BS 7671 Amendment 4 - Key Updates

BS 7671 Amendment 4: the transition deadline is approaching this week. What does it mean for your projects?

From 15 October 2026, BS 7671:2018+A4:2026 becomes the edition to use as the previous edition incorporating Amendments 2 and 3 is withdrawn. Until then, either edition may be used during the transition period.

The changes include new requirements for stationary secondary batteries, functional earthing and equipotential bonding for ICT systems, Power over Ethernet (PoE), and a substantial revision of Section 710 covering medical locations.

For engineering teams, the immediate priority is to ensure that the applicable edition is reflected consistently across design information, specifications, tender packages, installation procedures and verification documentation.

⚠️ However, a new edition does not automatically mean an existing electrical installation must be replaced or upgraded in its entirety.

The IET clarifies that BS 7671 is not generally retrospective. Existing installations must be considered in the context of the edition applicable when they were designed and installed, while compatibility and the requirements relevant to subsequent alterations still need to be assessed.

The practical response is neither to ignore the changes nor to assume a blanket upgrade is necessary. It is to review the affected scope, establish a clear design basis and ensure that new work is appropriately designed, installed and verified.

A standards transition is a design-control issue, not a blanket retrofit requirement.

Sound engineering decisions start with understanding what has changed, where it applies and what action is genuinely required.