The short answer
To test a safety switch, press its "T" or "Test" button. The switch should trip straight away and the power on the circuits it protects should go off. Then push the switch back to the on position. The NSW Government recommends doing this twice a year, about every six months. If the switch doesn't trip, or won't reset afterwards, call a licensed electrician. In a home this is a recommendation, not a legal requirement. Workplaces have stricter rules, with testing by a competent person and records kept.
Before you start
- Find your safety switches. Open the switchboard or meter box door. Safety switches (RCDs or RCBOs) have a small button marked "T" or "Test". If you can't find any, your board may not have safety switches at all. See safety switch rules in NSW.
- Warn the household. The power will go off on those circuits for a moment. Save work on computers and turn off sensitive equipment.
- Expect clocks to reset. Ovens, microwaves and some alarm clocks will need setting again.
- Don't take any covers off. Everything you need is on the front of the board. If the board is damaged, scorched, buzzing or smells like burning, don't touch it and call an electrician.
If your board is mounted on an old black backing board, don't drill, scrape or lean on it, as it may contain asbestos. You can still press the test buttons. See asbestos switchboards in NSW.
Step by step
- Press the test button on the first safety switch firmly, once.
- Check it tripped. The switch lever should drop to the off position.
- Check the power is off on the circuits it protects. A lamp plugged in nearby or a light switched on makes this easy to see.
- Reset it by pushing the lever back up to on.
- Check the power is back.
- Repeat for each safety switch on the board. If you have an RCBO on every circuit, that means pressing the button on each one.
- Write down the date, or set a reminder for six months.
What the result means
| What happens | What it means | What to do |
|---|---|---|
| Trips straight away and resets | The push-button test passed | Nothing. Test again in about six months |
| Doesn't trip when you press the button | The safety switch may not be working | Call a licensed electrician |
| Trips but won't reset | There may be a fault on the circuit or in the device | Call a licensed electrician |
| Resets, then trips again on its own | A fault on one of the circuits | See safety switch keeps tripping |
A safety switch that fails the test may not protect you from an electric shock. Until it is checked, take extra care with appliances on that circuit, especially outdoors and in wet areas.
What the test button does and doesn't prove
The test button creates a small, deliberate leak to earth inside the device and checks the switch mechanism trips. That confirms the switch is working mechanically. It doesn't measure how fast the switch trips or at what current. That is done with an operating-time test, using test equipment, by an electrician or competent person. In homes, the push-button test is what the NSW Government asks you to do. In workplaces, both kinds of test come into it.
Testing safety switches in workplaces
At work the rules are tighter. Under the NSW Work Health and Safety rules, a person with management or control of a workplace must make sure RCDs are tested regularly by a competent person. Records of tests, other than push-button tests, must be kept until the next test or until the device is disposed of.
Construction sites
On construction and demolition sites, AS/NZS 3012:2019 applies. It is called up as a mandatory standard by section 163 of the NSW WHS Regulation 2025. SafeWork NSW lists these RCD test intervals:
| RCD | Push-button test | Operating-time test |
|---|---|---|
| Portable | Before each use | Every 3 months |
| Fixed | Every month | Every 12 months |
Other workplaces
For other workplaces, RCD testing generally follows AS/NZS 3760:2022, In-service safety inspection and testing of electrical equipment and RCDs. The standard sets push-button and operating-time test intervals that depend on the type of environment, from dry, clean offices through to workshops and hostile environments with moisture, heat, vibration, dust or chemicals. Your interval should come from the standard and your own risk assessment, so we don't publish a one-size-fits-all number here.
Farm workshops, shearing sheds, pump sites and trade vans around the Riverina often fall into the harsher categories. If you aren't sure where your workplace sits, ask Nelson. For portable equipment, our test and tag service includes visual inspection, testing, tagging and a digital test register.
Who can test a safety switch?
At home: you can press the test button yourself. That is one of the few electrical checks a householder can do. Anything beyond that, such as replacing a faulty safety switch, is electrical wiring work and must be done by a licensed electrician. DIY electrical work is illegal in NSW.
At work: RCDs must be tested regularly by a competent person, and operating-time tests need the right test equipment.
Renting?
If you are a tenant and a safety switch fails the test, report it to your landlord or agent straight away. The NSW Government lists a faulty safety switch as an urgent repair. If you are a landlord, see landlord electrical obligations in NSW.
Common questions
How often should I test my safety switch?
The NSW Government recommends pressing the test button twice a year, about every six months. It is a recommendation for homes, not a legal requirement. Some people do it when the clocks change, as an easy reminder.
Is it safe to press the test button?
Yes. It is designed for householders to use. The only effect is that the power goes off on those circuits until you reset it.
What if my safety switch doesn't trip when I test it?
The switch may not be working and may not protect you from a shock. Call a licensed electrician to test and, if needed, replace it.
Does testing a safety switch damage it?
No. The test button is there to be used, and the NSW Government recommends using it regularly.
Why did testing one safety switch turn off half the house?
On boards with shared RCDs, one safety switch can protect up to three circuits, so testing it turns all of them off. With an RCBO on each circuit, only one circuit goes off at a time. See RCD vs RCBO.