Fuse box & consumer unit guide
Consumer Unit Replacement Cost London: Fuse Box Upgrade Prices
Thinking about replacing an old fuse box? Use this guide to understand the likely costs, the checks a safe installation needs, and how to compare quotations in South London.
Published August 2026 · Updated August 2026 · Top Volt Electrical
Typical consumer unit replacement costs
A modern consumer unit is often still called a fuse box or fuseboard. The price to replace one in London varies with the number of circuits, the kind of protection required, whether the existing wiring passes inspection, and the practical details of the installation.
As a broad market guide, smaller installations can begin around £350, while a larger home with 12 or more circuits can reach £800 or more before any additional repairs. The important point is that a consumer-unit change should never be priced as a simple box swap without testing the existing installation.
| Example installation | Broad market guide | Why the price changes |
|---|---|---|
| Small home, around 6 circuits | From around £350 | Smaller board and fewer protective devices |
| Typical family home | Around £485–£650 | Circuit count, RCBO configuration, access |
| Large home, 12+ circuits | Up to £800+ | Larger board and longer testing time |
| Relocation or significant defects | Quoted after survey | Extra cabling, repairs, and making good |
Indicative market figures only. A written site-specific quote is the reliable way to budget.
What should a proper fuse box upgrade include?
Consumer-unit replacement is notifiable electrical work. The existing installation needs appropriate checks before a new unit is fitted, followed by testing and certification once the work is complete.
A clear quote should set out the board specification, circuit protection, testing, certification, VAT position, and any work that is excluded. This prevents a seemingly cheap price becoming much more expensive after work has started.
- Assessment of the condition of the existing installation.
- Supply and installation of an appropriately specified consumer unit.
- Testing and commissioning of the completed work.
- Electrical Installation Certificate and Part P compliance documentation where applicable.
Signs it is time to arrange an assessment
An old unit is not automatically unsafe, but rewireable fuses, frequent unexplained tripping, no RCD protection, heat or discolouration around the board, and a plan to add high-demand equipment are all good reasons to ask for professional advice.
A new consumer unit may be only part of the solution. If testing finds wiring defects, those should be addressed first. A qualified electrician can explain whether repair, upgrade, or more extensive rewiring is appropriate.
Questions to ask before you book
Share photographs of the current board if you can, tell the electrician about additions such as an EV charger or extension, and mention any recurring faults. Ask exactly what form of circuit protection is proposed and whether the price includes certification.
For South London homes, access and parking can also affect the visit, so flag these before the appointment. You will receive a more useful, comparable quotation when these details are covered from the start.
Market guidance: Checkatrade’s 2026 consumer unit replacement cost guide. Every property is different, so request a written quote following a site assessment.
Thinking about a fuse box upgrade?
Talk to Top Volt Electrical about a consumer-unit assessment, testing, and a clear written quotation for your South London property.
Explore consumer-unit upgradesFrequently asked questions
How much does it cost to replace a fuse box in London?
A typical consumer-unit replacement varies from roughly £350 for a small installation to £800 or more for larger homes, with the final figure depending on circuit count, wiring condition, and scope.
Do I need to rewire before changing a consumer unit?
Not always. The existing wiring must be assessed as suitable before a new consumer unit is fitted. Any defects identified during testing may need repair before the upgrade can proceed safely.
How long does a consumer unit replacement take?
A straightforward replacement commonly takes most of a working day because the work includes installation, testing, and certification. Complex work or identified repairs can take longer.
Will the electricity be off during a fuse box upgrade?
Yes. Electricity must be isolated while the old unit is removed, the new unit is installed, and the work is tested. Your electrician should explain the expected outage before work begins.