Which device provides both residual current protection and overcurrent protection in one package?

• A. RCBO
• B. RCD
• C. MCB
• D. Fuse

Answer: (A)

An RCBO provides both residual current protection and overcurrent protection in one package. It combines an RCD function, which detects an imbalance between live and neutral currents and trips on earth leakage to prevent shock, with an overcurrent protection function (like an MCB) that trips on overload or short circuit. This single unit gives per‑circuit protection for both leakage and overcurrent.

A plain RCD only guards against earth leakage and won’t trip for overcurrent. A standard MCB protects only against overcurrent and doesn’t detect leakage. A fuse provides overcurrent protection but isn’t resettable and doesn’t detect leakage.