A plain-English explanation of RCDs — what they do, how they differ from circuit breakers, and why Queensland regulations require them on every circuit in a modern home.
An RCD — Residual Current Device — is the safety switch in your switchboard that protects you from electric shock. It is not the same as a circuit breaker, and the difference matters.
What a circuit breaker does
A circuit breaker protects the wiring and appliances. It trips when a circuit draws too much current — like a short circuit or an overloaded power board. It is designed to protect property, not people.
What an RCD does
An RCD monitors the flow of electricity through a circuit. The moment it detects that current is going somewhere it shouldn't — such as through a person — it cuts the power in milliseconds. Fast enough to prevent electrocution in most situations.
What Queensland requires
Queensland regulations require RCD protection on all power and lighting circuits in new installations and when significant electrical work is carried out. Many older homes pre-date these requirements and have no RCD protection at all, or only partial protection on one or two circuits.
How to check your home
Look at your switchboard. RCDs usually have a small test button marked 'T' or 'Test'. If you see only plain switches with no test buttons, or if only one or two circuits have them, your home may not be fully protected.
A switchboard assessment as part of any upgrade will confirm the state of your RCD coverage and identify any circuits that need it added.