What level of electrical distribution box is used on the construction site

Secondary (Level II) distribution boxes are most commonly used on construction sites for temporary power distribution.Overview of Distribution Box LevelsConstruction sites typically use a three-level distribution system:Primary (Level I) Distribution Box: Receives three-phase power from the transformer and serves as the main distribution point. It includes main circuit breakers, fuses, and metering systems. This box is usually fixed and rainproof, suitable for outdoor conditions .Secondary (Level II) Distribution Box: This is the most commonly deployed box on construction sites. It receives power from the primary box and distributes it to temporary circuits for tools, machinery, and lighting. It includes circuit breakers, fuses, and sometimes leakage protection switches. The box is designed for mobility, safety, and durability, often with IP55 protection to resist dust and water .Tertiary (Level III) Distribution Box: Located near specific equipment or appliances, this box provides the final connection point. It often includes a leakage protection switch and is used for individual machines or small groups of equipment .Key Features for Construction UseMobility: Secondary boxes are portable, allowing them to be moved as the site layout changes .Safety: Equipped with earth leakage circuit breakers to prevent electrical hazards .Protection Class: IP55 or higher is recommended to protect against dust and water jets .Cabling: Flexible rubber or H07RN-F cables are commonly used to connect equipment safely .Practical ConsiderationsTemporary Power: Secondary boxes are ideal for temporary power distribution because they balance capacity, safety, and mobility.Scalability: Multiple secondary boxes can be connected to a primary box to serve larger sites.Compliance: Using a three-level system ensures adherence to construction power safety standards, including the principle of "one machine, one switch, one protection" . In summary, while all three levels of distribution boxes are used on construction sites, secondary (Level II) distribution boxes are the standard choice for general temporary power distribution, providing a safe, flexible, and durable solution for powering tools, machinery, and temporary structures.