What a safety switch does
A safety switch, or RCD (residual current device), watches the current going out on a circuit and coming back. If some of it is leaking to earth, which is what happens when current passes through a person, it cuts the power very quickly. SafeWork NSW describes it as protection against electric shock, with some protection against electrical fires too.
Household safety switches required by the Wiring Rules are rated at no more than 30 mA. A circuit breaker is different: it protects the wiring from overload and short circuits, but it won't stop a shock. That's why you want both.
Two common ways to fit them:
- RCD: one safety switch protecting a group of circuits (up to three). If one circuit has a fault, every circuit on that RCD goes off.
- RCBO: a safety switch and circuit breaker in one device, protecting a single circuit. A fault on the hot water doesn't take out the kitchen lights.
We generally recommend an RCBO on every circuit. Our guide on RCD vs RCBO explains the difference in more depth.
Signs you should call us
- Your switchboard has no safety switches, or one old unit covering everything.
- You press the "T" or "Test" button and the power doesn't go off, or it won't reset.
- A safety switch keeps tripping, especially after rain or when a certain appliance goes on.
- You're adding a circuit, a power point or a light, which will need RCD protection on that circuit anyway.
- You're buying or renting out an older home.
If a switch is tripping often, don't keep resetting it. See why a safety switch keeps tripping, then call us to find the fault.
What the rules say in NSW
The NSW Wiring Rules are AS/NZS 3000:2018. Here's how they play out for safety switches, in plain terms:
- New and existing homes are treated differently. Clause 2.6.3.2.2 requires 30 mA RCD protection on all final subcircuits in domestic installations, at the switchboard. For existing homes, the national ERAC advisory note says that altering one circuit means only that circuit must get an RCD or RCBO. The rest of the house doesn't have to be upgraded.
- A new switchboard means safety switches on everything. If a switchboard is replaced for any reason, every applicable circuit from it must have RCD protection. See switchboard upgrades.
- Like-for-like swaps are repairs. Replacing a power point or light in exactly the same spot, without altering the circuit, counts as a repair, so no RCD is triggered. That includes swapping a single power point for a double.
- The RCD goes at the switchboard. When outlets, lights or equipment are added in an existing home, the RCD protecting them must be installed at the switchboard where the circuit starts.
- No more Type AC. Type AC RCDs can't be installed in new work in NSW since 1 May 2023, and can no longer be sold here. Type A detects both AC and pulsating DC faults. NSW says Type B is for circuits with higher DC leakage risk, such as EV chargers. Details are on the Building Commission NSW RCD page.
We could find no NSW law that makes owner-occupiers retrofit safety switches to an existing home, and NSW rental rules don't say a landlord must install one. The rental condition report does record whether a safety switch is present and working, and a faulty safety switch in a rental is an urgent repair. Our NSW safety switch rules guide goes through it.
Testing your safety switches
The NSW Government recommends testing them twice a year, about every six months. It's a recommendation, not a legal rule, and it's one of the few electrical jobs you're allowed to do yourself:
- Press the "T" or "Test" button on each safety switch.
- The power on that circuit should go off straight away.
- Switch it back on.
If it doesn't trip, or won't reset, call a licensed electrician. See how to test a safety switch.
Workplaces, sheds and farms
Workplace rules go further. Under section 164 of the NSW WHS Regulation, plug-in equipment needs RCD protection where it's used in conditions likely to damage it (moisture, heat, vibration, mechanical damage, corrosive chemicals or dust), moved between such places, or moved around often in normal use. That covers many farm workshops and machinery sheds around the Riverina. The person in control of the workplace must also make sure RCDs are tested regularly by a competent person, and keep the records (other than push-button tests) until the next test.
We can fit RCD protection at the board, test existing RCDs, and test and tag the portable gear on the same visit.
What affects the price
Adding safety switches to an existing board depends on what's there, whether there's room, and the condition of the wiring, so we quote it in writing after a look. Call or send the job through. If your board is old or full, a full switchboard upgrade with an RCBO on every circuit may be better value, and the instant switchboard estimate gives you a figure from your circuit count.
Common questions
Is a safety switch the same as a circuit breaker?
No. A circuit breaker protects the wiring from overload and short circuits. A safety switch detects current leaking to earth and protects people from shock. An RCBO does both jobs in one device.
Do I have to have safety switches on every circuit in NSW?
Not in an existing home just because it's old. RCD protection is required on circuits that are altered or added, and on every applicable circuit when the switchboard is replaced. New homes need it on all final subcircuits.
Do landlords have to install safety switches in NSW?
We found no NSW law requiring it. The condition report records whether one is present and working, and a faulty safety switch is an urgent repair the landlord must fix within a reasonable time.
How often should I test my safety switch?
The NSW Government recommends every six months using the test button. In workplaces, testing must be done regularly by a competent person and recorded.
Why does my safety switch trip when it rains?
Water getting into an outdoor power point, light or cable can let current leak to earth, and the safety switch is doing its job by cutting the power. It's a fault to find, not a switch to keep resetting. Call us and we'll trace it.