The national standard shell thickness for low-voltage distribution boxes is generally 1.5 mm for the enclosure, with doors and panels at 2.0 mm, and back panels at 3.0 mm.

Standard Thickness Requirements

• Enclosure (box body): The steel plate used for the main body of distribution boxes should be at least 1.5 mm thick for low-voltage applications, ensuring structural integrity and safety during operation .
• Doors and panels: The doors and removable panels of the distribution box should have a minimum thickness of 2.0 mm, providing additional mechanical strength and protection against impacts .
• Back panels: The back panel, which supports internal components and mounting rails, should be at least 3.0 mm thick to maintain rigidity and support heavier equipment .
• Auxiliary metal poles: For internal support structures, a thickness of 1.2 mm is generally recommended .

Additional Considerations

• Material type: Steel plates are standard, but stainless steel or aluminum may require slightly different thicknesses to meet equivalent strength and safety standards .
• Seismic and environmental factors: Thickness may be adjusted to improve earthquake resistance or withstand temperature variations, ensuring the box remains safe under mechanical stress .
• Box size: For wider boxes (≥800 mm), the minimum steel plate thickness is 1.5 mm, while smaller boxes (500–800 mm) may use 1.2 mm steel plates .
• Installation and safety: Distribution boxes must be installed straight and firmly, with proper mounting lugs and sealing for incoming/outgoing wires to comply with Class 3 sealing requirements .

In summary, the national standard shell thickness ensures mechanical strength, electrical safety, and durability, with 1.5 mm for the main body, 2.0 mm for doors/panels, and 3.0 mm for back panels as the baseline for low-voltage distribution boxes, while adjustments may be made based on material, size, and environmental conditions .