How is an RCD test performed?

The correct approach to performing an RCD (Residual Current Device) test involves simulating a fault condition to verify whether the device operates effectively by tripping within the specified time frame. This procedure is crucial because it assesses the device's ability to detect current leakage and cut off the electrical supply, thereby providing protection against electric shock and fire hazards.

Testing an RCD by simulating a fault condition typically involves introducing a known fault current into the circuit, often using a testing device that can apply this fault current at a set level. The RCD should respond by disconnecting the circuit within a defined period, usually specified by regulations or standards (often 30 milliseconds for domestic settings). This testing ensures that the RCD will function correctly in a real-world scenario.

Other methods, such as visually inspecting the device or measuring its temperature, do not effectively evaluate the operational integrity of the RCD under fault conditions, nor do they provide a reliable indication of its protective capabilities. Similarly, applying a known load to the circuit does not test the RCD's response to actual fault conditions. Thus, simulating a fault condition remains the most definitive method for testing an RCD.