Amendment 3 to Amendment 4: What Changes Today and What Does It Mean for Your Electrical Installation?

15 October 2026 | Eco-ESSIn this article, we discuss the key changes introduced by Amendment 4 Wiring Regulations and what they mean for industry professionals.

Today marks an important change for the UK electrical industry.

As of 15 October 2026, Amendment 4 of the 18th Edition Wiring Regulations (BS 7671:2018+A4:2026) becomes the current standard, replacing the previous version incorporating Amendment 3.

But what has actually changed, and what does it mean if you already have solar panels, battery storage or are planning a renewable energy installation?

At Eco-ESS, we’re breaking down the changes, what they mean for homeowners and installers, and why the way we design electrical installations is evolving.

First, what is the difference between Amendment 3 and Amendment 4?

The IET Wiring Regulations, known as BS 7671, set the national standard for electrical installations across the UK.

These regulations are regularly updated to reflect new technology, changing safety requirements and how electricity is used.

Amendment 3 (2024) introduced additional requirements, including updates relating to electrical safety and protective devices.

Amendment 4 (2026) builds on those existing regulations, introducing further requirements for emerging electrical technologies.

One of the most significant changes for the renewable energy industry is the introduction of a dedicated chapter covering stationary battery storage systems.

It also includes important changes relating to electrical systems with multiple power sources, bidirectional electricity flow and the selection of suitable protection equipment.

Put simply, electrical installations are becoming more complex, and the regulations are evolving to reflect this.

Why are the regulations changing?

Think about how electricity worked in a traditional home.

Power came from the national grid, entered your property through the electrical supply and was distributed to the circuits that needed it.

Today, your property might have:

• Solar panels generating electricity
• A battery storing electricity for later use
• An electric vehicle charger
• A heat pump
• Backup power during a grid outage
• Electricity supplied by the national grid

Rather than relying on one source of electricity, modern homes can generate, store and distribute power in different ways.

This means electricity may flow in more than one direction, and different sources may operate together.

Amendment 4 places greater emphasis on ensuring electrical installations are designed to accommodate these modern energy systems safely.

What changes for home battery storage?

One of the most relevant updates is the introduction of Chapter 57 – Stationary Secondary Batteries.

Previously, battery storage requirements were addressed through other parts of the Wiring Regulations.

Amendment 4 introduces a dedicated chapter, providing clearer requirements for the installation and integration of stationary batteries.

The considerations include:

• Where battery storage equipment is installed
• Suitable ventilation and thermal management
• Fire safety and equipment protection
• Electrical isolation and protective devices
• How batteries interact with inverters and other electrical supplies

Does this mean batteries now have to be installed outside?

No. Amendment 4 does not introduce a blanket requirement for every domestic battery to be installed outdoors.

However, the location of a battery remains an important safety consideration.

Depending on the property, equipment and installation requirements, locating battery storage externally may offer practical advantages.

Eco-ESS provides external battery and inverter enclosures, designed to support safer outdoor installation arrangements with features including temperature-controlled ventilation and protection from the elements.

What about your consumer unit?

Your consumer unit, sometimes referred to as your fuse box, is responsible for distributing electricity safely throughout your property.

Traditionally, many consumer units were designed around electricity being supplied from one main source.

But what happens when a property also has solar panels supplying electricity, a battery providing stored energy and potentially other sources operating alongside the grid?

The electrical system needs to be assessed to ensure the equipment and protective devices are suitable.

Amendment 4 includes updated requirements covering these arrangements, including how multiple electricity sources are connected and how protective devices respond to electricity flowing in different directions.

Does this mean everyone needs a new consumer unit?

No.

However, if you’re planning to install solar panels, battery storage or additional renewable energy equipment, your installer will need to assess whether your existing electrical distribution system is suitable.

In some circumstances, additional or upgraded distribution equipment may be required.

Eco-ESS offers renewables distribution solutions designed to support the safe integration of multiple energy sources.

What does Amendment 4 mean for existing solar and battery installations?

If you already have solar panels or battery storage installed, there’s no need to assume your system suddenly becomes unsafe or non-compliant.

Electrical regulations are not automatically retrospective.

An installation completed correctly under the standards applicable at the time does not necessarily require upgrading simply because the regulations have changed.

However, if you’re planning to expand or modify your installation, the relevant requirements of Amendment 4 need to be considered.

For example, you may be:

• Adding battery storage to an existing solar PV system
• Increasing your battery storage capacity
• Installing backup power functionality
• Adding additional energy generation equipment
• Relocating your battery or inverter
• Upgrading your electrical distribution equipment

In these situations, a qualified installer should assess the complete installation and identify whether any changes are necessary.

What about solar PV protection?

Another important consideration for modern installations is ensuring suitable electrical protection is in place.

Solar PV systems operate using direct current (DC), and their design requires careful consideration of isolation, equipment suitability and surge protection.

Amendment 4 includes updated requirements relevant to systems incorporating multiple electricity sources and bidirectional power flow.

For installers, this reinforces the importance of selecting the correct protective equipment for the installation.

Eco-ESS offers pre-wired DC isolators incorporating surge protection devices, helping installers simplify installation and integrate appropriately selected protection.

Surge protection requirements depend on the individual installation and should always be assessed against the applicable standards.

How Eco-ESS is supporting the transition to Amendment 4

The way we generate and use electricity is changing, and the infrastructure supporting it needs to evolve too.

At Eco-ESS, we specialise in practical electrical solutions that help installers and customers integrate renewable energy technology safely and effectively.

Our product range includes:

• External Battery & Inverter Enclosures: Supporting suitable outdoor installation arrangements with protective housing and temperature-controlled ventilation.
• Universal Gateway & Automatic Transfer Solutions: Helping integrate compatible backup power arrangements.
• Pre-wired DC Isolators with Surge Protection: Supporting safe and efficient solar PV installations.
• Renewables Distribution Boards: Designed to support the electrical distribution requirements of modern renewable energy systems.
• Battery & Inverter Relocation Solutions: Supporting customers who need to review or improve their existing equipment location.

While individual products can support the requirements of modern installations, compliance with BS 7671 always depends on the design, equipment selection and installation as a whole.

The future of electrical installations starts with safer infrastructure

The transition from Amendment 3 to Amendment 4 marks another step forward for the electrical industry.

With renewable energy technology becoming an increasingly important part of UK homes, electrical installations need to be designed for more than traditional grid supply alone.

For homeowners, the changes bring a clearer framework around modern electrical technologies.

For installers, they reinforce the importance of understanding how battery storage, solar PV, protective equipment and multiple electricity sources work together.

At Eco-ESS, we’re engineering safer, more resilient home energy systems for the future.

Whether you’re an installer preparing for Amendment 4 or a homeowner planning your next renewable energy upgrade, our team can help you explore suitable solutions.

Get in touch with Eco-ESS to discuss your installation requirements or explore our renewable energy product range.

For detailed installation and compliance requirements, consult BS 7671:2018+A4:2026, relevant manufacturer instructions and a suitably qualified electrical professional.