit breaker contacts.

## **What Are the Different Types of Miniature Circuit Breakers?**

Mini circuit breakers come in different types, 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.

## **Advantages of Miniature Circuit Breakers**
- **Safety and Protection**: MCBs provide superior protection against overloads, short circuits, and electrical faults compared to traditional fuses. They comply with Malaysian safety standards, including MS IEC 60898 and MS IEC 61008, to safeguard against overloads and short circuits, preventing damage to wiring, appliances, and other connected devices.
- **Reusability and Easy Reset**: Unlike [cartridge fuses](https://my.rs-online.com/web/c/fuses-circuit-breakers/fuses/cartridge-fuses/) that need replacement after tripping, miniature breakers can be easily reset and reused multiple times. This feature reduces maintenance costs and downtime.
- **Sensitivity and Reliability**: Miniature circuit breakers are more sensitive to current changes and faults than fuses, offering more reliable protection. They can detect even small fluctuations in current flow, ensuring better safety for electrical systems.
- **Versatility and Compact Size**: Available in various types and sizes, MCBs can be used in a wide range of applications, from residential to industrial settings. Their compact size allows for easy installation in electrical panels and distribution boards.
- **Quick Response Time**: MCBs have a short tripping time, ranging from 0.04 to 13 seconds depending on the type, ensuring rapid protection against electrical faults.
- **Visual Fault Indication**: Mini breakers for electrical panels provide clear visual indication when they trip, making it easy for users to identify and locate faults in the electrical system.
- **Customisable Protection**: Different types of MCBs (B, C, D, K, and Z) offer varying levels of sensitivity and tripping currents, allowing for customised protection based on specific application needs.
- **Enhanced Safety for DC Applications:** Specialised MCBs designed for DC voltages offer advantages like non-polarity, simplified wiring, and high rated voltage capabilities (up to 1000V DC), making them ideal for communication and photovoltaic systems.
- **Cost-Effective in the Long Run:** While initially more expensive than fuses, mini breakers are more cost-effective over time due to their reusability and reduced maintenance requirements.
- **Compliance with Safety Standards:** MCBs are designed to meet high safety standards, ensuring reliable protection for electrical installations across various environments.

These advantages make miniature circuit breakers an essential component in modern electrical systems, offering improved safety, efficiency, and reliability compared to traditional protective devices.

## **What Causes an MCB to Trip, and Can It Be Reset?**

Miniature Circuit Breakers (MCBs) trip primarily due to two conditions: overloads and short circuits. An overload occurs when the current flowing through the circuit exceeds the MCB's rated capacity, causing a bimetallic strip inside the MCB to heat up and bend, which triggers the trip mechanism to break the circuit. Short circuits happen when there is a direct connection between live and neutral wires, resulting in a sudden surge of current that activates the magnetic tripping mechanism almost instantaneously to prevent damage and hazards.

After an MCB trips, it can be reset easily by toggling its switch back to the 'ON' position. However, it is crucial to first identify and resolve the underlying issue that caused the tripping before resetting it. If the MCB trips again after being reset, it indicates that there is still a fault in the circuit, and further investigation or professional help may be required.

## **Industrial Applications of MCBs**

Micro circuit breakers are indispensable in ensuring operational continuity and safety across various sectors in Malaysia. MCBs are mostly used in the following areas:

### **Official and Commercial Facilities**

MCBs are crucial in business operations across Malaysia, providing reliable protection for electrical circuits that power computers, HVAC systems, and lighting circuits. By guarding against electrical faults, mini breakers help prevent potential data loss and ensure that business activities continue smoothly without disruption. Facilities managers often implement comprehensive MCB systems to manage the diverse array of electrical equipment, ensuring that all components are adequately protected against electrical anomalies.

### **Medical Facilities**

In medical facilities across Malaysia, the reliability of electrical systems is a matter of life and death. MCBs are critical components in these settings, safeguarding life-saving equipment from unexpected overcurrents. The adoption of mini circuit breaker panels in healthcare settings not only supports the functionality of medical devices but also enhances patient safety by minimising the risk of equipment failure.

### **Security Systems**

Security systems used in buildings and other facilities rely heavily on the functionality of MCBs. These mini breakers for electrical panels protect systems, ensuring that they remain operational 24/7, providing continuous security monitoring and protection. This is particularly crucial in high-security areas where constant surveillance is necessary to prevent and respond to security breaches effectively.

### **Telecommunications Facilities and Systems**

Telecommunications facilities depend extensively on MCBs to protect their operations. These facilities house sophisticated equipment for data transmission and telecommunication operations that are sensitive to electrical disturbances. MCBs ensure that the power supplied to this equipment is stable and within safe limits, preventing damage to delicate electronic components that could result in service interruptions.

## **Your Trusted MCB Supplier and Manufacturer**

When it comes to safeguarding your electrical circuits, trust RS Malaysia to provide you with high-quality miniature circuit breakers. As a leading supplier of electrical components, we offer a comprehensive selection from industry-leading brands like [ABB](https://my.rs-online.com/web/b/abb/), [Siemens](https://my.rs-online.com/web/b/siemens/), [Schneider Electric](https://my.rs-online.com/web/b/schneider-electric/), [Eaton](https://my.rs-online.com/web/b/eaton/), and [Lovato](https://my.rs-online.com/web/b/lovato/), ensuring you find the perfect MCBs to meet your specific needs and Malaysian safety standards.

Whether you need MCBs for residential, commercial, or industrial applications, RS is your reliable partner for electrical protection. Our commitment to quality extends beyond our products to our service. We offer competitive prices, expert technical support, and next-day delivery options to ensure a seamless experience for our customers in Malaysia. For more delivery information, please refer to our [delivery policy](https://my.rs-online.com/web/content/support/all-articles/delivery).



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Schneider Electric Acti9 SE10 MCB Mini Circuit Breaker 25A Curve C 10000 A Breaking Capacity

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ABB Cable for use with Miniature Circuit Breakers

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Legrand MCB

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