2025 Red Seal Construction Electrician Complete Practice Exam

RCD stands for Residual Current Device, and its primary function is to protect individuals from electric shock by monitoring the current flowing through live and neutral conductors in an electrical circuit. When the RCD detects an imbalance in the current – indicating that some of the current is leaking to earth, possibly through a person – it swiftly disconnects the circuit.

This functionality is crucial because it helps to prevent serious injuries or fatalities caused by electric shocks. The device operates by sensing the difference between the current entering and leaving the circuit; a typical threshold for disconnection is set between 30 mA (for personal protection) and 300 mA (for fire protection). Essentially, the RCD acts as a safety mechanism that enhances the overall protection of both individuals and electrical installations from fault conditions.

Understanding the nature and operation of RCDs is vital for anyone involved in electrical work, as effective usage can significantly reduce the risks associated with electrical faults.