Your consumer unit — the fuse board — is the nerve centre of your home's electrical system. When it fails to do its job, the consequences range from nuisance trips to genuine fire risk. Yet most South London homeowners only think about it when something goes wrong.

This guide explains the warning signs that mean your consumer unit needs replacing, what a modern upgrade involves, and what you can expect to pay in South London in 2026.

What Is a Consumer Unit and Why Does It Matter?

A consumer unit (also called a fuse board or distribution board) controls and protects every electrical circuit in your home. It houses the main switch, circuit breakers, and — in modern units — RCD (Residual Current Device) protection.

RCDs are the critical safety feature. They detect dangerous faults and cut the power in milliseconds, protecting against electric shock and fire. Older fuse boards — particularly those with rewirable fuses or early MCBs — often lack this protection entirely.

If your home was built or last rewired before 2000, there is a reasonable chance your consumer unit is no longer up to current standards.

What Are the Warning Signs You Need a New Consumer Unit?

Your Circuits Trip Frequently

An occasional trip is normal. Frequent trips — especially when you run multiple appliances — suggest your consumer unit is struggling to handle your home's electrical load. Modern homes use far more power than properties built 20 or 30 years ago, and an older board simply may not be rated for it.

You Still Have Rewirable Fuses

Rewirable fuses (the type where you replace a piece of fuse wire when something blows) are a clear sign your board is outdated. They offer no RCD protection and are significantly slower to respond to faults than modern circuit breakers. If you open your fuse board and see ceramic fuse holders with wire, it is time for an upgrade.

There Is No RCD Protection

Open your consumer unit and look for switches labelled "RCD" or "RCCB". If you cannot see any, your home lacks the protection required by current wiring regulations (18th Edition). This is a serious safety gap — particularly in kitchens, bathrooms, and outdoor circuits where the risk of electric shock is highest.

Your Board Is Showing Its Age

Signs of physical deterioration — scorch marks, a burning smell, discolouration around the casing, or a board that feels warm to the touch — are urgent warning signs. Do not ignore them. Call a qualified electrician immediately.

You Are Planning an Extension or Major Renovation

Adding new circuits for a kitchen extension, loft conversion, EV charger, or home office often requires your existing consumer unit to be assessed. If it is already at capacity or does not meet current standards, an upgrade will be required before the new work can be certified.

Your EICR Has Flagged It

An Electrical Installation Condition Report (EICR) grades defects from C1 (danger present) to C3 (improvement recommended). A consumer unit that lacks RCD protection or is in poor condition will typically receive a C2 (potentially dangerous) code — meaning it should be addressed promptly.

What Does a Consumer Unit Upgrade Involve?

A consumer unit upgrade is a straightforward job for a qualified electrician, typically completed in a single day. Here is what the process looks like:

1. Assessment — your electrician inspects the existing board and circuits to confirm the scope of work.
2. Isolation — the power is turned off at the meter (your DNO may need to be involved for older setups).
3. Removal — the old consumer unit is carefully removed and all circuits are labelled.
4. Installation — a new dual RCD or RCBO consumer unit is fitted and all circuits are reconnected.
5. Testing — every circuit is tested to confirm it is safe and correctly protected.
6. Certification — a BS 7671 Minor Works or Electrical Installation Certificate is issued, confirming the work meets current regulations.

The whole job typically takes four to six hours for a standard property.

How Much Does a Consumer Unit Upgrade Cost in South London?

Prices vary depending on the size of your property and the number of circuits, but here are typical ranges for South London in 2026:

• 1–2 bedroom flat: £450–£600
• 3 bedroom house: £550–£750
• 4–5 bedroom house: £700–£950
• Properties requiring additional work (e.g. damaged wiring, additional circuits): quoted separately

These prices include the new consumer unit, labour, testing, and certification. A reputable electrician will always provide a written quote before starting work.

Be cautious of quotes significantly below these figures — a consumer unit upgrade must be notified to your local authority under Part P of the Building Regulations, and the certification paperwork is a legal requirement.

Does a Consumer Unit Upgrade Add Value to My Home?

Yes — and it can also be a condition of sale. Mortgage lenders and surveyors increasingly flag outdated consumer units, and a C2 on an EICR can delay or derail a property transaction. Having a modern, certified consumer unit in place removes that risk entirely.

For landlords, it is also a legal requirement: rental properties must have a valid EICR, and a consumer unit that fails to meet current standards will result in a C2 or C1 code that must be remedied before the certificate can be issued.

Why Choose an NICEIC-Approved Electrician?

Consumer unit upgrades must be carried out by a Part P-registered electrician — someone who is authorised to self-certify electrical work without requiring a separate building control inspection. NICEIC-approved contractors meet this requirement and are assessed annually against the current wiring regulations.

Choosing an NICEIC-approved electrician means:

• The work is certified to BS 7671 (18th Edition)
• You receive a valid Electrical Installation Certificate
• The work is registered with your local authority
• You have recourse through the NICEIC complaints process if anything goes wrong

At Olectrics, every consumer unit upgrade is carried out by NICEIC-approved engineers and comes with full certification.

How Do I Book a Consumer Unit Upgrade in South London?

If you have spotted any of the warning signs above — or if you simply want peace of mind about your home's electrical safety — the next step is a free no-obligation quote.

We cover 24 South London boroughs including Wandsworth, Clapham, Wimbledon, Balham, Brixton, Tooting, Battersea, Putney, and Fulham. Same-day availability is often possible for assessments.

Get a free quote from Olectrics — NICEIC-approved, fully insured, and based in South London.

Frequently Asked Questions

How long does a consumer unit upgrade take?

Most consumer unit upgrades are completed in four to six hours. You will be without power for the majority of that time, so it is worth planning around it.

Do I need to notify anyone about a consumer unit upgrade?

Yes. Consumer unit upgrades are notifiable under Part P of the Building Regulations. An NICEIC-approved electrician can self-certify the work, which means they notify the local authority on your behalf as part of the job.

Will I need a new EICR after a consumer unit upgrade?

Not necessarily — your electrician will issue an Electrical Installation Certificate for the upgrade itself. However, if your existing EICR has expired or flagged other issues, it is worth addressing those at the same time.

Can I upgrade my consumer unit myself?

No. Consumer unit upgrades are notifiable electrical work under Part P and must be carried out by a registered electrician. DIY work is illegal, will not be insurable, and cannot be certified.

How do I know if my consumer unit has RCD protection?

Open the cover of your consumer unit and look for switches labelled "RCD" or "RCCB". If you only see MCBs (miniature circuit breakers) with no RCD, or if you have rewirable fuses, you do not have adequate RCD protection.