What type of indoor fiber optic cable should be used

For indoor installations, tight-buffered multimode or singlemode fiber cables with appropriate fire ratings (plenum, riser, or LSZH) are typically recommended.

Fiber Type

• Singlemode fiber has a small core (~9 µm) and is ideal for long-distance, high-bandwidth applications, such as connecting different buildings in a campus network .
• Multimode fiber has a larger core (50–62.5 µm) and is suitable for shorter distances, like within a data center or office building, supporting high-speed Ethernet and backbone connections .

Cable Construction

• Tight-buffered cables wrap each fiber in a protective 900-micron plastic buffer, making them flexible, easy to handle, and suitable for indoor runs, direct burial, or moderate-length networks .
• Loose-tube cables are less common indoors but provide better protection in harsh environments; they are typically used outdoors or in mixed indoor/outdoor applications .

Fire Safety Ratings

• Plenum-rated (OFNP/FT6) cables are designed for air-handling spaces like ceilings or raised floors, offering the highest fire resistance and low smoke emission .
• Riser-rated (OFNR/FT4) cables are suitable for vertical runs between floors in non-plenum areas .
• Low Smoke Zero Halogen (LSZH) cables are preferred in Europe or areas where toxic fumes must be minimized in case of fire .

Specialized Indoor Cables

• Breakout cables contain individually jacketed fibers, making them easy to separate and connect to multiple endpoints, ideal for multi-dwelling units or vertical risers .
• Distribution cables bundle fibers under a single jacket, suitable for horizontal runs and structured cabling within buildings .

Practical Recommendations

• For office or data center environments, a tight-buffered multimode cable with plenum or LSZH rating is often the best choice due to flexibility, ease of installation, and compliance with fire codes .
• For longer indoor runs or inter-building connections, singlemode tight-buffered or breakout cables are preferred to maintain high bandwidth over distance .
• Always consider space constraints, bend radius, and future scalability when selecting the cable type to ensure reliable performance and easier maintenance . By matching the fiber type, construction, and fire rating to your building's requirements, you can ensure a safe, high-performance indoor fiber optic network.