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 is one of the most important decisions in any electrical installation. Whether you’re upgrading an older fuse board, fitting out a new build, or carrying out a renovation, the consumer unit sits at the heart of your electrical system.

It controls, protects and distributes power throughout the property. Get it right, and you ensure safety, compliance and long-term reliability. Get it wrong, and you risk nuisance tripping, limited capacity or even failing to meet UK regulations.

RCDs, RCBOs and surge protection explained

Why compliance with UK regulations matters

 (sometimes called a fuse board) distributes electricity from your mains supply to individual circuits around your property.

Each circuit – such as lighting, sockets or cooker supply – is protected by a protective device that isolates the circuit if a fault occurs.

If you're replacing an older fuse box with rewireable fuses, upgrading to a modern unit significantly improves safety.

Not all consumer units are the same. The right choice depends on the size of the installation, level of protection required and current wiring regulations.

A split-load unit divides circuits across two banks. One side is protected by an RCD, while the other may be protected separately.

Suitable for smaller domestic installations

If the RCD trips, multiple circuits lose power at once

These are often used in standard domestic properties where budget and simplicity are key considerations.

Dual RCD units divide circuits across two RCDs. If one trips, the other half of the board stays live.

This is a popular choice for domestic properties and extensions.

RCBO boards provide individual RCD protection on each circuit. This means one fault won’t affect other circuits.

Ideal for modern homes with multiple appliances

These are increasingly common in new builds and higher-spec installations.

High integrity boards combine RCBOs and dual RCD protection. They are ideal where certain circuits (like alarms or freezers) need extra reliability.

Since the introduction of the 18th Edition Wiring Regulations (BS 7671), 

metal consumer units are now standard in domestic installations

✔ Fire-resistant
✔ Compliant with current regulations
✔ Required in most new installations

✖ Generally only suitable for specific non-domestic or replacement scenarios
✖ Not compliant for most new domestic installs

If you are installing a new unit in a domestic property, you should choose a 

Understanding RCDs, RCBOs and Surge Protection

An RCD (Residual Current Device) cuts power if it detects an imbalance in electrical current – helping prevent electric shock and fire risk.

An RCBO combines the following into a single device for individual circuit protection:

Surge Protection Devices (SPDs) protect against voltage spikes caused by lightning strikes or switching surges.

Under the 18th Edition regulations, SPDs are required in most domestic installations unless a risk assessment confirms they are not necessary.

Given the increase in sensitive electronics and smart home technology, SPDs are strongly recommended.

Sizing a consumer unit isn’t just about physical size. It’s about ensuring enough capacity for:

High-demand appliances (EV chargers, electric showers, heat pumps)


Count existing circuits and allow spare ways for future additions.


Calculate expected electrical load to ensure the main switch rating is sufficient (typically 100A in domestic installations).


Consider planned upgrades such as EV charging or solar PV systems.


Ensure the installation location complies with access and ventilation requirements.

Choosing a slightly larger board with spare capacity is often a smart long-term decision.

Why Choosing the Right Consumer Unit Matters

A properly specified consumer unit reduces:

How to Choose the Right Consumer Unit for Your Project

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