Residual current devices (RCDs) are:

Residual current devices (RCDs) are:

• A. A type of circuit breaker that breaks the circuit if more current flows through the live wire than the neutral wire
• B. A device that increases current when leakage occurs
• C. A resistor that limits current
• D. A device that eliminates earth leakage by increasing earth resistance

Answer: (A)

RCDs protect people by ensuring that the current leaving through the live wire returns through the neutral. They monitor both paths, and if some current leaks to earth, the current returning in the neutral is reduced. This difference is detected, and the device rapidly trips, breaking the circuit to prevent electric shock. So the description fits: it’s a circuit-breaking device that trips when the live current is not matched by the neutral return. It doesn’t try to increase current during leakage, it isn’t a resistor, and it doesn’t fix leakage by changing earth resistance.

RCDs protect people by ensuring that the current leaving through the live wire returns through the neutral. They monitor both paths, and if some current leaks to earth, the current returning in the neutral is reduced. This difference is detected, and the device rapidly trips, breaking the circuit to prevent electric shock. So the description fits: it’s a circuit-breaking device that trips when the live current is not matched by the neutral return. It doesn’t try to increase current during leakage, it isn’t a resistor, and it doesn’t fix leakage by changing earth resistance.