Main distribution box layer box circuit box

Distribution boxes, including main distribution boxes, layer boxes, and circuit boxes, are essential components that safely manage and distribute electrical power across a building or facility.

Main Distribution Box

The main distribution box (also called the main distribution board or MDB) is the primary hub where electrical power from the main supply enters a building. It contains the main switch, busbars, and circuit breakers that distribute electricity to sub-distribution boards or directly to large circuits. Its key functions include controlling the overall power supply, protecting circuits from overloads or short circuits, and providing a centralized point for maintenance and isolation of the electrical system .

Layer Box (Sub-Distribution Box)

A layer box, often referred to as a sub-distribution board, receives power from the main distribution box and distributes it to specific areas, floors, or sections of a building. It helps organize electrical circuits in a localized manner, making it easier to manage and maintain the system. Layer boxes typically contain circuit breakers or fuses for each branch circuit, ensuring protection and control for smaller sections of the electrical network .

Circuit Box (Final Distribution Box)

A circuit box or final distribution board is located closest to the electrical loads, such as appliances, lighting, or outlets. It receives power from a sub-distribution board and contains individual circuit breakers or fuses for each circuit. This allows for precise control and protection of specific devices or areas, preventing damage from overloads or faults .

Key Components Across Distribution Boxes

• Busbars: Conduct and distribute power to multiple circuits.
• Circuit breakers/fuses: Protect circuits from overcurrent and short circuits.
• Residual current devices (RCDs/RCBOs): Detect leakage currents and prevent electric shocks.
• Switches/isolators: Enable safe maintenance by disconnecting circuits.
• Surge protective devices (SPD): Protect equipment from voltage spikes.
• Earthing connections: Ensure safety and system stability .

Summary

• Main distribution box: Central hub, distributes power to sub-boards or large circuits.
• Layer box/sub-distribution board: Distributes power to specific areas or floors.
• Circuit box/final distribution board: Controls and protects individual circuits near the load. These boxes work together to ensure safe, organized, and efficient power distribution in residential, commercial, and industrial electrical systems .