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. Learn how to wire a distribution box step by step! This video shows real on-site footage of electrical installation, demonstrating safe and standardized wiring methods used by professionals. They typically have a horizontal arrangement designed to accept multi-pole and/or single pole OCPDs. Whether you're upgrading your home's electrical service, designing a commercial facility, or managing an industrial power system, selecting and sizing the right. Connection method: Each switch takes a wire from the incoming point and connects it to the incoming end of the switch, or uses parallel connection to reduce the difficulty of wiring. Wiring Direction: Wiring between the main circuit breaker and each branch circuit breaker in the box generally.