RCDs, or Residual Current Devices, are safety devices designed to prevent electric shock and electrical fires. They work by detecting imbalances in electrical current, which can occur if electricity leaks through a person or faulty equipment. When an imbalance is detected, the RCD quickly cuts off the electrical supply, reducing the risk of injury or damage. RCDs are commonly used in homes and workplaces, especially in areas where water is present, such as bathrooms and kitchens. They are an essential part of electrical safety systems and are often required by electrical codes in many regions to protect people from electrical hazards.