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The Working Mechanism and Types of RCD Switches

Nov 9

It is essential to be aware of the working mechanism and types of RCD switches to use them effectively for safety and performance. RCDs (Residual Current Devices) are an essential component in electrical circuits, and their primary purpose is to protect people and property from electric shock due to short-circuiting, overloads and other faults. They are also known as 'safety switches' and must be fitted in homes and workplaces by the relevant electrical authorities in many countries. 

What is an RCD Switch?

RCD stands for the residual current device. It is an electrical switch designed to disconnect automatically from the power supply circuit within a fraction of a second when any fault occurs. It protects from any electrical shock and is also used for safety against electrical fires. RCD Switches are automatic circuit breakers that monitor the current flow on the live and neutral lines and disconnect the power in case of an imbalance. This means the current must be the same in both lines for the switch to remain operational. At Powerlec, we can provide you with all the information you need about RCD switches, as well as the installation and maintenance services. 

Working Mechanism: How does an RCD switch work?

An RCD switch works by monitoring the current flowing through the live and neutral conductors of an electrical circuit. When it detects an imbalance, it will trip and disconnect the power supply in a fraction of a second. The RCD switch will trip when the current flowing through the live or neutral conductor significantly differs from the current flowing through the other. This can occur due to a short circuit, earth leakage, or if the current is more significant than the device can handle. The RCD switch is also able to sense any flow of electricity between the protected circuit and the earth.

Types of RCD Switches: Different variations are available

There are several types of RCD switches available, each with its unique purpose and features. The most common type of RCD switch is the 30mA RCD, which detects any fault current above 30mA and will trip the circuit accordingly. However, some applications may require higher sensitivity to detect any faults. For these applications, there are also 10mA RCDs available, which can detect any currents above 10mA. Other types of RCD switches include Surge Protection RCDs, Automatic Transfer Switch RCDs and Online RCDs.

Benefits and Importance of RCD Switches

RCD switches are an essential component in electrical safety and can be used to protect people and property from electrical shocks and fires. They are also essential components in areas where electrical supplies are unreliable or prone to faults. Installing an RCD switch, it can help to ensure an uninterrupted power supply and reduce the risk of unforeseen danger.

Typical Applications for RCD Switches

RCD switches are commonly used in residential homes, commercial buildings, industrial facilities and other environments where electrical safety is paramount. They are also used in medical facilities, laboratories and manufacturing plants. Additionally, RCD switches are often installed in public places such as schools, hospitals and public transportation services.

Installation and Maintenance of RCD Switches

It is important to ensure that RCD switches are installed correctly and that regular maintenance is carried out to ensure the device operates efficiently. As well as being installed in the correct position, it is also important to consider any potentially hazardous material that could affect the functioning of the switch. It is recommended to get a qualified electrician to carry out installations and maintenance of the RCD switch.


In conclusion, RCD switches are an essential component of electrical safety, and understanding the working mechanism and types of RCD switches is essential to ensure the correct use and installation.