This change elevates the importance of protection against transient overvoltages (surges) caused by atmospheric effects (lightning) and internal switching. BS 7671 18th edition PDF
1. SPDs as the Default (Regulation 443.4.1)
The most critical change is the deletion of the old calculation-based risk assessment method (the Calculated Risk Level or $C_RL$). Protection against transient overvoltages is now required in all cases unless specific exceptions apply.
SPDs are MANDATORY where the consequences of overvoltage could result in:
Serious injury to, or loss of, human life. (e.g., hospitals, care homes).
Failure of a safety service. (e.g., fire alarm systems, emergency lighting, evacuation equipment).
Significant financial or data loss. (e.g., banks, data centres, sophisticated industrial control systems).
The Catch-All Requirement: For all other cases (including standard domestic dwellings), protection against transient overvoltages shall be provided unless the owner of the installation declares that any resulting loss or damage is tolerable and they formally accept the risk of damage and consequential loss.
2. The Formal 'Opt-Out' Requirement
The burden of proof has shifted entirely. The installer is now obligated to include SPDs in the design. If the client, such as a homeowner, wishes to omit the device in a non-mandatory scenario, the following steps are required:
The installer must inform the owner of the risks and benefits.
The owner must formally and explicitly declare that the risk is acceptable and that damage is tolerable.
This declaration must be documented (usually via an addition to the Electrical Installation Certificate or a formal departure note) and retained for accountability.
This formalizes client-installer communication regarding asset protection.
3. Protection Against Switching Overvoltages (Regulation 443.4.2)
Amendment 2 also clarifies that protection must be considered where the installation contains equipment likely to produce high-energy switching overvoltages that could damage other equipment (e.g., large motors, transformers, high-current loads). This ensures that protection against internal surges is also addressed by the installer or designer.
Conclusion
To conclude, Amendment 2 elevates Surge Protection Devices (SPDs) from an optional measure to a critical, default component of installation safety. By making SPDs mandatory in high-consequence scenarios and requiring a documented risk assessment signed by the client to omit them in standard dwellings, the Regulations place a strong emphasis on formal risk management and client transparency. This change necessitates a clearer communication process between electricians and clients regarding asset protection.
