Requirements for Level 2 Distribution Boxes in Construction Sites

Level 2 distribution boxes on construction sites must be made of fireproof materials, equipped with proper leakage protection, and installed according to spacing, grounding, and accessibility standards.

Material and Construction

Level 2 distribution boxes should be constructed from cold-rolled steel plates or flame-retardant insulating materials, with steel plate thickness ranging from 1.5 mm for distribution boxes and at least 1.2 mm for switch boxes. The surface must be anti-corrosion treated, and the box should be rainproof, dustproof, and suitable for outdoor use. Electrical appliances inside the box must be mounted on metal or insulating plates, with the metal base plate electrically connected to the box body for grounding purposes .

Electrical Components and Protection

• Incoming and outgoing lines must use rubber-insulated cables, entering and exiting from the lower end of the box with protective rings .
• Leakage protection devices must be installed according to the product manual, tested regularly, and compatible with the rated values of branch switches .
• The box should include N-line and PE-line terminal boards, with the PE-line connected to the metal installation board and the N-line insulated from it .
• The number of electrical connection points should exceed the number of circuits by at least two, allowing for repeated grounding and PE-line entry .

Installation and Accessibility

• The main distribution box should be located near the power supply, while Level 2 distribution boxes should be installed close to concentrated electrical loads .
• The distance between the distribution box and the switch box should not exceed 30 meters, and the horizontal distance to controlled equipment should not exceed 3 meters .
• Boxes must be easily accessible, with a minimum clearance of 2 meters from other utility services such as water or telephone lines .
• The bottom of the distribution box should be directly buried and backfilled, with proper fixation using cement mortar to ensure stability .

Compliance and Standards

Level 2 distribution boxes must comply with national standards for electrical components and pass CCC certification. Installation and operation should follow AS/NZS 3012:2019 for construction site electrical installations, including in-service testing of portable and fixed equipment .

Summary

In essence, Level 2 distribution boxes on construction sites are temporary power distribution units designed for safety, accessibility, and reliability. They must be fireproof, corrosion-resistant, properly grounded, equipped with leakage protection, and installed with correct spacing to ensure safe operation and compliance with national and international standards .