A consumer unit replacement swaps your old fuse box or outdated board for a modern unit with RCD protection, so faults that could cause electric shock or fire are cut off within a fraction of a second. In most homes the job takes between a few hours and a day, and because it is notifiable under Part P of the Building Regulations it must be done by a registered competent person. Polarity Electrics is an NICEIC Approved Contractor and handles the installation, testing, certification and building control notification for you.
Do you need a fuse box replacement?
Not every older board needs replacing immediately, but there are common signs that it is time:
- Rewireable fuses – the old ceramic carriers with fuse wire offer no RCD protection and are easy to refit with the wrong wire.
- No RCD protection on sockets, or a single RCD that trips the whole house when one appliance develops a fault.
- Plastic enclosure – since Amendment 3 to the 17th Edition in 2016, consumer units in homes must have a non-combustible enclosure, typically metal.
- An EICR has flagged the board with C2 or C3 observations relating to protection or condition.
- Signs of heat damage, such as scorching, a burning smell, buzzing or a board that feels warm.
- You are adding circuits such as an EV charger, electric shower or extension and there is no spare capacity.
If you are unsure, an inspection will tell you. Our EICR service assesses the whole installation, including the consumer unit, and gives clear recommendations.
What's included
- A pre-installation check of the existing installation, earthing and bonding
- A new metal consumer unit from a reputable manufacturer, sized for your circuits with sensible spare capacity
- RCBO or dual-RCD configuration to suit your home and budget, plus surge protection where required by BS 7671
- Upgrading main protective bonding to gas and water pipes where it does not meet current standards
- Full testing of every circuit after installation
- Clear labelling of every circuit
- An Electrical Installation Certificate and building control notification under Part P
- Removal and disposal of the old fuse box
RCBOs or a dual-RCD board?
A dual-RCD board groups circuits under two RCDs. It is a cost-effective option, but a fault on one circuit can trip several others. An RCBO board gives each circuit its own combined overload and earth fault protection, so a fault only switches off the affected circuit. We will explain the differences in your quote and let you choose.
Consumer unit replacement pricing
We give a fixed written quote after understanding your property, so you know the full cost before we start. As a guide, the figures below are typical London market ranges rather than our published prices:
| Type of job | Typical London market range |
|---|---|
| Like-for-like dual-RCD board, small flat | £450 – £700 |
| RCBO board, typical 2–3 bed home | £650 – £1,000 |
| Larger home or board with extra circuits | £900 – £1,400+ |
The final price depends on the number of circuits, whether bonding needs upgrading, the condition of existing wiring and access to the meter position. Testing occasionally uncovers faults on existing circuits that must be fixed before a new board can be certified; if that happens we explain the issue and agree any extra cost with you before carrying on. Read our consumer unit replacement cost guide for more detail.
How the process works
- Quote – send photos of your current board via WhatsApp or book a visit, and we provide a fixed written quote.
- Booking – we agree a date. Power will be off for most of the job, so we will tell you how long to plan for.
- Pre-checks – we test the existing circuits so any hidden faults are found before the changeover.
- Installation – the old board is removed and the new unit fitted, connected and labelled.
- Testing and handover – every circuit is tested, we show you how the board works and how to reset a trip.
- Certification – you receive your Electrical Installation Certificate and building control notification follows.
Many straightforward replacements are completed in as little as 2 hours, while larger or more complex boards take longer.
Why choose Polarity Electrics
- NICEIC Approved Contractor (Enrolment No. 602034000) and Part P registered, so we self-certify and notify building control
- 8+ NICEIC-certified engineers and more than 5,000 jobs completed
- Metal enclosures as standard, compliant with current regulations
- No call-out charge and a fixed written quote before work begins
- 12-month workmanship guarantee and £10M public liability insurance
- Tidy, respectful engineers who explain what they find in plain English
Landlords can combine a consumer unit replacement with remedial work from an unsatisfactory EICR. Once the work is complete, you receive the paperwork you need to give written confirmation to tenants and the council. See what to do after an unsatisfactory EICR.
Areas covered
We replace consumer units across London and the Home Counties, including North London, South London, East London, West London, Barnet, Enfield, Ealing and Wandsworth, as well as Hertfordshire, Essex, Surrey and beyond. See our full list of areas covered.
Related services
- EICR London – find out whether your board and wiring need attention
- House rewiring – if the wiring itself is past its best
- EV charger installation – often installed alongside a board upgrade
- Emergency electrician – for trips you cannot reset or a burning smell
Ready to replace your fuse box? Call 0203 908 4790, WhatsApp photos of your board to +44 7932 046977, or book online for a fixed written quote.
Frequently asked questions
How long does a consumer unit replacement take?
A straightforward replacement can take as little as 2 hours, while larger boards or homes needing bonding upgrades can take most of a day. We confirm the expected time in your quote.
Do I need building control approval to replace a fuse box?
Consumer unit replacement is notifiable under Part P of the Building Regulations. As an NICEIC registered contractor we self-certify the work and notify building control on your behalf.
Does my new consumer unit have to be metal?
Yes. Since Amendment 3 to the 17th Edition in 2016, consumer units in homes must have a non-combustible enclosure, which in practice means metal.
How much does a consumer unit replacement cost in London?
Typical London market ranges run from around £450 for a small like-for-like board to £1,400 or more for larger RCBO installations. We give a fixed written quote before starting.
Will I be without power during the work?
Yes, the supply has to be isolated while the board is changed. We tell you in advance how long to expect and restore power as soon as testing allows.
What if testing finds faults on my existing circuits?
Some faults must be fixed before a new board can be certified. We explain what we have found and agree any extra cost with you before carrying on.