The main power distribution box on a construction site is typically located close to the primary power supply entry point, in a dry, ventilated, and accessible area.

Placement Guidelines

The main distribution box serves as the central hub for distributing electricity to sub-distribution boxes and switch boxes across the site. It should be installed near the incoming power source to minimize voltage drop and ensure efficient power distribution to all equipment and machinery .

Environmental and Safety Considerations

• Dry and ventilated location: Avoid areas exposed to water, steam, gas, or flammable substances .
• Accessibility: Ensure enough space around the box for at least two people to operate and maintain it safely, with no obstacles like stacked materials or vegetation .
• Protection: Use boxes made of durable materials such as steel or high-quality insulating materials, with a minimum thickness of 1.5 mm for metal enclosures .
• IP rating: For outdoor or harsh environments, the box should have at least IP55 protection to guard against dust and water jets .

Distribution Structure

• Sub-distribution boxes are installed closer to concentrated loads or equipment clusters, typically within 30 meters of the main distribution box .
• Switch boxes are positioned near the final electrical equipment, with a horizontal distance not exceeding 3 meters from the devices they control .
• Separation of circuits: Power and lighting circuits should be separated, either in different boxes or clearly segregated within the same box .

Practical Considerations

• Connection and wiring: All connections should use insulated wires, with secure joints and no exposed live parts. Protective neutral and grounding must be properly connected .
• Mobility and flexibility: On dynamic construction sites, distribution boards may be designed to be movable, weatherproof, and shock-resistant to adapt to changing site layouts . By following these guidelines, the main distribution box ensures safe, reliable, and efficient power delivery across the construction site, supporting all electrical equipment, lighting, and machinery while complying with safety standards .