Short answer: If your safety switch won’t stay on, something on that circuit is leaking current to earth. Unplug everything and switch off all circuit breakers, reset the safety switch, then turn breakers on one at a time. If it trips on one appliance, that appliance is the problem. If it won’t reset even with everything off, it’s likely a wiring fault, water in a fitting or a faulty switch, and you need an electrician.
A safety switch that trips once and resets is doing its job. One that refuses to go back on, or snaps straight back down the moment you push it up, is telling you there’s a fault right now. Here’s how to narrow it down safely, and when to stop and call someone.
If anyone has had a shock or there’s smoke, sparking or a burning smell, stop here. Call 000 for injuries and don’t touch the switchboard. Our electrical emergency guide covers what to do.
First, make sure it’s the safety switch
On most boards you’ll see two kinds of devices:
- Circuit breakers protect against overload and short circuits.
- Safety switches (RCDs) have a T or Test button and protect people against electric shock.
If the switch that won’t stay up has a Test button, it’s a safety switch. If you have older ceramic fuses and no Test button, see blown ceramic fuse: what to do instead.
The isolation test
This takes about ten minutes and tells you a lot.
- Unplug everything you can on the affected area. Don’t rely on switching off at the wall. Pull the plugs.
- Switch off every circuit breaker under that safety switch.
- Push the safety switch up. Does it stay on?
- Turn each breaker on one at a time, waiting a few seconds between each.
- Plug appliances back in one by one if all the circuits hold.
What the results mean
| What happens | Most likely cause | What to do |
|---|---|---|
| Stays on with everything unplugged; trips when one item is plugged in | Faulty appliance | Leave it unplugged and get it repaired or replaced |
| Trips when one particular breaker is turned on | Fault on that circuit’s wiring or a fixed appliance (oven, hot water, outdoor light) | Leave that breaker off and call an electrician |
| Won’t stay on even with every breaker off | Fault upstream of the breakers, or the safety switch itself | Call an electrician |
| Only trips in rain or after watering the garden | Moisture in an outdoor light, power point or junction box | Leave that circuit off and call an electrician |
Common culprits we find in Inner West homes
- Outdoor lights and power points in courtyards and side passages that take in water
- Old electric hot water systems with a failing element
- Ovens and cooktops with moisture or a failing element
- Fridges and freezers in laundries or garages
- Old cabling in terrace ceilings and subfloors where the insulation has broken down
- Renovation damage, such as a nail or screw through a cable
If the safety switch was only recently installed, for example as part of a switchboard upgrade, it may be finding a fault that old fuses could never detect. That’s covered in safety switch keeps tripping.
Things not to do
- Don’t hold the switch up or tape it in place. That defeats the protection.
- Don’t bypass it or swap it for a plain circuit breaker.
- Don’t keep resetting a switch that trips immediately with nothing connected.
- Don’t open the switchboard cover or remove fittings to look for water.
The NSW Government recommends safety switches because they can cut power quickly when current leaks to earth, which is exactly what’s happening when yours won’t reset.
Can a safety switch just fail?
Yes. Safety switches are mechanical and electronic devices, and they don’t last forever. A switch that won’t latch, feels loose, or trips randomly with no load can be faulty. Your electrician will test it with an RCD tester to check its trip time and current, and replace it if needed.
If the switch is covering many circuits and trips often, it may be worth splitting your circuits across more RCDs or fitting RCBOs. Then one fault doesn’t take out half the house.
Safety switch won’t reset? Leave the faulty circuit off and call 0421 772 661. Our fault finding team uses insulation testers to track down leaks rather than guessing.
Renting?
In a rental, a safety switch that’s faulty or keeps detecting a fault is an urgent repair, according to NSW Fair Trading. Tell your landlord or agent straight away. Landlords can see our landlord electrical safety checklist.
We find faults and replace safety switches across Hurlstone Park, Ashfield, Summer Hill and the Inner West. See our safety switch service in Croydon Park too.
Frequently asked questions
Why does my safety switch trip as soon as I turn it on?
There’s a fault on the circuits it protects, or the switch itself is faulty. Switch off all breakers and unplug everything, then reset. If it still won’t stay on, call an electrician.
Can a power point cause a safety switch to trip with nothing plugged in?
Yes. Moisture in an outdoor power point or light, damaged wiring or a fixed appliance can trip it even with nothing plugged in.
Is it safe to leave one circuit off?
Usually, as long as the rest of the house works normally and nothing smells or looks burnt. Keep the fridge in mind and get the fault fixed promptly.
How often should I test my safety switch?
Many manufacturers and safety authorities suggest pressing the Test button regularly, such as every three to six months. If it doesn’t trip when tested, call an electrician.