IET Guidance Note 1: Selection and Erection (BS 7671:2018+A4:2026)

IET Guidance Note 1: Selection and Erection (BS 7671:2018+A4:2026)

IET Guidance Note 1: Selection and Erection (BS 7671:2018+A4:2026) is a practical reference for anyone specifying, installing, inspecting or testing electrical installations. The 10th Edition provides clear guidance on applying the relevant parts of BS 7671, helping users make consistent, compliant decisions during design and installation work.

Fully updated to align with BS 7671:2018+A4:2026, this edition reflects modern installation methods and the growing mix of AC, DC and data-led systems found in today’s buildings. It’s designed to support correct selection of equipment, safe erection practices, and accurate interpretation of requirements across a wide range of installation types.

Key updates include guidance on BS 7671 notices and identification labels, bidirectional and unidirectional devices, and insulation monitoring devices (IMDs), plus improved clarity on coordination of RCD types connected in series. It also adds and updates guidance on protected escape routes, conductor classes, concealed cable installation in walls/partitions, functional earthing and functional equipotential bonding for ICT systems, stationary secondary batteries, distribution boards with multiple sources (with practical examples), and Power over Ethernet (PoE).

Key Features

• 10th Edition guidance for selection and erection aligned with BS 7671:2018+A4:2026
• For specifiers, installers and those inspecting and testing electrical installations
• Clear explanations on applying relevant BS 7671 requirements in real installations
• Guidance on BS 7671 notices and identification labels
• Covers bidirectional and unidirectional protective devices
• Includes guidance on insulation monitoring devices IMDs
• Guidance on coordination of RCD types connected in series
• Updated guidance for protected escape routes
• Includes conductor classes and selection considerations
• Updated guidance for cables concealed in walls and partitions
• Functional earthing and functional equipotential bonding guidance for ICT equipment and systems
• Includes coverage of stationary secondary batteries
• Guidance on rating distribution boards with multiple sources with practical examples
• Includes Power over Ethernet PoE guidance