Guidance Note 3: Inspection & Testing is a fundamental guidance book for all those involved with the testing and inspection of electrical installations. It also contains essential guidance for those studying for inspection and testing qualifications and has been fully updated to BS 7671:2018+A4:2026. 

This incorporates changes from all previous amendments to the standard. New inclusions within BS 7671:2018+A4:2026 are: Stationary Secondary Batteries where the purpose is for electrical storage and supply of electrical installations; Functional earthing and functional equipotential bonding for information and communication technology (ICT) equipment and systems; a new section on Power over Ethernet (PoE) and a major revision of Section 710 Medical Locations and the inclusion of a schedule of test results for recording the resistance of supplementary protective equipotential bonding conductors.