BS 7671 18th Edition (A4:2026): A Homeowner's Guide to UK Wiring Regulations

BS 7671, also called the IET Wiring Regulations, is the UK national standard for electrical installations. It is published jointly by the IET and BSI and applies to new installations, additions and alterations to existing ones, and periodic inspection and testing.

The 18th Edition was first published in 2018 and has been updated by amendments since. The current version is BS 7671:2018+A4:2026 (often called the "Orange Book"), published on 15 April 2026.

The previous version (BS 7671:2018+A2:2022+A3:2024, the "Brown Book") remains valid until 15 October 2026. Until then, electricians may work to either version; after that date, work should follow Amendment 4.

Key areas of change include:

• Stationary secondary batteries — a new chapter covering home battery storage, with or without solar PV, including inverters, protective devices suitable for two-way energy flow, battery location, ventilation and fire-risk reduction.
• Power over Ethernet (PoE) — a new section, relevant as more lighting and smart devices are powered over network cables.
• Functional earthing for ICT equipment — a new section on earthing and bonding for IT and communications systems.
• Updates across other areas, including types of RCD, isolation and switching, EV charging installations and inspection and testing.

For most homeowners, the practical takeaway is that home batteries, solar and vehicle-to-home systems now have clear, dedicated rules — so they should only be fitted by competent installers working to the current standard.

A residual current device (RCD) switches off the power within a fraction of a second if current leaks to earth — for example through a person. The 18th Edition requires 30 mA RCD protection for most socket outlets, for lighting circuits in homes, and for mobile equipment used outdoors.

RCDs come in different types. Older "Type AC" RCDs only detect pure AC leakage; modern appliances such as washing machines, induction hobs, EV chargers and heat pumps can produce leakage that needs Type A, F or B protection. Your electrician will choose the right type for each circuit.

Tip: press the "T" test button on your RCDs every few months — they should trip straight away.

Cables buried in walls or partitions at a depth of less than 50 mm generally need additional protection — usually 30 mA RCD protection — unless they are mechanically protected. This is one reason why "safe zones" (straight up, down or across from switches and sockets) matter. Always use a cable detector before drilling.

Surges from lightning or switching on the network can damage electronics. BS 7671 requires protection against transient overvoltages where the consequences could be serious, and in practice an SPD is now fitted in most new domestic consumer units. It is a small cost that helps protect TVs, routers, boilers and smart devices.

An AFDD detects dangerous arcing — such as from a damaged cable or loose connection — that an ordinary breaker or RCD may miss. BS 7671 recommends AFDDs for final circuits supplying socket outlets up to 32 A, and requires them in certain higher-risk premises such as higher-risk residential buildings and houses in multiple occupation. They are worth discussing when replacing a consumer unit.

Bathrooms are divided into zones around the bath and shower. Each zone limits what equipment can be installed and its IP (water) rating. All circuits in a bathroom need 30 mA RCD protection. Other special locations include gardens and outdoor lighting, swimming pools, solar PV and EV charging points.

In England, Part P of the Building Regulations covers electrical safety in homes. Notifiable work includes installing a new circuit, replacing a consumer unit, and most new work in a bathroom's special location. It must be carried out by a registered competent person (who self-certifies) or notified to building control.

Keep the certificates you receive (an Electrical Installation Certificate or Minor Works Certificate, plus a building regulations compliance certificate). Solicitors often ask for them when you sell your home.

An Electrical Installation Condition Report (EICR) checks the condition of an existing installation. A common recommendation is every 10 years for an owner-occupied home and on change of occupancy. Private landlords in England must have one at least every 5 years and give a copy to tenants.

You can safely test RCDs, reset tripped breakers once, check visible flex and plugs for damage, and replace like-for-like plug fuses. Anything involving fixed wiring, the consumer unit, new circuits or bathroom electrics should be left to a competent electrician.

Planning a consumer unit replacement? Read our consumer unit guide.