Minimum length requirement for fusion spliced ​​optical cables

The minimum length of fiber prepared for fusion splicing is typically 10–20 mm for the stripped fiber, with additional buffer tube lengths of about 1 meter inside the splice closure.

Fiber Strip Length

For fusion splicing, the bare fiber must be stripped of its coating to allow proper alignment and fusion. The recommended strip length is generally 10–20 mm, depending on the specific fusion splicer and fiber type (single-mode or multimode) to ensure a clean, precise splice without microfractures or damage to the glass core (Fiber Optic Fusion Splicing Guide) . The stripped fiber diameter is usually 250 µm for bare fibers and 900 µm for coated fibers .

Buffer Tube and Splice Tray Preparation

In addition to the bare fiber, the buffer tube or loose tube must be prepared to provide enough slack for handling and protection inside the splice closure. Typically, about 1 meter of buffer tube is required inside the closure, and approximately 1 meter of fiber is needed inside the splice tray to allow proper routing and bend radius control (FOA Reference for Fiber Optics) . This ensures that the splice is stable, protected from environmental stress, and accessible for future maintenance.

Additional Considerations

• Cable jacket stripping: Usually 2–3 meters of jacket is removed to expose the fibers and strength members for attachment to the closure .
• Cleaning: All water-blocking materials and fiber surfaces must be thoroughly cleaned before splicing to prevent contamination and high splice loss .
• Splice closure guidance: Always follow the manufacturer's instructions for splice tray and closure lengths, as requirements may vary depending on the enclosure type and fiber count . By adhering to these minimum lengths and preparation practices, fusion splices achieve low splice loss, high tensile strength, and long-term stability under expected environmental conditions (ITU-T L.400/L.12) .