Jordfelsreläet

Jordfelsreläet, or Residual Current Device (RCD) in English, is an electrical safety device designed to protect people from electric shock. It works by monitoring the flow of electricity in a circuit. Normally, the current flowing into a circuit is equal to the current flowing out. If there is a difference, it indicates that some current is leaking to the ground, possibly through a person. When a fault is detected, the RCD rapidly cuts off the power supply, preventing a potentially dangerous electric shock.

These devices are crucial for preventing electrocution, especially in areas where water is present, such as bathrooms and kitchens, or in outdoor electrical installations. They are distinct from circuit breakers or fuses, which primarily protect equipment from overcurrents and short circuits. RCDs are sensitive to small differences in current, typically in the range of 10 to 30 milliamperes, and can react within milliseconds.

Installation of RCDs is often mandated by electrical regulations in many countries to enhance safety in homes, workplaces, and public buildings. They can be installed as individual units protecting specific circuits or as a main switch protecting an entire electrical installation. Regular testing of RCDs is recommended to ensure they are functioning correctly and can provide the intended safety protection.