Procuring optical fiber cables is a professional undertaking that requires comprehensive consideration of technical, commercial, and ongoing maintenance considerations. An inappropriate choice can lead to substandard network performance, construction difficulties, and even high future upgrade costs.
I. Clarify Core Technologies and Specifications (This is the Foundation)
Fiber Type: Single-Mode vs. Multi-Mode
Single-Mode Fiber (SMF): Yellow jacket, thin core (9μm). It offers long transmission distances (up to tens or even hundreds of kilometers) and high bandwidth, primarily used in long-distance trunk lines, metropolitan area networks (MANs), and FTTH access networks. It is the absolute mainstream for current and future development.
Multi-Mode Fiber (MMF): Orange (OM1/OM2) or aquamarine (OM3/OM4/OM5) jacket, thick core (50/62.5μm). It offers shorter transmission distances (hundreds of meters to kilometers), moderate bandwidth, and low cost. It is primarily used within data centers, in local area networks (LANs), and for short-distance interconnections.
Selection Recommendation: Unless it’s a short-distance, low-cost LAN project, single-mode fiber is preferred to leave room for future upgrades.
Fiber Core Count
Determine the number of fibers based on the network topology and future redundancy requirements. Common fiber counts include 2, 4, 6, 8, 12, 24, 48, 96, and 144.
Principle: If budget and duct space allow, reserve an appropriate amount of redundant fibers (for example, if 8 fibers are actually needed, consider purchasing a 12- or 24-fiber cable) to prepare for future expansion or failure backup. This avoids the significant cost of re-routing the fiber cables.
Fiber Optic Cable Structure
Central Tube: The optical fibers are enclosed in a plastic tubing filled with moisture-proof gel. This offers a simple structure, light weight, and is suitable for duct installation.
Layer-Stranded: The optical fibers are stranded around a central reinforcement member. This offers excellent mechanical properties and high tensile strength, allowing for a large fiber count and adapting to various installation methods.
Bonded: The optical fibers are enclosed in a plastic sleeving. This provides excellent resistance to lateral pressure and is waterproof and moisture-resistant.
Ribbon cable: Multiple optical fibers (e.g., 12 fibers) are integrated into a flat ribbon unit, which is then combined into a cable. This cable offers the highest fiber density and is suitable for very large fiber counts (e.g., data center interconnects).
Jacket Material
Polyethylene (PE): The standard jacket for outdoor optical cables, offering excellent weather resistance, UV resistance, and abrasion resistance.
Polyvinyl chloride (PVC): The standard jacket for indoor optical cables, offering excellent flexibility and flame retardancy (the low-smoke zero-halogen (LSZH) version is safer), but with poor weather resistance.
Low-smoke zero-halogen (LSZH/LSZOH): Develops low-smoke, non-toxic combustion. This cable is a mandatory safety requirement and must be used indoors, in poorly ventilated ducts, subways, building shafts, and other crowded areas.
Water-blocking yarn/moisture-proof gel: Outdoor optical cables must exhibit excellent moisture and water resistance.
Reinforcement Members
Metal reinforcement members (e.g., steel wire): Offer exceptional tensile strength and are used in environments requiring high tensile forces, such as direct burial and aerial installations.
Non-metallic reinforcements (such as FRP and aramid yarn): High tensile strength, lightweight, and fully dielectrically insulated. Suitable for use near power lines, in minefields, and in locations requiring strong electromagnetic interference protection.
II. Selecting the fiber optic cable model based on the installation environment
This is key to ensuring the cable’s functionality and performance!
Outdoor fiber optic cables:
Aerial fiber optic cables: Requires internal messenger wires (steel wires) or self-supporting cables with attached messenger wires. These cables are highly tensile and weather-resistant.
Direct-buried fiber optic cables: Requires metal armor (such as steel tape or steel wire) to protect against soil pressure and rodent attack, and a corrosion-resistant sheath.
Duct fiber optic cables: Requires a smooth PE sheath with a waterproof construction for easy traction in ducts.
Underwater fiber optic cables: Require heavy armor and specialized sealing and waterproofing, posing the highest technical requirements.
Indoor fiber optic cables:
Vertical shafts: Either stranded or central bundled tube fiber optic cables are acceptable. The sheath must be low-smoke zero-halogen (LSZH).
Horizontal cabling: Choose flexible, lightweight drop cables (FTTH drop cables) or miniaturized indoor optical cables for easy installation in corridors and indoor conduits.
For patch cables between devices: Use pre-terminated optical cables (with connectors pre-installed on both ends) for plug-and-play convenience.
Special scenarios:
Data centers: Use high-density pre-terminated MPO/MTP optical cables, OM3/OM4/OM5 multimode fiber, or single-mode fiber.
Rodent/termite-resistant areas: Choose sheathing with rodent-resistant armor (such as glass yarn, hard plastic sheathing) or special chemical coatings.
For power lines laid in the same trench: Choose all-non-metallic optical cables (except ADSS/OPGW) to ensure safety.
III. Supplier and Business Considerations
Brand and Qualifications:
Choose well-known brands or reputable distributors for guaranteed quality.
Verify the supplier’s qualifications and request third-party product inspection reports and full performance test reports.
Price and Delivery Time:
Price isn’t the only criterion. “You get what you pay for” is a common practice in the optical cable industry. Excessively low prices may indicate cutting corners (e.g., using used fiber or inferior materials).
Specify delivery dates to ensure project deadlines are not impacted.
Sample Testing:
Before purchasing in bulk, be sure to request samples and send them to a third-party testing agency for key performance tests, such as:
Attenuation/Loss: Compliance with international/domestic standards such as G.652.D.
Geometric Parameters (core diameter, cladding diameter, concentricity, etc.): These affect splice loss.
Mechanical Properties (tensile strength, compression, repeated bending).
Environmental Properties (high and low temperature cycling, humidity and heat).
After-Sales Service and Warranty:
Specify the warranty period (typically, high-quality optical cables have warranties of 20 years or longer).
Understand the supplier’s technical support capabilities and after-sales response time.
IV. Construction and Acceptance
Supporting Products: Purchase fiber optic distribution frames, splice boxes, and pigtails that match the optical cables to ensure compatibility.
Retention and Bend Radius: Remind the construction team that the minimum bend radius must not be exceeded during cable laying and installation to avoid stress and microbending, which can increase losses.
On-site Acceptance:
OTDR Testing: After each fiber optic cable segment is spliced, an OTDR must be used to test it. This generates a fiber link test report (“fiber ID”) documenting the length, total loss, and loss at each splice point of each segment. Ensure that all specifications are within design ranges.
