Consumer unit replacement: pricing and time on site for CIS electricians

What the market pays, and what the CIS subcontractor keeps

Quote-aggregator data for 2026 puts a UK consumer unit replacement at roughly £350 to £850 including materials and labour, with a headline average around £525 and labour alone commonly quoted at £220 to £350. Those are homeowner-facing figures gathered from job postings, not a trade rate card, and they describe a job with nothing wrong behind it.

The number that decides whether the job was worth doing is what lands in your account afterwards. On a domestic job paid direct by a householder that is the full invoice less your material cost. On a board change carried out for a main contractor it is the invoice less materials less the 20% CIS deduction on the labour element, which you recover later. This guide covers realistic time on site by scenario, the specification decisions that move the price under the current wiring regulations, the Part P notification route, and how to invoice so the deduction only ever touches labour.

Time on site by scenario: what a subcontractor should actually price

The search question "how long does it take to change a consumer unit" has one honest answer for the customer and a more granular one for the person quoting it. The variable is almost never the board itself. It is what the existing installation forces you to do before you can energise the new one.

Scenario	Realistic time on site	What drives it
Like-for-like swap, modern installation, existing certification	4 to 6 hours	Isolation, board fit, reconnection, full test schedule, certificate
Upgrade with main protective bonding to be run	Full day, occasionally two visits	Bonding runs to gas and water, access, making good
Older property, circuits unidentified, no records	Full day plus	Circuit identification, labelling, dead testing before reconnection
Board change plus remedials found on test	Second visit almost certain	Borrowed neutrals, low insulation resistance, undersized CPCs
Rented property with certification deadline	Day plus paperwork turnaround	Inspection, remedials, certificate issue to the landlord's timetable

Two commercial points follow. First, the DNO cut-out seal is not yours to break, so any job needing the supply pulled has a third-party dependency in it and should never be sold as a fixed morning slot. Second, a genuine pre-works inspection converts every one of the rows above from a risk you carry to a variation the customer approves. Price the inspection, then price the board change from what the inspection found.

Specification decisions that move the price and the CIS deduction base

The current standard is BS 7671:2018+A4:2026, published in 2026. The previous version, BS 7671:2018+A2:2022+A3:2024, remains valid until 15 October 2026, so during the transition period installers may work to either edition. Verify the position with your scheme provider before you commit a specification in writing, because a quote issued now may well be installed after the transition closes.

Three specification points carry most of the cost variance on a domestic board change:

• RCBO versus dual-RCD boards. A fully populated high-integrity or RCBO board costs meaningfully more in devices than a dual-RCD board, and quote data for 2026 puts supply-only cost for a ten-way RCBO unit well above the equivalent dual-RCD unit. The benefit is discrimination: one faulty circuit no longer takes half the house out. Present it as a priced option, not a default you absorb.
• Surge protection. Regulation 443.4 requires a risk assessment to determine whether protection against transient overvoltages is needed, and the older calculation method was removed by Amendment 2. Whichever way the assessment goes, it needs recording. An SPD adds device cost and, in a full board, sometimes a way.
• Arc fault detection devices. Under Regulation 421.1.7, AFDDs are required on single-phase AC final circuits supplying socket-outlets rated up to 32 A in higher risk residential buildings, HMOs, purpose-built student accommodation and care homes, and are recommended elsewhere with the decision documented. AFDD or combined AFDD-RCBO devices are a step change in unit cost, so an HMO board change is a different job commercially from the identical work in a family home.

All of that device cost is materials, and materials are excluded from the CIS deduction base. Our guide to CIS deduction rates and how they are applied sets out the mechanics in full.

Part P notification: the route, the cost and the allowable expenses

In England and Wales, replacing a consumer unit is notifiable work under Part P of the Building Regulations. It is one of the small number of jobs, alongside new circuits and work in special locations, that cannot simply be certified and forgotten. There are three compliance routes:

• Self-certification as a member of a registered competent person scheme, such as NICEIC, NAPIT, ELECSA or STROMA, who then notify building control on your behalf
• Certification by a registered third-party certifier
• Notification to the local authority building control body, normally before work starts, with their fee attached

Scotland runs a building warrant system rather than Part P, so confirm the position locally before quoting Scottish work. Whichever route applies, the customer should receive an Electrical Installation Certificate with the full schedule of test results, and, on the notified routes, a building regulations compliance certificate.

Your scheme membership, annual assessment fee, instrument calibration and per-notification charges are all business costs. They belong on the quote as recoverable overhead and on your tax return as allowable expenses for a CIS subcontractor, alongside mileage at the 2026/27 AMAP rate of 55p per mile for the first 10,000 business miles.

Invoicing the job: splitting labour and materials for the CIS deduction

Where a board change is carried out for a main contractor rather than direct for a householder, CIS applies. The deduction is 20% for a registered subcontractor, 30% if unregistered, and 0% with gross payment status, and it is applied to the labour element only.

Consider a twelve-way RCBO board change on a contractor-run refurbishment, invoiced at £980 excluding VAT:

Invoice line	Amount	In the CIS deduction base?
Labour: board change, testing, certification	£620	Yes
Consumer unit and protective devices	£260	No
Bonding cable, glands, sundries	£100	No
Invoice total	£980
CIS deducted at 20% on £620 labour	£124
Net payment received	£856

Invoice the same job as a single line of £980 and a contractor applying 20% across the total deducts £196, not £124. The extra £72 is not lost, but it sits with HMRC until you reclaim it, and on a run of board changes across a refurbishment contract that working capital gap becomes real. The detail is in our guide to splitting labour and materials on CIS invoices. To model the effect on a specific invoice, run the figures through the CIS invoice splitter.

One further point for contractor work: if both parties are VAT and CIS registered and the customer is not the end user, the VAT domestic reverse charge applies and you invoice without charging VAT. A householder or a landlord occupying or letting the property is an end user, so direct domestic work stays on normal VAT rules.

Adjacent work a subcontractor can sell without overreaching

A board change is the natural moment to raise the condition of everything downstream of it, which is exactly why it attracts the wrong kind of upselling. The defensible version is sequential rather than opportunistic.

Inspect first. A periodic inspection carried out and charged before the board change tells you what you are reconnecting, gives the customer a documented reason for any remedial work, and stops you absorbing pre-existing defects inside a fixed price. Our guide to pricing EICR work covers how to structure and charge that inspection.

Then quote the board change, the remedials and the options as separate priced lines. Bonding upgrades, SPD, AFDD where recommended rather than required, and additional ways for a future EV charger or solar diverter each stand on their own. Customers accept priced options far more readily than a single large number, and separate lines also keep the labour and materials split clean for CIS.

Records that support the CIS split, Self Assessment and MTD

Every board change should leave four documents behind: the certificate and test schedule, the notification confirmation, the purchase invoices for the board and devices, and your sales invoice with the labour and materials split shown. Those four are what evidence the deduction base if HMRC queries an invoice, and what make the year-end reconciliation arithmetic rather than archaeology.

From April 2026, sole traders and partnerships with gross income above £50,000 fall within Making Tax Digital for Income Tax. Gross income for that test means turnover before CIS deductions, not the net figure that reaches your bank, which catches a good number of subcontractors by surprise. Job-level record-keeping in compatible software is now the practical baseline.

Consumer unit replacement is a job where the price is set by what the existing installation forces you to do, not by the board on the van, so the inspection has to come before the fixed quote. Specify to the current standard, notify through the right Part P route, and split labour from materials on every invoice so the CIS deduction only ever touches the labour. If you want your pricing, invoicing and CIS position reviewed together, see how we work with self-employed electricians and electrical contractors.