The consumer unit – often still called a fuse box – is the heart of your home's electrical system. It's where electricity enters your home and is distributed to individual circuits. Yet despite its importance, many homeowners have outdated consumer units that lack modern safety features. If your home still has an old fuse box with rewirable fuses, or even an early MCB board without RCD protection, upgrading to a modern consumer unit could be one of the most important safety improvements you make to your home.
What Is a Consumer Unit?
A consumer unit is the box where your electricity supply is controlled and distributed throughout your home. It contains protective devices that automatically cut the power if something goes wrong, preventing electrical fires and electric shocks. Modern consumer units contain several types of protective devices:
- Main Switch: Allows you to turn off all electricity to your home
- MCBs (Miniature Circuit Breakers): Protect individual circuits from overloads and short circuits
- RCDs (Residual Current Devices): Detect earth faults and protect against electric shock
- RCBOs (Residual Current Breaker with Overcurrent): Combine MCB and RCD protection in one device
Why Upgrade Your Consumer Unit?
Enhanced Safety
The primary reason to upgrade is safety. Modern consumer units include RCD protection, which can detect when electricity is flowing where it shouldn't (such as through a person) and cut the power in milliseconds. This can literally be the difference between life and death in the event of an electrical fault.
Older fuse boxes with rewirable fuses offer no RCD protection and can be easily fitted with the wrong fuse rating, creating a fire risk. Even early MCB boards often lack adequate RCD protection.
Compliance with Regulations
The 18th Edition of the Wiring Regulations (BS 7671) requires that all new installations and significant alterations include RCD protection for socket outlets and certain other circuits. If you're having any electrical work done, you may be required to upgrade your consumer unit to comply with current regulations.
Insurance Requirements
Some insurance companies are increasingly reluctant to cover properties with outdated electrical installations. Having a modern, compliant consumer unit can help ensure your home insurance remains valid and may even reduce your premiums.
Capacity for Modern Living
Older consumer units often don't have enough circuits for modern electrical demands. Upgrading gives you the opportunity to add circuits for things like:
- Electric vehicle chargers
- Home offices
- Garden rooms or outbuildings
- Additional kitchen appliances
- Smart home systems
Types of Consumer Unit
Split-Load Consumer Unit
This is the most common type in domestic properties. It has a main switch and one or more RCDs, each protecting a group of circuits. If an RCD trips, only the circuits it protects lose power – the rest of your home remains live.
Dual RCD Consumer Unit
A specific type of split-load unit with two RCDs, each protecting half of your circuits. This provides good protection while ensuring that a single fault doesn't plunge your entire home into darkness.
High Integrity Consumer Unit
These use RCBOs (combined RCD/MCB devices) for each circuit, providing the highest level of protection. If one circuit trips, all others remain unaffected. This is the premium option and is particularly useful for larger homes or where continuity of supply is important.
Main Switch Only Consumer Unit
Contains only a main switch and MCBs, with no RCD protection. These are no longer compliant for new installations but may be found in older properties. If you have one of these, upgrading should be a priority.
What Does a Consumer Unit Upgrade Involve?
A consumer unit upgrade typically takes half a day to a full day, depending on the complexity of your installation. The process involves:
- Assessment: The electrician will assess your current installation and discuss your requirements
- Isolation: Power to your home will be turned off at the meter
- Removal: The old consumer unit is carefully removed
- Installation: The new consumer unit is fitted and all circuits connected
- Testing: Comprehensive testing ensures everything works correctly
- Certification: You'll receive an Electrical Installation Certificate
Our fuse box replacement service includes all of these steps, plus notification to building control as required by Part P of the Building Regulations.
Consumer Unit Upgrade Costs
The cost of a consumer unit upgrade varies depending on several factors:
- Type of unit: High integrity units with RCBOs cost more than standard split-load units
- Number of circuits: More circuits require a larger unit
- Condition of existing wiring: If remedial work is needed, this adds to the cost
- Location: Accessibility of the existing unit affects labour time
As a rough guide, expect to pay between £400 and £700 for a standard domestic consumer unit upgrade, including the unit, installation, testing, and certification. High integrity units with RCBOs will be at the higher end of this range or above.
Signs You Need a Consumer Unit Upgrade
Consider upgrading your consumer unit if:
- You have an old fuse box with rewirable fuses
- Your consumer unit lacks RCD protection
- You're experiencing frequent tripping
- You're adding new circuits (e.g., for an EV charger)
- You're having other significant electrical work done
- Your EICR has identified the consumer unit as unsatisfactory
- You're buying or selling a property
If you're unsure whether your consumer unit needs upgrading, an EICR inspection will assess its condition and identify any issues.
Regulations and Certification
Consumer unit replacement is notifiable work under Part P of the Building Regulations. This means it must either be:
- Carried out by an electrician registered with a competent person scheme (like NICEIC or NAPIT), who can self-certify the work
- Notified to your local building control department, who will inspect the work
Using a registered electrician is usually the simpler and more cost-effective option. You should receive an Electrical Installation Certificate upon completion, which you should keep safe – you'll need it if you sell your property.
Metal vs Plastic Consumer Units
Since January 2016, regulations have required consumer units in domestic properties to be made of non-combustible material (typically metal) or be enclosed in a non-combustible cabinet. This is because consumer units are a potential source of fire, and metal enclosures help contain any fire that does occur.
If you still have a plastic consumer unit, it doesn't necessarily need immediate replacement, but when you do upgrade, the new unit will be metal.
Surge Protection
The latest edition of the Wiring Regulations recommends surge protection devices (SPDs) in consumer units. These protect your electrical equipment from voltage spikes caused by lightning strikes or switching operations on the power grid. While not mandatory for all installations, SPDs are increasingly common and worth considering, especially if you have expensive electronic equipment.
Our surge protection service can add this valuable protection to your installation.
Conclusion
Your consumer unit is the guardian of your home's electrical safety. While it might not be the most exciting home improvement, upgrading an outdated consumer unit to a modern unit with full RCD protection is one of the most important things you can do to protect your family and property.
If you're unsure about the condition of your consumer unit, or if you know it's due for an upgrade, contact a qualified electrician for an assessment. The peace of mind that comes from knowing your electrical system is safe and compliant is invaluable.
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