IET Guidance Note 3: Inspection & Testing (BS 7671:2018+A4:2026) - 10th Edition

The industry-standard manual for safe and accurate electrical inspection and testing.

Guidance Note 3: Inspection & Testing is a fundamental resource for all personnel involved in the initial verification and periodic inspection of electrical installations. This new 10th Edition has been fully updated to align with Amendment 4:2026 (The Orange Book), providing the most up-to-date procedures for testing modern electrical systems.

This edition consolidates previous updates, including the 2024 Amendment 3 requirements, ensuring you have a single, definitive guide for compliance.

Key Updates in the 10th Edition:

• Medical Locations (Section 710): Significant updates to testing requirements, specifically regarding the resistance of supplementary protective bonding in medical environments to ensure patient safety.

• Stationary Secondary Batteries: New inspection and testing protocols for Battery Energy Storage Systems (BESS) in line with the new Chapter 57.

• Power over Ethernet (PoE): Updated guidance on verifying and testing data cabling used for power delivery (Section 716).

• Consolidated Documentation: Includes the latest versions of the Schedule of Inspections and Electrical Installation Certificates (EIC), reflecting the changes brought in by Amendment 4.

• Harmonics and Earth Leakage: Refined guidance on testing in installations with high levels of harmonic distortion or significant earth leakage currents.

Why Guidance Note 3 is Essential:

Inspection and testing is one of the most critical parts of an electrician's job. GN3 provides more detail than the Wiring Regulations or the On-Site Guide, offering step-by-step instructions on how to perform tests correctly and interpret the results to ensure an installation is safe for use.

Essential for:

• Electrical Inspectors and Testers

• Qualifying Supervisors

• Electricians undertaking Periodic Inspection (EICRs)

• Students studying for City & Guilds 2391 or EAL inspection and testing qualifications

Important Compliance Dates:

• Published: 15th April 2026 (Implementable immediately).

• Mandatory: From 15th October 2026, all inspection and testing must be carried out to these standards.

Ensure your testing procedures meet the latest legal and safety requirements. Order the 10th Edition of Guidance Note 3 today.