IET Guidance Note 2: Isolation and Switching (BS 7671:2018+A4:2026)

IET Guidance Note 2: Isolation and Switching (BS 7671:2018+A4:2026)

The IET Guidance Note 2: Isolation and Switching (BS 7671:2018+A4:2026) provides practical, easy-to-follow guidance on one of the most commonly misunderstood areas of the Wiring Regulations. It explains how to apply BS 7671 requirements for isolation and switching so that designers, installers, inspectors and maintenance teams can make correct, consistent decisions on real installations.

Ideal for professionals involved in design, inspection and testing, maintenance and operational work, this updated edition aligns fully with BS 7671:2018+A4:2026. It helps clarify what type of device is required, where it should be located, how it should operate, and how to manage modern day systems where traditional assumptions about sources and supplies no longer apply.

Updates include guidance on isolation of multipole source systems, clearer direction on the selection of protective, isolation and switching devices, and coverage of bidirectional and unidirectional devices. It also includes guidance on firefighters’ switches, supporting safer isolation arrangements where emergency services access and building safety considerations apply.

Key Features

• Guidance on isolation and switching aligned with BS 7671:2018+A4:2026
• Designed to simplify one of the most complex areas of the Wiring Regulations
• Ideal for design, inspection and testing, maintenance and operational roles
• Guidance on isolation of multipole source systems
• Selection guidance for protective, isolation and switching devices
• Covers bidirectional and unidirectional devices
• Includes guidance on firefighters’ switches