Safety switches are one of those things people assume are required everywhere but the rules are actually a bit more nuanced. Here is what South Australian law actually says and what we recommend regardless.
What a safety switch is
A safety switch (also called an RCD or residual current device) monitors the electricity flowing in and out of a circuit. If it detects a difference of more than 30 milliamps, it shuts the power off within milliseconds. The difference would only happen if some current was leaking, which usually means going through a person. Safety switches stop fatal shocks.
What the rules require
South Australia requires safety switches on power point circuits and lighting circuits in any new home built since 1991. Homes built before then were not required to have them but most modern wiring works include retrofitting them.
For older homes that have never been rewired, you might still have only one safety switch on power points and none on lighting. That meets the original code at the time the home was built. It does not meet current standards.
What we recommend
Every circuit in your house should have an RCD, not just the power points. Lighting circuits cause electric shocks just as easily as power points - light switches, ceiling fan motors, anything that can fail.
Modern switchboard upgrades use RCD-protected circuit breakers (called RCBOs) on each individual circuit. If one circuit trips, the rest stay on. Much better than the old style where one trip took out half the house.
What it costs in Adelaide
Adding RCDs to an existing switchboard: $200 to $400 for the work, plus $80 to $150 per RCD installed. For a typical 3-bedroom home with 4 to 6 circuits, total cost around $700 to $1,200.
Full switchboard upgrade with new RCBOs on every circuit: $1,400 to $2,400 depending on board condition and complexity.
Worth the cost?
Electric shocks kill 15 to 20 Australians every year. Most could have been prevented by a working safety switch. The cost of a proper RCD installation is small compared to the alternative.
Test them monthly
Most safety switches have a test button. Press it every month or so. The switch should trip immediately. If it does not, call an electrician - a stuck RCD provides no protection. Make sure to test all of them, not just the most accessible one.