ᐅ RCCB / RCD does not trip

In an apartment (built in 1875, electrical system from around 1970), I replaced all wiring using new 20mm (approximately 0.8 inch) conduits with three-core cables. About four years ago, a professional company installed a new grounding system for the building, including equipotential bonding and a ground rod, and a grounding cable was routed into each apartment. The electrical panel was equipped with a 30mA residual current device (RCD) for single-phase alternating current and five circuit breakers (4 x 16A, 1 x 13A). After all wiring was installed and connected, the grounding and all circuits in the panel were connected to the grounding busbar. Since only one phase is supplied from the main distribution in the hallway to each apartment (cooking and heating are gas-powered), I first connected the phase and neutral conductor to the RCD, then bridged to the individual miniature circuit breakers (MCBs). In a simple test (connecting phase to grounding using a test lamp), the RCD does not trip. Could this be caused by a faulty building grounding? The tripping mechanism was tested immediately downstream of the MCBs in the electrical panel.

Hello!

This could, of course, be due to a faulty grounding. If there is a short circuit, the current flows away through the PE (protective earth). The RCD (residual current device) detects that the current returning on the neutral conductor (N) is no longer the same as the current supplied through the live conductor, since the current is flowing through the PE. It then trips. However, if no grounding is present, the current cannot flow away through the PE.

I would suggest having an electrician check the wiring. With the right measuring instruments, it is relatively quick to determine whether the RCD is working correctly and where the fault is.

Best regards

Flying-Spark