Typically, 10 to 20 meters of optical cable should be reserved per side in manholes or handholes to facilitate maintenance and splicing.

Reserve Length Guidelines

When installing optical fiber cables in communication pipelines, it is essential to leave extra cable, known as reserve or slack, in manholes, handholes, and joint locations. This ensures that future maintenance, repairs, or splicing can be performed without tensioning or damaging the cable .

• Connector Reserve: At each connector or splice point, it is recommended to reserve 10 meters per side to allow for proper handling and future adjustments .
• Handhole/Manhole Reserve: For every handhole, especially those at regular intervals (e.g., multiples of 5, 10, 15), a reserve of 20 meters is suggested to accommodate looping, splicing, and maintenance .
• Looping and Slack Management: When laying cable, loops should be formed carefully, often in a figure-8 pattern, to prevent twisting and maintain the minimum bend radius . This helps avoid fiber damage and ensures long-term reliability.
• Long Runs: For extended outside plant runs, additional slack may be required at intermediate points to facilitate pulling from multiple directions or for future network expansion .

Practical Considerations

• Bend Radius: Ensure that the reserved cable is looped without exceeding the minimum bend radius, typically 20 times the cable diameter during installation and 10 times during static conditions .
• Labeling: Clearly mark the ends of the reserved cable to identify the A and B ends for splicing and maintenance .
• Maintenance Access: Reserve lengths should be sufficient to allow technicians to work comfortably in confined spaces without stressing the cable. By following these guidelines, reserving 10 meters per side at connectors and 20 meters in handholes provides adequate slack for maintenance, future splicing, and network expansion while protecting the optical fibers from damage.