Choosing the Right RCDs for Your Electrical Installations: Understanding Types and Applications

At Electrical Discounted Supplies, we understand that safety is paramount in any electrical installation. Residual Current Devices (RCDs) are crucial for ensuring this safety, protecting against the risks of electric shock and fire hazards. However, with various types of RCDs available, choosing the right one for your specific needs can seem daunting. This guide aims to demystify the process, helping you understand the different types of RCDs and their applications, ensuring you make an informed decision for your electrical installations.

Understanding RCDs

Before diving into the types of RCDs, let’s briefly recap what an RCD is. An RCD is a safety device designed to instantly cut off the power supply when it detects an imbalance in electrical current. This imbalance often indicates a leak of electrical current from the system, which can be dangerous, potentially leading to electric shocks or fires.

Types of RCDs

Fixed RCDs

Fixed RCDs are installed within the consumer unit (fuse box) of a building and provide protection to one or more circuits. They are a permanent feature of the electrical installation and offer comprehensive protection for all connected appliances and users. Fixed RCDs are ideal for general household protection, especially in areas with a higher risk of electric shock, such as kitchens and bathrooms.

Socket-Outlet RCDs

Socket-outlet RCDs are integrated into socket outlets, providing protection at specific points of use. These are particularly useful in situations where additional protection is needed at the outlet level, such as for outdoor sockets or in older properties that might not have RCD protection as part of the consumer unit. They are easy to install and offer a convenient way to upgrade safety without the need for extensive electrical work.

Portable RCDs

Portable RCDs are designed to be plugged into any standard socket outlet, offering immediate protection for the user and the appliance being used. These devices are perfect for temporary situations or when using electrical equipment outdoors, such as lawn mowers or power tools. They provide a flexible and mobile solution for personal protection against electric shock.

Choosing the Right RCD

When selecting the right RCD for your electrical installations, consider the following factors:

  • Application: Determine where and how the RCD will be used. For comprehensive whole-house or business protection, fixed RCDs are the best choice. For targeted protection or additional safety for specific appliances or areas, socket-outlet or portable RCDs may be more suitable.
  • Sensitivity: RCDs are rated by the amount of current leakage they can detect before tripping, typically ranging from 10 mA to 500 mA. Lower ratings (e.g., 30 mA) offer greater protection against electric shock, while higher ratings may be used for fire protection or in industrial settings where normal equipment operation might cause nuisance tripping.
  • Compatibility: Ensure the RCD is compatible with your electrical system, including the type of wiring and the power requirements of your installation.
  • Regulatory Compliance: Always choose RCDs that comply with local and national electrical codes and standards. This not only ensures safety but also legality.


RCDs are a critical component in safeguarding against the dangers of electric shock and fire hazards in electrical installations. By understanding the different types of RCDs and their applications, you can make informed decisions that enhance the safety and efficiency of your electrical systems.

At Electrical Discounted Supplies, we’re committed to providing high-quality, reliable RCDs suitable for a wide range of applications. Whether you’re undertaking a new installation or upgrading an existing system, our expert team is here to help you choose the right RCDs for your needs. Visit our website or contact us today to explore our range and take the next step towards a safer electrical environment.