Types of circuit breakers. What you need to know.

Circuit breakers play a pivotal role in the safety of electrical systems in homes, businesses, and industries. These devices are designed to automatically interrupt the current flow in the event of an overload or short circuit, protecting people and property from electrical mishaps. In Australia, where electrical safety standards are stringent, it’s essential to understand the different types of circuit breakers available and their specific functions. 

Miniature Circuit Breakers (MCBs) 

  • Function: MCBs are commonly used in residential and commercial properties in Australia. They safeguard individual circuits from overloads and short circuits by breaking the circuit when the current flow exceeds the predetermined limit.
  • Design: MCBs have a manual switch that allows them to be reset once they trip. This feature makes them more user-friendly than older-style fuses, which need replacement after tripping.
  • Advantages: They are sensitive to small changes in current flow, which ensures timely disconnection in the event of a fault. Moreover, MCBs eliminate the need for regular fuse replacements, making them more cost-effective in the long run.

Residual Current Devices (RCDs)

  • Function: RCDs aim to protect against electric shock. They detect an imbalance between the active (live) and neutral currents, typically caused when the current inadvertently flows through a grounded person.
  • Design: RCDs continually monitor the current flowing in and out of a circuit. If there’s a difference (indicative of a potential shock hazard), the RCD will trip the circuit within a fraction of a second.
  • Advantages: The rapid response of RCDs significantly reduces the risk of severe electrical shocks. In Australia, RCDs are mandated for power outlets in all new homes and renovated properties, emphasizing their importance in household safety.

Moulded Case Circuit Breakers (MCCBs)

  • Function: MCCBs are designed for higher current capacities and are mainly used in commercial and industrial applications. They offer protection against overloads, short circuits, and, in some models, under-voltage situations.
  • Design: MCCBs come with an adjustable setting, allowing users to set the maximum current value. This flexibility makes them suitable for various applications that require higher current thresholds.
  • Advantages: Due to their robust design, MCCBs can handle higher current capacities, making them ideal for large commercial or industrial setups. They also offer the benefit of adjustable settings, providing more tailored protection based on specific needs.

Combination Residual Current Devices and Miniature Circuit Breakers (RCBOs)

  • Function: RCBOs combine the functionalities of RCDs and MCBs, offering protection against electrical shocks (by detecting current imbalances) and overloads or short circuits.
  • Design: The compact design of RCBOs allows them to fit into a single module in a switchboard, making them an excellent choice for areas with space constraints.
  • Advantages: By incorporating the protective features of both RCDs and MCBs, RCBOs provide comprehensive protection. This dual functionality ensures circuits are safeguarded from a broader range of electrical faults.

Air Circuit Breakers (ACBs)

  • Function: ACBs are designed for high-current applications, primarily in industrial settings. They provide protection against overloads and short circuits and can also be used as a master switch to control and protect the entire electrical installation.
  • Design: ACBs have air-filled chambers that act as arc extinguishers when the circuit breaker trips. They also have manual or automatic tripping mechanisms based on the detected fault.
  • Advantages: ACBs can handle extremely high current values, often reaching up to several thousand amperes. Their design ensures a rapid break in the circuit in case of faults, preventing potential damage to equipment and reducing downtime in industrial settings.

Vacuum Circuit Breakers (VCBs)

  • Function: VCBs are used primarily in medium voltage applications. They offer protection against overloads and short circuits by breaking the circuit within a vacuum.
  • Design: VCBs create an arc inside a vacuum chamber when they trip. The absence of air in the chamber ensures the arc is quickly extinguished.
  • Advantages: VCBs are known for their longevity and minimal maintenance. The vacuum chamber’s design ensures minimal wear and tear, even after multiple operations. Plus, VCBs offer rapid arc extinguishing, enhancing the safety of the connected systems.

Safety First: Regular Maintenance and Inspection

  • While understanding the various circuit breaker types is crucial, their regular maintenance and inspection are equally important. Regardless of the type of circuit breaker installed, periodic checks by licensed electricians will ensure their optimal functioning. 

Understanding the nuances of circuit breakers is crucial for Australians, given the nation’s commitment to electrical safety. Whether you’re building a new home, renovating an old one, or overseeing an industrial project, knowing which circuit breaker to use can ensure the safety of the infrastructure and its inhabitants. 

When dealing with electrical installations or concerns, it’s best to consult a licensed Australian electrician to ensure compliance with the Australian and New Zealand wiring standards (AS/NZS 3000).

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AllPhase can advise you on the best circuit breaker for your situation.

Choosing the correct circuit breaker based on specific needs, followed by regular maintenance, is the key to electrical safety and efficiency for residential, commercial, or industrial purposes.

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