How to coil the fiber optic cable when connecting it to the junction box

Coil fiber optic cable inside a junction box using the figure-eight method to prevent twists, maintain bend radius, and safely store slack.

Step-by-Step Guide

1. Prepare the Cable and Junction Box Before coiling, ensure the junction box is clean, free of sharp edges, and has enough space for the cable loops. Verify the cable length and leave sufficient slack for future maintenance or splicing . 2. Use the Figure-Eight Technique Lay the cable on the ground in a large figure-eight pattern, with each loop approximately 5–8 feet (1.5–2.4 meters) in diameter for loose tube cables . This prevents twisting and kinking. For shorter lengths (under 30 meters), small loops can be used, but avoid coiling in a single continuous direction . 3. Maintain Minimum Bend Radius Never bend the fiber beyond its specified minimum bend radius, typically indicated by the manufacturer. Exceeding this radius can cause microbends or signal loss . When coiling inside the junction box, form loops that respect this radius. 4. Place the Coiled Cable in the Box Gently lift the figure-eight loops and place them inside the junction box. Arrange the loops so that they do not press against sharp edges or each other, and avoid stacking too tightly. Use cable guides or spools inside the box if available to secure the loops . 5. Secure and Label Use Velcro straps or cable ties loosely to hold the loops in place without compressing the cable. Label the slack for easy identification during future maintenance . 6. Avoid Twists and Tension Ensure the cable is not twisted or under tension when coiled. Twists can damage the fiber and increase attenuation . If necessary, relieve pressure at crossover points with small shims or by forming a second figure-eight . 7. Final Check Verify that all fibers are properly routed to adapters or splices, and that the coiled cable does not interfere with the junction box cover or other components . By following these steps, you can safely coil fiber optic cable inside a junction box, preserving signal integrity and allowing for future maintenance or expansion.