This instruction manual is a step-by-step guide for end and mid-sheath access of armored fiber optic cables, including sheath removal, core preparation, and fiber preparation.
Fiber Optic Tools and Materials Needed:
- Eye and Hand Protection
- Clean Cotton Cloths
- Fiber Optic Cable Cutters
- Core Tube Removal Tool
- Tape Measure
- Tube Slitter
- Hot air gun
- Needle Nose Pliers
- Sheath Knife
- Primary Coating Stripping Tool
:: END-ACCESS PROCEDURE
This procedure is intended to be used with central loose tube single armor cable construction, utilizing an outer sheath and dry yarn construction.
The length of the outer cable sheath to be removed will depend on local company practices and vendor
specifications. Designate this distance from the end of the cable on the outer sheath. Using an sheath knife,
‘ring’ the circumference of the sheath at the designated distance.
Using the sheath knife, ‘ring’ the circumference of the outer sheath about three to five inches from the end of the cable. Apply enough pressure to cut through the outer sheath and score the underlying armor.
Flex the end of the outer sheath and the armor sheath should crack open. Slide the separated section off the cable end. The ripcord(s) will now be exposed.
Before pulling the ripcords, nick the armor with side cutters at the points where the ripcords disappear under the sheath. This gives a starting point for the ripcords to slit the armor.
Grasp and wrap one of the ripcords around the needle-nose pliers and pull the ripcord about 1.5” into the sheath. Repeat with the second ripcord. Now pull each ripcord in turn back to the predetermined ring cut.
Remove the split sheath from the cable.
:: CABLE CORE AND CENTRAL TUBE END PREPARATION
Once the outer sheath has been removed, the cable core is exposed. The cable core consists of the outer
fiberglass strength members, and a central loose tube containing the optical fibers.
Unwrap the strength members from around the CentraLink. Cut them to length as prescribed by closure manufacturer’s instructions.
Measure the length of central tube to be removed and mark it. The length of central tube to be removed will depend upon local practices or closure manufacturer’s specifications.
Check the blade depth setting on the buffer tube removal tool by ringing a small section of the central tube near its end. A proper depth setting will score the buffer tube without completely cutting through the tube. When gently flexed, the buffer tube will break at this point, allowing safe and easy access to the coated fibers.
Ring the tube in one or two foot sections and remove until the desired amount of fiber is exposed in accordance with the requirements of the protective closure being used.
Gently wipe the excess thixotropic gel from the exposed fibers with a soft dry cloth.
: MID-SHEATH ACCESS PROCEDURE
This section details the methods for entering an armored fiber optic cable mid-sheath.
To access the fibers in an armored cable at mid-sheath, first locate the appropriate area of the cable.
The length of the outer sheath to be removed will depend on local company practices and vendor specifications. If not specified otherwise, 72 inches (183cm) should be sufficient for most applications. Place marker tapes the required distance apart from each other on the section of cable to be accessed.
Using the sheath knife, “ring” the circumference of the outer jacket of the cable at each mark.
Next make two ring cuts approximately 5” inches (13 cm) apart at the mid-point of the section being removed.
Using a hot air gun heat the 5” section of jacket between the two ring cuts. Once the jacket has softened use a sheath knife to easily remove the jacket material down to the armor.
Now use the sheath knife to gently pry up the armor along its overlap seam. Nick the armor at each end of the 5” section and peel it back, removing and discarding.
The cable’s inner elements including ripcords are now exposed.
Cut the ripcords at the center of theexposed 5” section.
Before pulling the ripcords, nick the armor with side cutters at the points where the ripcords disappear under the sheath. This gives a starting point for the ripcords to slit the armor
Grasp and wrap one of the ripcords around the needle-nose pliers and pull the ripcord about 1.5” into the sheath. Repeat with the remaining three ripcords. Now pull all four ripcords in turn back to the predetermined ring cuts.
Remove the two sections of split sheath from the cable and discard them.
:: CABLE CORE AND CENTRAL TUBE MID-SPAN PREPARATION
Once the outer jacket has been removed, the cable core is exposed. The core consists of outer the outer fiber glass strength members and the central tube which contains the fibers.
Unwrap the fiber glass strength members. Cut them to a length as prescribed by local practices or closure manufacturer’s instructions.
Before attempting to access the fibers, check the blade settings on the tool to be used by testing it on a section of scrap cable. Core tube slitters have been used successfully on central core tube configured optical fiber cable. A proper depth setting for slitting will cut two small grooves in the wall of the tube without touching the underlying fibers.
Measure the length of tube to be removed. Refer to the requirements of the protective closure being used. Mark the tube at the required distance from the cable sheath butt at the ends of the exposed core.
After checking the blade depth, use the core slitter carefully to slit the central loose tube in between the two marks.
With the central loose tube now slit, but still intact, final removal can take place.
Peel the small slit section of the tube away and cut at both ends. Remove the fibers from the remaining split section of the tube.
Cut the vacated section of central tube at both ends and discard.
The optical fibers are now exposed and accessible for termination. Extreme care must be taken to avoid damaging the fibers while handling the cable.
Gently wipe the excess thixotropic gel from the exposed fibers with an appropriate wipe.
:: FIBER PREPARATION PRIOR TO TERMINATION
Using an approved primary coating stripping tool, remove the 250 μm diameter coating from the fiber.
Note: Blades should close to a diameter that is between 150 and 175 μm. The fibers are now exposed and accessible for termination.