Specifications of wires for a three-level distribution box

Three-level distribution boxes typically use copper or aluminum conductors for phase, neutral, and ground connections, with insulated wires sized according to load requirements. Main Distribution Board (Primary Level)The main distribution board receives power from the transformer at 0. 4 kV and acts as the central hub.

Copper or aluminum busbars are commonly used for the main connections due to their high conductivity and durability. Phase wires are usually insulated multi-strand copper or aluminum cables, while a separate neutral wire and grounding conductor are included for safety. The main board does not directly supply end-use equipment but distributes power to secondary boards through properly rated cables.

Secondary Distribution Board (Intermediate Level)Secondary boards distribute three-phase power to specific buildings, floors, or heavy loads like motors. Larger capacity three-phase circuit breakers are used, and the wiring typically consists of thicker insulated copper or aluminum conductors to handle higher currents. Protective measures such as dual-door enclosures and rainproof coatings are applied for outdoor installations.

The secondary board connects to the main board using appropriately rated insulated cables for phase, neutral, and ground. Tertiary Distribution Board (Final Level)Tertiary boards supply 220V single-phase power to individual devices or home systems. Each circuit is protected by its own RCD and circuit breaker, following the "one device, one breaker" principle.

Wires used here are generally smaller gauge insulated copper conductors, with separate neutral and grounding wires. These can be either fixed or portable boxes, ensuring safety and compliance with two-layer protection standards.

Summary of Wire Types

Phase wires: Insulated copper or aluminum conductors, sized according to load and voltage level. Neutral wires: Insulated copper or aluminum, providing a return path for current. Ground wires: Bare or insulated copper conductors for safety and fault protection.

Busbars: Copper or aluminum bars in main and secondary boards for high-current distribution. Using the correct type and size of wire ensures efficient power distribution, safety, and compliance with electrical standards in a three-level distribution system.