RCD’s Frequently asked questions

What is an RCD? An RCD is more commonly known as a ‘safety switch’, or ‘residual current device’

What does an RCD do? An RCD provides protection to you, your family and your pets from electrocution by measuring tiny amounts of electricity that leaks through to earth. If the RCD detects some electricity leaking through to earth, it will trip out, turning the electricity off before it reaches dangerous levels, most time before you even feel it.

Are RCD’s mandatory? As per the latest AS/NZS 3000 wiring rules, every single circuit in your house needs to be protected by an RCD. RCD’s are mandatory in almost every domestic and commercial application, with only a few exceptions.

Do RCD’s need to be tested? Most recognized RCD Manufacturers recommend 3 monthly testing of RCDs, however in commercial applications, 6 monthly testing by a licensed electrician is required to be carried out, along with a log book to log down the tripping speeds, tripping currents and any maintenance carried out. If an RCD is not tested frequently, it will quickly become seized up an may not trip when you need it to.

My RCD has tripped and I cant reset it? Most times, if an RCD has tripped, it is for a good reason. The first thing you need to do is to check to see if there is an obvious reason for it to trip out (see below for common reasons), if you can not identify anything obvious, you need to follow the “How to reset an RCD without a sparky” Step by step.

Why do RCD’s trip out? There are literally dozens of reasons why your RCD may be tripping out, below are just some of the common causes we come across every day:

  • Faulty appliance plugged in (Kettle, Toaster, Iron etc)
  • Water spilt over power boards behind bedside tables
  • Pets chewing on power cords
  • Water leaks from overfull gutters getting into light fittings on eaves
  • Rats/mice/possums damaging cables and junctions in roof space
  • Intermittent faults in wiring: Sometimes a fault can come and go depending on environmental factors such as moisture levels
  • Old Fluorescent lighting
  • CHEAP RCD’s – Sounds so simple, but so often CHEAP RCD’s just trip out for no good reason, other than theyr cheap and are unreliable.

How to reset an RCD without a sparky? Well this depends on the reason the RCD Has tripped out, however if you follow the next few steps logically, you will be able to find the cause, and safely reset the RCD 90 % of the time.


Identify which part of the house has been affected – E.g. Lights, Kitchen power, Laundry power etc


If it is a POWER CIRCUIT: Go around the house in the affected area (the areas that are not working) and UNPLUG every single appliance that is plugged in to a power point. Take care not to forget hidden ones such a range hoods, gas cooptop ignitors, Diswashers ETC.

Once you have done this, try and RESET the RCD.

If the RCD resets – go back around and plug back in all the appliances you have just removed, one by one – taking note when the RCD Trips again. Once it trips again, take note which appliance you just re-plugged in, and you have found your culprit – Congratulations.

If it is a LIGHTING CIRCUIT: This can be more tricky, as more often than not it will be either a fault with the light fitting, or with a cable in the roof space, but sometimes you can trace it down to the exact light that is causing the problem. To do this, simply go around and turn off every single light switch and see if the RCD Resets, if it does, then you can easily identify which light is causing the issue by switching them back on one by one until the RCD Trips again.


If you have managed to find the issue and successfully turn on the RCD after removing the faulty appliance, CONGRATULATIONS, you have saved yourself hard earned money.

If you still can not get the RCD to reset, it means something more sinister is going on, and you will need to get an electrician (hopefully one from Terrasol 😊) to come out and complete the rest of the troubleshooting.

You can take comfort in knowing we have electricians on call 24/7 and can attend to quickly and professionally fix the issue at a price that you can afford


No matter what your project is, from small domestic jobs to big commercial projects, for reliable, fast and friendly professional electricial services in Perth...


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