Here are the key considerations for outdoor installation of power distribution cabinets and distribution boxes, which need to fully account for the impact of environmental factors on equipment safety, service life, and operational stability:
I. Site Selection and Environmental Requirements
1. Geographical Location Selection
Avoid High-Risk Areas:
Keep away from waterlogged areas (e.g., low-lying lands, drainage ditches) to prevent water backflow and short circuits.
Steer clear of strong wind or seismic zones (e.g., wind gaps, seismic belts) to avoid cabinet shaking or structural damage.
Maintain distance from heat sources (e.g., boiler rooms, high-temperature equipment) and pollution sources (e.g., chemical plants, dusty workshops) to prevent accelerated equipment aging or component corrosion.
Facilitate Operation and Maintenance:
Ensure sufficient space around the installation site (at least 1.5 meters in front and 0.8 meters on the sides) for maintenance personnel to open cabinet doors and replace components.
Avoid installing near dense vegetation to prevent insects and small animals (e.g., snakes, rats) from entering the cabinet and causing failures.
2. Adaptation to Meteorological Conditions
Rain and Moisture Prevention:
The bottom of the cabinet must be at least 30 cm above the ground (raised by a concrete base or 支架), preventing surface water from intruding.
In coastal or high-humidity environments, select stainless steel cabinets resistant to salt spray corrosion and install moisture-proof heaters.
High and Low Temperature Protection:
In high-temperature summer areas, keep cabinets away from direct sunlight (use sunshades or light-colored cabinets to reduce heat absorption) and install internal cooling fans or air conditioners.
In severe cold regions, use low-temperature-resistant materials (e.g., cabinets rated for -40°C) and equip electric heating devices if necessary to prevent condensed water from freezing.
Lightning and Static Electricity Prevention:
Cabinets must be reliably grounded (ground resistance ≤4Ω) and equipped with surge protection devices (SPD) to prevent induction lightning from damaging internal components.
In dry and windy areas, take anti-static measures (e.g., conductive coatings on cabinet surfaces, anti-static packaging for internal components).
II. Equipment Selection and Cabinet Requirements
1. Protection Rating Standards
IP Rating Requirements:
Choose cabinets with an IP54 (dust-proof and water splashing-proof) rating or higher for general outdoor environments.
In high-humidity, rainy, or coastal areas, select IP65 (fully dust-proof and strong water jet-proof) or higher ratings (e.g., IP67 for water immersion).
Material Selection:
Prioritize stainless steel (304/316L) or engineering plastic (e.g., ABS+PC) cabinets, which offer better corrosion and impact resistance than ordinary carbon steel.
In cold northern regions, pay attention to the low-temperature brittleness of cabinet materials (e.g., carbon steel is prone to brittleness below -20°C, while stainless steel is more suitable).
2. Internal Component Configuration
Waterproof Sealing Design:
Install silicone sealing strips on cabinet doors and use waterproof cable glands for wiring entries to prevent rainwater and insects from entering.
Cables should enter the cabinet from the bottom or sides, avoiding top entry to prevent rainwater from flowing in along the cables.
Heat Dissipation and Ventilation:
Design cabinets with heat dissipation holes (fitted with dust filters) or louvers, and use temperature-controlled fans (automatically 启动 when temperature ≥40°C) to maintain internal constant temperature.
Install high-power devices (e.g., frequency converters, circuit breakers) in separate zones to avoid heat accumulation.
Anti-Corrosion Treatment:
Galvanize or powder-coat internal metal components (e.g., rails, mounting plates), and use stainless steel or nickel-plated terminal blocks.
III. Installation Specifications and Electrical Safety
1. Foundation Construction Requirements
Base Construction:
Pour the foundation with C25 concrete, at least 15 cm thick, with a flat surface and pre-embedded anchor bolt holes (matching the cabinet’s mounting holes).
The foundation should have a drainage slope (≥5%) and 预埋 drain pipes to prevent water accumulation.
Cabinet Fixing:
Secure the cabinet to the foundation with anchor bolts or expansion bolts, and treat the bolts with anti-rust coatings (e.g., hot-dip galvanizing).
When installing multiple cabinets side by side, connect adjacent cabinets with bolts to form a single structure and enhance wind resistance.
2. Electrical Connection Key Points
Grounding System:
Separately ground the cabinet shell, metal frame, and metal component casings to the grounding main (PE line); series grounding is prohibited.
Cross-sectional area of the grounding main: copper busbar ≥30mm², galvanized flat steel ≥40mm×4mm; ground resistance should be tested regularly (at least once a year).
Cable Handling:
Use outdoor-rated cables (e.g., YJV22 armored cables) for incoming and outgoing lines, protected by galvanized steel pipes or PVC pipes, with fireproof putty sealing the pipe openings.
Waterproof the cable joints (e.g., double-layer wrapping with heat-shrinkable sleeves and waterproof tape) to avoid moisture-induced short circuits.
Anti-Misoperation Design:
Install mechanical or electromagnetic locks on cabinet doors to prevent unauthorized access; high-voltage distribution cabinets must have "live warning" labels.
IV. Post-Installation Maintenance and Hazard Inspection
1. Regular Inspection Items
Cabinet Appearance:
Check whether the sealing strips are aged or cracked, and whether the cabinet is corroded or deformed; replace damaged parts promptly.
Clean debris (e.g., leaves, insect carcasses) from the dust filters of heat dissipation holes to ensure unobstructed ventilation.
Internal Components:
Test the normal operation of circuit breakers and contactors, and check for loose or overheating terminal connections (use an infrared thermometer for detection).
Inspect the status indicator of the surge protection device (SPD) and replace it immediately if it fails.
Environmental Monitoring:
Check the foundation drainage before the rainy season and clear snow from the cabinet top after snowstorms to prevent excessive load.
Monitor the internal temperature of the cabinet during high-temperature seasons (recommended ≤50°C) and inspect the heating devices in low-temperature environments.
2. Emergency Protection Measures
Install rain covers or protective sheds above outdoor cabinets to extend their service life.
In high-altitude areas, consider the reduced insulation strength due to thin air and appropriately increase component spacing or use plateau-type equipment.
In coastal typhoon-prone regions, reinforce cabinets against wind (e.g., increase the number of fixing bolts or add support brackets to the back of the cabinet).
V. Relevant Standards and Specifications for Reference
National Standards:
GB 7251.1-2013 Low-Voltage Switchgear and Controlgear Assemblies
GB 50171-2012 Code for Construction and Acceptance of Electrical Installation Engineering - Panel, Cabinet and Secondary Circuit Wiring
GB 50057-2010 Code for Design of Lightning Protection of Buildings (lightning grounding requirements)
Industry Standards:
DL/T 539-2016 Common Technical Requirements for High-Voltage Switchgear and Controlgear Standards (for outdoor high-voltage equipment)
NB/T 42021-2013 Outdoor Low-Voltage Distribution Boxes (special standards for outdoor distribution boxes)
Summary: Core Focus Areas
Dimension Key Measures
Environmental Adaptation Select IP65+ cabinets and stainless steel materials; raise the base with drainage and install sun/rain protection.
Electrical Safety Independent grounding (resistance ≤4Ω), surge protection, and waterproof cable gland sealing for wiring entries.
Structural Stability Concrete foundation + anchor bolt fixing; connect multiple cabinets in a row for enhanced wind resistance.
Maintenance Convenience Reserve operational space, use modular component layouts, and regularly inspect sealing strips, heat dissipation holes, and terminal tightness.
These measures can effectively improve the reliability of outdoor power distribution cabinets and boxes, reduce failure risks caused by environmental factors, and ensure long-term safe and stable operation.
