does an rcd trip if the earth break's but there is no short between live neutral and earth

duster, January 2010

if you short cicuit 2 of any of the 3 wires ( L-N, N-E OR E-L) when live the rcd will trip because thats what its designed to do, its basically a safety device to monitor residual current, even when the circuit braker for a specific circuit is switched of and you cut through a cable for that circuit it will still trip the RCD due to the N-E short circuit

stoozybhoy, February 2010

No, an RCD trips if there is sufficient imbalance in current (usually around 30mA) between live and neutral which is most likely to be lost via earth. If the earthing conductor is broken and there is a fault on a piece of equipment, the earthing path could be provided either by bonding (metal water and gas pipes should be bonded) or through someone or something touching it, which will cause the rcd to trip.

Remember if the RCD doesn't trip when you press the test button, something has gone wrong.

Adam, January 2010