In a distribution box, wires are separated by type—live (phase), neutral, and earth—and organized to connect safely to circuit breakers and busbars according to standard wiring practices.

Wire Separation and Connections

Live (Phase) Wires: The incoming live wires, often color-coded yellow (A phase), green (B phase), or red (C phase), are connected to the line terminals of the circuit breakers. Each circuit breaker controls a specific circuit, and the live wire is routed from the main breaker to the branch breakers to supply power to individual circuits . Neutral Wires: Neutral wires, typically blue, bypass single-pole breakers and connect directly to the neutral busbar. In two-pole breakers, both live and neutral wires are connected to the breaker and are disconnected simultaneously when the breaker trips . Protective Earth (PE) Wires: Earth wires are connected to the ground busbar and, in breakers with residual current protection (RCDs), to the dedicated terminal on the breaker. This ensures safety against earth faults .

Organization and Layout

• Circuit Breaker Arrangement: Breakers are usually arranged from left to right, with reserved positions on the right side of the box .
• Wiring Direction: Wiring from the main breaker to branch breakers generally runs on the left, while outgoing wiring from the box goes to the right .
• Wire Binding: Wires are tied with plastic ties to keep them straight and organized, ensuring no tangling or obstruction .
• Wire Sizing: Wire gauge is selected based on circuit load, e.g., 2.5mm² for lighting and sockets, 4mm² for high-load appliances like air conditioners .

Safety and Marking

Each wire and circuit should be clearly labeled for voltage type (AC/DC) and phase. After wiring, a safety inspection is performed to check for short circuits, overloads, or improper connections . Proper separation and organization of wires in the distribution box not only ensures safety but also simplifies maintenance and troubleshooting .