Damage Prevention Requires Looking Overhead as well as Underground

THERE IS AN OLD TERM I HAVE USED FOR YEARS in lecturing about fiber optics that most cable damage is called “backhoe fade.” At one seminar, a person from Bonneville Power responded that with his aerial cable plant in the western ranges, it was called “target practice.” Besides improving my lectures using his comment, it opened my eyes to aerial installation practices.

What I’ve seen isn’t pretty. Workmanship in aerial cable installations is sometimes very “neat and workmanlike,” a term I picked up from writing standards, but more often, it is terrible. It is so bad that the Fiber Optic Association (FOA) has gotten calls from upset government officials asking if there are standards for aerial construction, to which I answer, “Only if you write them.”

Fiber optic industry standards generally cover components and testing, not installation. Requirements for cable installation – underground or aerial – are mostly covered in a project SOW (Scope of Work) or other contract documents. Since every project is unique, the installation requirements are mainly in the project documentation.

Without standards for workmanship, you can imagine what happens. Underground cables are mostly abused while being pulled into conduit, overstressed by high pulling tension or exceeding cable bending limits. Aerial cable abuse is much more creative.

We see aerial cable held up with cable ties instead of proper lashing. We see drooping cables not fully lashed, cables bent much too tightly and large coils of cable left hanging on poles. We see bundles of maybe a dozen cables lashed together, probably exceeding the weight limit of the messenger wire.

The worst instance I’ve seen is a “figure-8” coil of about 300m (1000 feet) hung on a pole near a transit line in Los Angeles. When I first spotted it, I assumed it was left as temporary storage and the crew would be back quickly to finish the job. That coil was there for more than six months. Can the messenger handle hundreds of pounds of cable left hanging there? Bare loops of cable hanging off the messenger is an invitation to get damaged.

And that is what this is all about – damaging aerial cable. Obviously, large heavy loops of stored cable create stress on the messenger and cables attached to it, amplified by stress caused by wind, rain and especially snow and ice in winter.

The problem with aerial cable is the same as the problem with underground cable – careless contractors. Consider the potential damage these contractors can do to cables already in place when they do their work. If the workmanship we see is bad, what are they doing to other cables during their installations?

The situation has been made even worse in the U.S. by new FCC guidelines called “One Touch Make Ready” or OMTR. OMTR allows a contractor to not only install cables but to move other cables to make room for their installation. They can also “overlash” their cables to current cables without installing their own messenger.

Owners of aerial cable plants need to be aware of the potential damage to aerial as well as underground cables, and organizations focused on damage to underground cables might well look overhead also. Perhaps we need a One Call to remind owners of aerial cable that someone is working around their cables.

Jim Hayes is a VDV writer and trainer, and the president of The Fiber Optic Association. You can reach him at jim@thefoa.org.

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