Wenzhou Shangming Electric Co., Ltd. is a leading manufacturer and supplier of premium electrical equipment.

Shangming is a reliable manufacturer and supplier of distribution box enclosures. With our extensive experience, we offer products in a variety of materials and specifications, and can also provide customized solutions tailored to your specific needs.

Key Features

1. Physical Protection: Provides protection against dust, water, and foreign object ingress, while preventing accidental contact between personnel and live components.

2. Safety Isolation: Isolates high-voltage and high-current equipment from the operating environment, thereby reducing the risks of electric shock and fire.

3. Component Mounting Platform: The distribution box enclosure features DIN rails, mounting brackets, and pre-drilled holes to facilitate the standardized installation of components such as circuit breakers and electricity meters.

4. Electromagnetic Shielding: Minimizes the impact of external electromagnetic interference on internal control circuitry.

5. Environmental Adaptability: Through the use of various materials and protection ratings, the enclosure is suitable for a wide range of environments, including indoor, outdoor, and industrial settings.

Structural Components

Cabinet Door: Available in transparent and solid door options; custom configurations are available from Shangming.

Mounting Plate: A metal plate used for internally securing components; it is removable to facilitate assembly outside the cabinet.

Knockouts: Pre-punched cable entry ports designed to accommodate cables of various diameters.

Sealing Gasket: A highly elastic gasket lining the perimeter of the door panel, serving as the critical element for ensuring the specified IP protection rating.

Grounding Bolt: Essential for ensuring the metal enclosure is reliably grounded, thereby preventing the enclosure from becoming electrically energized.

Application Scenarios

I. Building Low-Voltage Power Distribution Systems

Our Distribution Box Enclosures serve as distribution boxes for commercial buildings, residential floors, and power distribution in public areas.

They act as mounting platforms for components such as circuit breakers and residual current devices, facilitating standardized wiring and safety protection while enhancing the overall neatness and safety of the power distribution system.

II. Industrial Equipment & Automation Control

They function as control boxes for machinery, control cabinets for automated production lines, and enclosures for PLC control systems.

Internally, they house components such as contactors, relays, and control modules, protecting this electrical equipment from dust and oil contamination while facilitating equipment integration and maintenance.

III. Outdoor Power Distribution & Engineering Projects

They serve as temporary outdoor power boxes, power distribution units for construction sites, and control boxes for road lighting.

If you require a customized product for these applications, we recommend selecting a high protection rating (e.g., IP54 / IP65) to ensure resistance against water, dust, and rain.

IV. Photovoltaic & New Energy Systems

Shangming offers enclosures for PV combiner boxes, grid-tied PV cabinets, and control boxes for energy storage systems.

As the foundational housing for new energy equipment, these enclosures provide protection, isolation, and mounting space, supporting the requirements for long-term outdoor operation.

V. Communications & Infrastructure

You can contact us to customize control boxes for communication equipment, distribution boxes for low-voltage systems, power supply boxes for surveillance systems, and more.

This ensures the protection of communication power equipment, prevents external interference and environmental impact, and enhances overall system stability.

What Factors Should Be Considered When Selecting a Distribution Box Enclosure?

1. Dimensions and Specifications

When making a selection, we do not recommend choosing an enclosure that merely fits the components exactly. The area occupied by internal components should not exceed 80% of the base plate area. The remaining 20% of space is reserved for wiring, heat dissipation, and potential future expansion; therefore, you should always allow for some headroom in your selection.

Regarding depth, you must account for the combined depth of the circuit breakers (including their operating handles), wire ducts, and the enclosure door itself. This is particularly critical for high-current molded-case circuit breakers, which have significant depth requirements; failing to account for this may prevent the door from closing properly.

2. Protection Rating (IP Code)

Please select the appropriate protection rating based on the severity of the installation environment:

Indoor Offices/Corridors: IP30 – IP40 is sufficient.

Industrial Workshops: IP54 is recommended to provide protection against dust and splashing water.

Outdoors/Photovoltaic Systems: IP65 or higher is mandatory, and the door seams must feature a continuous, integrated sealing gasket.

3. Material and Corrosion Resistance

Cold-Rolled Steel: The most versatile option, suitable for most dry, indoor environments.

Stainless Steel (304/316): Suitable for pharmaceutical, food processing, and coastal environments with high salt-spray exposure. Stainless steel 316 offers superior corrosion resistance compared to 304.

4. Thermal Management

Heat management is often an overlooked aspect of high-power distribution boxes. We recommend making your selection based on the following scenarios:

Passive Cooling: If the heat generated within the enclosure is minimal, a fully sealed enclosure is suitable.

Active Cooling: If the enclosure houses components such as variable frequency drives (VFDs), soft starters, or high-current contactors, you must select an enclosure equipped with ventilation louvers. In some cases, you may even need to select a model with pre-drilled mounting holes for an axial cooling fan.

Sunlight Protection: For outdoor enclosures, we recommend a double-roof structure to prevent direct sunlight from causing internal temperatures to skyrocket.

5. Ease of Installation and Operation

Door Opening Direction: Determine whether a left-opening or right-opening door is more convenient given the available space at the installation site. Some of Shangming's high-end enclosures feature doors that are reversible (can be configured to open from either the left or the right).

Cable Entry/Exit: Confirm whether cables will enter and exit from the top or the bottom of the enclosure. We recommend selecting an enclosure equipped with a removable flange plate; drilling cable entry holes into the flange plate offers greater flexibility and ensures a superior seal compared to drilling directly into the enclosure body.

Lock Type: Standard industrial triangular lock, keyed flush lock, or fire-safety cam lock.

In addition to various types of distribution box enclosures, Shangming also offers floor-standing power distribution cabinet enclosures—a key component of our high-quality product lineup. Choose us as your long-term supplier to benefit from one-stop customized solutions and direct-from-factory pricing.

Key Features

High Load-Bearing Capacity: For our floor-standing power distribution cabinet enclosures, we typically utilize cold-rolled steel plates with a thickness of 2.0mm or greater, which are either welded or assembled to form the structure. This robust construction enables the cabinet to securely support heavy frame-type circuit breakers, large-cross-section copper busbars, and transformer cables.

Modular Design: The interior features a modular hole pattern system, allowing for the flexible adjustment of crossbeams and mounting plates to suit specific requirements. This design facilitates convenient upgrades and expansions whenever necessary.

Ventilation and Heat Dissipation: Given the high current levels typically present within the cabinet, the enclosure is equipped with exhaust vents at the top and air intake vents at the bottom to ensure effective airflow. Additionally, customers may request a custom configuration to integrate a forced-air cooling system into the product.

Common Cabinet Classifications

Based on their structural form, floor-standing cabinets are primarily divided into two major categories:

1. Fixed Type

Characteristics: Internal components are rigidly mounted via support brackets; once wired, they cannot be moved.

Applications: Features a simple structure and low cost; typically used in settings where requirements for continuous power supply are not extremely stringent.

Representative Model: GGD-type AC Low-Voltage Power Distribution Cabinet.

2. Draw-out Type / Removable Type

Characteristics: Each individual circuit is housed within a separate, independent drawer unit.

Applications: Extremely convenient for maintenance. If a specific circuit fails, the corresponding drawer can simply be pulled out and replaced with a new one, without the need to cut off the main power supply.

Representative Models: GCK, GCS, and MNS-type Advanced Power Distribution Cabinets.

Floor-standing vs. Wall-mounted Distribution Boxes: What Is the Difference?

Product Selection and Configuration Recommendations

Based on your specific project requirements, during the pre-sales phase, Shangming will recommend the most suitable configuration for you. Generally speaking, the application scenarios we most frequently support are listed below, accompanied by corresponding configuration recommendations.

1. Industrial Main Power Distribution

Recommended Configuration:

Cabinet Dimensions: 1800–2200mm (H) × 600–1000mm (W) × 600–1000mm (D)

Material: Cold-rolled steel sheet (≥1.5mm)

Protection Rating: IP30 / IP40

Structure: Single cabinet or coupled cabinets (modular/splittable)

Interior: Designed for installation of ACB / MCCB + Busbar System

2. High-Current / Main Incoming Line Systems

Recommended Configuration:

Width: ≥800mm

Depth: ≥800mm

Structure: Double-door or multi-door design

Interior Space: Supports high-current copper busbars; includes reserved space for top or bottom cable entry.

3. Automation Control / PLC Control Cabinets

Recommended Configuration:

Dimensions: 1600–2000mm (H)

Material: Powder-coated steel sheet / Stainless steel

Protection Rating: IP40 / IP54

Interior: Mounting plate + DIN rails

4. Outdoor Applications

Recommended Configuration:

Protection Rating: IP54 / IP65

Material: Stainless steel (304/316) or outdoor-grade powder-coated steel

Features: Rainproof canopy + Sealing strips + Anti-condensation design

5. Highly Corrosive Environments

Recommended Configuration:

Material: 304 / 316 Stainless steel

Protection Rating: IP55+

Surface Treatment: Anti-corrosion coating

How to Perform Routine Maintenance on a Floor-Standing Power Distribution Cabinet Enclosure?

1. Cleaning and Dust Removal

Use a dry non-woven cloth and a vacuum cleaner to remove accumulated dust from inside the cabinet; the use of wet cloths or direct blasts of compressed air is strictly prohibited.

Pay particular attention to cleaning the busbars, insulators, circuit breaker arc chutes, and ventilation channels.

2. Tightening of Electrical Connections

Inspect all bolted connection points for looseness; use a torque wrench to re-tighten them to the specified torque values.

If signs of oxidation or arcing damage are detected, the terminals must be polished or replaced.

3. Component Functional Testing

Circuit Breakers: Verify that manual opening and closing operations are smooth and that the tripping mechanism is responsive.

Contactors/Relays: Inspect the condition of the contacts for wear and verify that the coil resistance is within the normal range.

Capacitors: Check for signs of capacitance degradation, bulging, or electrolyte leakage.

SPDs (Surge Protection Devices): Verify that the status indicator window is green and that the degradation indicator has not been triggered.

4. Insulation Performance Testing

Use a 500V or 1000V megohmmeter to measure and confirm the following:

Phase-to-phase insulation resistance: ≥ 1 MΩ;

Phase-to-ground insulation resistance: ≥ 1 MΩ;

If the measured values fall below these standards, investigate for potential causes such as moisture ingress or contamination.

5. Mechanical Structure Maintenance

Inspect the guide rails and interlocking mechanisms of drawer-type units to ensure they are not sticking or binding. Lubricate moving parts using grease specifically designed for electrical equipment.

Periodically verify the functionality of the "Five-Prevention" (interlocking) safety mechanisms.

Still searching for a reliable manufacturer and supplier of High and Low Voltage Switchgear? Choose Shangming Electric from China. We provide professional products and services, support various non-standard customization requests, and offer tailored solutions for your specific project needs.

Product Categories

1. High-Voltage Switchgear

This category comprises equipment with a rated voltage ranging from 3 kV to 35 kV and above. Its primary function is to receive and distribute electrical energy; furthermore, in the event of a fault on a power line, it works in conjunction with relay protection devices to rapidly interrupt short-circuit currents reaching thousands of amperes.

Key Components:

High-voltage circuit breakers (vacuum or SF6 type): Serving as the core arc-extinguishing elements.

Disconnectors (Isolating switches): Providing a visible physical air gap to ensure safety during maintenance.

Current/Voltage Transformers: Stepping down high-voltage signals into low-voltage signals for instrumentation and measurement purposes.

Typical Models: KYN28 (Metal-clad withdrawable type), XGN (Fixed-type ring main unit).

2. Low-Voltage Switchgear

This category comprises equipment with a rated voltage of 1000 V or less. Its primary function is to manage the final-stage distribution within a power system. It distributes electrical energy—stepped down by transformers—to various floors, production lines, or power-driven equipment.

Key Components:

Air Circuit Breakers (ACBs): Used for main incoming lines or high-capacity outgoing lines.

Molded Case Circuit Breakers (MCCBs): Used for the protection of branch circuits.

Capacitor Compensation Cabinets: Used to improve the system's power factor and reduce electricity costs.

Typical Models: GGD (Fixed type), GCK/GCS/MNS (Withdrawable/Drawer type).

High-Voltage and Low-Voltage Series: A Comparison

Application Scenarios

Our High and Low Voltage Switchgear finds widespread application and may often be deployed simultaneously within a single setting to fulfill distinct functions. You can customize a complete solution tailored to your specific requirements.

Common Faults and Troubleshooting Solutions

Shangming is a professional manufacturer providing comprehensive after-sales technical support services. Furthermore, accompanying the delivery of our products, we provide a complete set of inspection documentation as well as operation and maintenance guidelines. We have compiled a list of common issues below for your reference.

1. Common Issues with High-Voltage Switchgear

Symptom 1: Partial Discharge and Hissing Noises

Causes: Moisture ingress in insulation components; surface dust accumulation leading to creepage discharge; or corona discharge caused by burrs at busbar connection points.

Solutions:

1. Environmental Control: Verify that the heating and dehumidification units inside the cabinet are functioning correctly.

2. De-energized Cleaning: Wipe down insulators and bushings using anhydrous alcohol.

3. Ultrasonic Detection: Use a partial discharge detector during operation to pinpoint the exact location of the discharge source.

Symptom 2: High-Voltage Circuit Breaker Fails to Close or Open

Causes: Damaged energy-storage motor; burnt-out control circuit (closing/opening coils); or mechanical linkage seizure due to dried-out lubricant.

Solutions:

Secondary Circuit Inspection: Measure the resistance of the closing and opening coils, and ensure that the auxiliary power supply voltage is within the normal range.

Mechanical Lubrication: Reapply specialized low-temperature lubricant to the mechanical transmission components.

2. Common Issues with Low-Voltage Switchgear

Symptom 1: Abnormal Temperature Rise in Air Circuit Breakers (ACBs)

Causes: Insufficient contact pressure or oxidation at the primary plug-in contacts; loose busbar bolts.

Solutions:

Temperature Monitoring: Use an infrared thermal imager to scan the contacts and connection points.

Contact Maintenance: De-energize the system, withdraw the ACB, clean off any oxidation layers on the contacts, and apply electrical contact grease.

Symptom 2: Bulging or Ruptured Capacitors in Reactive Power Compensation Cabinets

Causes: Excessive harmonic content within the system; or overheating caused by frequent switching operations of the capacitors.

Solutions:

Capacitor Replacement: Promptly replace any bulging capacitors to prevent electrolyte leakage, which could lead to short circuits.

Installation of Series Reactors: Install series reactors within the compensation circuit to suppress harmonics.

3. General Faults

Symptom: Condensation—characterized by water droplets forming on the inner walls of the cabinet and flashover traces visible on the surfaces of insulation components.

Solution:

Sealing: The cable entry openings at the bottom of the cabinet must be completely sealed using fire-retardant putty to block moisture ingress from the cable trench.

Intelligent Upgrade: Install an automated temperature and humidity monitoring system paired with a condensation dehumidifier to replace traditional heating panels.