BS 7671 — also known as the IET Wiring Regulations — is the national standard for electrical installations in the UK. Every qualified electrician works to this standard, and understanding the basics helps you make sense of certificates, inspection reports and conversations with your electrician.
What Is BS 7671?
BS 7671 is published by the Institution of Engineering and Technology (IET) and the British Standards Institution (BSI). It specifies requirements for:
- Design and installation of electrical systems
- Selection and installation of electrical equipment
- Inspection and testing procedures
- Documentation and certification
The current edition is BS 7671:2018+A2:2022 — commonly called the 18th Edition (with its 2022 amendment). Electricians refer to this as "the Regs" or "the Wiring Regulations."
What Does BS 7671 Cover?
The standard covers every aspect of domestic electrical installations:
- Cable sizing — the correct cable cross-section for each circuit based on load and installation method
- Circuit protection — what type of MCB or fuse is required, and the correct rating
- RCD protection — which circuits require RCD protection (and since Amendment 2, surge protection)
- Earthing and bonding — how the installation connects to earth and how metalwork is bonded
- Special locations — additional requirements for bathrooms, kitchens, swimming pools, outdoor circuits and more
- Testing requirements — what tests must be carried out and what the acceptable values are
How It Affects Your Home
When an electrician installs new wiring or carries out an EICR, they are checking against BS 7671. Observation codes on an EICR (C1, C2, C3) refer to departures from the standard or from the standard that was current when the installation was originally installed.
Does Every Installation Need to Meet the Current Edition?
Existing installations are not required to be upgraded to the current edition unless they are dangerous (C1 or C2 on an EICR). Many homes have perfectly safe installations that pre-date elements of the current standard — for example, not having surge protection devices, which is now required for new installations but not retrospectively for existing ones.
Amendment 2 (2022)
The 2022 amendment introduced some significant changes, including:
- Surge protection devices (SPDs) now required in most new domestic installations
- Additional requirements for EV charger installations
- Updated requirements for PV solar installations
Onyx Electrical Solutions works to BS 7671:2018+A2:2022 on all installations. Call 07000 000000 if you have questions about your installation.