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What is the Purpose of an RCD
What is the Purpose of an RCD


What is the Purpose of an RCD?

Whether buying a home, checking the electrics of your existing home, or just overhearing a conversation between two electricians, you may have seen/heard the acronym RCD. But what does it mean? What role does it play in your home?

What’s an RCD?

Short for residual current device, an RCD only has one purpose – to save lives. Essentially, an RCD is used to prevent homeowners from getting a severe electric shock after touching a bare wire or another live portion of the electrical infrastructure. Depending on the RCD, some are even designed to prevent fires within the property. While circuit-breakers and fuses have their purpose, an RCD goes much further with regard to personal protection.

How Does an RCD Work?

If there’s a fault in the electrical system in your home or work building, an RCD shuts off the electricity as soon as possible. Over the years, earth faults have caused many fires around the world as well as many serious electrocution cases. Therefore, manufacturers developed a system that would prevent both. From here, the RCD was born.

As an example, let’s say that you’re mowing the lawn, and you happen to run over the cable. Without an RCD switch, this has potentially fatal repercussions. With an RCD switch, the system detects a problem and shuts off the electricity before you even know what’s happened.

A modern RCD system constantly monitors the supply of electricity around a building. As soon as it detects a problem, it shuts off the electrical supply. For example, this could be electricity flowing to an incorrect path (like a person touching a live wire). While RCD systems can’t always prevent injury, they shut the power off almost instantly, and this reduces the injury to a person significantly. You might get a small one-second shock rather than a much longer one coursing through the body.

Types of RCDs

Currently, there are a few different types of RCD systems. This includes:

  • Socket-Outlet RCDs – As the name suggests, these are RCD in-built socket-outlets for homes and commercial premises. Since it’s plugged into one single outlet, it only protects in this one location (and to the one individual). This being said, it’s helpful when working with specific pieces of equipment.
  • Fixed RCDs – Meanwhile, these RCDs are placed into the fuse box of a home or commercial premises. Therefore, it protects all sockets and wiring included within the circuit. Naturally, this means all appliances also use electricity from this circuit.
  • Portable RCDs – Rather than a socket-outlet itself, these RCDs plug into socket-outlets. Then, you plug the appliance into the RCD, and it provides protection. Although they only protect those using the appliance, you can move the RCD around the home and plug it into a socket outlet whenever (and wherever!) you need.


RCDs are a valuable addition to not only homes but also commercial premises like shops, factories, garages, and other business buildings. When installed correctly by the professionals at Jim’s test and tag services in Melbourne, they have the potential to save lives while also reducing potential injuries after an accident. With an RCD installed, you have the peace of mind that, should your child ever be in a position to touch a bare wire, the electricity will shut off instantly.

This being said, RCDs come with two warnings:

  • You still need to be careful with wiring and electric appliances
  • RCDs only remain effective with regular testing

Always check your RCDs and ensure that they’re providing the protection you and your family need!

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