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News : October 2017

How does an RCD Work?

how does an RCD workHave you ever wondered “how does an RCD work?” This week at Kerfoot, we’re explaining all things RCD. Also known as residual current devices, your safety switch is there to keep you safe. It is important to know how this life-saving device works in order to ensure your home or business is as safe as possible.

How does safety switch work?

The switch works by continuously monitoring the electrical current in:

  1. An entire building
  2. An individual circuit
  3. A piece of equipment

When a fault is detected, the RCD cuts off the power. Your system may be tripped by a short circuit, a circuit overload, or a ground fault.

When electricity moves through wiring, it travels through active wiring (for sending electricity) and neutral wiring (for returning electricity). When the flow between each type of wiring is equal, the residual current device will allow the electricity to function as normal. When an imbalance is detected, the safety switch will stop the flow of electricity.

Why does the RCD trip?

How does an RCD work when an electrical fault is detected? Put simply, it switches off the power. This can happen for a variety of reasons; however, the most common causes include short circuits, overloaded circuits, and ground faults.

Short Circuits

When electrical current travels outside of its intended route, it can miss its destination and continue to travel around a circuit. If the energy doesn’t reach the destination, the voltage is not reduced and the wires overheat as the current continues to move. RCD tripping will occur when a short circuit is identified.

Circuit Overload

Overloads happen when electrical circuits are overwhelmed. This can happen if you plug too many appliances into one power point/adaptor or if appliance voltages and power board capacities have been mismatched. Check the current recommendations of the side of your power distribution equipment as well as the voltage of your appliances/equipment.

Ground Fault

How does an RCD work when a ground fault is detected? A ground fault occurs when electricity travels outside of its intended route and enters the ground through a conductive surface. This can happen when a person makes contact with live electrical wiring. When a ground fault happens, the RCD detects the change in the return circuit and switches off the power.

Let’s Get Technical

How does an RCD work exactly?

We’ve given you a simplified version of how a fixed or portable RCD will work when a fault is detected. Check out this video for an in-depth look at the different parts and electrical mechanisms that go into a functional RCD.

RCD Replacement

If your RCD keeps tripping, it’s usually a symptom of a larger problem. Your equipment might be damaged or faulty, or there might be old wiring in your building. If these causes have been eliminated, there is a chance that your residual current device is faulty.

At Kerfoot, we offer RCD inspection, installation, and replacement services to businesses across Sydney. It is essential to ensure your building, staff, and guests are protected from electrical shock and electrocution. If you suspect that your device may be faulty, ask us to visit your property ASAP. Electrical safety is of utmost importance to our team.

If you do need a replacement, we can supply and install an industry-grade safety switch for your property. We offer a range of statutory testing services, so be sure to check out our website and let us know if you have any questions.

Based in NSW? Check out these RCD testing requirements and make sure your business is compliant with workplace safety standards.


Get in touch.