April 17, 2024

What Causes An RCD To Trip?

Author:  Nick Celenza

In the intricate construction of electrical safety mechanisms, Residual Current Devices (RCDs), play a pivotal role. Tasked with the monumental job of preventing electric shock and fire hazards in both residential and commercial properties, RCDs are fundamental to modern electrical systems. 

Yet, despite their critical function, many people ponder over the reliability of RCDs and question whether they can fail. 

This blog aims to answer the question of what causes an RCD to trip, explore its potential faults, and guide you in addressing any performance concerns.

RCD protection
RCD Protection

What is an RCD?

An RCD is a safety switch installed in electrical systems to prevent electric shocks and reduce the risk of electrical fires. It works by constantly monitoring the electricity supply through a circuit and quickly cutting off the power if it detects anything irregular, like electricity flowing through an unexpected path.

This could happen if someone accidentally touches a live wire, causing electricity to flow through their body. The RCD reacts instantly to these discrepancies by disconnecting the power, thus minimising the potential for harm. 

Essentially, RCD switches act as a safety feature, quickly addressing any irregularities in electrical current to prevent danger, thus protecting people and properties from potential electrical hazards.

Common Reasons Why Your RCD May Trip

As an electrical component, eventually, RCDs, while reliable, are not beyond experiencing faults throughout their lifetime. A faulty RCD can occur with a series of common causes:

Overloaded Circuits

When too many appliances or devices are used simultaneously on the same circuit, it can exceed the circuit’s capacity, causing an overload, and it to trip.

Aged Electrical Wiring

Over time, electrical wiring can deteriorate, with insulation breaking down and becoming less effective. This deterioration can allow small amounts of electricity to leak, potentially causing an RCD to trip as it detects these leakage currents.


Water and electricity are a dangerous combination. Moisture getting into electrical components can create unintended pathways for electricity, leading to leaking currents that may trigger the RCD to trip as a protective measure.

Electrical Surges

External factors like lightning strikes or sudden surges from the power supply can cause a brief, intense increase in electrical voltage. This can overwhelm the electrical system, with the RCD tripping to protect the circuit.

Incorrect Installation

Proper RCD installation is crucial for them to function correctly. If an RCD is incorrectly wired or if the wrong type of RCD is used for the specific requirements of a circuit, it can lead to frequent tripping or failure to provide adequate protection.

Interference from Other Devices

Some electrical devices, especially those with motors or components that draw a significant amount of power suddenly, can create electrical noise or interference. This can mistakenly cause the RCD to trip, interpreting these signals as fault conditions.

Loose Connections

Poor or loose electrical connections can lead to small arcs or sparks, which generate heat and can create unexpected electrical paths, causing the RCD to trip as a preventative measure.

Wear and Tear

With time and use, the mechanical and electrical components within an RCD can wear out. This natural wear and tear can affect the device’s sensitivity and reliability, potentially leading to either nuisance tripping or a failure to trip when required.

rdc installation and repairs

Diagnosing RCD Faults

Determining what causes an RCD to trip involves a systematic approach. Regular testing with the RCD’s test button is a simple, effective way to assess its status. An RCD that does not trip during a test is likely faulty. Other indicators of a problem include unexplained tripping and the inability to reset the RCD after testing.

RCD Protection

Solutions for Your RCD Issues

If you suspect that your RCD isn’t working as it should, this requires a professional evaluation. A licensed electrician, like any member of our team at PWA Electrical Services, will do an electrical inspection. They will be able to offer you a detailed assessment and undertake any necessary repairs or replacements to ensure your safety.

RCD Protection

How to Keep Your RCDs in Top Condition

Maintaining the integrity of RCDs involves proactive measures and routine maintenance. At PWA Electrical Services, we recommend an annual inspection to ensure that not only your RCDs work well but the electrical systems they protect are in good working order. 

We also encourage you to conduct 6 monthly RCD tests. Understanding the causes of nuisance tripping and addressing them, such as fixing or replacing faulty appliances, can enhance your RCD reliability.


Adhering to Compliance and Legal Standards

Adhering to the legal standards for RCDs goes beyond just ticking a box for regulatory compliance; it’s a fundamental part of maintaining electrical safety. In Western Australia, for example, the rules stipulate that RCD protection must be provided for all power points and lighting circuits in new constructions and significant refurbishments.

RCD Protection

The Importance of RCDs in Modern Electrical Safety

RCDs represent a significant advancement in electrical safety. An RCD in an electrical circuit reduces the risk of electrical accidents, making them indispensable in both residential and commercial settings. As technology advances and electrical installations become more complex, the role that RCDs play in safety and compliance becomes increasingly important.

Understanding exactly how RCDs operate, the potential for faults, and the appropriate steps to diagnose and rectify issues is essential for anyone responsible for maintaining an electrical system. Whether you are a homeowner, landlord, or an electrician, knowledge of RCDs and their maintenance is crucial.

Find Expert Solutions For RCD Faults With PWA Electrical Services

Acknowledging that RCDs might develop faults over time, what causes an RCD to trip and knowing how to effectively identify and rectify these issues are essential for upholding electrical safety for both you and your property. 

With our team of licensed electricians at PWA Electrical Services, we offer you a range of residential and commercial services, including RCD installations that adhere to all legal standards in Western Australia. 

At PWA Electrical Services, our goal is to provide quality service for all your electrical needs. Call us for more information from our team and book an appointment today.