RCDs are capable of offering much stronger protection than is the case with circuit breakers and fuses but also perform very different functions. RCDs can be life saving devices, intended to guard against hazards such as electric fires, electric shocks and electrocution. RCDs all come with a test button that needs to be activated on a monthly basis in order to make sure that the device is still functioning in the manner in which it is intended to.
It is a good idea to test RCDs in a morning during the working week so that if there is a failure the device will be able to be replaced at minimal cost on the same day. Testing the RCD in the evening or in the weekend would make it much more expensive to call out an electrician immediately.
What is an RCD?
RCD stands for Residual Current Devices, which are essentially safety switches that measure the electricity flows from circuits to which they are connected and will cut the supply of electricity to that circuit if any imbalance in the current is detected, greatly reducing the chances of electrocution.
Why do RCDs matter?
If anyone touches an object or wire that is live, an electric current will flow through their body. The RCD will immediately detect that the current is going elsewhere than through the RCD and shut the electricity off instantly.
When you push the test button on an RCD tester this causes a simulation of an earth leakage fault and if the RCD is operating in the correct manner this should result in the RCD switch being tripped. This test is referred to as a “push button test” and can be performed by anyone easily and safely.
1 Turn of all electronics
The first step when performing an RCD test is to turn off all sensitive electronic devices such as computers and televisions.
2 Testing the RCD
The next step is to actually perform the test on the RCD. Make sure the RCD is turned on and press the test button in order to simulate an earth leakage fault. The button needs to be pushed and then released, not held down for the duration of the test.
The operation of the RCD should see it cut off power to every one of the circuits to which it is connected. The RCD can then be turned back to the ON position in order to reset it. The test has then been completed. If the test does not work the way that has been described then there may be an issue with your RCD.
Common RCD faults
There are a number of issues that can arise as a result of a faulty RCD, such as not resetting after the conclusion of the test, not tripping instantaneously or even at all when the test button has been pushed, and the RCD switch being floppy following the test.
RCDs are life-saving devices, making it all the more important to use RCD testers to ensure they are functioning correctly.