Fiber optic splice closures are among the most widely used products in the optical communications industry. But how exactly are these splice closures secured? Let's explore this together!
There are two primary methods for installing aerial fiber optic splice closures: The first involves mounting the closure directly onto a utility pole, positioning it parallel to the pole (typical for "dome-type" closures). The second involves mounting the closure onto a messenger wire (suspension strand), positioning it parallel to the wire (commonly used for closures where fiber cables enter and exit from both ends).
When a horizontal-type aerial splice closure is mounted on a messenger wire, several issues may arise: First, because the flat profile of the closure is oriented vertically-perpendicular to the ground-it presents a larger surface area to the wind, making the closure prone to swaying. Second, the sealing seam faces upward; consequently, if the seal fails, water can easily ingress into the closure. Third, the fiber splicing trays inside the closure are oriented vertically; this makes it easy for the actual fiber splices and any reserved slack fiber to shift out of their original positions, resulting in an unstable configuration. However, if the splice closure is rotated by 90 degrees, these negative factors can be eliminated, provided that care is taken to ensure the fiber splicing trays remain facing upward.
Therefore, the installation of aerial fiber optic splice closures must take the following points into consideration:
1. Minimize wind resistance to reduce the extent of the closure's swaying.
2. Orient the sealing seams downward or to the side whenever possible to prevent rainwater ingress in the event of a seal failure.
3. Ensure the fiber splicing trays inside the closure are positioned horizontally and facing upward, thereby keeping the fiber splices and reserved slack fiber within the trays in a stable state. This approach helps minimize the likelihood of operational faults occurring.
Regarding dome-type aerial splice closures mounted directly onto utility poles: these are generally not prone to swaying under wind loads. Furthermore, since both the cable entry/exit ports and the sealing seams face downward, it is difficult for rainwater to enter the closure. However, because the closure itself is installed vertically, the internal fiber splicing trays are also oriented vertically; this configuration makes it easy for the fiber splices and reserved slack fiber to shift out of their original positions, thereby creating an unstable condition. This constitutes an inherent drawback of dome-type splice closures; therefore, it is imperative to securely anchor both the fiber splices and the slack fiber within the splice tray to ensure their stability; failure to do so will likely result in operational faults.
Regarding direct-buried and duct-mounted splice closures, the sole requirement is to ensure that the splice tray is oriented upwards.
To guarantee this upward orientation, the intended direction of the splice tray should be clearly marked on the exterior of the splice closure housing-a practice that is particularly critical for dome-type splice closures.