What does an RCD (Residual Current Device) do?

An RCD, or Residual Current Device, plays a crucial role in electrical safety by protecting individuals from electric shock. It serves by continuously monitoring the flow of current through a circuit. If it detects an imbalance between the live and neutral wires, which indicates that some of the current is leaking to the ground (often through a person's body), the device quickly disconnects the circuit to prevent injury. This functioning is critical in environments where the risk of electric shock is heightened, such as in marine applications where wet conditions can increase the risk of electrical hazards.

The other options do not accurately describe the function of an RCD. While increasing voltage or regulating battery charging cycles may be relevant to electrical systems, these tasks are not the primary responsibilities of an RCD. Monitoring solar power input is also unrelated to the protective role of an RCD, which focuses specifically on detecting leakage currents to enhance safety.