The intermediate terminal in a distribution box serves as a connection point for distributing power from the main supply to branch circuits, linking live, neutral, and earth conductors safely and efficiently.

Purpose of the Intermediate Terminal

The intermediate terminal, often referred to as a busbar or linking terminal, is used to distribute incoming power from the main breaker to multiple branch circuit breakers. It ensures that each branch receives a stable supply of live (phase), neutral, and earth connections while maintaining safety and organization within the distribution box .

Wiring Connections

1. Live (Phase) Wire Connection

• The incoming live wire from the main supply is connected to the line terminal of the main breaker.
• From the main breaker, the live wire is routed to the intermediate terminal or busbar, which then feeds each branch circuit breaker.
• For single-pole (1P) breakers, only the live wire passes through the breaker, while for double-pole (2P) breakers, both live and neutral wires are connected and disconnected simultaneously . 2. Neutral Wire Connection
• The neutral wire from the main supply is connected to the neutral busbar.
• For 1P breakers, the neutral bypasses the breaker and is connected directly to the neutral busbar, which then distributes neutral to each load.
• For 2P breakers, the neutral is connected to the breaker's designated terminal, allowing simultaneous disconnection with the live wire . 3. Earth (Protective) Wire Connection
• The protective earth (PE) wire is connected to the earth busbar.
• All equipment and load earth wires are linked to this busbar to ensure proper grounding and protection against faults .

Wiring Practices

• Routing: Wiring between the main breaker and branch breakers generally runs on the left side of the distribution box, while outgoing wires to loads exit on the right .
• Binding: Wires should be neatly tied with plastic ties at uniform spacing to prevent tangling and maintain a clean layout .
• Marking: Clearly mark AC, DC, or different voltage levels on the terminals to avoid confusion during maintenance .
• Safety Inspection: After wiring, perform a thorough inspection to check for short circuits, overloads, and proper connections .

Summary

The intermediate terminal acts as a central hub for distributing live, neutral, and earth connections from the main supply to branch circuits. Proper wiring involves connecting the live wire through the main breaker to the terminal, linking neutral and earth to their respective busbars, and ensuring neat, marked, and inspected wiring for safety and reliability . This setup supports both single-pole and double-pole breakers, providing effective protection and organized power distribution.