Why is it essential to regularly test RCDs?

Regular testing of Residual Current Devices (RCDs) is crucial to confirm their effectiveness in detecting earth leakage. RCDs are safety devices designed to prevent electric shock by cutting off the electrical supply when they detect an imbalance between the live (phase) and neutral currents. This imbalance could indicate that current is leaking through an unintended path, such as through a person's body to the ground.

By regularly testing RCDs, usually through a built-in test button, users can ensure that the device is functioning correctly and will activate when needed. If an RCD fails to trip during testing, it may not provide protection in the event of an electrical fault, which poses serious hazards. Thus, confirming their operability is essential for maintaining safety standards in an electrical system.

While the other options may seem relevant, they focus on characteristics of the RCD rather than its primary function as a safety device. Regular testing primarily emphasizes safety and efficacy rather than load handling, current capacity, or resistance monitoring.