[ITEM 2] QUESTION: Electrical: when is an RCD needed and how to know if it is faulty?

A residual current device, or RCD, is a crucial element of modern modular automation in an electrical panel. The main task of this device is to protect a person from electric shock in case of accidental contact with bare wires or damaged live parts of electrical appliances. The RCD constantly compares the current leaking through the phase wire and the current returning through the neutral wire, and instantly breaks the circuit at the slightest difference.

The installation of an RCD is a mandatory requirement for rooms with high humidity, such as bathrooms, kitchens, as well as for lines connected to powerful stationary consumers and general-purpose sockets in children's rooms. This device also protects property from fires that can occur due to current leakage through damaged insulation of hidden wiring in the wall.

You can tell that the RCD has failed or is operating incorrectly using the built-in self-test function. Each quality device has a special button marked "test". When this button is pressed, a small leakage current is artificially created inside the device, and a working RCD should instantly click and turn off the power supply in the protected zone.

If nothing happened when the test button was pressed and the circuit breaker did not trip, this clearly indicates a malfunction of the internal mechanism of the RCD. Such a device must be replaced immediately, as it no longer performs its protective functions. In addition, a sign of trouble can be the spontaneous tripping of the RCD without apparent reasons when turning on working electrical appliances, which often indicates the aging of the insulation of the line itself.

Regular testing of the RCD's performance using the test button should be carried out by homeowners at least once every few months. This simple procedure allows timely identification of protective automation failure and prevents emergency situations, preserving the health and safety of everyone living in the house.