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. An electrical panel box, also known as a breaker box or a distribution board, is a crucial component of any electrical system. It serves as a central hub for distributing electricity throughout a building, ensuring that power is delivered safely and efficiently to all the required locations. Whether you're an electrician or a DIY enthusiast, this guide will help you understand the basics of home electrical distribution. The Main feeder cable to the Distribution Board should be able to handle the total power anticipated when all the sub circuits in the Distribution Board. Distribution Board or DB is an electricity supply system or a common enclosure that distributes the electrical power feed into subcircuits. It includes isolator, RCCB (Residual current circuit breaker) or RCD (Residual-current device) devices, protective fuses or MCB's (Miniature Circuit Breaker).