This guide covers split load vs dual RCD vs RCBO board configurations, circuit arrangement and allocation, BS 7671 labelling requirements, type testing under BS EN 61439, SPD installation, wiring best practice, and the common mistakes found during EICR inspections. This guide gives you a clear, up-to-date overview for 2025: who the regs apply to, what they cover (and don't), how they link to Building Regulations and the Electricity at Work Regulations, the current 18th Edition with recent changes, and the essentials on RCDs, AFDDs, SPDs and bonding. You'll. Guidance Note 3: Inspection & Testing is a fundamental guidance book for all those involved with the testing and inspection of electrical installations. Find out more about WRAG in this quick introductory video. This technical guidance concerning the application of the requirements of BS 7671 (as amended). Done right, it ensures safety, compliance, and long-lasting performance. In this guide, we'll break down everything you need to know to install a distribution box correctly and confidently. Choose the right box based on environment (indoor/outdoor), load capacity, and durability. Check for proper. Due to the publication of BS EN 60445 in 2017, which was between the cut-off date for new work and the publication date for BS 7671:2018, it's necessary to amend Table 51.