RCD Protection. What is it and why do you need it?

Posted on 14th July 2016 by Kristine Dawson
RCD protection

As emergency electricians, one of the main reasons we are called ‘out of hours’ is because someone’s RCD or safety switch has tripped and they are not sure why or what to do about it.  In this blog I will discuss the importance of RCD protection, the 4 main reasons RCD’s trip and what you can do about it.  Being armed with this knowledge could save you hundreds of dollars or more importantly your life. 

What is RCD protection and what does it do? 

An RCD (Residual Current Device), also known as a safety switch is a device that quickly switches off the electricity if an electrical fault is detected. RCD protection can minimise the risk of injuries and deaths due to contact with electricity. The safety switch detects the moment a circuit is leaking and stops the flow of electricity in a fraction of a second. To put it into perspective if a person was to touch a bare, live wire the flow is stopped so fast the person wouldn’t even get a shock. Since RCD protection became mandatory in Queensland new builds 25 years ago many lives have been saved.  If a safety switch keeps tripping it can be annoying but having them is essential to the safety of your home or workplace. When a safety switch trips it is saving you from electrocution or death.  

What is causing my RCD to trip?

Here are the 4 most common reasons our emergency electricians have found to be the cause. 

  1. Faulty Electrical Appliances

Over an extended period of time and with extensive use, Electrical Appliances tend to wear and not function properly. If appliances are not maintained they will be one of the biggest causes of your safety switch tripping. The most common appliances to cause issues are electric kettles, toasters, fridges, freezers, irons, range-hoods and clothes dryers.

How do I find the appliance causing the problem? 

Last week our emergency electrician was called to a house in the Brisbane Southside Suburb of Holland Park because the owner had no power.  The RCD protection had worked. When he arrived he unplugged all the appliances with the owner, then reset the safety switch.  The electrician then plugged each appliance back in on at a time. When he plugged the kettle back in to the power point the safety switch tripped again.  The electrician knew that this must be the faulty appliance.  If your safety switch has tripped, you can use this method at home to fault find which of your appliances is faulty. You then need to dispose of the faulty appliance appropriately. 

It is important to regularly check your appliances to ensure the cords are intact and undamaged. Any appliance with a frayed cord or damaged plug should be discarded. 

2.  Nuisance Tripping 

Nuisance tripping is when your safety switch trips every few days.  We were recently called out to a property in the Brisbane suburb of Camp Hill because a safety switch kept tripping.  We found that a leak in the washing machine was causing the RCD protection to be activated every few days.  Another example, at a house in the Brisbane Southside suburb of Bulimba, there was an ants nest inside an outdoor powerpoint causing it to trip every few days. The electrical appliance or powerpoint at fault may not trip every time as it clears itself in between.  

It can be hard to find the fault when its nuisance tripping since the faults are not present at all times. An electrician can use their insulation resistance tester to find a reading to earth fault, however this only works if the electrical hazard is present at all times.  Otherwise it becomes a task of intense visual searching and can be time consuming. 

3. Faulty Electric Wiring

If you have ruled out the safety switch tripping being from electrical appliances then it is possibly electrical wiring causing the problem. Old electrical wiring deteriorates over time and the insulation around the wiring can become unsafe and brittle.

How do you know if you have old house wiring?

In the older inner Brisbane City suburbs of South Brisbane, West End, Highgate Hill, Greenslopes and Annerley this can be a particular problem. Houses built in the 1940’s-1960’s possibly still have black rubber insulated cables or split metal conduit with cotton cables as their electrical cables. Also if your house is more than 15 years old it is possible that rodents have eaten into your cables.  If you are concerned it is worth having an electrician check your wiring. 

4. Rain and Lightning

Whenever there is a big storm or lots of rain we always get a lot of emergency callouts. This is because excessive water can get in behind electrical items such as outdoor power points and outdoor light fittings. Sometimes a broken drainpipe or untrimmed tree branch will be sending water flooding straight into a power point. Thunder and lightning can also cause a safety switch to trip as safety switches don’t like voltage fluctuations and the imbalance in electrical supply will trigger a trip.  If your safety switch has tripped during heavy rain or a storm it is important that you call a Licensed electrician and do not try to fix the problem yourself. 

A final questioned answered

We often get asked “my safety switch keeps tripping, is it broken?”  No, it is not broken! It is doing the exact job it should be doing, protecting you and your family or workplace from electrocution and electric shock. 

It is recommended that you test your safety switches every month by pressing the test button.  If it doesn’t release or gets stuck that means it probably needs to be replaced. 

For more information regarding safety switches read here.