Helpful video reference. We use Artisan Electrics' UK tutorial "REPLACING A NEW BUILD CONSUMER UNIT" as the video reference here. Artisan Electrics is a Cambridge-based electrical company with a large UK subscriber base. Their video covers the practical challenges of new build boards - limited ways, tight cable entries, and the decisions an electrician makes when specifying the replacement.
1. Work out why the existing board needs replacing
The most common triggers in new build homes:
- No spare ways. The developer fitted the smallest board that covered the circuits at handover. Adding an EV charger, hot tub, or battery storage means there is nowhere to put the new MCB.
- Plastic enclosure. Consumer units in domestic premises must be housed in a metal or other non-combustible enclosure under BS 7671:2018. Plastic units fitted before this requirement became standard are increasingly flagged as C3 observations on EICR reports and some insurers are beginning to ask questions.
- Persistent RCD tripping. Budget MCBs and RCDs fitted in high-volume new builds can be prone to nuisance tripping. A board with individual RCBOs for each circuit eliminates the problem of losing half the house when one circuit develops a fault.
- Planning for the future. If you are going to add solar, a battery, and an EV charger in the next few years, doing the board now means one job instead of three.
2. Choose the right replacement board
A full RCBO board - where each circuit has its own combined RCD and MCB - is the best choice for most new build replacements. Circuits are individually protected so a single fault does not affect anything else. The board costs more in components but saves diagnostic time later.
If you are adding solar panels and a battery, tell the electrician at this stage. A battery-ready board has a dedicated isolator and MCB position for the battery inverter, correctly rated and labelled. Retrofitting this later costs more than including it now.
For homes planning a heat pump, the electrician will also confirm whether the existing supply cable from the meter is adequate for the combined load.
3. Raise the Part P notification
Before work starts, the electrician either notifies the local building control department (a building notice, which costs a small fee) or uses their self-certifying scheme membership to handle notification after completion. Either way, the homeowner gets a certificate - usually a Building Regulations Compliance Certificate via the scheme - at the end of the job. Keep this with your property documents.
4. Disconnect and inspect the existing wiring
Once the supply is isolated at the meter cut-out, the old board comes off the wall. The electrician inspects each incoming cable: checking that the insulation is intact, that the earth conductors are present and of the right size, and that the cables are correctly identified. New build properties occasionally have miswired circuits or incorrectly sized protective conductors from the original installation - this is the point at which these are found and corrected.
5. Fit the new consumer unit
The new metal unit is secured to the wall, the incoming tails from the meter are connected to the main switch, and each circuit cable is terminated at its dedicated MCB or RCBO. All conductors are correctly sleeved, the neutral bar and earth bar are connected, and the unit is labelled circuit by circuit before the cover goes on.
New build homes sometimes have the meter and consumer unit together in a tight cupboard. The electrician may need to reposition the board or use a compact unit to leave enough working space around the meter for the supplier's access requirements.
6. Test and certify
With the unit assembled and covers on, the electrician runs the full sequence of dead tests (continuity of protective conductors, insulation resistance of each circuit, polarity) before reconnecting the supply. Live tests follow: RCD operating times, earth fault loop impedance for each circuit, and a prospective fault current check at the origin.
The test results are recorded on an Electrical Installation Certificate, which is issued to you at the end of the job. The whole process - disconnection, new board, testing, paperwork - typically takes four to six hours for a standard ten-to-sixteen-way domestic board.
When to call us
Richard replaces consumer units across east Kent, including preparation for solar and battery storage. He is registered with a Part P scheme so you receive the correct certification without needing a separate building notice. Small local call-outs in Sandwich are charged at the £10 per 10-minute rate; a board replacement is quoted on site.
Board replacement in Sandwich?
Richard replaces and upgrades consumer units across east Kent - contact him for a quote, including if you are planning to add solar, battery, or an EV charger at the same time.
Contact Richard