Fiber Optic Cable tests - long haul - 1.25 miles
Fiber Optic Cable tests - long haul - 1.25 miles
(OP)
I have been tasked with developing a fiber optic spec to supply and install some single mode fiber over a mile through existing conduit (nearly empty) with no splices. My fiber experience is next to done but I have narrowed the tests I should require down to two:
Optical Loss test or OTDR.
Seems the OTDR might be over kill since we are requiring no splices and the cable run is fairly small. If I do require an OTDR test, how to quantify a pass or fail with that test? The Optical Loss is straight forward in establishing a pass/fail criteria.
Would you just require the Optical Loss test here or if you would recommend and OTDR, how do I establish a pass/fail level in the spec.
Thanks.
Optical Loss test or OTDR.
Seems the OTDR might be over kill since we are requiring no splices and the cable run is fairly small. If I do require an OTDR test, how to quantify a pass or fail with that test? The Optical Loss is straight forward in establishing a pass/fail criteria.
Would you just require the Optical Loss test here or if you would recommend and OTDR, how do I establish a pass/fail level in the spec.
Thanks.





RE: Fiber Optic Cable tests - long haul - 1.25 miles
Next, review the cable spec and figure out what should be achievable assuming it's installed perfectly.
Then you can split the difference. Maybe split it one-third / two-thirds in your favour since you're writing the spec. Don't be too hard on your installer as being overly tough can lead to contractual failure.
TDR testing is simply a question if you can afford to rent or buy the test set. Useful for locating faults.
Does the permanent equipment provide any feedback about signal quality? Perhaps you could use a short jumper to calibrate the permanent equipment, and then compare it when using the full cable.
Disclaimer: My experience is with RF cables. Not so much optical. We have the exact same questions about setting limits.
Ultimately it's a judgment call and depends on external factors too. Once in service, you'll tolerate more loss as long as the system works. Monitoring can track condition over time.
RE: Fiber Optic Cable tests - long haul - 1.25 miles
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RE: Fiber Optic Cable tests - long haul - 1.25 miles
Thanks for the feedback.
RE: Fiber Optic Cable tests - long haul - 1.25 miles
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RE: Fiber Optic Cable tests - long haul - 1.25 miles
If there were any damage tot eh cable during installation (over bending, stretching, etc), and OTDR could indicate a location that could cause issues later on.
I would also have them shoot the cable on the spool upon delivery to make sure the cable is good prior to acceptance.
RE: Fiber Optic Cable tests - long haul - 1.25 miles
My concern with the OTDR is the cost increase this could have with the contract. I suppose making this a requirement may eliminate some of the less professional cable installers from getting it.
RE: Fiber Optic Cable tests - long haul - 1.25 miles
Applies to you too.
RE: Fiber Optic Cable tests - long haul - 1.25 miles
This is OSP install of a little over a mile (48 fiber, loose tube, single mode)
Thank you
RE: Fiber Optic Cable tests - long haul - 1.25 miles
RE: Fiber Optic Cable tests - long haul - 1.25 miles
The spliced connector pigtails may be a little cheaper on install.
Any reason you are using SC or ST connectors? They take up a lot of room. We’ve go to LC connectors and can get a lot more connections into a smaller space. You can get jumpers that have the right ends to connect equipment.
Of course, this is all my humble opinion.
RE: Fiber Optic Cable tests - long haul - 1.25 miles
I would be interested to here more about splicing pigtails vs. field terminating connectors (ST SC or LC). Perhaps, this should be left up to the contractor if I require both a loss and OTDR.
I think understanding the stress points, etc in the cable after the pull and before would probably be a good idea so I will reconsider the OTDR test. I just didn't want to request something that was unnecessary but I can see where this test would have some real value at least in approving the install and identifying potential future trouble spots, even though it is a relatively short run in terms of OSP installations.
RE: Fiber Optic Cable tests - long haul - 1.25 miles
If you are providing the fiber, and just contracting the installation and termination, I highly recommend having the contractor verify the fiber integrity before it comes off the delivery truck. They can use low cost mechanical splices with test pigtails and an OTDR to accomplish this. It is worth the added expense, because once it is installed, it is hard to argue who is at fault if there is a broken strand halfway down the cable. I unfortunately know this from experience.
If the contractor is buying the cable, they will likely do it anyway. If they install the cable they provide and there is a broken strand, they have to replace the cable.
RE: Fiber Optic Cable tests - long haul - 1.25 miles
I think I will give them the option of using pigtails and splicing or terminating the ends in the field. Although it means more writing for me, we can all agree a well written contract is good for everyone. Unfortunately, I have had only a week to put this together so I appreciate all the suggestions and recommendations.
RE: Fiber Optic Cable tests - long haul - 1.25 miles
Best 'o luck to ya.
RE: Fiber Optic Cable tests - long haul - 1.25 miles
On a side note, Corning cable has a program where if an approved installer installs and tests Corning cable and connectors, Corning (not the installer) will warrant the material for 25 years.
RE: Fiber Optic Cable tests - long haul - 1.25 miles
RE: Fiber Optic Cable tests - long haul - 1.25 miles
Thanks again.