Replacing a consumer unit is an alteration to that installation. Additions and alterations are classed as new work. The work must therefore be designed, erected and verified in accordance with the requirements of the current edition of BS 7671, as amended (Regulation 110.1.2(vi)) and must not impair the safety of the existing installation (Regulation 610.4). On completion of the verification of the work and Electrical Installation Certificate must be issued (Regulation 631.1) BS 7671 does not require existing circuits to be upgraded to current standards in order for them to be connected to the outgoing ways of the replacement consumer unit. However, circuits that are defective or non-compliant with the requirements of BS 7671 in a way that would result in immediate or potential danger must not be reconnected to the consumer unit. Where a consumer unit is being replaced, additional protection by means of RCD‘s in accordance with Regulation 415.1 must be provided to the extent required by the current edition of BS 7671, as amended, such as for:
  • socket-outlets (Regulation 411.3.3)
  • mobile equipment for use outdoors (Regulation 411.3.3)
  • cables concealed in floors, ceilings, walls or partitions (Regulations 522.6.201 to 203 as appropriate)
  • low voltage circuits serving a location containing a bath or a shower or passing through the zones of the location (Regulation 701.411.3.3)
Circuits that are to be provided with RCD protection must be divided between a sufficient number of RCD’s or otherwise designed as necessary to avoid hazards and minimise inconvenience in the event of a fault (Regulation 314.1 and 314.2)