What is the capacity of the secondary power distribution box on the construction site

Secondary power distribution boxes on construction sites typically handle between 63A and 200A, depending on the model and site requirements.

Overview

A Secondary Distribution Box (SDB) receives power from the main distribution box and distributes it to branch circuits for tools, machinery, and temporary site modules. These boxes are designed to handle varying loads depending on the construction phase, the number of connected devices, and the type of equipment used.

Typical Capacity

Current Rating: Most construction site SDBs are rated between 63A and 200A. Power Rating: Temporary power distribution boxes can deliver up to 3. 8 kW for smaller single-phase setups, while larger three-phase units can handle significantly higher loads.

Voltage: Commonly supplied as 230V single-phase for small tools and 400V three-phase for heavy machinery.

Safety and Protection

Secondary distribution boxes often include: Earth leakage circuit breakers (RCDs/GFCIs) to prevent electric shock. Overcurrent protection for each branch circuit to avoid overloads. IP55 or higher protection class to ensure dust and water resistance in harsh construction environments.

Practical Considerations

Load Planning: The capacity should be chosen based on the simultaneous operation of equipment, peak loads, and duty cycles. Flexibility: Many SDBs allow custom wiring with terminal blocks to adapt to changing site requirements. Distribution Structure: SDBs are part of a layered distribution system, feeding floor modules or work zones from the main power source.

In summary, the capacity of a secondary power distribution box on a construction site varies depending on the model and site needs, but typical units range from 63A to 200A, with appropriate safety features and voltage configurations to support both small tools and heavy machinery.