What current does an RCD trip at?

Whilst RCDs have a nominal tripping current (IΔn), they may trip below the nominal value; for instance, a 30 mA RCD is required to trip at a current between 18 mA to 28 mA.

What does RCD protect against?

An RCD is designed to protect against the risks of electrocution and fire caused by earth faults. For example, if you cut through the cable when mowing the lawn and accidentally touched the exposed live wires or a faulty appliance overheats causing electric current to flow to earth.

What is the difference between RCD and earth leakage?

ELCBs have one advantage over RCDs: they are less sensitive to fault conditions, and therefore have fewer 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.

Will a short circuit trip an RCD?

Faulty electrical wiring can cause a short circuit. This can result in fire or electrical shock. In the case of a short circuit, it is actually the circuit breaker that turns off the power – not the RCD as is commonly the mistake. Most RCDs in buildings are accompanied by circuit breakers.

How does an RCD detect a problem in the circuit?

RCDs operate by measuring the current balance between two conductors using a differential current transformer. This measures the difference between current flowing through the live conductor and that returning through the neutral conductor.

How does an RCD detect earth leakage?

Inside every RCD is an iron core. The electricity that flows into the RCD from the live cables passes through a switchgear and a coil that goes around the iron core. When this electricity passes around the coil it generates a magnetic field. If there is a fault in an appliance some electricity can leak away to ground.

Why does my RCD trip when it rains?

When it rains, water can make its way into the cord, cause a short and trip the breaker. Interior extension cord-Indoor extension cords ends aren’t made to be water-tight. So after a good rain, water can get in the cord and cause the tripping breaker.