MCBs

Miniature Circuit Breakers (MCBs) are essential electrical devices designed to protect circuits from damage caused by overcurrent or short circuits. These compact breakers automatically detect and interrupt the flow of excessive current, helping to prevent overheating and potential electrical fires. MCBs are widely used in electrical distribution systems for residential, commercial, and industrial applications.

How Does a Miniature Circuit Breaker Work?

MCBs work by monitoring the current flowing through an electrical circuit. If the current exceeds the rated capacity, the MCB trips and disconnects the circuit, thereby preventing overheating and damage to wiring, appliances, or other connected devices. This process ensures the protection of both equipment and individuals from potential electrical hazards.

Tripping Mechanism of an MCB

The tripping mechanism of an MCB consists of both thermal and magnetic components. The thermal tripping mechanism operates in response to prolonged overcurrent conditions, using a bimetallic strip that heats up and bends to disconnect the circuit. The magnetic tripping mechanism, on the other hand, reacts instantly to short-circuit currents by creating a magnetic field that moves a latch to break the circuit. This dual approach ensures comprehensive protection against both long-term overloads and sudden short circuits.

Types of MCB Circuit Breaker

Type B

Type B MCBs are general-purpose circuit breakers suitable for domestic installations. They trip between 3 and 5 times the rated current, providing effective protection against typical household electrical faults.

Type C

Type C MCBs are designed for installations with higher inrush currents, such as motors and transformers. They trip between 5 and 10 times the rated current, making them suitable for more demanding electrical environments.

Type D

Type D MCBs are intended for circuits with significant inrush currents, commonly associated with high-powered industrial equipment. They trip between 10 and 20 times the rated current, ensuring reliable protection for heavy machinery and sensitive equipment.

Where Are MCBs Installed?

MCBs are typically installed in distribution boards or consumer units, where they serve as the primary protective devices for individual circuits. They are often used in conjunction with residual current devices (RCDs) for enhanced electrical safety, providing a robust solution for safeguarding electrical systems in homes, offices, and industrial facilities.

How to Reset an MCB?

After tripping due to overcurrent, an MCB can be manually reset by switching it back to the "ON" position. It is crucial, however, to investigate the cause of the overcurrent before resetting to ensure the underlying issue is resolved, preventing further potential hazards.

Applications of Miniature Circuit Breakers

• Residential Electrical Panels: MCBs protect household circuits, preventing electrical overloads and safeguarding appliances.
• Industrial Equipment: MCBs are used to protect heavy machinery and motor systems from short circuits and overcurrent.
• Commercial Buildings: In commercial settings, MCBs ensure reliable electrical distribution and protection across multiple circuits.
• Data Centres: MCBs provide critical protection for data centre power supplies, ensuring stable and uninterrupted operation.
• Lighting Circuits: MCBs protect lighting systems from faults, contributing to overall safety and longevity of lighting installations.

Protect Your Electrical Circuits with Reliable MCBs

RS New Zealand is your trusted supplier and distributor of premium-quality MCBs from renowned brands like ABB, Siemens, Schneider Electric, Eaton, Rockwell Automation and Lovato. Whether you're protecting residential circuits or managing industrial applications, our range of miniature circuit breakers ensures optimal safety and reliability. Shop with RS NZ today and keep your electrical systems secure!

Ordering & Delivery Information for NZ

Ordering MCBs from RS New Zealand is simple and hassle-free with our online catalogue, making it easy to choose the right product for your application. We provide fast delivery throughout New Zealand, and you can find more information about delivery times and associated fees on our Delivery Information page.