RCD / RCBO faults
Nuisance tripping and earth-leakage hunting.
RCD / RCBO keeps tripping
An RCD or RCBO trips repeatedly — immediately on reset, randomly during the day, or only when certain equipment runs. The earth-leakage protection is doing its job; something is leaking.
RCD trips only in wet weather or after wash-down
The RCD holds fine when dry but trips after rain, washdown, or in damp conditions — pointing to moisture creating an earth-leakage path somewhere outdoors or in wet areas.
RCD won't reset at all
The RCD won't stay reset — the toggle won't latch up, or it trips instantly every time, so the circuit can't be restored.
RCD nuisance tripping with lots of electronics
An RCD trips intermittently with no single faulty appliance — typically where many electronic devices (with filters/SMPS) share one RCD, each adding a little standing leakage.
RCD test button doesn't trip the RCD
Pressing the RCD's test button doesn't trip it — a serious sign the RCD may not operate on a real earth fault, even though the circuit is live and working.
RCBO tripping — telling overload from earth leakage
An RCBO (combined RCD + MCB) keeps tripping and you need to know whether it's tripping on overcurrent/overload or on earth leakage — the fix is very different for each.
RCD trips the moment a specific load is switched on
The RCD is fine until a particular appliance/circuit is switched on, then it trips immediately — clearly pointing at that load or its switch-on behaviour.
RCD passes test but doesn't trip on a real leakage test
The RCD's own button trips it, but a proper instrument test shows it doesn't trip within the required time/current — so it may not protect adequately in a real fault.
RCD trips randomly with no obvious pattern
An RCD trips occasionally with nothing obviously changing — not tied to a clear appliance, weather, or time — the frustrating 'tripped again overnight' type.
Safety switch trips only at night / at a set time
A safety switch trips at a consistent time (often overnight) — pointing at a time-controlled load (off-peak hot water, slab heating, irrigation, pool) with an earth-leakage fault that only runs then.
Safety switch trips during storms / lightning activity
A safety switch trips during thunderstorms/lightning — usually transient surges or moisture, sometimes a marginal install — and it's about telling a transient nuisance from a real fault.