This comes up on nearly every extension. The short version for England and Wales is that certain electrical work in a dwelling is notifiable under the building regulations, and it must either be notified to your local authority building control before it starts, or carried out and self certified by an electrician registered with a government approved competent person scheme. Rules differ in Scotland and Northern Ireland, and they are revised from time to time, so treat this as orientation and confirm the current position with your own local authority building control.
Work that is commonly notifiable
As a rule of thumb, the bigger and more permanent the change to the fixed wiring, the more likely it is notifiable. Extensions almost always involve at least one item on this list.
- A new circuit added to the installation, for example a ring or radial in a new extension
- Replacement of a consumer unit
- Work in a special location such as a room containing a bath or shower
- A full or partial rewire
- New supplies to outbuildings, garden rooms and garages
Work that is usually not notifiable
Like for like repairs and additions to an existing circuit outside a special location generally sit outside notification, though they still have to comply with BS 7671 and still deserve testing and a certificate.
- Replacing a damaged socket, switch or light fitting
- Adding a socket or a lighting point to an existing circuit outside a special location
- Repairing a broken cable on an existing circuit
Two routes to sign off
Route one is a registered electrician self certifying the notifiable work through a competent person scheme, which produces a building regulations compliance certificate for you. Route two is a building notice or full plans application to the local authority, with their inspection and their charge. On an extension the building control officer is usually already involved for the structure, and the electrical items form part of the wider approval.
What you should hold at the end
Keep everything together with your build file. If you sell later, a buyer's solicitor will ask.
- An Electrical Installation Certificate with schedules of inspection and test results
- A building regulations compliance certificate for notifiable work
- A circuit schedule that matches the labels inside the consumer unit
Common questions
- Who is responsible for notifying?
- The person doing the work notifies through their scheme, or the homeowner applies to building control. Agree which route applies before the job starts.
- Does the builder handle the electrics paperwork?
- Sometimes. On many jobs the electrician certifies the electrical work and the builder handles the wider building control application.
- What if work was done years ago with no paperwork?
- An inspection and test report gives you an assessment of the current condition, though it is not a retrospective building regulations certificate.
- Where is the definitive answer?
- Your local authority building control team. Requirements change, and they confirm what applies to your address.
Send us your extension drawings and we will tell you which parts are likely to be notifiable before you commit.
Related guides
- Part P Explained for HomeownersPart P is about electrical safety in dwellings. It is shorter and simpler than most people expect.
- How Much Does It Cost to Wire an ExtensionExtension electrics are priced by scope and access, not by floor area alone.
- Do I Need a New Consumer Unit for an ExtensionSometimes yes, often no. Testing answers it rather than guesswork.