Sockets Need Rcbos
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Are MCBs Becoming Obsolete?

Keith Willcock, Product Manager for Siemens Alpha circuit protection products reviews requirements for additional protection on socket outlets in BS7671: Amendment 2.


Regulation 411.3.3 – All For The User

Regulation 411.3.3: in AC systems additional protection, by use of a 30mA residual current device, must be provided for socket outlets (not rated above 32A) in locations where they are likley to be used by persons of capabilty BA1, BA2 & BA3. There are no exceptions to this requirement.


BA1, BA2 & BA3 are explained in Appendix 5 BS7671, table B, under sub heading  ‘Utilization’ BA refers to the capability of persons. BA1 is an ordinary person (a person who is neither skilled or instructed) BA2 is children,  BA3 is disabled persons.


Which locations?

Its hard to exclude any locations, the requirement can mean all workplaces, all leisure facilities, all living accommodation, all locations, consider  schools, universities, offices, factories, hospitals, nurseries, care facilities, hotels, indoor & outdoor locations. Remember, no exceptions permitted.


Which Socket Outlets?

A socket outlet is a device, provided with contacts, which is intended to be installed to the fixed wiring, and intended to receive a plug. Socket outlets that must have additional protection by a 30mA device will include 2A, 5A, 13A, 15A, 16A, 20A & 32A. round pin. square pin, switched, unswitched, indoor & outdoor sockets.


The Solution?

Use an individual Type A 30mA RCBO on each socket outlet circuit. This will provide additional protection, avoid unwanted tripping & maintain power continuity.