18th Edition Amendment 2 — what changed and what is coming next
Amendment 2 was the largest revision since the 18th Edition landed. If your last regulations course predates it, several of the answers you learned are now wrong.
Updated 2026-08-16
Surge protection became the default
The risk assessment route that let most domestic installations skip an SPD was tightened. In practice, surge protective devices are now expected on most new installations and consumer unit changes unless a documented justification says otherwise.
Arc fault detection devices
AFDDs moved from 'recommended' to 'shall be provided' for socket-outlet circuits in specified higher-risk premises, including HMOs, purpose-built student accommodation and care homes. For general domestic work they remain a recommendation supported by risk assessment.
Prosumer low-voltage installations
A new Part 8 section addressed installations that both consume and generate, which is now most homes with solar and battery storage. It brings energy efficiency and local generation into the same framework as everything else.
Bidirectional devices and EV charging
Section 722 tightened around PME earthing and open-PEN protection, and device selection now has to account for DC fault currents from vehicle and battery systems. This is the area where existing installers most often carry outdated habits.
- · Check the RCD type against the equipment's DC leakage
- · Confirm the open-PEN arrangement is either an approved device or a compliant electrode
- · Document the load assessment, not just the final circuit design
What comes next
The direction of travel is clear: more emphasis on energy storage, bidirectional power flow and smart control. Whatever the next amendment number is, budgeting a regulations refresh into every scheme cycle is the safest assumption.