Which protection capability is provided by an RCBO that a standard MCB does not typically provide?

• A. Higher voltage rating.
• B. Residual current protection plus overcurrent protection.
• C. Earth fault protection only.
• D. It has no differences.

Answer: (B)

The main idea is that some protective devices combine two functions: they guard against overcurrent and also detect earth leakage. An RCBO does exactly that—it provides residual current protection (earth fault detection) in addition to overcurrent protection. A standard MCB only protects against overcurrent and does not sense leakage to earth, so it cannot respond to an earth fault. That makes the RCBO capable of tripping for both types of fault, which is why it offers protection the MCB does not. The other options aren’t right because a higher voltage rating isn’t what distinguishes an RCBO from an MCB, RCBOs protect against more than just earth faults, and there are clear differences in functionality between the two.