A Residual Current Device, or an RCD, is a safety device. An RCD disconnects a circuit if a potentially dangerous fault is detected. It operates on the principle of line and neutral conductors. It continuously monitors the balance of these two conductors. If the balance tips and the current has been lost and is being diverted elsewhere, which indicates a fault that could be dangerous. The RCD will disconnect the circuit to prevent the risk of a fire and to prevent electrical shocks.
Types of Residual Current Devices
There are three common types of Residual Current Devices – portable, fixed, and socket outlets.
- Portable
Portable RCDs can be plugged directly into a standard outlet, which means you can easily swap them between sockets, whether you’re at home or working. A portable RCD will only protect the person who is using the equipment plugged into this socket.
- Fixed
A fixed RCD is generally fitted to fuse boxes and consumer units. The fixed device provides the highest possible level of protection. It doesn’t just protect an individual circuit, it provides protection to a group of circuits, which means all of the wiring is protected, and all of the sockets and the appliances connected to those sockets are protected.
- Socket Outlet
This form of RCD is built into the socket directly. Much like a portable RCD, the person using that socket is the only one protected from faulty equipment.
How to Use an RCD Tester Properly
To ensure the fixed RCD tester performs properly, you must fit it correctly. Once it’s fitted, you should test it once a quarter. Testing your RCD tester is simple – each device features a test button, and you only need to press and release it. It does require an electrical supply to operate efficiently and test.
When you press the test button it simulates a leakage fault to determine whether the RCD tester is operating properly. To restores its power you simply need to move the power position to on. However, in the event of a fault, you may need to reset timing devices and electrical clocks.
Ensuring Accurate Readings
Using RCDs is an excellent way to reduce risks, whether it’s in a commercial, domestic or industrial environment. However, they are an additional layer of safety. An RCD does not replace the need for PAT testing or the need for proper wiring and installations. Whatever type of RCD you rely on, testing is required. All RCDs should undergo regular inspection and undergo testing to ensure it is providing you with reliable and suitable protection.
There are three basic steps to RCD testing.
- There must be an electrical supply.
- You need to connect the test leads on the earth, neutral, and line terminals.
- You should complete testing with 50%, 100%, and 500% using the 0° and 180° settings. Certain testers will do this automatically, but others will require you to carry this out manually.
You can also plug a small appliance into a power point and turn it on to ensure it works. Then turn off all electronic equipment and push the RCD test button. If it doesn’t turn off, you need to enlist the services of an electrician.
Check the lamp to ensure it does not turn on. You can take the lamp to all of the relevant sockets to test. If it turns on at any point, a wiring issue requires professional attention. Once the test is over, you can turn the RCD back on and recheck the lamp in the original socket.
