The Difference Between an RCD Switch and a Circuit Breaker

In the world of electrical systems, safety is paramount. That's where appliances like Residual Current Devices (RCDs) and circuit breakers come into play.

These devices are not just simple switches but the unsung heroes that prevent potential fires and disasters by using electrical shocks and safeguarding our homes and workplaces from electrical accidents.

The Importance of Knowing It

Understanding the distinction between an RCD switch and a circuit breaker is crucial for maintaining electrical safety and preventing potential hazards.

While both devices play integral roles in safeguarding electrical systems, their functionalities diverge significantly. An RCD switch, or Residual Current Device, is a frontline defence against electric shock by rapidly detecting and interrupting even the slightest leakage currents.

On the other hand, a circuit breaker safeguards against overloads and short circuits that can lead to fires and equipment damage. A clear comprehension of these differences empowers individuals to make informed decisions about their electrical installations, ensuring that the appropriate protective measures are employed in various scenarios.

Whether for residential, commercial, or industrial applications, this knowledge is essential for creating safer environments and reducing the risks associated with electrical malfunctions.

Understanding Circuit Breakers

Definition and Function

A circuit breaker is like a guardian angel for your electrical circuits. It’s a switching device or switch that automatically stops the flow of electric current when things go awry. Imagine your home’s electrical wiring as a busy highway.

When too many vehicles (current) start racing down that road, the circuit breaker steps in to protect people to avoid traffic jams – or worse, accidents.

Circuit breakers in switchboard

How Circuit Breakers Work

Inside the circuit breaker, you’ll find ingenious mechanisms at work. Bimetallic strips, for instance, are made of two different metals bonded together.

When heated, these strips expand and contract at different rates, causing the miniature circuit breaker to open when excess current flows through. Electromagnets also play a role in moulded case circuit breakers; they create a magnetic field that triggers the circuit breaker to trip when current spikes.

The tripping process is fascinating. If there’s an overload, fault, short circuit, or faulty wiring or appliance, the circuit breaker detects the abnormal current surge. It reacts swiftly, springing into action to halt the high current flow out of electricity. It prevents wires from overheating, sparks from flying, and appliances from getting fried.

Types of Circuit Breakers

Circuit breakers aren’t one-size-fits-all. They come in various flavours, mainly categorised by voltage levels.

From Low voltage circuit breakers to medium-voltage circuit breakers, circuit breaker panels and breakers are your everyday household heroes, guarding against usual electrical glitches.

On the other hand, high-voltage circuit breakers tackle industrial giants, protecting them from catastrophic power surges.

Within these categories, you’ll find different types of protection: thermal, electrician magnetic, and thermal-magnetic circuit breakers. Thermal circuit breakers react to temperature changes caused by current overload.

Magnetic ones respond to sudden current spikes, and the thermal-magnetic hybrid combines both techniques for comprehensive protection.

Understanding Residual Current Devices (RCDs)

Definition and Function

Residual Current Devices (RCDs) are a primary function like the safety net of your electrical system. Their purpose? Preventing electric shocks and grounding faults.

Picture this: if an electrical appliance starts leaking current due to a ground fault, the RCD detects even the tiniest imbalance between the live and neutral currents, thus preventing potential harm.

How RCDs Work

The magic happens through differential current sensing. The RCD monitors the electrical current flowing through the live and neutral wires.

If there’s a leakage of rated current – say, a person accidentally touching a live wire – the RCD senses this mismatch and the switch instantly trips, cutting off all the wiring and electricity supply. This rapid response minimises the risk of severe damage caused by electric shock.

Types of RCDs

RCDs aren’t a one-type-fits-all deal, either. Tailored to different scenarios, Type AC RCDs find everyday use in standard residential settings, detecting a broad range of current imbalances.

Type A RCDs are more sensitive, able to pick up even pulsating direct currents, often found in industrial environments. Then there’s Type B, the precision instrument, capable of detecting alternating and direct currents in highly specialised setups like medical equipment.

Key Differences between RCDs and Circuit Breakers

The fundamental contrast between RCDs and circuit breakers lies in their primary functions. Circuit breakers are the knights in shining armour for your circuits, protecting them from overloads and short courses that could cause fires.

RCDs, on the other hand, are the guardians of electrical circuits and human safety, detecting current imbalances that could lead to potentially lethal electric shocks.

Tripping criteria is another area of distinction. Circuit breakers trip when they sense abnormal currents – like a traffic cop diverting cars in a gridlock. RCDs, however, trip when they detect even the slightest current imbalance – like a vigilant watchman spotting a shadowy figure in a quiet alley.

Usage scenarios also differ. Circuit breakers are your everyday part designed to protect power lessors, present in residential, commercial, and industrial settings. RCDs take centre stage in places where human safety is paramount, like bathrooms, kitchens, and construction sites.

RCDs and circuit breakers are electrical safety devices that protect people and equipment from electrical faults and hazards.

Still, they serve different purposes and have distinct differences. Here are the critical differences between RCDs and circuit breakers:

Electrical switchboard

Function and Purpose:

  • RCD: An RCD detects and swiftly interrupts current flow in the electrical circuit upon seeing a leakage current or residual current. A fault in the wiring, a faulty appliance, a ground fault, or someone coming into contact with live parts of an appliance could cause this leakage current. RCDs are primarily used to prevent electrical shock and are especially important in damp environments.
  • Circuit breaker: Designers create circuit breakers to shield circuits from overloads and short circuits. It trips and interrupts the course when the current exceeds a predetermined value. The primary purpose of circuit breakers is to prevent fires and equipment damage caused by excessive current flow.

Detection Method:

  • RCD: RCDs operate based on measuring the difference between the voltage current flowing into the circuit and the current returning from the course. Any imbalance indicates a leakage current, and the RCD trips to cut off the power to the standard current.
  • Circuit breaker: Circuit breakers operate based on thermal and magnetic protection principles. They use a bimetallic strip to detect heat caused by current overload and a magnetic coil to detect sudden high currents (short circuits).

Tripping Time:

  • RCD: RCDs are designed to trip quickly, often within milliseconds, upon detecting a leakage current. This rapid response helps to load current and prevent electric shock.
  • Circuit breaker: Circuit breakers may have different tripping characteristics depending on their type and application. They can have short delay settings to protect power out against short circuits and more extended delay settings to accommodate temporary power overloads.


  • RCD: RCDs are commonly used in areas where the risk of electric shock is high, such as bathrooms, kitchens, outdoor spaces, and industrial environments.
  • Circuit breaker: Circuit breakers are installed throughout electrical installations to protect circuits from overloads and short circuits. They are present in distribution boards and panels.


  • RCD: RCDs come in different types, including Type AC (for general use), Type A (for higher sensitivity and additional protection against pulsating DC currents), Type F (for enhanced protection against fire hazards), and Type B (for protection against specific equipment and medical applications).
  • Circuit breaker: Circuit breakers have various types, including thermal-magnetic circuit breakers, electronic circuit breakers, miniature circuit breakers (MCBs), moulded case circuit breakers (MCCBs), and more.

When to Use Each Device:

Choosing between circuit breakers and RCDs depends on the context. Circuit breakers are the go-to choice for safeguarding circuits and appliances from overloads and short circuits. When it’s all about human safety, RCDs are non-negotiable, especially when installed in areas where water and electricity could meet, potentially spelling disaster.

In modern electrical panels, harmony between these devices is crucial. Circuit breakers and RCDs often team up, working correctly and creating a formidable defence mechanism.

Circuit breakers handle the circuit protection, while RCDs ensure that current imbalances don’t put lives at risk. It’s like a dynamic duo working together to keep both circuits connected and people safe.

Know More About Your Electrical Systems

As we wrap up our exploration, it’s clear that RCD switches and circuit breakers are essential components of a secure electrical system. These unsung heroes work tirelessly to prevent electrical accidents, keep electrical fires out, and avoid potential harm to individuals.

While circuit breakers shield circuits from overload and short courses, RCDs are vigilant sentinels, guarding against electric shocks. Their symbiotic relationship ensures a safer, more resilient electrical landscape, emphasising the importance of understanding and integrating both devices into our daily lives.

Contact specialists and experts when dealing with electrical issues and installing safety switches at home.

Please note: This information is provided for advice purposes only. Regulations differ from state to state, so please consult your local authorities or an industry professional before proceeding with any work. See Cyber Electrical’s Terms & Conditions here.

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