Configuration of Level 2 Distribution Box for Construction Sites

A Level 2 distribution box on construction sites serves as an intermediate power distribution point, typically equipped with a main switch, branch circuit protection, multiple socket types, and organized copper wiring for both three-phase and single-phase loads.

Key Components

Main Switch: Rated according to the outgoing current to Level 3 boxes or end equipment. For example, if the outgoing current is 63A, the main switch should also be 63A; for 100A outgoing, select a 100A main switch. Branch Circuit Protection: Miniature Circuit Breakers (MCBs) or fuse holders are installed to protect individual circuits and connected equipment.

Sockets and Outlets: Include industrial sockets, waterproof 5-hole sockets, AC30 sockets, or terminal blocks. For three-phase equipment requiring a neutral line, 5-core sockets are used; 4-core sockets are sufficient for equipment without a neutral. Wiring: Copper wiring is recommended for higher current capacity, with tidy, straight layouts to facilitate maintenance and safety.

Enclosure: Typically made of robust sheet steel or thermoplastic materials, with IP65–IP67 protection for dust and water resistance, and IK08–IK10 impact resistance.

Layout and Design Considerations

Tiered Distribution: Level 2 boxes are positioned close to construction areas, usually within 30 meters of concentrated electrical equipment, forming a tree-like network with Level 1 (main) and Level 3 (tertiary) boxes. Load Capacity: A single Level 2 box typically handles 50–150 kW, depending on the number of downstream boxes and connected equipment. Emergency and Safety Features: Include emergency stop buttons, key-locked doors, strain-resistant cable hooks, and optional floodlights or indicator devices.

Flexibility: Circuits should accommodate both three-phase and single-phase loads for emergency or temporary use. Pre-wired or empty versions allow customization based on site requirements.

Application Scenarios

Powering Hand Tools: Concrete vibrators, drills, grinders, and welders. Small Machinery: Mortar mixers, steel bar cutters, small water pumps. Temporary Lighting: Foundation pits, corridors, and night construction areas.

Terminal Distribution Points: Close to fixed or mobile equipment for efficient power delivery.

Standards and Compliance

Level 2 distribution boxes should comply with EN 61439-4 and IEC 60364 standards for safety, performance, and electromagnetic compatibility. Proper labeling of inputs, outputs, and circuits is essential for safe operation and maintenance. By following these guidelines, a Level 2 distribution box can provide safe, reliable, and flexible power distribution for construction sites, ensuring compliance with standards and efficient operation of tools, machinery, and lighting.