No lazy shortcuts, keep fiber ends clean!

I was working on a major network upgrade project this week with a vendor from a fortune 500 company, most of you would recognize the name of this company if I told you who it was.  The field engineer I was working with was one of their more experienced and highly regarded network engineers.  For the most part he really is pretty sharp, however, at the beginning of the project he started pulling out fiber right and left and tossing it onto the floor with the ends uncovered.  I asked him not to do that and his response was “OK, if you want to be Mr. Clean”.  I explained that we needed to keep the ends of the fiber clean, his response was “don’t worry about it, this stuff is tough”.  What does tough fiber jackets and cladding have to do with understanding that dirty fiber ends can obstruct light and result in optical power loss?  Besides, how long does it really take to cap fiber ends after carefully removing the connectors from patch panels and SFP’s?  It pays to do the job right, no lazy shortcuts allowed!

Facility cabling & fiber installation – What you don’t know can eat you alive

This article is a sequel to the Improperly Polished Fiber Terminations post.

The two cores need to mesh up together flat.

When inserting a patch cord the plastic connector needs to snap into place, if the two ends don’t mesh up flat excessive pressure is required to get the connectors to latch together, this places unusually high strain on the adhesive holding the cladding to the jacket.  If this adhesive cracks or breaks loose then the light’s path is adversely affected and data loss occurs.  When the ends are not completely polished the core also becomes susceptible to cracking & chipping as the  connectors are pushed into the patch panel.

The scary part is that improperly polished ends frequently still pass power-loss & OTDR testing 

Unless the ends are visually inspected with a magnifier no one may even know there is a problem with the fiber terminations until years down the road when the adhesive cracks.   The worst part of all is that the link may not fail completely, it may just become intermittent and/or degrade in overall throughput.

Tips on selecting a data installation vendor

1. Unless you have absolute confidence in a vendor separate out the bids for data installation and data testing.  Have the testing done by a different company than the one that installs the data.
2. Directly contract with the data install vendor, avoid subcontracting in this part of the project.  It is much easier to address data installation issues directly than through multiple levels of contacts and administration.  Position data cabling, data installation and data testing in the construction project in such a way that the I.T. department has control over it.  Do not leave this area solely to the discretion and oversight of a general contractor and/or construction project manager.
3. If you have never used a data vendor before check references from projects of a similar or larger size.

Requirements documents & specifications:  State the obvious

Review the data installation test requirements and never assume - Educate yourself on how to interpret the results of any tests, and understand what constitutes proper, professional installation, otherwise how will you know if the job is done right?

1.  Don’t assume that whoever wrote the test specifications for data installation knows what they are doing.  Educate yourself.
2. Specify the types of certifications you require for the installers and testers.  Ask to see their certifications.
3. Check the calibration sticker dates on test equipment used.  Ask the installers to show you what ranges/settings they are using and record them.  If you aren’t sure of the correct settings, educate yourself.
4. It is a lot easier to challenge poor workmanship if you explicitly list the obvious in the specifications, even if it is an industry standard or in the manufacturer’s installation and/or usage manual.  Provide the installer & tester with a checklist of items you want to see performed or validated.
5. Require testing in both directions, and know how to interpret and validate the test results, particularly if you are dealing with long fiber runs that require OTDR testing.

Improperly Polished Fiber Terminations

Do you implicitly trust your fiber installation vendor?  In partnership with my prefered fiber installation & testing vendor we discovered these unpolished terminations.  These ends passed both the two-way power-loss tests and OTDR tests, but I’ll demonstrate the hidden dangers of having unpolished fiber ends in a future post . 

Cracked Faces on Poorly Installed Fiber Terminations

What you can’t see can’t hurt you, right?  Think again.  Unless you’re willing to put  your career in the hands of fiber installation vendors, either use a separate vendor for testing or inspect and test the terminations yourself.  See the pictures below, the two (2) on the right show problems that were found after the vendor installed and claimed to have tested the ends: