HUARUI 
The Distribution Box
A distribution box is a low-voltage complete power distribution device in which components such as switching devices, measuring instruments, protective electrical appliances, and auxiliary equipment are assembled in a closed or semi-closed metal enclosure according to electrical wiring requirements. As the terminal equipment of the low-voltage power distribution system, its core functions are to properly distribute electrical energy, control electrical equipment, and provide protection against overload, short circuit, and leakage.
Adopts a modular structure that can be flexibly combined according to requirements, adapting to different circuit quantities and configuration schemes.
Compact structure with small footprint. Available in surface-mounted and flush-mounted installation methods, suitable for residential, commercial, industrial, and other locations.
Enclosure protection level not lower than IP2XC, effectively preventing ingress of foreign objects. Equipped with multiple protections such as leakage, overload, and short circuit, ensuring electrical safety.
Optional configuration of miniature circuit breakers (MCB), isolating switches, residual current devices (RCD), surge protective devices (SPD), watt-hour meters, etc., to meet different distribution requirements.
Made of high-quality cold-rolled steel plate or stainless steel, with anti-corrosion surface treatment. High impact resistance, with a service life of over 10 years.
Standardized internal mounting dimensions allow interchangeable components within the same series, facilitating future capacity expansion, retrofitting, and maintenance.
Enclosure
Made of high-quality cold-rolled steel plate or stainless steel, with phosphating and electrostatic spray coating anti-corrosion treatment. Available in surface-mounted and flush-mounted types, with protection level not lower than IP2XC.
Miniature Circuit Breaker (MCB)
Used for overload and short circuit protection, mounted on TH35-7.5 standard rail, selected according to circuit rated current, with breaking capacity generally 4.5~10kA.
Isolating Switch
Used as main incoming or branch isolation device, ensuring clear disconnection of power supply during maintenance to ensure operator safety.
Residual Current Device (RCD)
Detects residual current and trips automatically in case of electric shock or leakage faults, with rated operating current generally 30mA.
Busbar (Copper Bar)
Used to distribute electrical power to each branch circuit, made of high-conductivity copper, selected according to current carrying capacity.
Terminal Blocks
Used for incoming and outgoing cable connections, divided into cable terminals and wire terminals, selected according to conductor cross-section and current.
Surge Protective Device (SPD)
Optional, used to suppress lightning overvoltage and switching overvoltage, protecting downstream equipment from transient surge damage.
Watt-hour Meter
Optional, used for electrical energy metering management, available in single-phase and three-phase types, supporting mechanical or electronic types.
Panel and Marking
The panel is equipped with operating handles, indicator lights, and transparent observation windows. Each circuit is clearly marked for easy identification and operation.
Neutral and Earthing Terminal Blocks
Used for centralized connection of neutral conductors (N) and protective earthing conductors (PE), ensuring a reliable earthing system.
Pressure Relief and Protection Devices
Pressure relief channels are provided at the top of the busbar and cable compartments, directing high-pressure gases away during internal faults. The cabinet protection level is up to IP40, with transparent observation windows.
1. Core Product Advantages
1. Modular Design, Flexible Configuration: Adopts standard modular structure with components mounted on TH35-7.5 rail, allowing flexible combination according to requirements, adapting to different circuit quantities and configuration needs.
2. Compact Size, Convenient Installation: Compact structure with small footprint. Available in surface-mounted and flush-mounted types, suitable for residential, commercial, industrial, and other locations, with simple and quick installation.
3. Safe and Reliable, Multiple Protections: Enclosure protection level not lower than IP2XC, effectively preventing ingress of foreign objects. Equipped with leakage, overload, and short circuit protections, ensuring electrical safety.
4. Flexible Configuration, Strong Adaptability: Optional configuration of miniature circuit breakers, isolating switches, residual current devices, surge protective devices, watt-hour meters, etc., meeting the requirements of various power consumption scenarios.
5. Sturdy and Durable, Long Service Life: Made of high-quality cold-rolled steel plate or stainless steel, with phosphating and electrostatic spray coating anti-corrosion treatment, providing high impact resistance.
6. Good Interchangeability, Easy Maintenance: Components within the same series have standardized mounting dimensions and are interchangeable, facilitating future capacity expansion, retrofitting, and daily maintenance.
7. High Cost-Effectiveness: Low cost, simple installation, economical maintenance – it is the most cost-effective power distribution equipment in terminal distribution systems.
2. Service Life
Under standard operating conditions and proper usage, the overall design service life of the distribution box can reach 10 to 15 years.
① Enclosure Life: Made of high-quality cold-rolled steel plate or stainless steel, with phosphating and electrostatic spray coating anti-corrosion treatment. Under normal indoor conditions, the service life can reach over 15 years.
② Component Life: Miniature circuit breakers have a mechanical life of 10,000 to 20,000 operations and an electrical life of 4,000 to 8,000 operations, and can be used for over 10 years under normal operating conditions. Residual current devices have an electronic component aging cycle of approximately 8 to 10 years. Surge protective devices have a decreasing lifespan depending on the number of lightning strikes and overvoltage impacts, generally requiring inspection or replacement every 5 to 8 years.
1. Daily Maintenance
1. Appearance and Environment Inspection: Weekly check whether the enclosure is deformed or rusted, whether there are foreign objects or water accumulation inside the box, and whether the temperature and humidity around the distribution box are within specified ranges.
2. Operating Parameter Monitoring: Daily observe whether current and voltage readings of each circuit are normal, whether indicator lights display correctly, and whether there are any abnormal alarms or odors.
3. RCD Testing: Monthly press the "Test" button on the residual current device (RCD) to confirm whether it operates sensitively and reliably, ensuring the leakage protection function is normal.
4. Terminal Tightening Inspection: Every six months check whether incoming/outgoing terminals, neutral terminals, and earthing terminal blocks are loose. Tighten immediately if looseness is found.
5. Interior Cleaning: At least once a year, use a vacuum cleaner or dry compressed air to clean dust inside the box, focusing on circuit breaker surfaces and terminal connections.
6. SPD Inspection: Annually check whether the status indication window of the surge protective device (SPD) is normal (green = normal / red = failed). Replace immediately if failed.
7. Label Inspection: Every six months check whether circuit labels are clear and complete. Replace or complete any that are missing or faded to prevent incorrect operation.
2. Safety Regulations
1. Power-Off Operation Principle: Before maintenance, the upstream power supply must be disconnected. Strictly follow the procedures of power cut, voltage verification, and hanging of "Do Not Close" signs. Live working is strictly prohibited.
2. Voltage Verification and Earthing: Before contacting conductors, use a voltage detector to verify the absence of voltage. Only after confirmation of no voltage may work begin. Install earthing wires where necessary.
3. Personal Protective Equipment: Operators must hold valid certificates and work in compliance with regulations. Wear insulated shoes and insulated gloves, and stand on an insulating mat during operation.
4. No Operation Under Load: It is strictly prohibited to open or close circuit breakers or isolating switches under load. Operation shall only be performed after confirming that the load has been disconnected.
5. Fault Handling Procedures: In case of emergency such as smoke or fire, immediately disconnect the upstream power supply and use a dry powder fire extinguisher to put out the fire. Do not use water.
6. Maintenance Record Requirements: After each maintenance operation, complete maintenance records including maintenance date, maintenance content, problems found, and handling results. Establish equipment files.
1. Residential Buildings: Used for terminal power distribution and protection of indoor lighting, sockets, air conditioners, and other electrical loads in residential buildings, apartments, and villas.
2. Commercial Buildings: Used for power supply to lighting, air conditioning, elevators, and other equipment in shopping malls, supermarkets, office buildings, hotels, restaurants, and other commercial establishments.
3. Industrial Plants: Used for power distribution and control of industrial equipment (motors, pumps, fans, etc.) in factory workshops and production lines.
4. Public Facilities: Used for lighting and power distribution in public places such as schools, hospitals, gymnasiums, exhibition centers, and government office buildings.
1. Environmental Risks
1. High Temperature Overheating Risk: When the distribution box is installed in poorly ventilated areas, under direct sunlight, or near heat sources, the internal temperature rises, accelerating component aging, reducing service life, and in severe cases, causing circuit breaker misoperation or burnout.
2. Moisture and Condensation Risk: High humidity causes condensation on insulation parts inside the box, reducing insulation resistance, potentially leading to phase-to-phase short circuits, leakage, or creepage discharge, endangering personal safety.
3. Dust Contamination Risk: Conductive dust accumulates on circuit breakers and terminal surfaces, reducing creepage distance, potentially causing partial discharge, short circuit faults, or poor contact resulting in overheating.
4. Corrosive Gas Risk: Corrosive gases in chemical plants, sewage treatment facilities, and similar locations corrode metal parts, causing box rusting, terminal oxidation, increased contact resistance, and intensified heating.
5. Vibration Impact Risk: Proximity to large vibrating equipment may cause terminal loosening and displacement of internal circuit breaker mechanisms, affecting contact reliability and protection accuracy.
6. Water Ingress Risk: When installed in basements or low-lying areas, heavy rain or pipe bursts may cause water ingress, leading to short circuits, leakage, or even equipment scrapping.
7. Overvoltage Surge Risk: Lightning strikes or switching overvoltages may enter the distribution box through the lines, potentially damaging surge protective devices or electronic components, causing equipment damage or data loss.
2. Installation Restrictions
1. Ambient temperature shall not exceed +40°C, and shall not be lower than -5°C. The average temperature over any 24-hour period shall not exceed +35°C.
2. Indoor installation and use. The altitude at the installation site shall not exceed 2000m.
3. Relative humidity of the surrounding air shall not exceed 50% at a maximum temperature of +40°C.
4. The inclination of the equipment installation from the vertical plane shall not exceed 5°. The equipment shall be installed in locations free from severe vibration and impact, as well as corrosive conditions that may damage electrical components. If the user has special requirements, they shall be resolved through negotiation with the manufacturer.
When placing an order, the customer shall provide the following information:
1. Main circuit scheme and single-line system diagram;
2. Secondary circuit schematic diagram;
3. Enclosure external dimensions.
