What is a nuisance trip?

Nuisance trips are clearly defined as unwarranted circuit breaker trips with either no electrically based reason for the trips, or, the breaker deems there to be a fault when one does not exist. Nuisance Tripping is not the tripping of a breaker when doing its designed function.

Then, what causes RCD switch to trip?

RCDs (Residual Current Devices) are electrical safety switches that remove the supply to an electrical circuit when the circuit is unsafe; if an RCD 'trips' it has tripped for a reason, the problem is rarely a faulty RCD. Judge Electrical 'Find & Reset An RCD + Investigate A Constantly Tripping RCD' web page.

Why does my RCD keep tripping out?

An RCD that trips again (and again) after reset is a 'constantly tripping RCD'. The problem is unlikely to be the RCD. The problem is most likely an electrical appliance causing the RCD to trip; the RCD is 'doing its job'; the RCD is removing the supply to an unsafe electrical circuit.

What causes the earth leakage to trip?

Nuisance trips. While voltage and current on the earth line is usually fault current from a live wire, this is not always the case, thus there are situations in which an ELCB can nuisance trip. Another cause of nuisance tripping is due to accumulated or burden currents caused by items with lowered insulation resistance
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