How to tell whether you have one
Go and look at your switchboard. An RCD is a switch with a small button marked T or TEST, usually labelled to test every three months. If nothing on your board has a test button, you have no residual current protection anywhere in the house.
Plenty of homes here have a partial situation — one RCD covering the power points, added when someone did a kitchen twenty years ago, and nothing on lighting. That leaves you unprotected every time somebody changes a light fitting.
Press the test button. It should trip immediately. Reset it. Do that every three months. If it doesn't trip, it has failed and is giving you no protection while looking like it is — worse than not having one. The push-button test only proves the mechanism moves; a trip-time test with an instrument measures whether it's still fast enough, and older devices do degrade.
What it costs
Adding RCD protection to an existing board is usually a few hundred dollars per device if the board has spare ways and is in good condition. If it's an old ceramic fuse box there is physically nowhere to fit them, and a switchboard upgrade is the honest answer.
How fast
An RCD added to an existing board is usually an hour or two and bookable within days. A full board change is half a day to a day.
What South Australia requires
Any new or altered circuit must be RCD protected under AS/NZS 3000, which is why most renovation work triggers at least a partial upgrade. Rental properties carry additional landlord obligations and the requirements change — confirm the current position with Consumer and Business Services SA. For an owner-occupied older home there is no rule compelling a retrofit. There is also no good argument against one.
Common questions
What's the difference between a safety switch, a circuit breaker and a fuse?
A fuse and a circuit breaker protect the wiring from overload and short circuit — they stop fires. A safety switch (RCD) detects current leaking to earth, including through a person, and cuts power in about 30 milliseconds. It's the only one of the three that protects people from electrocution.
How much does it cost to install a safety switch?
A few hundred dollars per device on a board with spare capacity. On an old ceramic fuse board there's nowhere to fit one, so the real cost is a switchboard upgrade.
How often should I test my safety switch?
Every three months, using the test button. Ten seconds. An untested RCD that has silently failed is more dangerous than no RCD, because you think you're protected.
Why does my safety switch keep tripping?
It's detecting earth leakage — usually a faulty appliance, moisture in an outdoor or bathroom circuit, or degraded cable insulation. Unplug everything on the circuit, reset, then reconnect one at a time. If it trips with nothing plugged in, the fault is in the fixed wiring.
Related
Serving Unley, Parkside, Goodwood and Malvern. See what electrical work costs in Adelaide.