Practical Industrial Data Networks:Design, Installation and ...

6.7.1 Splicing traysFiber optics overview 85Splices are generally located in units referred to as ‘splicing centers’, ‘splicing trays’ or‘splicing organizers’. The splicing tray is designed to provide a convenient location tostore and to protect the cable and the splices. They also provide cable strain relief to thesplices themselves.Splicing trays can be located at intermediate points along a route where cables arerequired to be joined or at the termination and patch panel points at the end of the cableruns.The incoming cable is brought into the splicing center where the sheath of the cable isstripped away. The fibers are then looped completely around the tray and into a spliceholder. Different holders are available for different types of splices. The fibers are thenspliced onto the outgoing cable if it is an intermediate point or on to pigtails if it is atermination point. These are also looped completely around the tray and then fed out ofthe tray. A typical splicing tray is illustrated below:OutgoingCableClipsIncomingCableSplice HolderSplice ProtectorFigure 6.6A typical splicing trayThe cables are physically attached to the splice tray to provide strain relief. The cablesnormally enter the tray on one side only to facilitate moving the tray/joint enclosure to amore accessible jointing location. The fibers are looped completely around the tray toprovide slack, which may be required to accommodate any changes in the future, and alsoto provide tension relief on the splices.Each splice joint is encased in a splice protector (plastic tube) or in heat shrink before itis clipped into the holder.Splicing trays are available that have patching facilities. This allows different fibers tobe cross-connected and to be looped back for testing purposes.6.7.2 Splicing enclosuresThe splicing trays are not designed to be left in the open environment and must be placedin some type of enclosure. The enclosure that is used will depend on the application. Thefollowing are examples of some enclosures used for splicing trays.