Consumer unit replacement
Plain English. Practical detail. UK context.
Consumer unit replacement changes the distribution and protective equipment serving an electrical installation. It is more than swapping a box: existing circuits, earthing, bonding, supply arrangements and protective-device selection all need assessment. Replacing the unit does not replace hidden wiring or automatically resolve every fault on connected circuits.
Safety: use a registered electrician, for example one registered with a competent person scheme such as NICEIC or NAPIT, for electrical installation work. Do not remove covers or open electrical equipment yourself.
Last reviewed: (editorial review against the public sources listed below).
What the electrician assesses
A survey should identify the circuits, the condition of the existing equipment and any work needed before safe reconnection. Earthing and protective bonding need particular attention. Modern protection can expose existing faults that an older arrangement did not reveal in the same way. Discuss these possibilities before the work begins rather than assuming the quoted enclosure is the entire job. Access, available space and safe arrangements for isolating the incoming supply also matter.
Specification and installation
The specification may use individual RCBOs, other suitable RCD arrangements and surge protection, depending on design requirements. Protective devices must be compatible with the assembly; mixing products because they appear to fit can undermine the manufacturer’s verified arrangement. The designer should explain any arc fault detection requirements relevant to the building. A neat finish is useful, but correct cable entry, connections, labels and verification are more important than an attractive photograph of a closed lid.
Paperwork and notification
An Electrical Installation Certificate with the relevant schedules is the appropriate certification for the replacement work; an EICR is not the replacement installation certificate. In England, consumer unit replacement is notifiable under Part P. Agree the compliance route and who supplies the building regulations notification evidence. Other UK nations have their own procedures. Ask for a legible circuit schedule and an explanation of user-operated test buttons and reset arrangements at handover.
Common mistakes and alternatives
Do not buy the largest advertised board before a survey or assume the lowest number of devices gives equivalent protection. A targeted repair or a designed additional distribution arrangement may be appropriate in some circumstances, while serious wiring defects may require broader work. An electrician should justify the recommendation from the installation’s condition and intended use. There is no universal replacement age that decides every case. Keep the certificates with the property records for future alterations and inspection.
A useful question before accepting the scope
Ask: what assessment of the existing circuits is included before replacement, and how will unexpected defects be handled? Also identify supplies that must not be interrupted without a plan, such as essential medical equipment. A promise to change the box in a fixed time is not a substitute for this preparation.
Frequently asked questions
Will this make all existing wiring new?
No. Existing circuits remain unless the agreed scope includes their replacement.
Should I get an EICR or an installation certificate?
The replacement needs installation certification. An earlier EICR may inform the scope, but is a separate document.
Can I select the board from an online photograph?
A photograph cannot establish circuit condition, supply adequacy or the complete protective design.
Sources and further reading
Public sources and further reading. Sources checked: 8 November 2026. Consult the original for details and later changes.