IET On-Site Guide Book (BS 7671:2018+A4:2026), 9th Edition
Essential, practical guidance for electricians working with BS 7671 on site.
The On-Site Guide (BS 7671:2018+A4:2026), 9th Edition provides a convenient and easy-to-use reference for competent electricians and installers working with the latest requirements of the IET Wiring Regulations.
Designed to support work on installations up to 100 A, 3-phase, the guide brings together essential information in a practical format that helps support safe, compliant decision-making while working on site.
This latest edition has been fully updated to align with BS 7671:2018+A4:2026 and incorporates changes from all four amendments to the 18th Edition.
With updated guidance covering protective devices, RCD selection, prospective fault current and Stationary Secondary Batteries, the 9th Edition provides electricians with a focused reference for applying current BS 7671 requirements in everyday installation work.
Why Choose the 9th Edition On-Site Guide?
- Fully aligned with BS 7671:2018+A4:2026
- Incorporates changes from all four amendments to the 18th Edition
- Designed for competent electricians and installers working on installations up to 100 A, 3-phase
- Provides essential BS 7671 information in a convenient, easy-to-use format
- Supports safe and compliant decision-making on site
- Includes guidance on bidirectional and unidirectional protective devices
- Covers Stationary Secondary Batteries
- Includes updated guidance on RCD selection
- Includes guidance on prospective fault current for protective devices
Updated for BS 7671:2018+A4:2026
The 9th Edition has been further updated to reflect the full amendments to the IET Wiring Regulations and now aligns with BS 7671:2018+A4:2026.
The On-Site Guide includes updated and additional guidance covering important areas of electrical installation work, including:
- Bidirectional and unidirectional protective devices
- Stationary Secondary Batteries
- Amended rationale for maximum Zs values for protective devices
- Guidance on the selection of RCDs
- Guidance on prospective fault current for protective devices
Built for Practical On-Site Use
The On-Site Guide is designed to give competent electricians access to essential information from BS 7671 in a format that is practical for day-to-day use.
Its focused approach makes it easier to reference important requirements while working on installations up to 100 A, 3-phase, helping electricians keep current information close at hand when making installation decisions.
Who is the On-Site Guide For?
The On-Site Guide is intended for competent electricians and installers working with electrical installations covered by BS 7671.
It is specifically designed to support those working on installations up to 100 A, 3-phase who need convenient access to essential information from the current IET Wiring Regulations.
Your Practical Companion to BS 7671
The full Wiring Regulations contain extensive technical requirements, but electricians often need focused information quickly while working on site.
The 9th Edition On-Site Guide brings essential guidance together in a more convenient format, covering practical areas including protective devices, RCD selection, prospective fault current, Zs values and Stationary Secondary Batteries.
For competent electricians working with installations up to 100 A, 3-phase, it provides a valuable reference for keeping pace with the latest requirements of BS 7671:2018+A4:2026.
Product Details
| Features | |
| Edition | 9th Edition |
| Aligned With | BS 7671:2018+A4:2026 |
| Subject | Electrical Regulations |
| Publication Year | 2026 |
| Pages | 256 |
| ISBN-13 | 978-1-83724-039-5 |
| Part Number | PIETOSG184 |
| Format | Spring Bound Book |
| Installation Coverage | Up to 100 A, 3-phase |