What Is BS 7671?

BS 7671 is the British Standard that sets the requirements for electrical installations in the UK. It is published jointly by the British Standards Institution (BSI) and the Institution of Engineering and Technology (IET), and is commonly referred to as the IET Wiring Regulations or simply “the regs.”

The 18th Edition

The current version is BS 7671:2018+A2:2022, also known as the 18th Edition. It covers all aspects of the design, erection, and verification of electrical installations operating at up to 1000 V AC. This includes domestic houses, commercial premises, industrial installations, and temporary installations (such as construction sites and events).

What BS 7671 Covers

• Protection against electric shock — Earthing arrangements, RCD protection, bonding requirements.
• Protection against overcurrent — Circuit breaker and fuse selection, cable sizing to prevent overheating.
• Cable selection — Current-carrying capacity, voltage drop limits, correction factors for temperature, grouping, and thermal insulation.
• Special locations — Additional requirements for bathrooms, swimming pools, saunas, solar PV, and EV charging.
• Inspection and testing — Procedures for initial verification and periodic inspection of installations.

BS 7671 and Part P

In England and Wales, Part P of the Building Regulations makes certain domestic electrical work notifiable to building control. BS 7671 is the standard that Part P references for the technical requirements. Work carried out by a registered competent person (e.g., NICEIC, NAPIT, ELECSA) can be self-certified without a separate building control notification.

Who Needs to Know BS 7671?

All qualified electricians in the UK are trained to BS 7671. While DIYers can carry out some minor electrical work (like changing a socket for like-for-like), any notifiable work — such as adding a new circuit, working in a bathroom or kitchen, or installing an EV charger — should be designed and tested in accordance with BS 7671.