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. Why do you need GFCI or AFCI breakers? Choosing the right size and setup for your distribution box keeps your electrical system safe and working well. You lower the chance of circuits getting too hot or overloaded when you pick the right box for your needs. Surge protectors help protect against any large power spikes that could potentially damage equipment.