Published: 10 June 2005
Category: Technical articles
David Pitt, Circuit Breaker Product Manager, at Eaton MEM takes a look at discrimination in terms of RCDs:
Discrimination (or selectivity) is the selection of protective devices so that the device nearest to a fault will operate rather than any upstream device. The purpose is to ensure that the fault is isolated and supply is maintained to other parts of the installation without disruption.
For example, in a domestic installation, a fault in a ring final circuit should result in the protective device for that circuit operating, while lighting and other circuits remain energised. If the fault resulted in operation of the supply authority's service fuse, loss of power for lighting and other circuits could present a safety risk and would result in unnecessary cost and inconvenience for the householder.
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