In this artical, we will introduce general information for the installation of aerial fiber optic cables.
There are two methods of lashing fiber optic cable
1. The moving reel method of cable placement
When reel-carrying vehicles can drive the majority of the cable route, you should use the moving reel method. Using this method, the fiber optic cable is raised and lashed to the strand in one operation.
2. The stationary reel method of cable placement
The stationary method is used when reel-carrying vehicles cannot drive the majority of the cable route. Using this method, the fiber optic cable is pulled into place beneath the strand using cable blocks. Lashing the cable to the strand then begins at the far end of the cable route with the lasher being pulled toward the stationary reel location at the near end.
A pre-survey of the fiber cable route is very important in planning for an aerial optical fiber cable project. Each section of the route must be properly prepared before cable installation begins.
Some objectives should to pre-survey:
1. Determine where each reel of fiber optic cable is to be placed. Slack locations and cable storage requirements must also be considered along with splice locations. The pre-survey will verify construction methods, special tools required, or possibly require a revision of preliminary splice locations.
2. The characteristics of the ground along the route. Clearance issues over roadways, driveways, etc.
3. The method of cable placement and the tools necessary for placement are dependent upon vehicle accessibility to the cable route.
Placing cable using the moving reel method procedure
1. The moving reel method is used in locations where a cable reel trailer or aerial lift truck can be moved along the pole line and there are no obstructions between the reel and the suspension strand.
2. The moving reel method of cable placement has an advantage over the stationary reel method in that temporary cable blocks and pull-in lines are not necessary. Whenever possible, the moving reel method should be used.
3. When it is practical, the movement of the reel should be in the same direction as any nearby traffic.
4. Cable suspension clamps are to be tightened at least one span ahead of the cable lashing operation to prevent tension build-up in the strand as lashing progresses.
5. Start the cable lashing operation by removing enough cable from the reel to reach from strand level to a splicing vehicle below plus 16 feet or so of extra slack.
6. Lift the cable guide and lasher to the strand. Using a lift or a hand line, raise the cable up to the strand and pass it through the cable guide, positioning the cable in the lasher. The lashing wire should be placed around the tension rollers and then terminated in the lashing wire clamp.
Lashing wire clamp
7. Attach separate pulling lines from the vehicle to the lasher and the cable guide
8. As the reel movement begins, secure the cable at the pole to prevent any movement along the strand until the lasher has moved 50 feet down the strand.
9. The cable reel must allow smooth cable pay-out to allow the cable to smoothly enter the cable guide at stand level. Hand pull cable from the reel to ensure a tension-free feed into the cable guide preceding the lasher
10. The reel-carrying vehicle should maintain an approximate 50-foot lead distance ahead of the lasher, and drive as close to the pole line as possible.
11. If it becomes necessary to stop the lasher mid-span, aproper tension and bend radius of the cable must be maintained at the lasher.
12. Upon reaching a pole:
13. Continue the cable installation, span-by-span from the starting point towards the end of the cable until the entire cable run is completely lashed and properly sagged.
Placing cable using the stationary reel method procedure
1. Unlike the moving reel method in which the cable placement and lashing operations take place at the same time, the stationary reel method requires two separate operations.
2. Cable reel trailers should be disconnected from their towing vehicles. The reel should be leveled and the trailer wheel securely chocked.
3. A cable guide should be installed to guide the cable from the reel to its position beneath the strand.
4. If it has not been installed by the factory, attach a pulling eye or pulling grip to the cable. This in turn must be attached to a pulling swivel and the pulling swivel attached to a pulling rope.
5. Able blocks are suspended beneath the strand to receive the pulling rope
6. All cable blocks are to be placed on the strand facing the same direction with their locking levers (if present) set to release as the lasher strikes them.
7. Cable blocks are to be set at a maximum distance of 50 feet apart on the strand. When local company’spractices call for closer intervals follow that practice. Make sure a sufficient number of blocks are available before installation begins.
8. Attach the pulling rope to the pulling swivel that has been connected to the pulling eye or pulling grip on the cable.
9. Begin unrolling the cable, lifting it up to strand level and through the cable guide as tension is applied to the pulling rope. Control the rotation of the reel to prevent free running of the cable.
10. The pull begins with the rope running through the cable guide and over the first cable block. As the cable pays out, the rope is then lifted and placed into the second cable block and the pull continues.
11. For winch-assisted pulls, the pulling rope is first placed in position through all the cable blocks from the stationary reel’s location to the winch’s location. The entire length of cable is then pulled in using the winch’s pulling force.
12. Where the cable route changes direction snatch blocks must be used to make each corner.
13. With the cable pulled into place beneath the strandand supported by cable blocks, the next step in the procedure is to lash the cable to the strand.
14. First, install the necessary spacers and straps at the pole farthest from the reel end. Then place the lasher on the strand and prepare it for lashing as per the instructions for the type of lasher being used. Stranding must begin at the far end and proceed to wards the reel end with any cable slack being worked back towards the reel.
15. The lashing operation is begun by the lasher being pulled by rope along the path of the strand. The lasher must be pulled with a downward pressure to keep the lasher mechanism spinning. Always maintain tension on the lasher to keep the lashing wire from wrapping the fiber optic cable around the strand.
16. The lasher is pulled the length of the span to the next pole. The cable blocks are pushed ahead of the lasher as it progresses down the cable route. Upon reaching the next pole, the cable blocks are removed from the strand.
17. Before releasing the lasher brake, the lashing wire must be temporarily clamped to the stand with a clamp. After the wire is secured, enough wire must be pulled out of the lasher for termination before cutting.
18. Transfer the lashing equipment to the other side of the pole and continue the lashing operations. Be sure to check all work at each pole before continuing on to lashing the next span.
19. Each span must be securely lashed into place starting at the pull end and proceeding back to the reel’s location. Cable slack must be carefully worked ahead of the lasher, span-by-span, back to the cable reel. Each span’s lashing wire must be secured to a lashing wire clamp before moving the lasher to the next span. This process continues until the entire cable run is lashed and properly sagged.