In the UK (and probably elsewhere), on "normal" mains systems:Grounding and earths are for safety to ensure things are at the same voltage (bonded) and in some safety systems to detect if there is a leak of mains current to earth.
Earthing is not now used to detect "earth leakage" directly, because the current detection used on earth wires in Earth Leakage Circuit Breakers could fail open-circuit, leaving no detection and a potentially live (line voltage) earth system. Instead, the balance of line and neutral, or of all the live (non-earth) conductors, is measured, and any residual current is treated as leakage. Hence, the trips are now called "Residual Current Devices". The practical implementations are RCCBs (Residual Current Circuit Breakers), RCBOs (RCCBs with Overload protection) and now AFDDs (Arc Fault Detection Devices, which include an RCBO).
Inspecting electricians will strongly recommend replacement of ELCBs on sight. I have frequently found non-operational ELCBs, but seldom failed RCDs. Satisfactory protection by RCD does depend on regular testing (normally every six months).
Statistics: Posted by davidcoton — Wed Mar 20, 2024 10:55 pm