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    Keep your RCDs in Check with an RCD Tester

    By on Last modified: October 13, 2021

    Safety has been the number one priority since the discovery of electricity and while that hasn’t always been at a top-level, nowadays it is thanks to RCDs. While an RCD (Residual Current Device) isn’t the only component that helps keep your household installation safe it is quite an effective one. The same way you stay safe by wearing PPE, an RCD ensures that the flow of electricity causes damage to electrical installations and appliances.

    Also known as an ELCB or earth leakage circuit breaker it is able to shut off power to the circuit as soon as it detects any irregularities. This is all possible thanks to electromagnetism with a special switch called a relay connected to the toroid. But to check whether or not an RCD is operational you need an RCD loop tester.

    How Does an RCD Tester Work


    An RCD loop tester is a device that helps identify if an RCD is able to shut power off when there is current leakage. This is done by having various levels of leakage current sent to the electrical system. This way RCD testers help detect the time needed for the RCD to shut off the power to the circuit which is known as trip time. This process is executed in a safe manner but it can only be done so with RCD testers.

    When Should an RCD be Tested?


    To keep things working as they should an RCD should ideally be tested every 12 months. This is in accordance with AS/ NZS 3760 standards and once a test has been carried out a tag should be placed on the device identifying the person that carried out the test and when the test was done. But sometimes testing an RCD can be done earlier than the preferred 12 month period and there are some signs that point to that.

    Signs of a Faulty RCD


    Current Rating

    The reason why your RCD is faulty or it keeps tripping all the time could be one to do with the current rating of the RCD. Every RCD relies on a particular current rating and if that rating is either surpassed or met it can cause the RCD to trip. But if an RCD has too low of a current rating then it can trip excessively. If an RCD doesn’t stop tripping over and over again it is probably set at the wrong current rating.

    Motor or Pump

    There are many appliances that rely on motors or pumps and if either one of these components causes a surge it can be enough to trip an RCD. If an RCD only trips when certain appliances are turned on or off then the issue is not necessarily with the RCD but rather the appliance itself. This doesn’t always have to do with the pump or motor of the appliances as there are plenty of other components that can cause a surge. Other appliances with motors are electric razors, hairdryers, and fans while washers are mainly appliances that use pumps.

    Washing Machines/ Dryers


    Talking about washing machines they can easily be the cause for an accidental trip of an RCD. Not because of the pump though as older washing machines and dryers too are known to cause RCDs to trip from time to time. Your dryer or washing machine could be in perfect condition but something may be causing a spike in electricity that is enough to make an RCD trip without causing any issues to the dryer/ washer first.

    Central Heating

    Usually, central heating comes with a timer that starts the heat generation process. With the timer turning on an RCD could trip. If you find out that this is the case it means that the timer is faulty and if you do not replace it soon you’ll be spending money on more expensive repairs. This can happen occasionally or on a regular basis depending on how bad the timer is.


    When it comes to outside electrical boxes and sockets moisture can be the main culprit for an RCD tripping so frequently. If weather seals are decayed and loose then there probably is moisture in the box or socket. SO make sure to replace weather seals on time to avoid replacing something else that will cost you a lot more time and money.


    Sometimes simply a low-quality RCD can be the cause of it tripping so much. Low-quality RCDs are known to either not being able to reset a circuit properly or to reset it correctly before tripping which happens a few minutes afterwards. In this case, just replace the RCD with a higher quality one and you’re good to go.


    While components in certain appliances can cause RCDs to trip excessively sometimes a faulty appliance can be the cause of it. This way the RCD will trip constantly to get rid of the surge of power to the circuit. While this is the task of an RCD it shouldn’t be constantly put to the test as like other devices and appliances it also has a certain lifespan. This issue is usually known to occur when there are multiple appliances plugged in than what you usually have.