1 Answer
A Residual Current Device (RCD) protects against electric shock by detecting any difference between the live (active) and neutral conductors of an electrical circuit. Here's how it works:
In short, an RCD acts as a safety switch, cutting off the electricity when it detects that some of the current is escaping the normal path, which could happen if someone is being shocked. This quick action minimizes the time the person is exposed to electricity, reducing the chances of harm.
- Current Balance: In a properly functioning circuit, the current flowing into a device via the live wire should equal the current flowing back out through the neutral wire. Essentially, the amount of current entering the device should be the same as the amount of current leaving it.
- Leakage Detection: If a person touches a live wire, part of the current may flow through their body to the ground (earth), creating a difference between the live and neutral currents. This is called a "residual current" or leakage.
- Immediate Response: The RCD constantly monitors the balance of current between the live and neutral wires. If it detects an imbalance (even as small as 30 milliamps), it assumes that some of the current is flowing through an unintended path, such as a person’s body, and it trips the circuit.
- Quick Disconnect: Once the RCD detects this imbalance, it rapidly disconnects the power supply to the circuit (within milliseconds), stopping the flow of electricity and reducing the risk of serious injury or death from electric shock.
In short, an RCD acts as a safety switch, cutting off the electricity when it detects that some of the current is escaping the normal path, which could happen if someone is being shocked. This quick action minimizes the time the person is exposed to electricity, reducing the chances of harm.