During an RCD trip test, what result confirms proper operation?

• A. The supply remains connected indefinitely.
• B. The RCD trips only after manual reset.
• C. The supply is cut within the specified trip time.
• D. The RCD trips only on overload condition.

Answer: (C)

RCD protection relies on quick disconnection when there is a leakage current to earth. A trip test checks that this protective device responds promptly to a detected imbalance. When you simulate the fault, the RCD should cut the supply within the time specified by the manufacturer. That timely disconnection confirms proper operation because it means the device will shut off power quickly to minimize electric shock risk.

If the supply stays connected, or if tripping only occurs after manual reset, or only under an overload condition, those indicate the device isn’t functioning correctly as a protective RCD would.