Do You Need a New Consumer Unit? Signs, Types & What to Expect (2026)

Your consumer unit is the most important safety device in your home. Every circuit — lighting, sockets, cooker, shower, EV charger — passes through it. If it fails to disconnect a faulty circuit quickly enough, the consequences range from a damaged appliance to an electrical fire or a fatal electric shock.

Modern consumer units use circuit breakers and residual current devices that react in milliseconds. Older fuse boxes with rewirable fuses are far slower and far less reliable. If your consumer unit is more than 15-20 years old, it almost certainly lacks the level of protection that current regulations require — and that your family deserves.

This guide walks you through everything you need to know about consumer unit replacement: how to tell if yours needs upgrading, the different types available, what the installation involves, the regulations that apply, and which brands to look for. If you want to jump straight to pricing, see our full consumer unit upgrade cost guide for detailed 2026 prices.

Not every old consumer unit needs immediate replacement, but several warning signs should prompt you to arrange an inspection sooner rather than later. Some are safety-critical; others relate to compliance and capacity.

1. Rewirable Fuses

If your fuse box uses porcelain or bakelite fuse carriers with fuse wire visible inside, it dates from before miniature circuit breakers (MCBs) became standard. Rewirable fuses are imprecise — they rely on a thin wire melting to break the circuit, which is much slower than a modern MCB that trips in milliseconds. Worse, they can be fitted with the wrong rating of fuse wire (a common bodge), creating a serious fire risk because the fuse won't blow before the cable overheats.

2. No RCD Protection

Residual Current Devices (RCDs) detect earth faults — the type of fault most likely to cause electric shock — and disconnect the supply within 30 milliseconds. Consumer units installed before the mid-2000s typically have no RCD protection at all. Since the 17th Edition wiring regulations (2008), and reinforced by the 18th Edition (2018), RCD protection has been mandatory on virtually all circuits. If your consumer unit lacks RCDs, your protection against electric shock is dramatically reduced.

3. Burning Smell or Scorch Marks

Any discolouration, melted plastic, or burning odour coming from the consumer unit indicates overheating connections — a serious and immediate fire risk. Do not ignore this. Turn off the main switch if you can do so safely and call an electrician urgently. Overheating connections are one of the leading causes of domestic electrical fires in the UK.

4. Frequent or Unexplained Tripping

If your RCDs or MCBs trip regularly without an obvious cause (such as a known faulty appliance), the consumer unit or its internal components may be failing. Older RCDs can become oversensitive and trip without a genuine fault — which is dangerous in itself, because occupants eventually start leaving the RCD switched off, removing the protection entirely.

5. You Need to Add Circuits

Adding an EV charger, garden office, extension, or electric shower requires new circuits. If your consumer unit has no spare ways to accommodate them, it needs replacing with a larger board. Running out of space leads to dangerous workarounds like double-feeding circuits or connecting new loads without proper individual protection.

6. Plastic Enclosure

Since January 2016, regulations have required all new consumer units to be housed in a non-combustible (metal) enclosure. If you have a plastic consumer unit, it doesn't need replacing solely for this reason — but any modification to the unit (even adding a single circuit) triggers the requirement for a metal replacement. From a safety perspective, a metal enclosure contains any internal arc or fire and prevents it spreading to surrounding materials.

7. Unsatisfactory EICR

If an Electrical Installation Condition Report (EICR) flags your consumer unit with C1 (danger present) or C2 (potentially dangerous) observation codes, replacement is required. Common EICR findings that trigger a consumer unit upgrade include lack of RCD protection, inadequate earthing arrangements, and non-compliant or damaged components.

If you recognise any of these signs — particularly burning smells, scorch marks, or rewirable fuses — arrange an inspection with a registered electrician promptly.

Consumer units come in several configurations, each offering different levels of protection and convenience. Understanding the differences helps you have an informed conversation with your electrician and choose the right specification for your home.

Main Switch Only

The simplest type, containing just a main switch and MCBs — no RCDs or RCBOs. This offers overload and short-circuit protection on each circuit but no earth fault protection. Main-switch-only boards are no longer compliant for new domestic installations because they lack the RCD protection required by current regulations. You may still find them in older properties.

Verdict: Not suitable for new installations. If you have one, upgrading should be a priority.

Dual-RCD (Split-Load)

The most common and cost-effective option for domestic properties. Two RCDs each protect a group of circuits. If an earth fault occurs on one circuit, the RCD protecting that group trips — but it also cuts power to every other circuit in the same group. You might lose half your sockets because one appliance has a fault.

Pros: Meets all current regulations; most affordable option; widely available.
Cons: A fault on one circuit affects all circuits sharing the same RCD. Your fridge-freezer could lose power because of a faulty lamp in another room.
Best for: Budget-conscious upgrades where the priority is getting RCD protection in place.

High-Integrity (Split-Load with RCBOs)

A hybrid design where critical circuits (fridge-freezer, burglar alarm, home office, medical equipment) get individual RCBO protection, while less critical circuits share RCDs. This gives you the best balance of protection and cost — faults on RCBO-protected circuits are fully isolated, while the remaining circuits benefit from standard RCD protection.

Pros: Critical circuits are individually protected; good value compromise.
Cons: Non-critical circuits still share RCDs and can affect each other.
Best for: Most homes — particularly if you work from home or have a freezer full of food you can't afford to lose.

Full RCBO Board

Every single circuit has its own RCBO, providing completely independent protection. A fault on any circuit only trips that one circuit — everything else stays on. This is the premium option and provides the highest level of convenience and reliability.

Pros: Complete circuit isolation; maximum reliability; easiest fault diagnosis.
Cons: Higher cost (typically £150-£300 more than dual-RCD).
Best for: Homes with medical equipment, home offices, multiple high-value circuits, or anyone who wants maximum reliability.

RCBO Board with AFDDs

The highest specification available. In addition to full RCBO protection, Arc Fault Detection Devices (AFDDs) are fitted on circuits in bedrooms and living areas. AFDDs detect dangerous arc faults — caused by damaged cables, loose connections, or deteriorated insulation — that standard MCBs and RCDs cannot detect. Arc faults are a significant cause of electrical fires.

Pros: Maximum protection against both electric shock and fire; future-proof as AFDDs are likely to become mandatory.
Cons: Highest cost; AFDDs add £40-£80 per circuit.
Best for: New builds, major renovations, older properties with wiring of uncertain condition, or maximum peace of mind.

For detailed pricing on each type, see our consumer unit upgrade cost guide, or use our free consumer unit cost calculator to estimate your specific project.

Knowing what to expect on installation day helps you plan around it and understand what you're paying for. A consumer unit replacement typically takes 4-8 hours for a straightforward swap, or up to a full day if earthing upgrades or circuit modifications are needed.

Before Installation Day

Your electrician may visit for a preliminary assessment, or carry it out remotely using photographs and a detailed phone conversation. They'll check your existing installation, count circuits, assess the earthing arrangement, identify any additional work needed, and provide a fixed-price quote. This is the time to ask about board specification (dual-RCD vs RCBO), brand preference, and whether any earthing or bonding upgrades are likely.

Step 1: Power Off and Old Unit Removal (30-60 minutes)

The electricity supply is turned off at the main switch. This is unavoidable — all circuits must be disconnected from the old consumer unit and reconnected to the new one. The electrician carefully disconnects every circuit, labelling each cable to record which circuit it serves. The old unit is then removed from the wall.

Step 2: Earthing and Bonding Check (30-60 minutes)

With the unit removed, the electrician tests the earthing arrangement and main protective bonding conductors (to gas, water, and oil pipes). If the earthing is inadequate — common in older properties — it's upgraded at this stage. This might involve installing a new earth rod or upgrading the main earth conductor. Bonding upgrades (connecting gas and water pipes to earth) are also done now if needed.

Step 3: New Unit Installation (1-2 hours)

The new consumer unit is mounted (usually in the same location as the old one) and all circuits are reconnected. Each MCB, RCD, or RCBO is rated to match the cable size and load of the circuit it protects. The electrician will also install a Surge Protection Device (SPD) if required under current regulations.

Step 4: Testing (1-2 hours)

This is the most time-consuming part and the one that separates a competent electrician from a cowboy. Every circuit is tested for:

• Continuity of protective conductors: Verifying that the earth path is intact throughout every circuit
• Insulation resistance: Checking that live and neutral conductors are properly insulated from each other and from earth
• Earth fault loop impedance: Measuring whether a fault would cause the protective device to operate quickly enough
• RCD operation: Confirming that each RCD or RCBO trips within the required time (30ms at rated current)
• Polarity: Ensuring live, neutral, and earth are correctly connected throughout

Step 5: Labelling and Certification (30 minutes)

Each circuit is clearly labelled on the consumer unit door (e.g., "Kitchen sockets", "Upstairs lighting", "Cooker"). You'll receive an Electrical Installation Certificate (EIC) detailing all test results. If the electrician is registered with a competent person scheme (NICEIC, NAPIT, ELECSA), they'll also notify building control under Part P on your behalf.

Planning Your Day

Expect to be without electricity for 4-6 hours minimum. Charge phones and laptops the night before, fill a thermos, plan cold meals, and let any vulnerable household members know. Most electricians aim to restore power by mid-to-late afternoon. If you work from home, consider working elsewhere for the day or arranging mobile data backup.

Consumer unit replacement is notifiable work under Part P of the Building Regulations in England and Wales. This means it must be certified and building control must be informed. Here's what that means in practice.

The Self-Certification Route (Recommended)

If your electrician is registered with a competent person scheme — such as NICEIC, NAPIT, ELECSA, or STROMA — they can self-certify the work. This means they carry out the installation, test it, issue the Electrical Installation Certificate (EIC), and notify building control on your behalf. You don't need to do anything extra. This is included in their normal service and is by far the simplest and most common route.

The Building Control Route

If you use an electrician who is not registered with a competent person scheme, you must apply to your local authority's building control department before work starts. A building control inspector will need to inspect and approve the work, which adds delay and typically costs £200-£400 on top of the installation cost. This route is less convenient and more expensive — it's almost always better to use a registered electrician.

Why Does Part P Apply?

Consumer unit replacement involves working on the main electrical supply to your property. Incorrect installation can cause fire, electric shock, and death. Part P exists to ensure that this safety-critical work is carried out competently and tested to the required standard. The certification also protects you when selling your property — buyers and their solicitors will ask for electrical certificates.

What About Scotland and Northern Ireland?

Scotland has its own building regulations (Building Standards), and Northern Ireland is governed by the Building Regulations (Northern Ireland). The principle is similar — electrical work must comply with BS 7671 and be certified — but the notification process differs. Check with your local authority if you're outside England and Wales.

What Certificates Should You Receive?

After a consumer unit replacement, you should receive:

• Electrical Installation Certificate (EIC): Details the work carried out, the specification of the new consumer unit, and full test results for every circuit
• Building Regulations Compliance Certificate: Issued by the competent person scheme or building control, confirming the work complies with Part P

Keep both certificates safe — you'll need them if you sell the property or make an insurance claim.

The brand of consumer unit matters. Cheap units from unknown manufacturers may technically meet regulations but tend to have lower build quality, less precise trip characteristics, and shorter lifespans. Here are the brands most commonly recommended by qualified electricians in the UK.

Hager

German manufacturer with an excellent reputation among UK electricians. Hager boards are well-built, easy to work with, and offer a comprehensive range from basic dual-RCD to full RCBO configurations. Their Design 10 range is particularly popular for domestic installations. Price range: Mid-range. Warranty: Typically 2 years on components.

Schneider Electric

A global electrical manufacturer offering the well-regarded Square D and Acti9 ranges. Known for reliability and wide availability through electrical wholesalers. Good mid-range option with a strong track record. Price range: Mid-range. Warranty: 3 years on consumer units.

Wylex

A long-established UK brand, now manufactured by Electrium (part of Siemens). Wylex boards have been a staple of the UK market for decades and are well-understood by electricians. Their NMRS range (metal, dual-RCD) is one of the most commonly installed domestic consumer units in the country. Price range: Budget to mid-range. Warranty: 2 years.

MK Electric

Premium brand known for high build quality and durability. MK's Sentry range is popular in higher-specification installations and commercial properties. More expensive than Hager or Wylex but built to a very high standard. Price range: Premium. Warranty: 6 years (one of the longest in the industry).

British General (BG)

A widely available brand stocked by most DIY stores and wholesalers. BG consumer units are competitively priced and meet all regulatory requirements. They're a solid budget choice, though some electricians prefer the build quality and component precision of Hager or Schneider for more demanding installations. Price range: Budget. Warranty: 2 years.

Which Should You Choose?

In most cases, your electrician will recommend a brand they know and trust. This is usually fine — a competent electrician won't fit a substandard board. If you have a preference, discuss it before the quote is finalised. The most important factor is not the brand name but the specification (dual-RCD vs RCBO vs AFDD) and the quality of the installation and testing.

A consumer unit replacement is not just a box swap — it brings your home's electrical protection into the modern era. Here's what changes.

Safety

• Before: No RCD protection — earth faults (the type most likely to cause electric shock) go undetected until something fails catastrophically
• After: RCD or RCBO protection on every circuit, detecting earth faults in under 30 milliseconds and disconnecting before injury can occur

Fire Protection

• Before: Plastic enclosure that can melt and spread fire; rewirable fuses with potentially incorrect ratings
• After: Metal enclosure that contains any internal fire; MCBs/RCBOs with precise, factory-set trip ratings that cannot be tampered with

Convenience

• Before: A blown fuse means finding fuse wire, rewiring the carrier, and hoping you've used the right rating. Or a tripped RCD takes out half the house
• After: A tripped MCB or RCBO is reset with a flick of a switch. With an RCBO board, only the affected circuit loses power

Capacity

• Before: No spare ways for new circuits. Adding an EV charger or garden office means replacing the whole board anyway
• After: A properly specified board includes spare ways for future additions without further disruption

Surge Protection

• Before: No protection against voltage spikes from lightning or grid switching — your electronics are vulnerable
• After: An integrated SPD absorbs transient overvoltages before they reach your appliances and devices

Compliance and Property Value

• Before: An outdated consumer unit will almost certainly result in C2 codes on an EICR — a potential issue when selling or letting the property
• After: Full compliance with BS 7671 18th Edition, with certificates to prove it. One less thing for a buyer's surveyor to flag

While this guide focuses on helping you decide whether you need a new consumer unit and what type to choose, here's a quick pricing overview for 2026.

A consumer unit replacement typically costs £250-£1,200 depending on the specification:

• Dual-RCD board: £350-£500 (most affordable, meets all regulations)
• Full RCBO board: £500-£800 (every circuit individually protected)
• High-integrity with AFDDs: £700-£1,200 (maximum protection)

These prices include the unit, installation, full testing of all circuits, and Part P certification. London and South East prices are typically 20-30% higher.

Additional costs may apply for earthing upgrades (£100-£250), bonding upgrades (£100-£250), meter tail replacement (£100-£250), or relocating the consumer unit (£300-£600).

For a comprehensive breakdown of all costs, factors that affect pricing, and tips on saving money, see our full consumer unit upgrade cost guide for 2026. You can also use our free consumer unit cost calculator to get an estimate tailored to your property.