The distance between a construction site distribution box and a three-level distribution box should not exceed 30 meters, with switch boxes located within 3 meters of the equipment they control.

Recommended Distances and Placement

In a three-level power distribution system at construction sites, the main distribution box serves as the primary hub, supplying power to secondary distribution boxes, which in turn supply tertiary switch boxes. To maintain efficiency and safety:

• The distance between a distribution box and its switch box should not exceed 30 meters .
• The horizontal distance between a switch box and the fixed electrical equipment it controls should preferably not exceed 3 meters .
• The main distribution box should be installed close to the power source, while secondary distribution boxes should be placed where electrical loads are concentrated .

Installation Considerations

• Distribution boxes and switch boxes should be installed in dry, ventilated, and normal temperature environments with sufficient space for two people to operate simultaneously .
• Fixed distribution boxes should have a vertical distance from the ground of 1.3–1.5 meters, while mobile boxes should be 0.6–1.5 meters above the ground .
• The hierarchical structure must be maintained: no equipment should bypass levels, ensuring that power flows from the main distribution box to secondary boxes, then to switch boxes, and finally to the equipment .

Practical Implications

Following these distance guidelines ensures minimal voltage drop, efficient power distribution, and compliance with safety standards. It also facilitates maintenance and operational safety, preventing overloading and reducing the risk of electrical hazards on construction sites. By adhering to the 30-meter maximum for distribution-to-switch box distance and 3-meter maximum for switch box-to-equipment distance, construction sites can maintain a safe and effective three-level power distribution system .