Safety Switch Keeps Tripping? Causes, Safe Checks and Fixes

A safety switch (RCD) that keeps tripping is annoying, but it’s doing its job. It cuts the power when it detects electricity leaking where it shouldn’t, which could be through a faulty appliance, damp wiring or a person. Here’s how to find the cause safely, and when it’s time to call an electrician.

Common causes

• A faulty appliance. This is the most common cause. Kettles, toasters, heaters, fridges, washing machines and old power boards are frequent culprits.
• Moisture. Outdoor power points, garden lights and pool equipment often trip after rain or heavy dew.
• Damaged wiring. Look for cables hit by a nail or screw, chewed by rodents, or deteriorated in an old home.
• Too much on one safety switch. Many appliances each leak a tiny amount. Added together, they can trip a switch that protects too many circuits. This is common in homes with only one or two safety switches.
• Fixed appliances such as an oven, cooktop, hot water system, air conditioner or EV charger.
• A faulty safety switch. They do wear out.

Trips with nothing plugged in?

If it still trips after you’ve unplugged everything, the fault is likely in the fixed wiring, a light fitting or a hard-wired appliance such as the oven, hot water system or air conditioner. That needs a licensed electrician with proper test equipment to find. It’s one of the most common fault-finding jobs I do.

Trips at night, or randomly?

Look for anything that switches on by itself: a fridge or freezer compressor, an off-peak hot water system, a pool pump on a timer, a heated towel rail, outdoor lights on a sensor, or an EV charger on scheduled charging.

A safe way to narrow it down

1. Unplug everything on the affected circuits, or switch appliances off at the wall.
2. Reset the safety switch.
3. Plug appliances back in one at a time, waiting a minute between each.
4. If it trips when a particular appliance goes back in, stop using that appliance and get it checked or replaced.
5. If it trips with nothing plugged in, or you can’t find the cause, call me.

Test your safety switches regularly

Most safety switches have a “T” or “Test” button. Pressing it should cut the power to those circuits straight away. Manufacturers generally recommend testing every few months. If it doesn’t trip when tested, get it checked.

Only one or two safety switches?

Older switchboards often have one safety switch covering lots of circuits, or none at all. Spreading the protection across more safety switches, or adding RCBOs (a combined safety switch and circuit breaker for each circuit), means one fault won’t black out half the house. See my switchboard upgrades in Sydney and electrical fault finding.

Written by Dario Bustamante, licensed electrician (NSW Contractor Licence 475813C), Tesla Certified Installer and Ocular Certified Partner. This guide is general information. Every site is different, so I’ll confirm what your property needs on inspection.