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OPLIN 4Cast #225: How to bury a cable

Posted in 4cast

This week’s 4cast diverges from our usual offerings, in that it does not concern any hot new tech news we’ve gathered from the media. Fiber optic Internet connections have been on our mind lately, as we prepare to install fiber this summer to 146 Ohio public libraries that are currently connected to OPLIN with copper T1 circuits. This will be the biggest change to the OPLIN network since it was first installed in 1995-96. Then we saw the story about the old woman who cut off the Internet to Armenia when she mistakenly dug up a fiber optic trunk line while trying to steal copper cable. We had to wonder if that trunk line was correctly installed, which eventually brought us to the Fiber Optic Association’s “Reference Guide To Fiber Optics: Outside Plant Fiber Optic Network Installation .” If you’re as curious as we were about fiber optic installation procedures, you might find these quotes from that Reference Guide interesting.

  • “Outside plant (OSP) installations of fiber optic cables can be much more diverse than premises installations. OSP installs may include installing aerial cable, direct-buried cable, underground cable in conduit or installing conduit or innerduct and then pulling cable, or placing cable underwater. A single link may include several types of installation, for example aerial in one section, pulling in conduit on a bridge crossing and burying the rest of the cable.”
  • “Heavy-duty cables can be buried directly or cables in ducts for extra protection can be installed using direct burial techniques. Cables can be supplied already in ducts for burial. […] Typically trunk cables in most areas are installed 3-4 feet deep (1-1.2 m), but in residential or urban areas, cables may be buried only 2 feet (0.6 m) deep. Some cables can be directly installed in sawn grooves in roads, but these are only buried a few inches deep, still within the roadway material and are filled with sealer.”
  • “Cables can sometimes be installed by blowing special cable types into ducts called duct lines, micro-ducts or sub-ducts which have been installed in larger conduit or even pipes for carrying water, sewage or gas. High pressure compressed air provides an aerodynamic effect, floating the cable on the air stream and carrying it down the duct, allowing installation lengths as long as 2 km (6,500 feet.)”
  • “OSP cables generally do not meet NEC flammability requirements, so the cable entering a building must be terminated or spliced to indoor cables soon after entry, generally within 50 feet (16 meters) to meet fire codes. Some OSP cables have double jackets, an outer one for outdoors and an inner one rated for indoor use, so the outer jacket can be stripped off inside the building and the cable run to the equipment room.”

Price fact:
While the cost of building fiber-optic networks has historically been high when compared to copper networks, copper metal pricing is expected to hit $11,000 per metric ton sometime this year, leading to both higher purchase costs and increased theft of copper cable.