Outdoor Optical Cable Distribution Box For Four-Network Integration And Optical Fiber Splitting Applications
I. Capacity Specification Parameters: Adapting to Fiber Density Requirements of Different Scenarios
The capacity parameters of the optical fiber distribution box directly determine the number of optical fibers it can carry and the connection scale. They need to be accurately matched according to the fiber core number requirements of the application scenario, mainly including the following core indicators:
1. Fiber Core Capacity
Basic Specifications: Common capacities include 8-core, 12-core, 16-core, 24-core, 36-core, 48-core, 72-core, 96-core, 144-core, 288-core, etc. Some large-scale boxes can support 576 cores and above.
8-24 cores: Suitable for families, small offices, or corridor units to meet the fiber access needs of a small number of users;
48-144 cores: Mostly used in community computer rooms and medium-sized enterprise computer rooms to support multi-user aggregation or inter-device connections;
288 cores and above: Mainly used in communication hubs and core areas of data centers to adapt to the centralized management of high-density optical fiber links.
Design Logic: The core capacity is determined by the number of fusion splice trays and distribution modules in the box. For example, a 12-core box is usually equipped with one 12-core fusion splice tray, and a 48-core box is equipped with four 12-core fusion splice trays (or two 24-core fusion splice trays) to ensure that each fiber core has an independent fusion splicing and storage space.
2. Number of Adapter Ports
Matching Relationship: The number of adapter ports corresponds to the number of fiber cores one-to-one (or with 1:1.2 redundancy reserved). For example, a 24-core box needs to be equipped with 24 or 28 adapter ports to support the active connection of optical fiber jumpers.
Port Types: Supports mainstream interface types such as SC, LC, ST, FC, and MT-RJ. Among them, SC (square) and LC (miniaturized) are the most commonly used - SC interfaces are easy to plug and unplug, suitable for outdoor scenarios; LC interfaces are only half the size of SC, adapting to high-density wiring (such as a 1U height box in data centers can integrate 48 LC ports).
3. Fusion Splice Tray Capacity
The fusion splice tray is a core component for optical fiber fusion splicing. The capacity of a single tray is usually 12 cores or 24 cores, and some small boxes use 6-core fusion splice trays. For example, a 96-core box needs to be equipped with 8 12-core fusion splice trays (or 4 24-core fusion splice trays), and the fusion splice trays need to support flipping or disassembly to facilitate on-site fusion splicing operations.
The storage radius of the fusion splice tray must be ≥ 40mm to ensure that the fiber bending loss at the fusion splice point is ≤ 0.1dB, avoiding signal attenuation caused by excessive bending.
II. Optical Performance Parameters: Core Indicators for Ensuring Signal Transmission Quality
The optical performance of the optical fiber distribution box directly affects the transmission efficiency and stability of optical signals, which are mainly measured by the following indicators:
1. Insertion Loss
Definition: The power attenuation value of an optical signal when passing through connectors, fusion splice points, and adapters inside the box, in dB.
Standard Requirements:
Adapter connection loss: ≤ 0.3dB (multimode fiber), ≤ 0.2dB (single-mode fiber);
Fusion splice loss: ≤ 0.05dB (single-mode fiber, fusion splicer hot melt), ≤ 0.15dB (multimode fiber);
Overall link loss: The total insertion loss of the box is ≤ 0.5dB (including all connection points).
Impact: Low insertion loss can reduce signal attenuation and extend the transmission distance. For example, if the insertion loss is reduced from 0.5dB to 0.2dB, the transmission distance can be increased by about 5km at a 10Gbps rate (single-mode G.652D fiber).
2. Return Loss
Definition: The ratio of the energy of the optical signal reflected back to the light source at the connection point to the incident energy, in dB. A higher value indicates less reflection.
Standard Requirements:
Single-mode fiber: ≥ 50dB (SC/LC/UPC interface), ≥ 60dB (APC inclined end face interface, suitable for CATV and other scenarios sensitive to reflection);
Multimode fiber: ≥ 20dB (ST interface), ≥ 25dB (SC interface).
Impact: High return loss can avoid reflected light from interfering with the original signal, especially in high-speed (such as 25Gbps/100Gbps) transmission, where reflected signals may lead to an increase in bit error rate. Therefore, data center scenarios usually require a return loss of ≥ 55dB.
3. Fiber Bending Radius
Static Bending Radius: The minimum curvature radius when optical fibers are routed inside the box. For single-mode fibers, it is ≥ 30mm; for multimode fibers, it is ≥ 25mm. If bending-insensitive fibers (such as G.657A1) are used, it can be reduced to 15mm (short-term)/30mm (long-term).
Dynamic Bending Radius: The allowable value for temporary bending of optical fibers during installation or maintenance, usually 1/2 of the static radius (such as the dynamic bending radius of single-mode fibers is ≥ 15mm).
Significance: Excessive bending will cause "macrobending loss". For example, when the bending radius of a single-mode fiber is 10mm, the loss per meter can reach 0.5dB, far exceeding the standard requirements. Therefore, a dedicated fiber routing channel must be designed inside the box to forcefully standardize the fiber path.
4. Plugging Durability
The plugging life of adapters and connectors must be ≥ 1000 times, and after 1000 plugging cycles, the change in insertion loss is ≤ 0.2dB, and the change in return loss is ≤ 5dB.
This indicator ensures the stability of the equipment during long-term operation and maintenance, especially in scenarios such as data centers where fiber links need to be adjusted frequently.
III. Mechanical Structure Parameters: Adapting to Installation Environment and Maintenance Needs
The mechanical structure of the optical fiber distribution box must take into account installation flexibility, operational convenience, and structural stability. The core parameters include:
1. Overall Dimensions and Installation Methods
Dimension Specifications:
Wall-mounted: Small (such as 300mm×200mm×100mm, 8-12 cores), medium (450mm×350mm×150mm, 24-48 cores), large (600mm×500mm×200mm, 72-144 cores);
Rack-mounted (19-inch standard): Height 1U (44.45mm, 48-96 core LC interface), 2U (88.9mm, 144-288 cores), depth is usually 300mm or 450mm, adapting to standard cabinet installation;
Pole-mounted (outdoor): Diameter Φ114mm-Φ160mm (adapting to electric poles or communication poles), height 500mm-800mm (72-144 cores).
Installation Methods: Supports wall mounting (fixed with expansion screws), pole mounting (fixed with stainless steel hoops), overhead mounting (suspended by optical cable hangers), embedded mounting (reserved holes in walls), etc. Some boxes can be compatible with multiple installation methods (such as "wall-mounted + pole-mounted" dual-purpose design).
2. Box Material and Protection Level
Material Classification:
Indoor type: ABS engineering plastic (lightweight, corrosion-resistant, low cost), cold-rolled steel plate (surface spray coating, high strength, suitable for computer rooms);
Outdoor type: Stainless steel (304 material, salt spray resistant, rust resistant, suitable for coastal or industrial areas), SMC composite material (glass fiber reinforced plastic, UV resistant, high and low temperature resistant, service life ≥ 20 years).
Protection Level (IP Code):
Indoor type: IP30 (protection against solid foreign objects with diameter ≥ 2.5mm, protection against splashing water), IP40 (protection against solid foreign objects with diameter ≥ 1mm);
Outdoor type: IP65 (completely dust-tight, protection against low-pressure water jets), IP66 (protection against high-pressure water jets), IP68 (waterproof under 1m water for 30 minutes, suitable for underground pipe wells).
Supplement: Outdoor boxes also need to have "three-proof" capabilities - corrosion resistance (salt spray test ≥ 1000 hours), mildew resistance (GB/T 2423.16 standard, grade 0 no mold growth), and rodent and ant resistance (metal mesh protection or ant-proof agent treatment).
3. Internal Structure Design
Zoning Layout: It is necessary to clearly divide the fusion splicing area, distribution area, and fiber storage area to avoid fiber cross-interference. For example:
Fusion splicing area: Place the fusion splice tray, supporting the removal of the tray (some models can take the fusion splice tray to the workbench for fusion splicing to improve efficiency);
Distribution area: Install the adapter panel, which can be flipped or pulled out to facilitate plugging and unplugging jumpers;
Fiber storage area: Reserve space for storing excess fiber length. The excess fiber must be wound with a radius ≥ 30mm and fixed with cable ties (direct winding or extrusion is prohibited).
Door Lock and Opening Method: Outdoor types use anti-theft locks (such as triangular key locks), and indoor types can use push-type buckles; the door opening angle is ≥ 120°, and some models support 180° full opening to ensure that maintenance personnel can operate internal components without obstacles.
Load-bearing Capacity: Rack-mounted boxes must be able to withstand a static load of ≥ 50kg (such as stacking other equipment), and wall-mounted boxes must be able to withstand a pulling force of ≥ 30kg (to prevent falling off).
IV. Environmental Adaptability Parameters: Ensuring Stable Operation Under Extreme Conditions
Optical fiber distribution boxes need to adapt to the climatic environments of different regions, and their environmental parameters directly determine the service life and reliability of the equipment:
1. Operating Temperature and Humidity
Operating Temperature Range:
Indoor type: 0℃~+40℃ (ordinary computer rooms), -5℃~+55℃ (industrial environments);
Outdoor type: -40℃~+70℃ (from frigid to tropical regions), and some plateau models can support -50℃~+70℃.
Storage Temperature Range: -40℃~+85℃ (when exceeding the operating temperature, the equipment must be stored without power).
Relative Humidity: 5%~95% (no condensation). In high-humidity environments (such as the plum rain season in southern China), a condensation water guide groove must be designed inside the box to prevent moisture from directly contacting optical fibers or metal components.
2. Resistance to Environmental Interference
Vibration and Impact:
Vibration: Can withstand sinusoidal vibration of 10Hz~55Hz with an amplitude of 0.35mm, and the change in insertion loss after testing is ≤ 0.1dB;
Impact: Can withstand an impact of 15g acceleration (11ms duration), with no structural damage after testing and qualified optical performance.
Application Scenario: Outdoor boxes along traffic routes (such as railways and highways) need to strengthen anti-vibration design.
Air Pressure Adaptation: Can work normally in the altitude range of 0~5000m (the air pressure in plateau areas is low, and it is necessary to ensure that the sealing performance of the box is not affected).
Sunlight and UV Resistance: Outdoor boxes must pass the UVB-313 lamp aging test (after 1000 hours of irradiation, the material has no cracking or discoloration, and the strength retention rate is ≥ 80%) to avoid long-term sunlight causing the shell to become brittle.
V. Safety Protection Parameters: Ensuring Equipment and Personnel Safety
Optical fiber distribution boxes must meet electrical safety and structural safety requirements, and the core parameters include:
1. Electrical Insulation and Grounding
Insulation Resistance: The insulation resistance between the metal parts of the box and the grounding device is ≥ 1000MΩ (tested with 500V DC voltage) to prevent electric leakage risks.
Withstand Voltage Performance: Apply 3000V DC voltage between the grounding device and the metal parts of the box for 1 minute, with no breakdown or arcing, to ensure that it can withstand induced high voltage in thunderstorm weather.
Grounding Requirements: The box must reserve a grounding terminal with a cross-sectional area of ≥ 6mm², and the grounding resistance is ≤ 10Ω (connected to the building grounding grid through a grounding wire to release static electricity or lightning current).
2. Fire Resistance and Flame Retardancy
The material of indoor boxes must meet the UL94 V-0 flame retardant standard (in the vertical burning test, the flame is extinguished within 10 seconds, and no dripping ignites the cotton pad below);
Although there is no mandatory flame retardant requirement for outdoor types, they must have self-extinguishing ability when away from fire (to avoid fire spread).
The optical fiber itself is made of quartz (non-combustible), but the plastic parts inside the box (such as adapters and fiber routing grooves) must meet flame retardant requirements, especially in scenarios with high fire protection levels such as data centers.
3. Corrosion Resistance and Aging Resistance
Metal parts (such as stainless steel locks and screws) must pass the neutral salt spray test (5% NaCl solution, 35℃ environment, no obvious rust after 48 hours of testing);
Plastic parts must pass the artificial accelerated aging test (temperature +70℃, humidity 95%, after 1000 hours of testing, the tensile strength retention rate is ≥ 80%).
VI. Functional Expandability Parameters: Meeting Network Upgrade Needs
Modern optical fiber distribution boxes need to have flexible expansion capabilities to adapt to the iteration of network architectures (such as from GPON to XG-PON, 10G-PON). The core parameters include:
1. Module Compatibility
Optical Splitter Integration: Supports built-in PLC optical splitters (1:2, 1:4, 1:8, 1:16, 1:32). The insertion loss of the splitter must be ≤ 7dB (1:8), ≤ 10.5dB (1:16), and reserve splitter installation slots (such as 1U height can install 2 1:16 splitters);
Wavelength Division Multiplexer (WDM): Some models can integrate coarse wavelength division multiplexers (CWDM) to support wavelength separation such as 1310nm/1550nm, adapting to the co-fiber transmission of data and CATV signals in FTTH networks;
Optical Attenuator: Reserve an attenuator installation position (such as fixed attenuation values of 5dB, 10dB) for adjusting the optical signal strength (to avoid overload at the receiving end).
2. Identification and Management Functions
Each optical fiber must be equipped with an independent identifier (such as a label slot, laser engraving) to mark the core number, fusion splice position, corresponding user/equipment information;
Some intelligent models support electronic tags (RFID), and optical fiber link information can be read through handheld terminals to realize digital management (suitable for large data centers or complex link scenarios).
3. Multi-Fiber Type Support
Compatible with single-mode fibers (G.652D, G.657A1/A2), multimode fibers (OM3, OM4), and bending-insensitive fibers (G.657B3). The adapter interface must match the fiber type (such as multimode LC interfaces use beige shells, and single-mode ones use blue/green shells).
VII. Application Scenario Adaptation Parameters: Targeted Design to Meet Subdivision Needs
Different scenarios have different parameter requirements for optical fiber distribution boxes. The following are parameter adaptation cases for typical scenarios:
Application Scenario Core Parameter Requirements Recommended Model Specifications
FTTH Corridor Distribution 24-48 cores, IP54 protection, wall-mounted installation, built-in 1:16 splitter 450mm×350mm×150mm (SMC material)
Data Center Cabinet 96-288 cores, 1U/2U rack-mounted, LC interface, return loss ≥ 55dB 482.6mm×88.9mm×300mm (cold-rolled steel plate)
Outdoor Base Station 72-144 cores, IP65 protection, 304 stainless steel material, operating temperature -40℃~+70℃ 600mm×500mm×200mm (pole-mounted)
Industrial Plant 48 cores, anti-vibration (10Hz~55Hz), corrosion resistance, IP66 protection 500mm×400mm×180mm (SMC material)
Summary
The parameter design of the Optical Fiber Distribution Box must achieve a three-dimensional balance of "performance, structure, and environment": optical performance ensures signal transmission quality, mechanical structure adapts to installation and maintenance needs, and environmental parameters ensure reliable operation of the equipment under extreme conditions. As optical fiber networks evolve towards high density and intelligence, new-generation distribution boxes also need to have modular expansion and digital management capabilities to meet the upgrade needs of 5G, Data Center Interconnect (DCI), smart city and other scenarios. When selecting a model, it is necessary to match parameters according to the specific scenario's fiber core number, installation environment, transmission rate and other factors to maximize the efficiency of the equipment.
