Installation of electrical distribution box in civil defense wall

Electrical distribution boxes in civil defense walls must be installed using pre-embedded, blast-proof conduits with airtight treatments, ensuring compliance with civil defense and electrical safety standards.

Placement and Conduit Requirements

For civil defense walls, distribution boxes should be connected via pre-embedded conduits installed during peacetime construction. All conduits penetrating exterior, free-standing, or blast-proof partition walls must be hot-dip galvanized steel pipes with a minimum wall thickness of 2.5 mm to ensure durability and resistance to blast effects . Exposed conduits should include pre-embedded airtight sleeves for crossing walls and roof slabs, following civil defense electrical codes .

Blast-Proof and Airtight Treatments

Electrical pipelines passing through civil defense partition walls and roof slabs require blast-proof airtight treatment as specified in civil defense standards (e.g., Atlas 05SFD10). Steel plates of 3–4 mm thickness may be used to fabricate airtight flanges for electrical conduits, which are welded to structural steel bars to maintain airtight integrity .

Power Supply and Circuit Routing

Each distribution box should receive one low-voltage circuit from the basement power distribution room. The civil defense power supply must be capable of switching to a wartime regional power station within a 3-day conversion period . Conduits for power circuits should be installed in advance, with reserved openings for future equipment installation.

Installation Practices

• Height and Accessibility: Install distribution boxes at a safe and accessible height, typically around 1.5 meters, ensuring proper ventilation and maintenance access .
• Wiring and Protection: Use correct wire gauge, secure grounding, and include protection devices such as breakers, fuses, and surge protectors for each circuit .
• Coordination: Verify dimensions, coordinates, and elevations of reserved pipes against all discipline drawings to avoid conflicts with other utilities or structural elements .
• Material Selection: Choose distribution boxes with appropriate IP/NEMA ratings for protection against dust, moisture, and mechanical damage .

Compliance and Testing

Ensure all installations comply with local electrical codes, NEC, IEC standards, and civil defense regulations. After installation, perform visual inspections and multimeter tests before energizing the system . Maintain detailed records for future inspections and schedule regular maintenance to ensure long-term reliability. By following these guidelines, the electrical distribution box will be secure, functional, and compliant with both civil defense and electrical safety requirements, ensuring operational readiness during peacetime and wartime scenarios.