What is an RCBO and what protection does it provide?

• A. A single device that provides residual current protection and overcurrent protection
• B. A device that provides only residual current protection
• C. A device that provides only overcurrent protection
• D. A device that provides voltage surge protection

Answer: (A)

An RCBO is a single device that combines two protection functions: residual current protection and overcurrent protection. It watches the current flowing in the live and neutral conductors and will trip if there’s an imbalance, which means current is leaking to earth and could pose a shock risk. It also acts as a circuit breaker, tripping when the current exceeds its rated value or a short circuit occurs, preventing damage and fire. Because both protections are in one unit, it can protect people from electric shocks and protect the circuit from faults, unlike devices that only do residual current protection, only overcurrent protection, or surge protection for voltage spikes. Residual current protection is typically set to a low threshold (often around 30 mA for personal protection), while overcurrent protection is set to the circuit’s rated current.