Consumer Unit Replacement London: Costs, Rules & Process

So how much does a replacement actually cost? What are the current regulations? And what does the process look like from start to finish? These are the questions most people have before they pick up the phone, and they're exactly what this guide covers. We've broken down real-world pricing, the legal requirements you need to know about (especially if you're a landlord), and each step of a typical installation so you know what to expect.

At Electrical Testing London, we carry out consumer unit replacements across London, Greater London, and the South East every week. Our engineers each have a minimum of 10 years' experience and handle everything from outdated fuse boxes in Victorian terraces to full upgrades in commercial premises. This guide draws directly from that hands-on experience, no filler, just the practical information you need to make the right decision for your property.

What a consumer unit replacement covers

A consumer unit replacement is not simply a box swap. When a qualified electrician carries out the work, they remove the old unit completely, assess the condition of the existing circuits, and install a new compliant unit that meets the current edition of BS 7671, the UK Wiring Regulations. Understanding exactly what that involves helps you ask the right questions before you book anyone.

What goes out and what comes in

The old consumer unit, whether it contains rewirable fuses, cartridge fuses, or older MCBs without RCD protection, gets disconnected and removed. In its place, the electrician fits a new unit that typically contains a main switch, one or more RCDs (Residual Current Devices), and a set of MCBs (Miniature Circuit Breakers) sized to match each circuit in your property. Modern units split into two sections, so if one RCD trips, you do not lose power to the entire property.

Regulation 132.5 of BS 7671 requires that the design of a new installation is appropriate for the intended use, which is why a replacement is always specified to your property, not taken off the shelf without assessment.

The electrician will also check that the main earthing and bonding connections meet current standards. Bonding conductors link services like gas and water pipes back to earth, and older properties often have undersized bonding that needs upgrading at the same time.

Why the wiring outside the box matters too

The circuits running from the consumer unit through your walls and ceilings are outside the box itself, but they directly affect how the new unit is configured. Before any consumer unit replacement London electricians carry out, they need to understand what circuits are present, what loads they carry, and whether any existing wiring presents a risk. Aluminium wiring, rubber-insulated cables, or cables without an earth conductor all affect what protective devices are suitable.

This is why most reputable electricians carry out a visual inspection of the installation before they quote. It is not extra work for the sake of it; it is how they make sure the new unit they install will actually protect your property correctly. In some cases, they will recommend an Electrical Installation Condition Report (EICR) alongside the replacement, particularly if the wiring has not been inspected for some time.

What you end up with after a compliant replacement is a fully documented, certificated installation that meets current safety standards and, if you are a landlord, satisfies the requirements of the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020.

Step 1. Confirm rules and hire the right electrician

Before you book anyone for a consumer unit replacement London property owners must first understand one firm rule: replacing a consumer unit is notifiable work under Part P of the Building Regulations. That means only an electrician registered with a government-approved competent person scheme can carry out the work legally and self-certify it. If someone unregistered does the job, you need to apply separately for building regulations approval through your local authority, which adds cost and delays.

Understand the competent person schemes

The schemes most widely recognised in England are NICEIC, NAPIT, and ELECSA. Registration with any of these means the electrician has been independently assessed against the current wiring regulations and carries appropriate insurance. You can verify an electrician's registration directly on each scheme's public register before you commit to anything. Ask for their registration number upfront; a genuine professional will provide it without hesitation.

If an electrician cannot give you a registration number with a recognised scheme, do not hire them for this work regardless of the price they quote.

What to confirm before you book

Once you have verified registration with a recognised scheme, there are four further checks you should complete before signing anything. A written quote protects you from unexpected costs and makes the scope of work clear from the start.

• Property type experience: a Victorian terrace with older wiring needs different decisions to a modern flat.
• Itemised quote: labour, the consumer unit itself, and any bonding upgrades should appear as separate line items.
• Public liability insurance: ask for a copy; reputable electricians carry at least £2 million cover.
• Certification confirmation: they must issue an Electrical Installation Certificate (EIC) on completion, the legal proof that the work is compliant.

Step 2. Work out likely costs in London

Pricing for a consumer unit replacement London electricians quote varies more than most people expect, and the difference between a £400 job and a £900 job usually comes down to your property, not the brand of unit fitted. Understanding what drives costs helps you evaluate quotes accurately rather than simply picking the lowest figure you receive.

What drives the price up or down

Several factors directly affect what you pay. Property size is the most obvious: more circuits mean a larger consumer unit with more MCBs, and more work to check each circuit before the electrician connects it. Bonding upgrades are another common addition, particularly in older London properties where the original bonding conductors are undersized by current standards. If the earthing arrangement needs updating or the main cable from the meter needs adjustment, that adds further labour.

Quotes that seem unusually low rarely include bonding upgrades or a post-installation test, so always confirm what is and is not covered in writing before you agree to anything.

Typical price ranges to expect

The table below reflects realistic market rates in London based on property type. These figures include labour, a standard metal consumer unit, and the Electrical Installation Certificate, but they exclude any remedial wiring work identified during the job.

Labour typically accounts for 50-60% of the total cost, so the cheapest quote does not always reflect faster work; it can mean corners cut on testing or documentation. Always confirm that the final price includes the EIC and any required notification to the competent person scheme.

Step 3. Know what happens on the day

A typical consumer unit replacement London job takes between four and six hours for a standard house or flat. Knowing the sequence of work helps you plan your day realistically, arrange access, and understand why certain stages take longer than others.

What the electrician does first

The electrician starts by isolating the supply at the meter, which means your property will have no power from that point until the new unit is connected and tested. Before removing the old unit, they label every cable so each circuit reconnects to the correct MCB in the new unit. This labelling stage takes time and is a sign of careful, methodical work, not inefficiency.

Once the new consumer unit is fitted and circuits are reconnected, the electrician runs a series of electrical tests on each circuit before restoring power. These tests check insulation resistance, earth continuity, and RCD trip times, and they are a legal requirement under BS 7671. Each circuit gets tested individually, which is why the job takes several hours even in a smaller property.

Skipping or rushing the test stage is the most common shortcut taken on cheap jobs, and it means faults can go undetected until something goes wrong.

What to prepare before they arrive

Clear access to the fuse box location and the meter is the single most useful thing you can do before the electrician arrives. Move any furniture or stored items that block the area. You should also inform everyone in the property that there will be no power for most of the working day so people can charge devices, work elsewhere if needed, and avoid repeatedly opening fridges during the outage. A bit of preparation on your side keeps the job running without unnecessary delays.

Step 4. Get certificates and keep it safe

Once the electrician completes a consumer unit replacement London job, the paperwork is just as important as the physical installation. Without the correct certificates, you cannot prove the work was done legally, which creates real problems when you sell, remortgage, or need to satisfy a landlord compliance check.

The Electrical Installation Certificate explained

Your electrician must issue an Electrical Installation Certificate (EIC) on the day they complete the work. This document, required under BS 7671, records the design, construction, and verification of the new installation. It includes the test results for every circuit, the details of the devices fitted, and the registration details of the competent person who carried out the work. Check all of these fields before the electrician leaves, because errors on the certificate are far harder to correct once they have submitted their notification to their scheme.

Keep the original EIC in a safe place and never hand it over permanently to a third party, always provide a copy instead.

Where to store your certificate and why it matters

Store your EIC alongside any previous electrical inspection reports for the property, such as earlier EICRs. If you are a landlord, the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 require you to provide a copy to existing tenants within 28 days of the work being completed, and to new tenants before they move in. Keep a digital copy in cloud storage alongside the physical original so you are not left searching for paperwork when a compliance request arrives at short notice.

For homeowners, your mortgage lender or solicitor may request the certificate during a remortgage or sale. Knowing exactly where it is saves a significant amount of time when it matters most.

Final checks

A consumer unit replacement London job is only truly complete when you have the physical installation, the test results, and the paperwork all confirmed and stored correctly. Run through this list before you consider the job closed: the new unit is a metal-clad, dual-RCD type that meets BS 7671; every circuit is labelled clearly on the unit itself; the Electrical Installation Certificate is in your hands with all fields completed; and your competent person scheme notification has been confirmed. If anything is missing, contact the electrician immediately while the job is fresh.

Landlords should also confirm that tenant notification has gone out within 28 days as required by the 2020 regulations. For everyone else, storing a digital copy of the EIC alongside the physical original is the simplest way to stay prepared. If you are ready to book or want an accurate quote for your property, request a quote from Electrical Testing London and one of our engineers will get back to you promptly.