In any New Zealand home, electrical safety is a top priority. Circuit protection devices are essential for preventing damage to your electrical system and ensuring the safety of everyone in the household. In this guide, we’ll take a look at the types of circuit protection used in residential properties, including RCDs, MCBs, RCBOs, and plug-in/rewireable ceramic fuses. These devices help safeguard your home from electrical faults like short circuits, overloads, and electric shocks.
What is Circuit Protection?
Circuit protection refers to the safety devices used to prevent damage to electrical circuits and to protect users from the risks of electrical faults, including electric shock or fire. Without circuit protection, an electrical fault could cause serious damage or pose a life-threatening hazard. Let’s explore the different types of circuit protection commonly found in residential properties in New Zealand.
Types of Circuit Protection in New Zealand
Here is a summary of the types of circuit protection devices we use in New Zealand, to keep people and property safe.
Residual Current Devices (RCDs)
What is an RCD?
An RCD (Residual Current Device) is an essential safety device used in modern electrical installations to prevent electric shocks. It monitors the flow of electricity through a circuit and detects any imbalance between the live and neutral conductors. If a fault occurs, such as a person coming into contact with a live wire, the RCD will instantly shut off the power to prevent serious harm.
Why are RCDs Important?
RCDs are crucial for protecting human life. They can prevent electrocution by disconnecting the power if there’s a leakage of current that could pose a risk. In New Zealand, RCDs are required in all new residential installations for circuits that supply power to areas where people are at risk of electric shock, like bathrooms, kitchens, and outdoor areas.
RCDs are required for all circuits that supply power to socket outlets, and for fixed appliances where there is a risk of electric shock. It is also best practice to put lighting circuits on RCDs.
Miniature Circuit Breakers (MCBs)
What is an MCB?
An MCB (Miniature Circuit Breaker) is a device that automatically cuts off the electrical supply to a circuit if there’s an overload or short circuit. MCBs are commonly used in residential properties to protect individual circuits from damage caused by excessive current. They come in various ratings depending on the power needs of the circuit.
Why Use an MCB?
MCBs are essential for preventing overheating and damage to appliances or the wiring system. They trip automatically when the current exceeds a safe limit, preventing potential hazards such as fires or equipment failure. MCBs are often found in the main electrical panel (switchboard) of residential properties.
Plug-in/Ceramic Fuses
What is a Plug-in or Ceramic Fuse?
A plug-in fuse or ceramic fuse is a safety device used to protect circuits from overloads. Unlike MCBs, fuses work by melting the wire inside the fuse casing when the current exceeds safe levels, interrupting the circuit. While these fuses were once standard, they should no longer be used in new installations. If found in older systems, they should be replaced with MCBs by a licensed electrician.
Why Use Fuses?
Fuses are reliable, low-cost protection devices but have some key drawbacks. Once a fuse blows, it must be replaced or rewired. This process can be inconvenient and, in the past, led to safety concerns, as people often rewired blown fuses with the wrong wire, bypassing the safety mechanism. This poses a significant fire and shock risk.
In contrast, MCBs provide superior protection, as they can be easily reset without needing to be replaced. They also offer better, more reliable protection than fuses, making them the preferred choice in modern electrical installations.
RCBOs
What is an RCBO?
RCBO (Residual Current Breaker with Overcurrent Protection)
An RCBO is a combination of an RCD (Residual Current Device) and an MCB (Miniature Circuit Breaker). It provides dual protection by combining the features of both devices into one unit. An RCBO offers protection against electric shocks from residual current leakage (just like an RCD) and overcurrent due to overload or short circuit (just like an MCB).
Key Features of an RCBO:
- Dual Protection: It combines the functions of an RCD and MCB, providing both earth leakage protection and overcurrent protection in one device.
- Protects Against Electric Shocks: Like an RCD, an RCBO detects any imbalance between the live and neutral conductors, which could be caused by leakage to earth, and disconnects the circuit to prevent electric shock.
- Protects Against Overload and Short Circuits: Like an MCB, an RCBO also trips the circuit if there’s an overload or short circuit, preventing potential damage to wiring and appliances.
Why Use an RCBO? An RCBO is especially useful in situations where both types of protection are required on individual circuits, but space or budget constraints make it more convenient to use a single device instead of two separate ones. For example, RCBOs are often used in residential properties, offering comprehensive protection for circuits such as lighting, power outlets, and appliances.
Choosing the Right Circuit Protection for Your Home
When it comes to protecting your home from electrical faults, the right circuit protection devices can make all the difference. New Zealand homes require a variety of protections based on the type of circuits and appliances you use. It’s important to ensure that your home is equipped with the appropriate devices, such as RCDs, RCCBs, MCBs, and fuses, to keep your electrical system running safely.
Need Professional Help?
If you’re unsure about your current circuit protection or need to upgrade your system, it’s always best to consult a licensed electrician. They can assess your electrical system and ensure that all the necessary protections are in place, keeping your home safe from electrical hazards.