Published In December 2000
In the telephone business, the guys who terminate fiber optics are called splicers. They follow the cable pullers who install those gigantic spools of fiber. Some cable pullers have plows that dig trenches to bury the fiber optic cable. Some have pulling machines that pull cable through conduit. Some are specialists who know how to install aerial or underwater cables. The splicers usually have a nice, clean truck in which to work. The fusion splicer is a fairly delicate, $20,000 to $40,000 machine. Fiber needs to be spliced in a temperate, clean room, so their trucks have AC, clean plastic work surfaces, and plenty of room to work with large cables. They have little doors through which the cables are taken into the truck and spliced. Some of the cables they splice are big, too: there are as many as 864 fibers in a popular cable style used today. Since the fiber optic cable has to be brought to the work site on reasonably sized spools, the cable is limited to about 4 km (21/2 miles) so the spools don’t get too large. Even with the best lubricants, cables cannot be pulled even that far. They may have to pull half the cable one way, unspool and “figure eight” the rest, then pull it in the opposite direction. Therefore, the splicers must perform their specialty every 4 km or so, splicing every fiber in that cable, testing it, and stowing it in a water-tight housing. At the ends, they splice on pigtails with connectors. After splicing, each fiber will be tested for loss with an optical loss test set and inspected with an optical time domain reflectometer (OTDR) to verify each splice. Do the math. If we are talking about 864 fiber cables going hundreds of miles, these guys will be busy! Does that sound like the fiber optics work the typical electrical contractor does? Hardly! Most electrical contractors are involved in premises cabling, installing fiber optics inside buildings or between buildings on a campus. They pull cable short distances in or between buildings through conduit or innerduct, but most fiber is installed inside one building in cable trays or innerduct. Pulling is done by hand, not by machine, and lubrication is rarely needed for these short pulls. Terminations are very different in premises cabling. Cables are rarely spliced. Lengths of cable, even in campus backbones, are relatively short, only a few hundred meters. Instead, large fiber-count backbone cables are pulled between locations inside a building, where they are terminated with connectors in patch panels to allow the moves, adds, and changes (MACs) common to a premises network. Connectors are directly attached to the fibers using adhesive/polish or quick termination techniques. Since most premises fibers are multi-mode, terminations are not as critical as outside plant singlemode fibers require. The singlemode fibers used in backbones can even be directly terminated, since the performance requirements are much lower. These differences in outside plant (OSP) telco or CATV and premises cabling installation are important for the electrical contractor to understand. If most of the jobs electrical contractors do will be premises cabling, this affects how their personnel need to be trained, what equipment they need to buy, and who they market their services to. The OSP contractor will invest heavily in equipment for his installation crews. By the time you add up the splicing truck or bucket truck for aerial installations, a fusion splicer, OTDR, loss test sets, and tools, the investment will approach $250,000 per crew. Every installer will need several weeks of training at a cost of $5,000 or more each. You can see that a serious OSP installer has millions of dollars invested in capital equipment. Premises cabling installers, meanwhile, get by with a substantially lower investment. A good set of tools and test equipment costs $1,500. Simpler installation techniques can be taught in an inexpensive two-day course, if crew members already have the extensive background of a journeyman electrician in cable installation and code compliance. The contractor who is getting into fiber optics must know which fiber optics he’s going to pursue, in order to make the most of his investment. The thing he has to remember first is that most fiber optic technicians are not “splicers.” HAYES is president of Fotec/Fiber U, Medford, Mass. He can be reached at email@example.com.