What to expect from a consumer unit upgrade

Helpful video reference. We use Artisan Electrics' video "A MAJOR ELECTRICAL TRANSFORMATION! - Consumer Unit Upgrade" as the visual reference here. Artisan Electrics is a Cambridge-based electrical company and one of the UK's best-known electrical YouTube channels. Their video shows a real-world consumer unit changeover carried out to current 18th Edition standards, which gives a clear sense of the scale and sequence of the work.

1. Book an EICR before the quote is finalised

Before specifying a new board, a thorough electrician will want to know the condition of the circuits they are connecting to it. An Electrical Installation Condition Report (EICR) classifies faults as C1 (danger present, immediate action required), C2 (potentially dangerous) or C3 (improvement recommended).

Some electricians include the EICR cost in the consumer unit quote. Others charge separately. Either way, see the results before work starts. Any C1 or C2 faults have to be fixed before the new board can be certified, and discovering them on the day adds time and cost to the job.

2. Understand what the new board must include

Since 2016, all new consumer unit installations in domestic properties must use a metal-clad enclosure. Plastic consumer units were withdrawn for new installations because internal arcing could ignite the plastic casing. Existing plastic-clad boards remain legal until they need replacing.

A compliant modern domestic board will typically provide:

• 12 or more ways for individual circuit breakers, with at least one or two spare ways for future additions.
• Individual RCBOs on each circuit. A combined RCD and MCB in one device means a fault on one circuit only drops that circuit, not the whole floor or house.
• Type 2 surge protection device (SPD), now the default under Amendment 2 of BS 7671:2018 for new consumer unit installations, protecting electronics from voltage spikes on the supply.
• Main isolation switch giving a single point to disconnect all circuits safely for future maintenance.

3. Confirm your electrician is Part P registered

Ask to see registration with NAPIT, NICEIC, ELECSA or another government-approved competent person scheme before work starts. A registered electrician self-certifies the work directly to your local Building Control, so the compliance certificate is included. If your electrician is not registered, you need to apply for a building notice from your local authority and pay the associated fee yourself, before the job begins.

Unregistered electrical work on a consumer unit shows up on conveyancing searches. Buyers and their solicitors will ask questions, and the absence of a Part P certificate can hold up or derail a house sale.

4. Prepare the property for the day

The supply will be off for most of the working day, usually from early morning until late afternoon. Charge laptops, phones and tablets the night before. If you work from home, plan around the outage or arrange to work elsewhere. Most fridge-freezers cope fine for a single day powered off, but check yours. Move anything heat-sensitive out of appliances that rely on continuous power.

Clear the area around the consumer unit. The electrician needs unobstructed access to the board and ideally a clear metre around it. Move any shelving, clutter or stored items before they arrive.

5. What happens at the DNO cut-out

The cut-out is the sealed fuse immediately ahead of your meter. It belongs to your Distribution Network Operator (UK Power Networks in Kent and east Sussex) and carries the full incoming supply from the street. Only the DNO or a qualified person with the correct authorisation can open that seal.

For most straightforward consumer unit changes on properties with adequate meter tail length, the electrician works at the consumer unit side without needing to break the DNO seal. Where tails are too short, the arrangement is awkward, or the metering needs adjustment, the DNO may need to attend first. This adds lead time, so a good electrician raises it during the survey stage rather than on the day.

6. Old board out, new board in

With the supply isolated, the electrician works through each circuit in turn: disconnecting from the old board, checking the cable sheathing and insulation condition, resleeving earth conductors where needed, and connecting to the new unit. Each circuit is labelled as it is connected. A standard three-bedroom house has between eight and twelve circuits, and this stage takes the bulk of the working day.

If the incoming meter tails are in poor condition, the earthing electrode or main bonding conductors are substandard, or a circuit has a fault that was not caught by the EICR, remedial work happens here. This is the main reason to insist on the EICR first: surprises at this point cost both time and money.

7. Verification testing before the board goes live

Before switching anything back on, the electrician works through a full schedule of tests on every circuit:

• Continuity of the circuit protective conductors and, on socket circuits, the ring final.
• Insulation resistance at 500 V DC, checking for any breakdown between conductors or to earth.
• Polarity confirmed both at the consumer unit and at the furthest point of each circuit.
• Earth fault loop impedance (Zs) at the furthest point, compared against the maximum values in BS 7671 Table 41.2 for TN systems or Table 41.4 for TT systems.
• RCD and RCBO operation tested with the loop tester at the rated trip current, confirming correct trip time. The test button alone is not sufficient for a verification schedule.

All results go onto the schedule of test results, which forms part of your certification pack.

8. Certification and Building Regulations sign-off

At the end of the job you should receive three documents:

• An Electrical Installation Certificate (EIC) signed by the electrician, describing the installation and confirming it was designed, installed and inspected by the same registered person.
• A Schedule of Test Results covering every circuit, with the measured values recorded against BS 7671 limits.
• A Building Regulations Compliance Certificate from the Part P scheme, usually issued within a few weeks and also sent to your local Building Control office.

Keep all three documents. Your solicitor will ask for them when you sell the property. Without them you may need to commission an EICR to demonstrate the installation is safe, which costs money and can delay completion.

When to call us

Richard carries out consumer unit replacements across Sandwich, Deal, Dover, Ramsgate and the surrounding villages. The standard job includes an EICR of the existing circuits, the supply of and fitting of a metal-clad consumer unit with individual RCBO protection and a Type 2 SPD, full verification testing, the Electrical Installation Certificate and schedule of test results, and Part P notification. Send a WhatsApp photo of your current board for a written quote, usually within 24 hours.